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Biochemistry, Genetics and Molecular Biology â€ș Cell Biology

Muscle metabolism and nutrition

Works Count: 70769

Description

This cluster of papers focuses on the metabolism of protein, amino acids, and creatine in the context of exercise, nutrition, and aging. It explores the effects of different protein sources, timing of protein intake, and resistance training on muscle protein synthesis and anabolic signaling pathways.

Keywords

Protein; Metabolism; Exercise; Nutrition; Amino Acids; Muscle Protein Synthesis; Resistance Training; Leucine; Whey Protein; Aging

Nutrition and Athletic Performance

2009-02-18
Nancy R. Rodriguez , Nancy M Di Marco , Susie Langley
It is the position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine that physical activity, athletic performance, and recovery from exercise are enhanced 
 It is the position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine that physical activity, athletic performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of foods and fluids, timing of intake, and supplement choices for optimal health and exercise performance. This updated position paper couples a rigorous, systematic, evidence-based analysis of nutrition and performance-specific literature with current scientific data related to energy needs, assessment of body composition, strategies for weight change, nutrient and fluid needs, special nutrient needs during training and competition, the use of supplements and ergogenic aids, nutrition recommendations for vegetarian athletes, and the roles and responsibilities of the sports dietitian. Energy and macronutrient needs, especially carbohydrate and protein, must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue. Fat intake should be sufficient to provide the essential fatty acids and fat-soluble vitamins and to contribute energy for weight maintenance. Although exercise performance can be affected by body weight and composition, these physical measures should not be a criterion for sports performance and daily weigh-ins are discouraged. Adequate food and fluid should be consumed before, during, and after exercise to help maintain blood glucose concentration during exercise, maximize exercise performance, and improve recovery time. Athletes should be well hydrated before exercise and drink enough fluid during and after exercise to balance fluid losses. Sports beverages containing carbohydrates and electrolytes may be consumed before, during, and after exercise to help maintain blood glucose concentration, provide fuel for muscles, and decrease risk of dehydration and hyponatremia. Vitamin and mineral supplements are not needed if adequate energy to maintain body weight is consumed from a variety of foods. However, athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume unbalanced diets with low micronutrient density may require supplements. Because regulations specific to nutritional ergogenic aids are poorly enforced, they should be used with caution and only after careful product evaluation for safety, efficacy, potency, and legality. A qualified sports dietitian and, in particular, the Board Certified Specialist in Sports Dietetics in the United States, should provide individualized nutrition direction and advice after a comprehensive nutrition assessment.

Effects of insulin, glucose, and amino acids on protein turnover in rat diaphragm.

1975-01-01
Richard M. Fulks , J B Li , Alfred L. Goldberg
A simple method is described for measuring rates of protein synthesis and degradation in isolated rat diaphragm. Muscles incubated in Krebs-Ringer bicarbonate buffer showed a linear rate of synthesis for 
 A simple method is described for measuring rates of protein synthesis and degradation in isolated rat diaphragm. Muscles incubated in Krebs-Ringer bicarbonate buffer showed a linear rate of synthesis for 3 hours. At the same time, the muscle released tyrosine and ninhydrin-positive material, primarily amino acids, at a linear rate. This release was not a nonspecific leakage of material from the intracellular pools, but reflected net protein degradation. Tyrosine was chosen for studies of protein turnover, since it rapidly equilibrates between intracellular pools and the medium, it can be measured fluorometrically, and it is neither synthesized nor degraded by this tissue. To follow protein degradation independently of synthesis, muscles were incubated in the presence of cycloheximide. Under these conditions, the amount of tyrosine in the intracellular pools was constant, while the muscle released tyrosine at a linear rate. This tyrosine release was used as a measure of degradation. This preparation was used to study the influence of various factors known to be important for muscle growth on protein synthesis and degradation. Similar effects were obtained with diaphragms of normal and fasted rats although the latter showed decreased synthesis and increased protein degradation. Insulin by itself not only stimulated synthesis but also inhibited protein degradation (even in the presence of cycloheximide). These two effects served to reduce the net release of tyrosine from muscle protein to comparable extents. Effects of insulin on synthesis and degradation were greater when glucose was also present in the medium. Glucose by itself inhibited protein degradation but in the absence of insulin glucose had no significant effect on synthesis. Nevertheless, glucose stimulated incorporation of radioactivive tyrosine into protein, but this effect was due to an increased intracellular specific activity. Unlike glucose neither beta-hydroxybutyrate or octanoic acid had any demonstrable effects on protein degradion. The addition of amino acids at plasma concentrations both promoted protein synthesis and inhibited degradation in the diaphragm. Five times normal plasma concentrations of the amino acids had larger effects. The three branched chain amino acids together stimulated synthesis and reduced degradation, while the remaining plasma amino acids did not affect either process significantly. Thus leucine, isoleucine, and valine appear responsible for the effects of plasma amino or isoleucine and valine together, also were able to inhibit protein degradation and promote synthesis.

Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation

1992-09-01
Roger C. Harris , Karin Söderlund , E. Hultman
1. The present study was undertaken to test whether creatine given as a supplement to normal subjects was absorbed, and if continued resulted in an increase in the total creatine 
 1. The present study was undertaken to test whether creatine given as a supplement to normal subjects was absorbed, and if continued resulted in an increase in the total creatine pool in muscle. An additional effect of exercise upon uptake into muscle was also investigated. 2. Low doses (1 g of creatine monohydrate or less in water) produced only a modest rise in the plasma creatine concentration, whereas 5 g resulted in a mean peak after 1 h of 795 (sd 104) ÎŒmol/l in three subjects weighing 76–87 kg. Repeated dosing with 5 g every 2 h sustained the plasma concentration at around 1000 ÎŒmol/l. A single 5 g dose corresponds to the creatine content of 1.1 kg of fresh, uncooked steak. 3. Supplementation with 5 g of creatine monohydrate, four or six times a day for 2 or more days resulted in a significant increase in the total creatine content of the quadriceps femoris muscle measured in 17 subjects. This was greatest in subjects with a low initial total creatine content and the effect was to raise the content in these subjects closer to the upper limit of the normal range. In some the increase was as much as 50%. 4. Uptake into muscle was greatest during the first 2 days of supplementation accounting for 32% of the dose administered in three subjects receiving 6 × 5 g of creatine monohydrate/day. In these subjects renal excretion was 40, 61 and 68% of the creatine dose over the first 3 days. Approximately 20% or more of the creatine taken up was measured as phosphocreatine. No changes were apparent in the muscle ATP content. 5. No side effects of creatine supplementation were noted. 6. One hour of hard exercise per day using one leg augmented the increase in the total creatine content of the exercised leg, but had no effect in the collateral. In these subjects the mean total creatine content increased from 118.1 (sd 3.0) mmol/kg dry muscle before supplementation to 148.5 (sd 5.2) in the control leg, and to 162.2 (sd 12.5) in the exercised leg. Supplementation and exercise resulted in a total creatine content in one subject of 182.8 mmol/kg dry muscle, of which 112.0 mmol/kg dry muscle was in the form of phosphocreatine.

An improved procedure for serum creatine phosphokinase determination.

1967-04-01
Rosalki Sb

Biochemical Adaptations in Muscle

1967-05-01
John O. Holloszy
The capacity of the mitochondrial fraction from gastrocnemius muscle to oxidize pyruvate doubled in rats subjected to a strenuous program of treadmill running.Succinate dehydrogenase, reduced diphosphopyridine nucleotide dehydrogenase, DPNH cytochrome 
 The capacity of the mitochondrial fraction from gastrocnemius muscle to oxidize pyruvate doubled in rats subjected to a strenuous program of treadmill running.Succinate dehydrogenase, reduced diphosphopyridine nucleotide dehydrogenase, DPNH cytochrome c reductase, succinate oxidase, and cytochrome oxidase activities, expressed per g of muscle, increased approximately Z-fold in hind limb muscles in response to the training.The concentration of cytochrome c was also increased 2-fold, suggesting that the rise in respiratory enzyme activity was due to an increase in enzyme protein.The total protein content of the mitochondrial fraction increased approximately 60%.These changes in the concentration of cytochrome c and total mitochondrial protein are of special interest because they suggest that exercise could serve as a useful tool for studying the biosynthesis of mitochondrial proteins.Mild exercise, such as that used in previous studies, was found to have no effect on the level of succinate dehydrogenase in muscle, suggesting that the failure of earlier studies to show an increase in respiratory enzyme activity resulted from the use of an insufficient exercise stimulus.Mitochondria from muscles of the exercised animals exhibited a high level of respiratory control and tightly coupled oxidative phosphorylation.Thus, the increase in electron transport capacity was associated with a concomitant rise in the capacity to produce adenosine triphosphate.This adaptation may partially account for the increase in aerobic work capacity that occurs with regularly performed, prolonged exercise.Comparative studies have shown that a good correlation exists between the ability of a muscle to perform prolonged exercise and its content of respiratory enzymes (1, 2).Paul and Sperling (1) found the breast muscle of the nonflying chicken to have low

Skeletal Muscle Adaptability: Significance for Metabolism and Performance

1983-12-01
Bengt Saltin , P. D. Gollnick
Abstract The sections in this article are: Motor Unit Fibers per Motor Unit Contractile Properties Biochemical Basis for Differences in Twitch Properties Histochemical Differentiation of Muscle Fibers Ultrastructural Basis for 
 Abstract The sections in this article are: Motor Unit Fibers per Motor Unit Contractile Properties Biochemical Basis for Differences in Twitch Properties Histochemical Differentiation of Muscle Fibers Ultrastructural Basis for Skeletal Muscle Fiber Typing Maximal Contractile Force Speed of Contraction Fatigue Characteristics Metabolic Characteristics Ionic Composition of Skeletal Muscle Summary Muscle Fiber Composition in Human Skeletal Muscle Motor‐Unit Recruitment Adaptive Response in Skeletal Muscle Muscle Size Metabolic Capacity Connective Tissue Capillaries Methodology Anatomy Capillary Density Capillary Length and Diameter Use and Disuse Regulation Significance of Adaptation Muscular Size Substrate Stores Enzyme Activities Summary

A rapid and convenient technique for measuring the rate of protein synthesis in tissues by injection of [3H]phenylalanine

1980-11-15
P.J. Garlick , M.A. McNurlan , Victor R. Preedy
A rapid procedure for measuring the specific radioactivity of phenylalanine in tissues was developed. This facilitates the accurate determination of rates of protein synthesis in a wide range of tissues 
 A rapid procedure for measuring the specific radioactivity of phenylalanine in tissues was developed. This facilitates the accurate determination of rates of protein synthesis in a wide range of tissues by injection of 150 mumol of L-[4-(3)H]phenylalanine/100 g body wt. The large dose of amino acid results in a rapid rise in specific radioactivity of free phenylalanine in tissues to values close to that in plasma, followed by a slow but linear fall. This enables the rate of protein synthesis to be calculated from measurements of the specific radioactivity of free and protein-bound phenylalanine in tissues during a 10 min period after injection of radioisotope.
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Mixed muscle protein synthesis and breakdown after resistance exercise in humans

1997-07-01
Stuart M. Phillips , Kevin D. Tipton , Asle Aarsland +2 more
Mixed muscle protein fractional synthesis rate (FSR) and fractional breakdown rate (FBR) were examined after an isolated bout of either concentric or eccentric resistance exercise. Subjects were eight untrained volunteers 
 Mixed muscle protein fractional synthesis rate (FSR) and fractional breakdown rate (FBR) were examined after an isolated bout of either concentric or eccentric resistance exercise. Subjects were eight untrained volunteers (4 males, 4 females). Mixed muscle protein FSR and FBR were determined using primed constant infusions of [2H5]phenylalanine and 15N-phenylalanine, respectively. Subjects were studied in the fasted state on four occasions: at rest and 3, 24, and 48 h after a resistance exercise bout. Exercise was eight sets of eight concentric or eccentric repetitions at 80% of each subject's concentric 1 repetition maximum. There was no significant difference between contraction types for either FSR, FBR, or net balance (FSR minus FBR). Exercise resulted in significant increases above rest in muscle FSR at all times: 3 h = 112%, 24 h = 65%, 48 h = 34% (P < 0.01). Muscle FBR was also increased by exercise at 3 h (31%; P < 0.05) and 24 h (18%; P < 0.05) postexercise but returned to resting levels by 48 h. Muscle net balance was significantly increased after exercise at all time points [(in %/h) rest = -0.0573 +/- 0.003 (SE), 3 h = -0.0298 +/- 0.003, 24 h = -0.0413 +/- 0.004, and 48 h = -0.0440 +/- 0.005], and was significantly different from zero at all time points (P < 0.05). There was also a significant correlation between FSR and FBR (r = 0.88, P < 0.001). We conclude that exercise resulted in an increase in muscle net protein balance that persisted for up to 48 h after the exercise bout and was unrelated to the type of muscle contraction performed.

Biochemical Adaptations to Endurance Exercise in Muscle

1976-03-01
John O. Holloszy , Frank W. Booth
Two quite distinct adaptive responses can be induced in skeletal muscle by regularly performed, strenuous exercise. The nature of the exercise stimulus determines the type of adaptation. One type of 
 Two quite distinct adaptive responses can be induced in skeletal muscle by regularly performed, strenuous exercise. The nature of the exercise stimulus determines the type of adaptation. One type of adaptation involves hypertrophy of the muscle cells with an increase in strength; it is exemplified in its most extreme form by the muscles of weight lifters and body builders. The second type of adaptation involves an increase in the capacity of muscle for aerobic metabolism with an increase in endurance and is found in its most highly developed form in the muscles of competi­ tive middleand long-distance runners, long-distance cross-country skiers, bicy­ clists, and swimmers. Although many types of physical activity can bring about varying degrees of both types of adaptation in the same muscle, it does appear that these adaptations can occur quite independently of each other in their most extreme forms. For example, the hypertrophied muscles of weight lifters do not appear to have an increased respiratory capacity (45), whereas the muscles of rodents trained by prolonged daily running, which have a large increase in respiratory capacity, are not hypertrophied (56, 92) and show no increase in strength (12). This review deals with the biochemical adaptations induced in skeletal muscle by the endurance type of exercise and with the physiological consequences of these adaptations.

Diet, Muscle Glycogen and Physical Performance

1967-10-01
Jonas Bergström , L. Hermansen , E. Hultman +1 more
Abstract The muscle glycogen content of the quadriceps femoris muscle was determined in 9 healthy subjects with the aid of the needle biopsy technique. The glycogen content could be varied 
 Abstract The muscle glycogen content of the quadriceps femoris muscle was determined in 9 healthy subjects with the aid of the needle biopsy technique. The glycogen content could be varied in the individual subjects by instituting different diets after exhaustion of the glycogen store by hard exercise. Thus, the glycogen content after a fat ± protein (P) and a carbohydrate‐rich (C) diet varied maximally from 0.6 g/100g muscle to 4.7 g. In all subjects, the glycogen content after the C diet was higher than the normal range for muscle glycogen, determined after the mixed (M) diet. After each diet period, the subjects worked on a bicycle ergometer at a work load corresponding to 75 per cent of their maximal O 2 uptake, to complete exhaustion. The average work time was 59, 126 and 189 min after diets P, M and C, and a good correlation was noted between work time and the initial muscle glycogen content. The total carbohydrate utilization during the work periods (54–798 g) was well correlated to the decrease in glycogen content. It is therefore concluded that the glycogen content of the working muscle is a determinant for the capacity to perform long‐term heavy exercise. Moreover, it has been shown that the glycogen content and, consequently, the long‐term work capacity can be appreciably varied by instituting different diets after glycogen depletion.

Amino acids: metabolism, functions, and nutrition

2009-03-19
Guoyao Wu

Calibration of the Computer Science and Applications, Inc. accelerometer

1998-05-01
Patty S. Freedson , Edward L. Melanson , John R. Sirard
Purpose: We established accelerometer count ranges for the Computer Science and Applications, Inc. (CSA) activity monitor corresponding to commonly employed MET categories. Methods: Data were obtained from 50 adults (25 
 Purpose: We established accelerometer count ranges for the Computer Science and Applications, Inc. (CSA) activity monitor corresponding to commonly employed MET categories. Methods: Data were obtained from 50 adults (25 males, 25 females) during treadmill exercise at three different speeds (4.8, 6.4, and 9.7 km·h-1). Results: Activity counts and steady-state oxygen consumption were highly correlated(r = 0.88), and count ranges corresponding to light, moderate, hard, and very hard intensity levels were ≀ 1951, 1952-5724, 5725-9498, ≄ 9499 cnts·min-1, respectively. A model to predict energy expenditure from activity counts and body mass was developed using data from a random sample of 35 subjects (r2 = 0.82, SEE = 1.40 kcal·min-1). Cross validation with data from the remaining 15 subjects revealed no significant differences between actual and predicted energy expenditure at any treadmill speed (SEE = 0.50-1.40 kcal·min-1). Conclusions: These data provide a template on which patterns of activity can be classified into intensity levels using the CSA accelerometer.

Physiology of Sport and Exercise

1995-05-01
Jack H. Wilmore , D. L. Costill , Gilbert W. Gleim
Chapter 1. Structure and Function of Exercising Muscle Chapter 2. Fuel for Exercise: Bioenergetics and Muscle Metabolism Substrates Chapter 3. Neural Control of Exercising Muscle Chapter 4. Hormonal Control During 
 Chapter 1. Structure and Function of Exercising Muscle Chapter 2. Fuel for Exercise: Bioenergetics and Muscle Metabolism Substrates Chapter 3. Neural Control of Exercising Muscle Chapter 4. Hormonal Control During Exercise Chapter 5. Energy Expenditure and Fatigue Chapter 6. The Cardiovascular System and Its Control Chapter 7. The Respiratory System and Its Regulation Chapter 8. Cardiorespiratory Responses to Acute Exercise Chapter 9. Principles of Exercise Training.

Role of ferritin as a lipid oxidation catalyst in muscle food

1990-03-01
Eric A. Decker , Barbara Welch
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRole of ferritin as a lipid oxidation catalyst in muscle foodEric A. Decker and Barbara WelchCite this: J. Agric. Food Chem. 1990, 38, 3, 674–677Publication Date (Print):March 
 ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRole of ferritin as a lipid oxidation catalyst in muscle foodEric A. Decker and Barbara WelchCite this: J. Agric. Food Chem. 1990, 38, 3, 674–677Publication Date (Print):March 1, 1990Publication History Published online1 May 2002Published inissue 1 March 1990https://pubs.acs.org/doi/10.1021/jf00093a019https://doi.org/10.1021/jf00093a019research-articleACS PublicationsRequest reuse permissionsArticle Views2869Altmetric-Citations869LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Protein intake and exercise for optimal muscle function with aging: Recommendations from the ESPEN Expert Group

2014-04-24
Nicolaas E.P. Deutz , JĂŒrgen M. Bauer , Rocco Barazzoni +7 more
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Evidence-Based Recommendations for Optimal Dietary Protein Intake in Older People: A Position Paper From the PROT-AGE Study Group

2013-07-16
JĂŒrgen Bauer , Gianni Biolo , Tommy Cederholm +7 more
New evidence shows that older adults need more dietary protein than do younger adults to support good health, promote recovery from illness, and maintain functionality. Older people need to make 
 New evidence shows that older adults need more dietary protein than do younger adults to support good health, promote recovery from illness, and maintain functionality. Older people need to make up for age-related changes in protein metabolism, such as high splanchnic extraction and declining anabolic responses to ingested protein. They also need more protein to offset inflammatory and catabolic conditions associated with chronic and acute diseases that occur commonly with aging. With the goal of developing updated, evidence-based recommendations for optimal protein intake by older people, the European Union Geriatric Medicine Society (EUGMS), in cooperation with other scientific organizations, appointed an international study group to review dietary protein needs with aging (PROT-AGE Study Group). To help older people (>65 years) maintain and regain lean body mass and function, the PROT-AGE study group recommends average daily intake at least in the range of 1.0 to 1.2 g protein per kilogram of body weight per day. Both endurance- and resistance-type exercises are recommended at individualized levels that are safe and tolerated, and higher protein intake (ie, ≄ 1.2 g/kg body weight/d) is advised for those who are exercising and otherwise active. Most older adults who have acute or chronic diseases need even more dietary protein (ie, 1.2-1.5 g/kg body weight/d). Older people with severe kidney disease (ie, estimated GFR <30 mL/min/1.73 m(2)), but who are not on dialysis, are an exception to this rule; these individuals may need to limit protein intake. Protein quality, timing of ingestion, and intake of other nutritional supplements may be relevant, but evidence is not yet sufficient to support specific recommendations. Older people are vulnerable to losses in physical function capacity, and such losses predict loss of independence, falls, and even mortality. Thus, future studies aimed at pinpointing optimal protein intake in specific populations of older people need to include measures of physical function.
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Free fatty acid-induced insulin resistance is associated with activation of protein kinase C theta and alterations in the insulin signaling cascade.

1999-06-01
Michael Griffin , M. Marcucci , Gary W. Cline +7 more
To examine the mechanism by which free fatty acids (FFAs) induce insulin resistance in vivo, awake chronically catheterized rats underwent a hyperinsulinemic-euglycemic clamp with or without a 5-h preinfusion of 
 To examine the mechanism by which free fatty acids (FFAs) induce insulin resistance in vivo, awake chronically catheterized rats underwent a hyperinsulinemic-euglycemic clamp with or without a 5-h preinfusion of lipid/heparin to raise plasma FFA concentrations. Increased plasma FFAs resulted in insulin resistance as reflected by a approximately 35% reduction in the glucose infusion rate (P &amp;lt; 0.05 vs. control). The insulin resistance was associated with a 40-50% reduction in 13C nuclear magnetic resonance (NMR)-determined rates of muscle glycogen synthesis (P &amp;lt; 0.01 vs. control) and muscle glucose oxidation (P &amp;lt; 0.01 vs. control), which in turn could be attributed to a approximately 25% reduction in glucose transport activity as assessed by 2-[1,2-3H]deoxyglucose uptake in vivo (P &amp;lt; 0.05 vs. control). This lipid-induced decrease in insulin-stimulated muscle glucose metabolism was associated with 1) a approximately 50% reduction in insulin-stimulated insulin receptor substrate (IRS)-1-associated phosphatidylinositol (PI) 3-kinase activity (P &amp;lt; 0.05 vs. control), 2) a blunting in insulin-stimulated IRS-1 tyrosine phosphorylation (P &amp;lt; 0.05, lipid-infused versus glycerol-infused), and 3) a four-fold increase in membrane-bound, or active, protein kinase C (PKC) theta (P &amp;lt; 0.05 vs. control). We conclude that acute elevations of plasma FFA levels for 5 h induce skeletal muscle insulin resistance in vivo via a reduction in insulin-stimulated muscle glycogen synthesis and glucose oxidation that can be attributed to reduced glucose transport activity. These changes are associated with abnormalities in the insulin signaling cascade and may be mediated by FFA activation of PKC theta.

LIVER MICROSOMES

1956-03-25
George E. Palade , Philip Siekevitz
Rat liver, liver homogenates, and microsome fractions separated therefrom were examined systematically in the electron microscope in sections of OsO(4)-fixed, methacrylate-embedded tissue and pellets. It was found that most microsomes 
 Rat liver, liver homogenates, and microsome fractions separated therefrom were examined systematically in the electron microscope in sections of OsO(4)-fixed, methacrylate-embedded tissue and pellets. It was found that most microsomes are morphologically identical with the rough surfaced elements of the endoplasmic reticula of hepatic cells. They appear as isolated, membrane-bound vesicles, tubules, and cisternae which contain an apparently homogeneous material of noticeable density, and bear small, dense particles (100 to 150 A) attached to their outer aspect. In solutions of various osmolar concentrations they behave like osmometers. The findings suggest that they derive from the endoplasmic reticulum by a generalized pinching-off process rather than by mechanical fragmentation. The microsome fractions contain in addition relatively few vesicles free of attached particles, probably derived from the smooth surfaced parts of the endoplasmic reticula. Dense, peribiliary bodies represent a minor component of the same fractions. The microsomes derived from 1 gm. wet weight liver pulp contained (averages of 10 experiments) 3.09 mg. protein N, 3.46 mg. RNA (RNA/protein N = 1.12), and 487 microg. phospholipide P. They displayed DPNH-cytochrome c reductase activity and contained an alcohol-soluble hemochromogen. The microsome preparations proved resistant to washing and "aging." Treatment with versene and incubation with ribonuclease (30 minutes at 37 degrees C.) resulted in appreciable losses of RNA and in partial or total disappearance of attached particles. Treatment with deoxycholate (0.3 to 0.5 per cent, pH = 7.5) induced a partial clarification of the microsome suspensions which, upon centrifugation, yielded a small pellet of conglomerated small, dense particles (100 to 150 A) with only occasionally interspersed vesicles. The pellet contained approximately 80 to 90 per cent of the RNA and approximately 20 per cent of the protein N of the original microsomes. The supernatant accounted satisfactorily for the materials lost during deoxycholate treatment. The findings suggest that the microsomal RNA is associated with the small particles whereas most of the protein and nearly all of the phospholipide, hemochromogen, and DPNH-cytochrome c reductase activity are associated with the membrane or content of the microsomes.
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Mechanism of free fatty acid-induced insulin resistance in humans.

1996-06-15
Michael Roden , Thomas B. Price , Gianluca Perseghin +4 more
To examine the mechanism by which lipids cause insulin resistance in humans, skeletal muscle glycogen and glucose-6-phosphate concentrations were measured every 15 min by simultaneous 13C and 31P nuclear magnetic 
 To examine the mechanism by which lipids cause insulin resistance in humans, skeletal muscle glycogen and glucose-6-phosphate concentrations were measured every 15 min by simultaneous 13C and 31P nuclear magnetic resonance spectroscopy in nine healthy subjects in the presence of low (0.18 +/- 0.02 mM [mean +/- SEM]; control) or high (1.93 +/- 0.04 mM; lipid infusion) plasma free fatty acid levels under euglycemic (approximately 5.2 mM) hyperinsulinemic (approximately 400 pM) clamp conditions for 6 h. During the initial 3.5 h of the clamp the rate of whole-body glucose uptake was not affected by lipid infusion, but it then decreased continuously to be approximately 46% of control values after 6 h (P < 0.00001). Augmented lipid oxidation was accompanied by a approximately 40% reduction of oxidative glucose metabolism starting during the third hour of lipid infusion (P < 0.05). Rates of muscle glycogen synthesis were similar during the first 3 h of lipid and control infusion, but thereafter decreased to approximately 50% of control values (4.0 +/- 1.0 vs. 9.3 +/- 1.6 mumol/[kg.min], P < 0.05). Reduction of muscle glycogen synthesis by elevated plasma free fatty acids was preceded by a fall of muscle glucose-6-phosphate concentrations starting at approximately 1.5 h (195 +/- 25 vs. control: 237 +/- 26 mM; P < 0.01). Therefore in contrast to the originally postulated mechanism in which free fatty acids were thought to inhibit insulin-stimulated glucose uptake in muscle through initial inhibition of pyruvate dehydrogenase these results demonstrate that free fatty acids induce insulin resistance in humans by initial inhibition of glucose transport/phosphorylation which is then followed by an approximately 50% reduction in both the rate of muscle glycogen synthesis and glucose oxidation.
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Hormone-fuel interrelationships during fasting.

1966-11-01
George F. Cahill , M. Guillermo Herrera , Alfred P. Morgan +5 more
Over 50 years ago, Benedict (2) published his extensive monograph on the metabolism of fasting in man, in which he demonstrated that carbohydrate stores provide a small but significant component 
 Over 50 years ago, Benedict (2) published his extensive monograph on the metabolism of fasting in man, in which he demonstrated that carbohydrate stores provide a small but significant component of the body's fuel for only the first few days. Thereafter, protein and fat are the sole sources of fuel, the former contributing 15% of the calories and the latter the balance. The primary role of fat as fuel was apparent to Benedict and his contemporaries; it is plentiful and expendable. The significance of the protein requirement, however, was less clear; in fact, it was not fully understood until nearly 20 years later when the obligatory dependence of the central nervous system on glucose was firmly established (3). Since glycogen stores in man were known to approximate only 200 g, it was readily apparent that glucose has to be derived from protein in order to maintain cerebral metabolism during a prolonged fast. More recently, our understanding of the fasted state has been further clarified by the demonstration that free fatty acid is both the major transport form of lipid leaving adipose tissue (4, 5) and a substrate that is
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Free radicals and tissue damage produced by exercise

1982-08-01
Kelvin J.A. Davies , Alexandre Quintanilha , George A. Brooks +1 more

Percutaneous Needle Biopsy of Skeletal Muscle in Physiological and Clinical Research

1975-01-01
Jonas Bergström
(1975). Percutaneous Needle Biopsy of Skeletal Muscle in Physiological and Clinical Research. Scandinavian Journal of Clinical and Laboratory Investigation: Vol. 35, No. 7, pp. 609-616. (1975). Percutaneous Needle Biopsy of Skeletal Muscle in Physiological and Clinical Research. Scandinavian Journal of Clinical and Laboratory Investigation: Vol. 35, No. 7, pp. 609-616.

Simultaneous radioenzymatic determination of plasma and tissue adrenaline, noradrenaline and dopamine within the femtomole range

1976-10-01
M. Da Prada , G. ZĂŒrcher

Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans

2007-11-09
Kirsten A. Burgomaster , Krista R. Howarth , Stuart M. Phillips +4 more
Low‐volume ‘sprint’ interval training (SIT) stimulates rapid improvements in muscle oxidative capacity that are comparable to levels reached following traditional endurance training (ET) but no study has examined metabolic adaptations 
 Low‐volume ‘sprint’ interval training (SIT) stimulates rapid improvements in muscle oxidative capacity that are comparable to levels reached following traditional endurance training (ET) but no study has examined metabolic adaptations during exercise after these different training strategies. We hypothesized that SIT and ET would induce similar adaptations in markers of skeletal muscle carbohydrate (CHO) and lipid metabolism and metabolic control during exercise despite large differences in training volume and time commitment. Active but untrained subjects (23 ± 1 years) performed a constant‐load cycling challenge (1 h at 65% of peak oxygen uptake before and after 6 weeks of either SIT or ET ( n = 5 men and 5 women per group). SIT consisted of four to six repeats of a 30 s ‘all out’ Wingate Test (mean power output ∌500 W) with 4.5 min recovery between repeats, 3 days per week. ET consisted of 40–60 min of continuous cycling at a workload that elicited ∌65% (mean power output ∌150 W) per day, 5 days per week. Weekly time commitment (∌1.5 versus ∌4.5 h) and total training volume (∌225 versus ∌2250 kJ week −1 ) were substantially lower in SIT versus ET. Despite these differences, both protocols induced similar increases ( P &lt; 0.05) in mitochondrial markers for skeletal muscle CHO (pyruvate dehydrogenase E1α protein content) and lipid oxidation (3‐hydroxyacyl CoA dehydrogenase maximal activity) and protein content of peroxisome proliferator‐activated receptor‐γ coactivator‐1α. Glycogen and phosphocreatine utilization during exercise were reduced after training, and calculated rates of whole‐body CHO and lipid oxidation were decreased and increased, respectively, with no differences between groups (all main effects, P &lt; 0.05). Given the markedly lower training volume in the SIT group, these data suggest that high‐intensity interval training is a time‐efficient strategy to increase skeletal muscle oxidative capacity and induce specific metabolic adaptations during exercise that are comparable to traditional ET.
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Regulation of endogenous fat and carbohydrate metabolism in relation to exercise intensity and duration

1993-09-01
J. A. Romijn , Edward F. Coyle , Labros S. Sidossis +4 more
Stable isotope tracers and indirect calorimetry were used to evaluate the regulation of endogenous fat and glucose metabolism in relation to exercise intensity and duration. Five trained subjects were studied 
 Stable isotope tracers and indirect calorimetry were used to evaluate the regulation of endogenous fat and glucose metabolism in relation to exercise intensity and duration. Five trained subjects were studied during exercise intensities of 25, 65, and 85% of maximal oxygen consumption (VO2max). Plasma glucose tissue uptake and muscle glycogen oxidation increased in relation to exercise intensity. In contrast, peripheral lipolysis was stimulated maximally at the lowest exercise intensity, and fatty acid release into plasma decreased with increasing exercise intensity. Muscle triglyceride lipolysis was stimulated only at higher intensities. During 2 h of exercise at 65% VO2max plasma-derived substrate oxidation progressively increased over time, whereas muscle glycogen and triglyceride oxidation decreased. In recovery from high-intensity exercise, although the rate of lipolysis immediately decreased, the rate of release of fatty acids into plasma increased, indicating release of fatty acids from previously hydrolyzed triglycerides. We conclude that, whereas carbohydrate availability is regulated directly in relation to exercise intensity, the regulation of lipid metabolism seems to be more complex.

Adaptations of skeletal muscle to endurance exercise and their metabolic consequences

1984-04-01
J. O. Holloszy , Edward F. Coyle
Regularly performed endurance exercise induces major adaptations in skeletal muscle. These include increases in the mitochondrial content and respiratory capacity of the muscle fibers. As a consequence of the increase 
 Regularly performed endurance exercise induces major adaptations in skeletal muscle. These include increases in the mitochondrial content and respiratory capacity of the muscle fibers. As a consequence of the increase in mitochondria, exercise of the same intensity results in a disturbance in homeostasis that is smaller in trained than in untrained muscles. The major metabolic consequences of the adaptations of muscle to endurance exercise are a slower utilization of muscle glycogen and blood glucose, a greater reliance on fat oxidation, and less lactate production during exercise of a given intensity. These adaptations play an important role in the large increase in the ability to perform prolonged strenuous exercise that occurs in response to endurance exercise training.

Slow and fast dietary proteins differently modulate postprandial protein accretion

1997-12-23
Yves Boirie‌ , Martial Dangin , Pierre Gachon +3 more
The speed of absorption of dietary amino acids by the gut varies according to the type of ingested dietary protein. This could affect postprandial protein synthesis, breakdown, and deposition. To 
 The speed of absorption of dietary amino acids by the gut varies according to the type of ingested dietary protein. This could affect postprandial protein synthesis, breakdown, and deposition. To test this hypothesis, two intrinsically 13C-leucine-labeled milk proteins, casein (CAS) and whey protein (WP), of different physicochemical properties were ingested as one single meal by healthy adults. Postprandial whole body leucine kinetics were assessed by using a dual tracer methodology. WP induced a dramatic but short increase of plasma amino acids. CAS induced a prolonged plateau of moderate hyperaminoacidemia, probably because of a slow gastric emptying. Whole body protein breakdown was inhibited by 34% after CAS ingestion but not after WP ingestion. Postprandial protein synthesis was stimulated by 68% with the WP meal and to a lesser extent (+31%) with the CAS meal. Postprandial whole body leucine oxidation over 7 h was lower with CAS (272 +/- 91 micromol.kg-1) than with WP (373 +/- 56 micromol.kg-1). Leucine intake was identical in both meals (380 micromol.kg-1). Therefore, net leucine balance over the 7 h after the meal was more positive with CAS than with WP (P < 0.05, WP vs. CAS). In conclusion, the speed of protein digestion and amino acid absorption from the gut has a major effect on whole body protein anabolism after one single meal. By analogy with carbohydrate metabolism, slow and fast proteins modulate the postprandial metabolic response, a concept to be applied to wasting situations.

Anabolic signaling deficits underlie amino acid resistance of wasting, aging muscle

2004-12-13
Daniel J. Cuthbertson , Kenneth Smith , John Babraj +6 more
The nature of the deficit underlying age-related muscle wasting remains controversial. To test whether it could be due to a poor anabolic response to dietary amino acids, we measured the 
 The nature of the deficit underlying age-related muscle wasting remains controversial. To test whether it could be due to a poor anabolic response to dietary amino acids, we measured the rates of myofibrillar and sarcoplasmic muscle protein synthesis (MPS) in 44 healthy young and old men, of similar body build, after ingesting different amounts of essential amino acids (EAA). Basal rates of MPS were indistinguishable, but the elderly showed less anabolic sensitivity and responsiveness of MPS to EAA, possibly due to decreased intramuscular expression, and activation (phosphorylation) after EAA, of amino acid sensing/signaling proteins (mammalian target of rapamycin, mTOR; p70 S6 kinase, or p70(S6k); eukaryotic initiation factor [eIF]4BP-1; and eIF2B). The effects were independent of insulin signaling since plasma insulin was clamped at basal values. Associated with the anabolic deficits were marked increases in NFkappaB, the inflammation-associated transcription factor. These results demonstrate first, EAA stimulate MPS independently of increased insulin availability; second, in the elderly, a deficit in MPS in the basal state is unlikely; and third, the decreased sensitivity and responsiveness of MPS to EAA, associated with decrements in the expression and activation of components of anabolic signaling pathways, are probably major contributors to the failure of muscle maintenance in the elderly. Countermeasures to maximize muscle maintenance should target these deficits.

Hormonal Responses and Adaptations to Resistance Exercise and Training

2005-01-01
William J. Kraemer , Nicholas A. Ratamess

Skeletal Muscle Triglyceride Levels Are Inversely Related to Insulin Action

1997-06-01
David Pan , Stephen Lillioja , A. D. Kriketos +5 more
In animal studies, increased amounts of triglyceride associated with skeletal muscle (mTG) correlate with reduced skeletal muscle and whole body insulin action. The aim of this study was to test 
 In animal studies, increased amounts of triglyceride associated with skeletal muscle (mTG) correlate with reduced skeletal muscle and whole body insulin action. The aim of this study was to test this relationship in humans. Subjects were 38 nondiabetic male Pima Indians (mean age 28 ± 1 years). Insulin sensitivity at physiological (M) and supraphysiological (MZ) insulin levels was assessed by the euglycemic clamp. Lipid and carbohydrate oxidation were determined by indirect calorimetry before and during insulin administration. mTG was determined in vastus lateralis muscles obtained by percutaneous biopsy. Percentage of body fat (mean 29 ± 1%, range 14–44%) was measured by underwater weighing. In simple regressions, negative relationships were found between mTG (mean 5.4 ± 0.3 ÎŒmol/g, range 1.3–1.9 ÎŒmol/g) and log10M (r = −0.53, P ≀ 0.001), MZ (r = −0.44, P = 0.006), and nonoxidative glucose disposal (r = −0.48 and −0.47 at physiological and supraphysiological insulin levels, respectively, both P = 0.005) but not glucose or lipid oxidation. mTG was not related to any measure of adiposity. In multiple regressions, measures of insulin resistance (log10M, MZ, log10[fasting insulin]) were significantly related to mTG independent of all measures of obesity (percentage of body fat, BMI, waist-to-thigh ratio). In turn, all measures of obesity were related to the insulin resistance measures independent of mTG. The obesity measures and mTG accounted for similar proportions of the variance in insulin resistance in these relationships. The results suggest that in this human population, as in animal models, skeletal muscle insulin sensitivity is strongly influenced by local supplies of triglycerides, as well as by remote depots and circulating lipids. The mechanism(s) underlying the relationship between mTG and insulin action on skeletal muscle glycogen synthesis may be central to an understanding of insulin resistance.
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Human muscle metabolism during intermittent maximal exercise

1993-08-01
G. C. Gaitanos , C. Williams , L. Boobis +1 more
Eight male subjects volunteered to take part in this study. The exercise protocol consisted of ten 6-s maximal sprints with 30 s of recovery between each sprint on a cycle 
 Eight male subjects volunteered to take part in this study. The exercise protocol consisted of ten 6-s maximal sprints with 30 s of recovery between each sprint on a cycle ergometer. Needle biopsy samples were taken from the vastus lateralis muscle before and after the first sprint and 10 s before and immediately after the tenth sprint. The energy required to sustain the high mean power output (MPO) that was generated over the first 6-s sprint (870.0 +/- 159.2 W) was provided by an equal contribution from phosphocreatine (PCr) degradation and anaerobic glycolysis. Indeed, within the first 6-s bout of maximal exercise PCr concentration had fallen by 57% and muscle lactate concentration had increased to 28.6 mmol/kg dry wt, confirming significant glycolytic activity. However, in the tenth sprint there was no change in muscle lactate concentration even though MPO was reduced only to 73% of that generated in the first sprint. This reduced glycogenolysis occurred despite the high plasma epinephrine concentration of 5.1 +/- 1.5 nmol/l after sprint 9. In face of a considerable reduction in the contribution of anaerobic glycogenolysis to ATP production, it was suggested that, during the last sprint, power output was supported by energy that was mainly derived from PCr degradation and an increased aerobic metabolism.
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The underappreciated role of muscle in health and disease

2006-12-01
Robert R. Wolfe
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Skeletal Muscle Lipid Content and Insulin Resistance: Evidence for a Paradox in Endurance-Trained Athletes

2001-12-01
Bret H. Goodpaster , Jing He , Simon C. Watkins +1 more
We examined the hypothesis that an excess accumulation of intramuscular lipid (IMCL) is associated with insulin resistance and that this may be mediated by the oxidative capacity of muscle. Nine 
 We examined the hypothesis that an excess accumulation of intramuscular lipid (IMCL) is associated with insulin resistance and that this may be mediated by the oxidative capacity of muscle. Nine sedentary lean (L) and 11 obese (O) subjects, 8 obese subjects with type 2 diabetes mellitus (D), and 9 lean, exercise-trained (T) subjects volunteered for this study. Insulin sensitivity (M) determined during a hyperinsulinemic (40 mU·m−2min−1) euglycemic clamp was greater (P &amp;lt; 0.01) in L and T, compared with O and D (9.45 ± 0.59 and 10.26 ± 0.78 vs. 5.51 ± 0.61 and 1.15 ± 0.83 mg·min−1kg fat free mass−1, respectively). IMCL in percutaneous vastus lateralis biopsy specimens by quantitative image analysis of Oil Red O staining was approximately 2-fold higher in D than in L (3.04 ± 0.39 vs. 1.40 ± 0.28% area as lipid; P &amp;lt; 0.01). IMCL was also higher in T (2.36 ± 0.37), compared with L (P &amp;lt; 0.01). The oxidative capacity of muscle determined with succinate dehydrogenase staining of muscle fibers was higher in T, compared with L, O, and D (50.0 ± 4.4, 36.1 ± 4.4, 29.7 ± 3.8, and 33.4 ± 4.7 optical density units, respectively; P &amp;lt; 0.01). IMCL was negatively associated with M (r = −0.57, P &amp;lt; 0.05) when endurance-trained subjects were excluded from the analysis, and this association was independent of body mass index. However, the relationship between IMCL and M was not significant when trained individuals were included. There was a positive association between the oxidative capacity and M among nondiabetics (r = 0.37, P &amp;lt; 0.05). In summary, skeletal muscle of trained endurance athletes is markedly insulin sensitive and has a high oxidative capacity, despite having an elevated lipid content. In conclusion, the capacity for lipid oxidation may be an important mediator of the association between excess muscle lipid accumulation and insulin resistance.

Short‐term sprint interval <i>versus</i> traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance

2006-07-07
Martin J. Gibala , Jonathan P. Little , M. van den Broekvan Essen +5 more
Brief, intense exercise training may induce metabolic and performance adaptations comparable to traditional endurance training. However, no study has directly compared these diverse training strategies in a standardized manner. We 
 Brief, intense exercise training may induce metabolic and performance adaptations comparable to traditional endurance training. However, no study has directly compared these diverse training strategies in a standardized manner. We therefore examined changes in exercise capacity and molecular and cellular adaptations in skeletal muscle after low volume sprint-interval training (SIT) and high volume endurance training (ET). Sixteen active men (21 +/- 1 years, ) were assigned to a SIT or ET group (n = 8 each) and performed six training sessions over 14 days. Each session consisted of either four to six repeats of 30 s 'all out' cycling at approximately 250% with 4 min recovery (SIT) or 90-120 min continuous cycling at approximately 65% (ET). Training time commitment over 2 weeks was approximately 2.5 h for SIT and approximately 10.5 h for ET, and total training volume was approximately 90% lower for SIT versus ET ( approximately 630 versus approximately 6500 kJ). Training decreased the time required to complete 50 and 750 kJ cycling time trials, with no difference between groups (main effects, P </= 0.05). Biopsy samples obtained before and after training revealed similar increases in muscle oxidative capacity, as reflected by the maximal activity of cytochrome c oxidase (COX) and COX subunits II and IV protein content (main effects, P </= 0.05), but COX II and IV mRNAs were unchanged. Training-induced increases in muscle buffering capacity and glycogen content were also similar between groups (main effects, P </= 0.05). Given the large difference in training volume, these data demonstrate that SIT is a time-efficient strategy to induce rapid adaptations in skeletal muscle and exercise performance that are comparable to ET in young active men.
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Creatine and Creatinine Metabolism

2000-07-01
Markus Wyss , Rima Kaddurah‐Daouk
The goal of this review is to present a comprehensive survey of the many intriguing facets of creatine (Cr) and creatinine metabolism, encompassing the pathways and regulation of Cr biosynthesis 
 The goal of this review is to present a comprehensive survey of the many intriguing facets of creatine (Cr) and creatinine metabolism, encompassing the pathways and regulation of Cr biosynthesis and degradation, species and tissue distribution of the enzymes and metabolites involved, and of the inherent implications for physiology and human pathology. Very recently, a series of new discoveries have been made that are bound to have distinguished implications for bioenergetics, physiology, human pathology, and clinical diagnosis and that suggest that deregulation of the creatine kinase (CK) system is associated with a variety of diseases. Disturbances of the CK system have been observed in muscle, brain, cardiac, and renal diseases as well as in cancer. On the other hand, Cr and Cr analogs such as cyclocreatine were found to have antitumor, antiviral, and antidiabetic effects and to protect tissues from hypoxic, ischemic, neurodegenerative, or muscle damage. Oral Cr ingestion is used in sports as an ergogenic aid, and some data suggest that Cr and creatinine may be precursors of food mutagens and uremic toxins. These findings are discussed in depth, the interrelationships are outlined, and all is put into a broader context to provide a more detailed understanding of the biological functions of Cr and of the CK system.

Decreased effect of insulin to stimulate skeletal muscle blood flow in obese man. A novel mechanism for insulin resistance.

1990-06-01
Markku Laakso , Steven V. Edelman , Ginger Brechtel +1 more
Obesity is characterized by decreased rates of skeletal muscle insulin-mediated glucose uptake (IMGU). Since IMGU equals the product of the arteriovenous glucose difference (AVGd) across muscle and blood flow into 
 Obesity is characterized by decreased rates of skeletal muscle insulin-mediated glucose uptake (IMGU). Since IMGU equals the product of the arteriovenous glucose difference (AVGd) across muscle and blood flow into muscle, reduced blood flow and/or tissue activity (AVGd) can lead to decreased IMGU. To examine this issue, we studied six lean (weight 68 +/- 3 kg, mean +/- SEM) and six obese (94 +/- 3 kg) men. The insulin dose-response curves for whole body and leg IMGU were constructed using the euglycemic clamp and leg balance techniques over a large range of serum insulin concentrations. In lean and obese subjects, whole body IMGU, AVGd, blood flow, and leg IMGU increased in a dose dependent fashion and maximal rates of all parameters were reduced in obese subjects compared to lean subjects. The dose-response curves for whole body IMGU, leg IMGU, and AVGd were right-shifted in obese subjects with an ED50 two- to threefold higher than that of lean subjects for each parameter. Leg blood flow increased approximately twofold from basal 2.7 +/- 0.2 to 4.4 +/- 0.2 dl/min in lean, P less than 0.01, and from 2.5 +/- 0.3 to 4.4 +/- 0.4 dl/min in obese subjects, P less than 0.01. The ED50 for insulin's effect to increase leg blood flow was about fourfold higher for obese (957 pmol/liter) than lean subjects (266 pmol/liter), P less than 0.01. Therefore, decreased insulin sensitivity in human obesity is not only due to lower glucose extraction in insulin-sensitive tissues but also to lower blood flow to these tissues. Thus, in vivo insulin resistance can be due to a defect in insulin action at the tissue level and/or a defect in insulin's hemodynamic action to increase blood flow to insulin sensitive tissues.
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Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men

2009-07-10
Jason E. Tang , Daniel R. Moore , Gregory W. Kujbida +2 more
This study was designed to compare the acute response of mixed muscle protein synthesis (MPS) to rapidly (i.e., whey hydrolysate and soy) and slowly (i.e., micellar casein) digested proteins both 
 This study was designed to compare the acute response of mixed muscle protein synthesis (MPS) to rapidly (i.e., whey hydrolysate and soy) and slowly (i.e., micellar casein) digested proteins both at rest and after resistance exercise. Three groups of healthy young men ( n = 6 per group) performed a bout of unilateral leg resistance exercise followed by the consumption of a drink containing an equivalent content of essential amino acids (10 g) as either whey hydrolysate, micellar casein, or soy protein isolate. Mixed MPS was determined by a primed constant infusion of l-[ ring- 13 C 6 ]phenylalanine. Ingestion of whey protein resulted in a larger increase in blood essential amino acid, branched-chain amino acid, and leucine concentrations than either casein or soy (P &lt; 0.05). Mixed MPS at rest (determined in the nonexercised leg) was higher with ingestion of faster proteins (whey = 0.091 ± 0.015, soy = 0.078 ± 0.014, casein = 0.047 ± 0.008%/h); MPS after consumption of whey was ∌93% greater than casein (P &lt; 0.01) and ∌18% greater than soy (P = 0.067). A similar result was observed after exercise (whey &gt; soy &gt; casein); MPS following whey consumption was ∌122% greater than casein (P &lt; 0.01) and 31% greater than soy (P &lt; 0.05). MPS was also greater with soy consumption at rest (64%) and following resistance exercise (69%) compared with casein (both P &lt; 0.01). We conclude that the feeding-induced simulation of MPS in young men is greater after whey hydrolysate or soy protein consumption than casein both at rest and after resistance exercise; moreover, despite both being fast proteins, whey hydrolysate stimulated MPS to a greater degree than soy after resistance exercise. These differences may be related to how quickly the proteins are digested (i.e., fast vs. slow) or possibly to small differences in leucine content of each protein.

A new predictive equation for resting energy expenditure in healthy individuals

1990-02-01
MD Mifflin , ST St Jeor , LA Hill +3 more

The Effect of Insulin on the Disposal of Intravenous Glucose: Results from Indirect Calorimetry and Hepatic and Femoral Venous Catheterization

1981-12-01
Ralph A. DeFronzo , E Jacot , E JĂ©quier +3 more
The effect of insulin on the disposal of intravenous glucose was examined employing the euglycemic insulin clamp technique in 24 normal subjects. When the plasma insulin concentration was raised by 
 The effect of insulin on the disposal of intravenous glucose was examined employing the euglycemic insulin clamp technique in 24 normal subjects. When the plasma insulin concentration was raised by approximately 100 ÎŒU/ml, total glucose metabolism rose to 6.63 ± 0.38 mg/kg · min. Basal splanchnic (hepatic venous catheter technique) glucose production, 2.00 increased only slightly. These results suggest that the ability of higher doses of insulin to further stimulate glucose metabolism is primarily the result of increased glucose storage by peripheral tissues, most likely muscle. 0.15 ± mg/kg · min, reverted to a small net glucose uptake which averaged 0.33 mg/kg · min over the ensuing 2 h. This represented only 5% of the total glucose metabolized. In contrast, leg (femoral venous catheterization) glucose uptake rose from 1.18 ± 0.14 to 8.40 ± 1.06 mg/kg of leg wt. per min. If all muscles in the body respond similarly to those in the leg, muscle would account for 85% of the total glucose metabolism. To determine the relative contributions of glucose oxidation versus glucose storage by peripheral tissues following hyperinsulinemia, we performed euglycemic insulin clamp studies in combination with indirect calorimetry. Basal glucose oxidation, 1.21 ± 0.10 mg/kg min, rose to 2.28 ± 0.16 (P &amp;lt; 0.01), and this increase above baseline accounted for only 20% of the total glucose metabolized, 5.44 ± 0.38 mg/kg · min. Following insulin, glucose storage increased to 3.18 ± 0.34 mg/kg min and was responsible for 59% of the total glucose metabolized. These results indicate that the primary effect of insulin on muscle tissue is to enhance glucose storage, presumably as glycogen. When a higher degree of hyperinsulinemia (163 ± 19 ÎŒl/ml) was created while maintaining euglycemia, total glucose metabolism (7.99 ± 0.58) and glucose storage (5.30 ± 0.80) both increased (P &amp;lt; 0.01) compared with the lower dose insulin clamp study, but glucose oxidation (2.70 ± 0.16 mgÎŒkg min)increased only slightly. These results suggest that the ability of higher doses of insulin to further stimulate glucose metabolism is primarily the result of increased glucose storage by peripheral tissues, most likely muscle.

Strength conditioning in older men: skeletal muscle hypertrophy and improved function

1988-03-01
Walter R. Frontera , C. N. Meredith , Kevin O’Reilly +2 more
The effects of strength conditioning on skeletal muscle function and mass were determined in older men. Twelve healthy untrained volunteers (age range 60-72 yr) participated in a 12-wk strength training 
 The effects of strength conditioning on skeletal muscle function and mass were determined in older men. Twelve healthy untrained volunteers (age range 60-72 yr) participated in a 12-wk strength training program (8 repetitions/set; 3 sets/day; 3 days/wk) at 80% of the one repetition maximum (1 RM) for extensors and flexors of both knee joints. They were evaluated before the program and after 6 and 12 wk of training. Weekly measurements of 1 RM showed a progressive increase in strength in extensors and flexors. By 12 wk extensor and flexor strength had increased 107.4 (P less than 0.0001) and 226.7% (P less than 0.0001), respectively. Isokinetic peak torque of extensors and flexors measured on a Cybex II dynamometer increased 10.0 and 18.5% (P less than 0.05) at 60 degrees/s and 16.7 and 14.7% (P less than 0.05) at 240 degrees/s. The torque-velocity relationship showed an upward displacement of the curve at the end of training, mainly in the slow-velocity high-torque region. Midthigh composition from computerized tomographic scans showed an increase (P less than 0.01) in total thigh area (4.8%), total muscle area (11.4%), and quadriceps area (9.3%). Biopsies of the vastus lateralis muscle revealed similar increases (P less than 0.001) in type I fiber area (33.5%) and type II fiber area (27.6%). Daily excretion of urinary 3-methyl-L-histidine increased with training (P less than 0.05) by an average 40.8%. Strength gains in older men were associated with significant muscle hypertrophy and an increase in myofibrillar protein turnover.

Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate

1986-07-01
Edward F. Coyle , Andrew R. Coggan , M. K. Hemmert +1 more
The purpose of this study was to determine whether the postponement of fatigue in subjects fed carbohydrate during prolonged strenuous exercise is associated with a slowing of muscle glycogen depletion. 
 The purpose of this study was to determine whether the postponement of fatigue in subjects fed carbohydrate during prolonged strenuous exercise is associated with a slowing of muscle glycogen depletion. Seven endurance-trained cyclists exercised at 71 +/- 1% of maximal O2 consumption (VO2max), to fatigue, while ingesting a flavored water solution (i.e., placebo) during one trial and while ingesting a glucose polymer solution (i.e., 2.0 g/kg at 20 min and 0.4 g/kg every 20 min thereafter) during another trial. Fatigue during the placebo trial occurred after 3.02 +/- 0.19 h of exercise and was preceded by a decline (P less than 0.01) in plasma glucose to 2.5 +/- 0.5 mM and by a decline in the respiratory exchange ratio (i.e., R; from 0.85 to 0.80; P less than 0.05). Glycogen within the vastus lateralis muscle declined at an average rate of 51.5 +/- 5.4 mmol glucosyl units (GU) X kg-1 X h-1 during the first 2 h of exercise and at a slower rate (P less than 0.01) of 23.0 +/- 14.3 mmol GU X kg-1 X h-1 during the third and final hour. When fed carbohydrate, which maintained plasma glucose concentration (4.2–5.2 mM), the subjects exercised for an additional hour before fatiguing (4.02 +/- 0.33 h; P less than 0.01) and maintained their initial R (i.e., 0.86) and rate of carbohydrate oxidation throughout exercise. The pattern of muscle glycogen utilization, however, was not different during the first 3 h of exercise with the placebo or the carbohydrate feedings. The additional hour of exercise performed when fed carbohydrate was accomplished with little reliance on muscle glycogen (i.e., 5 mmol GU X kg-1 X h-1; NS) and without compromising carbohydrate oxidation. We conclude that when they are fed carbohydrate, highly trained endurance athletes are capable of oxidizing carbohydrate at relatively high rates from sources other than muscle glycogen during the latter stages of prolonged strenuous exercise and that this postpones fatigue.

Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance

2009-02-26
Nancy R. Rodriguez , Nancy M. DiMarco , Susie Langley

Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance

2016-02-23
D. Travis Thomas , Kelly Anne Erdman , Louise M. Burke

The Effects of Dietary Protein Restriction and Blood-Pressure Control on the Progression of Chronic Renal Disease

1994-03-31
Saulo Klahr , Andrew S. Levey , Gerald J. Beck +4 more
Restricting protein intake and controlling hypertension delay the progression of renal disease in animals. We tested these interventions in 840 patients with various chronic renal diseases. Restricting protein intake and controlling hypertension delay the progression of renal disease in animals. We tested these interventions in 840 patients with various chronic renal diseases.
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Quantitation of Muscle Glycogen Synthesis in Normal Subjects and Subjects with Non-Insulin-Dependent Diabetes by<sup>13</sup>C Nuclear Magnetic Resonance Spectroscopy

1990-01-25
Gerald I. Shulman , Douglas L. Rothman , Thomas Jue +3 more
To examine the extent to which the defect in insulin action in subjects with non-insulin-dependent diabetes mellitus (NIDDM) can be accounted for by impairment of muscle glycogen synthesis, we performed 
 To examine the extent to which the defect in insulin action in subjects with non-insulin-dependent diabetes mellitus (NIDDM) can be accounted for by impairment of muscle glycogen synthesis, we performed combined hyperglycemic—hyperinsulinemic clamp studies with [13C]glucose in five subjects with NIDDM and in six age- and weight-matched healthy subjects. The rate of incorporation of intravenously infused [1–13C]glucose into muscle glycogen was measured directly in the gastrocnemius muscle by means of a nuclear magnetic resonance (NMR) spectrometer with a 15.5-minute time resolution and a 13C surface coil.
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Enzyme activity and fiber composition in skeletal muscle of untrained and trained men.

1972-09-01
Paul Gollnick , R. B. Armstrong , C. W. Saubert +2 more

Nutrition and Athletic Performance

2016-02-19
D. Travis Thomas , Kelly Anne Erdman , Louise M. Burke
It is the position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine that the performance of, and recovery from, sporting activities 
 It is the position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine that the performance of, and recovery from, sporting activities are enhanced by well-chosen nutrition strategies. These organizations provide guidelines for the appropriate type, amount, and timing of intake of food, fluids, and supplements to promote optimal health and performance across different scenarios of training and competitive sport. This position paper was prepared for members of the Academy of Nutrition and Dietetics, Dietitians of Canada (DC), and American College of Sports Medicine (ACSM), other professional associations, government agencies, industry, and the public. It outlines the Academy's, DC's and ACSM's stance on nutrition factors that have been determined to influence athletic performance and emerging trends in the field of sports nutrition. Athletes should be referred to a registered dietitian/nutritionist for a personalized nutrition plan. In the United States and in Canada, the Certified Specialist in Sports Dietetics (CSSD) is a registered dietitian/nutritionist and a credentialed sports nutrition expert.

Energy and protein requirements*

2019-03-05

The effects of carbohydrate supplementation on the gh/igf-i axis, cortisol, insulin, and glucose in adult runners

2025-06-25
Alyne Oliveira , Henrique Santa Capita Cerqueira , José Maurício Magraner +3 more | Human Movement
Purpose Hormones are largely responsible for the integrated communication of various physiological systems that modulate cell growth and development. However, specific hormonal influences must be considered in the context of 
 Purpose Hormones are largely responsible for the integrated communication of various physiological systems that modulate cell growth and development. However, specific hormonal influences must be considered in the context of the entire endocrine system and their relationship with other physiological systems. The serum concentrations of these hormones can directly affect athlete performance and reflect training status during preparation. Methods Concentrations of growth hormone (GH), insulin-like growth factor-I (IGF-I), cortisol, insulin, and glucose were measured at rest 30 min before a simulated race and 30 min after race completion. Student’s t-test for paired samples analysed normally distributed data, while Wilcoxon’s non-parametric test assessed other variables. A significance level of &lt;i&gt;p&lt;/i&gt; 0.05 was adopted. Results GH and cortisol serum concentrations increased after running, with (GH: &lt;i&gt;p&lt;/i&gt; = 0.03; cortisol: &lt;i&gt;p&lt;/i&gt; = 0.001) and without (GH: &lt;i&gt;p&lt;/i&gt; = 0.001; cortisol: &lt;i&gt;p&lt;/i&gt; = 0.004) carbohydrate supplementation. Glucose concentrations only increased at the end of the race with carbohydrate supplementation (&lt;i&gt;p&lt;/i&gt; = 0.01) but remained unchanged after the race without supplementation. Insulin concentrations rose at the end of the race with carbohydrate supplementation (&lt;i&gt;p&lt;/i&gt; = 0.05) and lowered without supplementation (&lt;i&gt;p&lt;/i&gt; = 0.03). IGF-I levels did not change with or without carbohydrate supplementation. Conclusions Changes in serum GH, cortisol, and insulin during the race appeared to contribute to serum IGF-I and glucose concentration maintenance and runner performance.

Evidence-Based Supplementation Strategies for Wrestlers: A Systematic Review

2025-06-25
Michelle Coutiño Díaz , Arnold Prieto Martínez , Reza Zare +2 more | Current Nutrition Reports

In-silico profiling of phenolic acids for gallstone prevention: a basis for in-vitro studies in high physical activity and rapid weight loss

2025-06-25
S Rajendran , Chitra Vellapandian | Retos
Background: Cholelithiasis is increasingly seen in individuals with rapid weight loss or high physical stress, such as athletes. Existing therapies like ursodeoxycholic acid have limited efficacy, prompting interest in safer 
 Background: Cholelithiasis is increasingly seen in individuals with rapid weight loss or high physical stress, such as athletes. Existing therapies like ursodeoxycholic acid have limited efficacy, prompting interest in safer natural options. Aim: To assess the anti-cholelithiatic potential of selected phenolic acids via molecular docking and pharmacokinetic profiling. Methodology: Molecular docking, ADMET analysis, and molecular dynamics simulations were performed for sinapic, p-coumaric, caffeic, and ferulic acids, focusing on targets involved in cholesterol and bile acid regulation (LXR, FXR, PPAR-γ, NPC1L1). Tools used included AutoDock 4.2, SwissADME, and GROMACS 2019.4. Results: Sinapic acid showed the strongest binding with LXR (-6.65 kcal/mol), suggesting enhanced cholesterol efflux, while p-coumaric acid showed significant interaction with FXR (-4.86 kcal/mol), implicating a role in bile acid regulation. Both compounds exhibited stable binding and favourable pharmacokinetics with low toxicity. Conclusion: Sinapic and p-coumaric acids appear promising for gallstone prevention, particularly in active individuals or those with rapid weight loss, warranting further in-vitro, in-vivo, and clinical studies.

Effects of dietary sodium butyrate supplementation on fat metabolism in lamb adipose and liver tissues

2025-06-24
Yue Zhang , Hongbo Qu , Yueying Guo +7 more | Animal Bioscience
Sodium butyrate (SB) is a potentially useful feed additive, however, its effects on lipid metabolism in adipose and liver tissues of lambs are still not fully explored. This study systematically 
 Sodium butyrate (SB) is a potentially useful feed additive, however, its effects on lipid metabolism in adipose and liver tissues of lambs are still not fully explored. This study systematically examined the effects and underlying mechanisms of dietary SB supplementation on lipid metabolism in lamb adipose and liver tissues from an adipose-blood-liver-perspective. Twelve 3-month-old male lambs (22.37 ± 2.05 kg) were randomly divided into a control group and a SB group. The adipose tissue cellular morphology and lipid metabolism-related indices in both adipose and liver tissues were measured. The results indicated that SB significantly reduces abdominal and perirenal adipose tissue mass, as well as in the average area and diameter of adipocytes (P < 0.05). Dietary supplementation with SB activated adenosine 5'-monophosphate -activated protein kinase α1 (AMPKα1) in lamb adipose tissue, resulting in upregulated mRNA expression of hormone-sensitive triglyceride lipase (HSL) and downregulated mRNA expression of sterol regulatory element-binding protein 1 and fatty acid synthase (P < 0.05). Simultaneously, adiponectin secretion and receptor expression in adipose tissue, as well as serum adiponectin levels, were significantly elevated (P < 0.05). Moreover, dietary supplementation with SB increased the levels of TCA cycle metabolites in lamb liver, including oxaloacetate, citrate, cis-aconitate, and succinate (P < 0.05), while simultaneously activating the liver AMPKα1 signaling pathway. This led to upregulated HSL, platelet glycoprotein 4, and long-chain acyl-CoA synthetase mRNA expression (P < 0.05), thereby enhancing liver fatty acid metabolism. In summary, dietary supplementation with SB alters adiponectin levels in lambs, activates the AMPK signaling pathway, promotes adipose tissue lipolysis, and regulates liver lipid metabolism. The findings provide valuable insights into the use of SB for managing lamb body fat reserves and offer a robust basis for further research in animal bioscience.

Die Rolle von Ballaststoffen bei der Gewichtsregulation

2025-06-24
Thomas Skurk | CardioVasc

Balancing Muscle Mass and Energy Needs in A Female Strength Athlete: A Case Study

2025-06-24
Menuja Deeghanu , M.S. Haseena Banu
<title>Abstract</title> This case study explores the nutritional and physiological profile of a 22-year-old female university student and competitive weightlifter engaged in an intensive training regimen. Despite her high physical activity 
 <title>Abstract</title> This case study explores the nutritional and physiological profile of a 22-year-old female university student and competitive weightlifter engaged in an intensive training regimen. Despite her high physical activity level (PAL = 2.18) and lean body composition (17.2% body fat), dietary analysis revealed substantial gaps in her macronutrient and micronutrient intake. Her daily caloric consumption averaged 1260.5 kcal, significantly below her estimated energy expenditure of 3184.89 kcal, indicating an energy deficit that may impair performance and recovery. While her dietary fat intake was within recommended limits, both protein (52.05 g/day vs. recommended 112.2 g/day) and carbohydrate intake (181.75 g/day vs.330–528 g/day) were critically inadequate for supporting muscle synthesis and anaerobic performance demands. Micronutrient deficiencies were also noted, particularly in calcium, magnesium, iron, potassium, and omega-3 and omega-6 fatty acids, which could compromise metabolic health and athletic output. A tailored nutritional management plan was developed, emphasizing increased protein (1.7 g/kg), carbohydrate (6 g/kg), and healthy fat intake (25% of total calories), with attention to nutrient timing, especially around training sessions. Creatine monohydrate supplementation was deemed appropriate and safe. Ongoing monitoring of body composition, dietary intake, and clinical biomarkers was recommended to guide adjustments and ensure long-term performance sustainability. The case highlights the critical role of personalized sports nutrition and education in meeting the complex demands of elite female strength athletes and preventing potential health and performance impairments.

SARMs, Metabolic Modulators and Growth Hormone Secretagogues in Suspected Illegal Medicines, Bought as Sport Performance Enhancers: A Retro‐ and Prospective Study Within the GEON

2025-06-23
M. Mendoza Barrios , Eric Deconinck , CĂ©line Vanhee +7 more | Drug Testing and Analysis
Although the abuse of muscle-building compounds in elite sports is already known for a long time, these products have become more popular in recreational sport over the past years. Although 
 Although the abuse of muscle-building compounds in elite sports is already known for a long time, these products have become more popular in recreational sport over the past years. Although anabolic steroids are still the most popular ones in this context, the use of other molecules with anabolic properties is on the rise. Three categories of such products are the selective androgen receptor modulators (SARMs), the metabolic modulators and the growth hormone secretagogues (GHS). Based on this trend and the outcomes of a previous market surveillance study in the domain of illegal products (MSSIP), the Falsified Medicines Working Group of the General European Official Medicines Control Laboratories (OMCL) Network (GEON) decided to conduct an MSSIP with focus on SARMs, metabolic modulators and GHS over a period of 5 years. In total 324 samples and 354 results, reported by 14 laboratories in 13 countries, members of the GEON, were taken into account, for which the majority of the samples originated from illegal distribution. Sixty-five percent of the seized products were represented as medicine, though 24% as dietary supplements, which is of concern because here the (recreational) sporter is not aware he is taking an (unapproved) pharmaceutical. Eighteen different molecules, within the scope of the study, were reported with as top 5: ibutamoren, ligandrol, ostarine, cardarine and andarine. From the limited quantitative data reported, it can be assumed that the majority of the samples contain active doses and some are even overdosed, so health risks for the consumers cannot be neglected.

Glycine Supplementation Enhances the Growth of Sow-Reared Piglets with Intrauterine Growth Restriction

2025-06-23
Shengdi Hu , David W. Long , F. W. Bazer +3 more | Animals
Glycine has the greatest rate of deposition in whole-body proteins among all amino acids in neonates, but its provision from sow’s milk meets only 20% of the requirement of suckling 
 Glycine has the greatest rate of deposition in whole-body proteins among all amino acids in neonates, but its provision from sow’s milk meets only 20% of the requirement of suckling piglets. The results of our recent studies indicate that piglets with intrauterine growth restriction (IUGR) have a reduced ability to synthesize glycine. The present study determined the role of glycine in the growth of sow-reared IUGR piglets. In Experiment 1, 56 newborn piglets (postnatal day 0) with a low birth weight (&lt;1.10 kg) were selected from 14 litters, providing 4 IUGR piglets/litter that were allotted randomly into one of four treatment groups (14 piglets/group). Piglets received oral administration of either 0, 0.1, 0.2 or 0.4 g glycine/kg body weight (BW) twice daily (i.e., 0, 0.2, 0.4 or 0.8 g glycine/kg BW/day) between 0 and 14 days of age. L-Alanine was used as the isonitrogenous control. The BWs of all piglets were recorded each week during the experiment. Two weeks after the initiation of glycine supplementation, blood and tissue samples were collected for biochemical analyses. In Experiment 2, rates of muscle protein synthesis in tissues were determined on day 14 using the 3H-phenylalanine flooding dose technique. Compared with piglets in the control group, oral administration of 0.2, 0.4 and 0.8 g glycine/kg BW/day did not affect their milk intake (p &gt; 0.05) but increased (p &lt; 0.05) concentrations of glycine in plasma by 1.52-, 1.94-, and 2.34-fold, respectively, and body weight by 20%, 37%, and 34%, respectively. The dose of 0.4 g glycine/kg BW/day was the most cost-effective. Consistent with its growth-promoting effect, glycine supplementation stimulated (p &lt; 0.05) the phosphorylation of mechanistic target of rapamycin (MTOR), eukaryotic initiation factor 4E binding protein 1 (4E-BP1), and ribosomal protein S6 kinase beta-1 (p70S6K) as well as protein synthesis in skeletal muscle, compared with the control group. Collectively, oral administration of glycine activated the MTOR signaling pathway in skeletal muscle and enhanced the growth performance of IUGR piglets. These results indicate that endogenous synthesis of glycine is inadequate to meet the needs of IUGR piglets during the suckling period and that oral supplementation with glycine to these compromized neonates can improve their growth performance.

Incorporation of Protein Hydrolysate into Rapeseed Meal-Based Materials to Improve Flexibility

2025-06-22
Sara Aquilia , Claudia Bello , Michele Pinna +5 more | Polymers
This study investigates the potential of rapeseed meal (RM), a protein-rich by-product of the rapeseed oil industry, as a raw material for the development of renewable materials. Due to the 
 This study investigates the potential of rapeseed meal (RM), a protein-rich by-product of the rapeseed oil industry, as a raw material for the development of renewable materials. Due to the presence of antinutritional compounds, rapeseed meal is underutilized, primarily in low-value applications such as animal feed. In this work, rapeseed meal protein hydrolysates were enzymatically obtained and incorporated as plasticizers into rapeseed meal-based materials to improve their mechanical properties, water permeability, and thermal stability. Collagen hydrolysate has also been utilized as a low-cost additive to further enhance the material performance. The glycerol content was reduced to address permeability and migration issues associated with hydrophilic plasticizers. The results demonstrated that the incorporation of hydrolysates into rapeseed meal-based materials modulated thermal stability, water permeability, and mechanical properties—particularly elongation at break and flexibility. The latter increased proportionally with the hydrolysate content of RM-based materials. Additionally, aerobic biodegradation behavior, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) supported the material’s favorable performance characteristics, highlighting the potential of rapeseed meal as a viable, biodegradable alternative for sustainable materials in industrial applications.

Concentration Changes in Plasma Amino Acids and Their Metabolites in Eventing Horses During Cross-Country Competitions

2025-06-22
Flora Philine Reemtsma , Johanna Giers , Stephanie Horstmann +2 more | Animals
Plasma amino acid (PAA) concentration in horses vary according to the exercise type. This study evaluated the changes in PAA levels and the associated metabolites, urea and ammonia, following short-duration, 
 Plasma amino acid (PAA) concentration in horses vary according to the exercise type. This study evaluated the changes in PAA levels and the associated metabolites, urea and ammonia, following short-duration, high-intensity cross-country exercise in eventing horses. Twenty eventing horses participated in 55 rides at 14 international competitions (2* to 4* levels) across five venues in Germany and Poland. Blood samples were collected at four timepoints: before exercise (TP0), at 10 min (TP1), and at 30 min (TP2) post-exercise, as well as in the morning on the day after the competition (TP3). A total of 23 different PAAs and two metabolites (ammonia and urea) were analyzed. PAA concentration difference over time was assessed by a mixed ANOVA. Significant fluctuations were observed in 18/25 parameters. For 21/23 PAAs, levels increased at TP1 and/or TP2, while cysteine concentrations decreased. Concentrations returned to pre-competition levels for 21/23 PAAs by TP3. Proline levels remained elevated (p = 0.002), while those of glycine significantly decreased (p = 0.027) at TP3. Plasma ammonia and urea levels increased at TP1, TP2 and TP3. This study provides foundations for supplementation strategies and can inform future works exploring PAAs’ role in performance and training adaptation in eventing horses and their potential as performance-related biomarkers.

Dynamic electro‐clinical features in Guanidinoacetate N‐methyltransferase deficiency: A familial case series

2025-06-21
Mariapaola Schifino , Emanuele Bartolini , Stefano Pagano +3 more | Epilepsia Open
Abstract Guanidinoacetate N‐methyltransferase deficiency is an inborn error of creatine metabolism, responsible for the absent conversion of guanidinoacetic acid into creatine, resulting in cerebral creatine deficit. It could present a 
 Abstract Guanidinoacetate N‐methyltransferase deficiency is an inborn error of creatine metabolism, responsible for the absent conversion of guanidinoacetic acid into creatine, resulting in cerebral creatine deficit. It could present a variety of symptoms such as neurodevelopmental delay, epilepsy, movement disorder (ataxia, dystonia, and chorea), and behavioral disturbances. After intellectual disability, epilepsy is the second most frequent expression of the disorder, usually arising during infancy with febrile seizures that are typically followed by generalized seizures and electroencephalographic anomalies. Herein, we describe three siblings with the same homozygous truncating variant in GAMT , all of whom showed significant global developmental delay during early infancy. The eldest two developed initially neglected atypical absences, preceded by focal motor seizures in the older brother, with complete remission with antiseizure medications and dietary treatment. Despite seizure freedom, during follow‐up, both developed overt focal epileptiform discharges that have persisted after 2 years of creatine supplementation. Neither seizures nor electroencephalographic abnormalities were noted in the youngest brother who took advantage of an earlier diagnosis and treatment. The dynamic electroclinical pattern we observed has never been reported beforehand. Further studies are needed to assess the long‐term prognosis of epilepsy in patients who have introduced dietary treatment after the seizure onset. Plain Language Summary GAMT deficiency is a rare genetic disorder that prevents the brain from getting enough creatine, leading to developmental delay, seizures, movement disorders, and behavior problems. This condition often starts in infancy with seizures in fever and can be partially limited by creatine supplementation. In this paper, we present three siblings with the same mutation. The older two had seizures that improved with treatment, but their brain activity remained abnormal. The youngest, diagnosed and treated earlier with supplementation, did not develop epilepsy. More research is needed to understand electro‐clinical features of this condition and the long‐term effects of early or late dietary treatment.

Does Protein Ingestion Timing Affect Exercise-Induced Adaptations? A Systematic Review with Meta-Analysis

2025-06-21
Rafael A. Casuso , Lennert Goossens | Nutrients
Background/Objectives: Muscle strength and mass are key determinants of exercise performance and a hallmark of health span. Recently, several meta-analyses have concluded that protein supplementation timing does not alter muscle 
 Background/Objectives: Muscle strength and mass are key determinants of exercise performance and a hallmark of health span. Recently, several meta-analyses have concluded that protein supplementation timing does not alter muscle strength and mass gains. However, these meta-analyses did not directly compare several supplementation timings within the same study, thus limiting their conclusions. The objective of this study was to conduct a meta-analysis including only studies directly comparing protein intake before and after exercise. Methods: Three databases (PubMed (n = 748), Web of Science (n = 1458), and Scopus (n = 1105)) and reference lists were searched from inception to January 15, 2024 to identify studies where subjects were randomized to consume protein before or after each training session for at least 4 weeks. Risk of bias was evaluated using the critical appraisal checklist for RCT. A meta-analysis was performed using random-effect models. The outcomes were strength and lean body mass. Results: Of 3311 records identified, 6 reports (5 studies) were eligible and all were considered of sufficient quality to be included in the meta-analysis. For the chest press exercise, there was no effect of protein timing on repeated maximum (RM) (SMD: 0.07; 95% CI: −0.248 to 0.395; I2 = 0%, p = 0.653). For the leg press exercise, consuming protein before training increased the RM more than after training (SMD: 0.70; 95% CI: 0.005 to 1.388; I2 = 31%, p = 0.048). However, subgroup analysis did not reveal a significant effect difference (p = 0.07) for leg press and chest press. Lean body mass was not differently modulated by protein supplementation timing (SMD: −0.08; 95% CI: −0.398 to 0.244; I2 = 0%, p = 0.641). Conclusions: Protein timing does not importantly modify exercise-induced changes in lean body mass. While upper and lower limbs strength may respond differently, more investigation is needed to reach a more robust conclusion. The present review was registered in PROSPERO (CRD42023464503).

Whey Protein Nutrition in Sports: Action Mechanisms and Gaps in Research

2025-06-21
Pan Dong , Zidong Zhang , Na Liu +1 more | Current Nutrition Reports

Neither pre-sleep nor post-exercise protein consumption influences resistance exercise training adaptations in older adults

2025-06-20
Alex Klemp , Michael J. Ormsbee , Ming‐Chia Yeh +4 more | Journal of the International Society of Sports Nutrition
Limited data exists that compare pre-sleep versus post-exercise protein intake during resistance exercise training (RET) in older adults. This study examined whether 40 g of protein consumed post-exercise (PRP) or 
 Limited data exists that compare pre-sleep versus post-exercise protein intake during resistance exercise training (RET) in older adults. This study examined whether 40 g of protein consumed post-exercise (PRP) or pre-sleep (PSP) enhances muscle thickness (MT) and strength compared to RET alone (RETO) in older men. Thirty untrained older men (65.7 ± 4.0 yrs) completed 12 weeks of supervised RET (2×/week) and were randomized to PRP (n = 9), PSP (n = 11), or RETO (n = 10). MT of the vastus lateralis (VL), rectus femoris (RF), and vastus intermedius (VI) and 1-repetition maximum (1-RM) for leg and chest press were assessed at weeks 0, 6, and 12. VL (0 to 12 weeks: + 0.16 cm, 95% C.I. [0.06, 0.25]), RF (0 to 12 weeks: + 0.13 cm, 95% C.I. [0.03, 0.23]), and VI MT (0 to 12 weeks: + 0.18 cm, 95% C.I. [0.05, 0.31]) and chest press (0 to 12 weeks: + 10.9 kg, 95% C.I. [5.50, 16.3]) and leg press (0 to 12 weeks: + 28.3 kg, 95% C.I. [19.63, 37.1]) 1-RM increased (p < 0.050) with no group differences. Consuming 40 g of protein post-exercise or pre-sleep did not enhance RET-induced improvements in muscle thickness or strength in older adults with adequate baseline protein intake (≄1.0 g/kg/day). RET alone elicited significant gains, emphasizing that adherence to training and meeting daily protein requirements are more critical than timing strategies for untrained older adults. ClinicalTrials.gov identifier: NCT05922475, 06/23/2023, retrospectively registered.

A INFLUÊNCIA DA NUTRIÇÃO LIPÍDICA EM ATLETAS DE ALTO RENDIMENTO: UMA REVISÃO SISTEMÁTICA

2025-06-20
Maria Clara Borges Toledo , João Gabriel Ferreira Brustoloni , Isabel Rocha +7 more | Revista CPAQV - Centro de Pesquisas Avançadas em Qualidade de Vida
Os lipĂ­dios sĂŁo componentes fundamentais da dieta de atletas de alto rendimento, especialmente por sua densidade energĂ©tica e papel na preservação da função celular, hormonal e recuperação muscular. Esta revisĂŁo 
 Os lipĂ­dios sĂŁo componentes fundamentais da dieta de atletas de alto rendimento, especialmente por sua densidade energĂ©tica e papel na preservação da função celular, hormonal e recuperação muscular. Esta revisĂŁo integrativa teve como objetivo analisar a influĂȘncia da nutrição lipĂ­dica no desempenho esportivo, com foco na dieta cetogĂȘnica e na suplementação de ĂĄcidos graxos ĂŽmega-3. A busca foi realizada nas bases de dados PubMed, LILACS e BVS, considerando publicaçÔes entre 2020 e 2025, resultando na seleção de oito artigos que atenderam aos critĂ©rios de inclusĂŁo. A literatura aponta que dietas cetogĂȘnicas, caracterizadas pela alta ingestĂŁo de gorduras e baixa de carboidratos, promovem maior oxidação lipĂ­dica e podem reduzir a gordura corporal, embora haja controvĂ©rsias quanto Ă  preservação da massa muscular devido Ă  depleção de glicogĂȘnio. Paralelamente, a suplementação com EPA e DHA tĂȘm demonstrado efeitos anti-inflamatĂłrios, neuroprotetores e de promoção da recuperação muscular, com impacto positivo na regulação gĂȘnica relacionada ao metabolismo energĂ©tico. Estudos indicam redução de citocinas inflamatĂłrias como IL-1ÎČ e IL-6, alĂ©m de melhora na dor muscular tardia e menor dano muscular apĂłs exercĂ­cio. Contudo, a resposta Ă  dieta e Ă  suplementação varia conforme o tipo de esporte, intensidade do treinamento e caracterĂ­sticas individuais do atleta. Conclui-se que a nutrição lipĂ­dica, quando estrategicamente planejada, pode contribuir de forma significativa para a performance e recuperação de atletas de elite, sendo essencial a personalização das estratĂ©gias nutricionais conforme as demandas especĂ­ficas de cada modalidade esportiva.

Erkek Voleybolcuların Beslenme Tutumlarının, Egzersiz Bağımlılıklarının ve Egzersizde DavranÄ±ĆŸsal DĂŒzenlemelerinin Ä°liƟkisi

2025-06-20
GönĂŒl Rezzan Tizar , Metin Can KALAYCI , Ercan Tizar +3 more | Dicle Medical Journal / Dicle Tip Dergisi
Amaç: Bu araƟtırma erkek voleybolcuların beslenme tutumlarının, egzersiz bağımlılıklarının ve egzersizde davranÄ±ĆŸsal dĂŒzenlemelerinin iliƟkisini incelemek amacıyla yapılmÄ±ĆŸtır. Yöntemler: AraƟtırma, belirlenen amaç doğrultusunda nicel araƟtırma tĂŒrĂŒnde korelasyonel araƟtırma desenine uygun olarak 
 Amaç: Bu araƟtırma erkek voleybolcuların beslenme tutumlarının, egzersiz bağımlılıklarının ve egzersizde davranÄ±ĆŸsal dĂŒzenlemelerinin iliƟkisini incelemek amacıyla yapılmÄ±ĆŸtır. Yöntemler: AraƟtırma, belirlenen amaç doğrultusunda nicel araƟtırma tĂŒrĂŒnde korelasyonel araƟtırma desenine uygun olarak gerçekleƟtirildi. AraƟtırmanın evrenini TĂŒrkiye’deki erkek voleybolcular oluƟtururken; örneklemini ise yaƟları 18 ile 32 arasında değiƟen toplam 170 erkek voleybolcu oluƟturdu. AraƟtırmada kullanılan veri toplama aracı iki bölĂŒmden oluƟmakta olup, birinci bölĂŒmde katılımcıların demografik bilgilerini belirlemeye yönelik “KiƟisel Bilgi Formu”, ikinci bölĂŒmde ise katılımcıların beslenme tutumları beslenme tutumlarını belirlemeye yönelik “Beslenme Tutum Ölçeği”, egzersiz bağımlılıklarını belirlemeye yönelik “Egzersiz Bağımlılığı Ölçeği” ve egzersizde davranÄ±ĆŸsal dĂŒzenlemelerini belirlemeye yönelik ise “Egzersizde DavranÄ±ĆŸsal DĂŒzenlemeler Ölçeği” kullanılmÄ±ĆŸtır. Verilerin analizinde SPSS istatistik paket programı kullanılmÄ±ĆŸtır. Anlamlılık dĂŒzeyi p˂0,05 olarak kabul edilmiƟtir. Bulgular: Elde edilen sonuçlara göre; erkek voleybolcuların beslenme tutumlarının, egzersiz bağımlılıklarının ve egzersizde davranÄ±ĆŸsal dĂŒzenlemeleri arasında anlamlı bir iliƟki bulunmadı(p

ÎČ-Hydroxy-ÎČ-methyl butyrate (HMB) supplementation elevates testosterone levels without significant changes to cortisol, IGF-1, or growth hormone in adults: a GRADE-assessed systematic review and meta-analysis of controlled trials

2025-06-19
Mohammad Vesal Bideshki , Behrad Sadeghi , Mehrdad Behzadi +3 more | Frontiers in Nutrition
Background and aim Increasing interest in improving physical performance and muscle mass in adults has highlighted the potential benefits of ÎČ -hydroxy-ÎČ-methyl butyrate (HMB) supplementation. While numerous studies have been 
 Background and aim Increasing interest in improving physical performance and muscle mass in adults has highlighted the potential benefits of ÎČ -hydroxy-ÎČ-methyl butyrate (HMB) supplementation. While numerous studies have been conducted in this area, the hormonal response to HMB remains unclear. We hypothesized that HMB supplementation would significantly increase anabolic hormone levels, particularly testosterone, while not affecting the cortisol, IGF-1, or growth hormone levels in adults. Methods A comprehensive search of databases, including PubMed, Web of Science, and Scopus, was performed to identify relevant studies until January 2024. The protocol was registered with Prospero (CRD42024552074). The studies evaluated the impact of HMB supplementation on hormonal outcomes, including testosterone, cortisol, insulin-like growth factor-1 (IGF-1), and growth hormone (GH). Utilizing a random-effects model, the standardized mean differences (SMDs) and their corresponding 95% confidence intervals (CIs) were computed, and the GRADE framework was applied. Results A total of 15 controlled trials (CTs) comprising 712 participants were included. HMB supplementation significantly increased testosterone levels (SMD: 0.82, 95% CI: 0.35, 1.29, p = 0.001). However, no significant changes were observed in the cortisol (SMD: −0.39, 95% CI: −0.92, 0.14, p = 0.14), IGF-1 (SMD: −0.18, 95% CI: −0.54, 0.18, p = 0.33), and GH (SMD: 0.04, 95% CI: −0.73, 0.82, p = 0.91) levels. According to the GRADE criteria, the quality of evidence was rated as ranging from low to high. Conclusion HMB supplementation significantly elevates testosterone levels in adults without distinct impacts on other hormonal pathways. However, it does not appear to significantly influence the cortisol, IGF-1, or GH levels.

A Comprehensive Study on the Nutritional Profile and Shelf Life of a Custom-Formulated Protein Bar Versus a Market-Standard Product

2025-06-19
Corina Duda-Seiman , Liliana Mititelu-Tarțău , Simona Biriescu +6 more | Foods
With growing interest in healthy lifestyles, protein bars have gained popularity. However, many commercial bars contain excessive calories, sugar, and artificial additives that undermine their health benefits. This study aimed 
 With growing interest in healthy lifestyles, protein bars have gained popularity. However, many commercial bars contain excessive calories, sugar, and artificial additives that undermine their health benefits. This study aimed to develop a protein bar using natural ingredients with a balanced macronutrient profile. The protein bar formulation used soy protein extract, a plant-based protein source, known for its complete amino acid profile but limited in methionine, which was complemented by oats to nutritionally balance this deficiency. A database was created to evaluate the cost-effectiveness of commercially available protein bars based on consumer feedback. The experimental bar was tested for nutritional value, shelf life, and physiological impact, using only natural ingredients for texture, flavor, and stability. The experimental protein bar had higher protein and fiber content than a selected commercial bar but a shorter shelf life (7 days vs. 90 days) due to the absence of preservatives. The database helped identify target consumer groups and ensure the product was affordable and nutritionally effective. This study demonstrates that using natural, complementary ingredients can create a protein bar with a more balanced nutrient profile while avoiding harmful additives. The final product supports muscle protein synthesis through its high-quality protein content and promotes glycemic control and satiety via its fiber-rich, low-sugar formulation and metabolic processes, offering a healthier alternative to commercial options, with a focus on consumer health and cost-effectiveness.

THE IMPACT OF PROTEIN SUPPLEMENTATION ON HUMAN HEALTH: A LITERATURE REVIEW OF RENAL, HEPATIC, CARDIOVASCULAR AND GASTROINTESTINAL EFFECTS

2025-06-19
BartƂomiej Czerwiec , Malwina M. Wojtas , Julia SkowroƄska-Borsuk +7 more | International Journal of Innovative Technologies in Social Science
Introduction and purposeProtein is a key nutrient, especially for physically active individuals. The growing popularity of whey protein (WP) supplementation among athletes and fitness enthusiasts is driven by its benefits 
 Introduction and purposeProtein is a key nutrient, especially for physically active individuals. The growing popularity of whey protein (WP) supplementation among athletes and fitness enthusiasts is driven by its benefits for muscle regeneration and metabolism. However, concerns arise regarding excessive and unmonitored intake, particularly its effects on kidney and liver function, gut microbiota, and cardiovascular health. This review aims to summarize current knowledge on the health impacts of WP, highlighting both benefits and risks. MethodsA literature review was conducted using PubMed, Scopus, and Google Scholar with terms such as “whey protein”, “adverse effects”, “liver toxicity”, “kidney function”, “gut microbiota”, and “cardiovascular health”. Priority was given to studies from the last decade, including clinical trials and systematic reviews. Brief description of the state of knowledgeWP supports muscle growth, insulin sensitivity, and satiety. It may positively affect cardiovascular health by increasing GLP-1 levels, which help reduce blood glucose, blood pressure, and body weight. Nonetheless, excessive intake may strain liver and kidney function, particularly in those with pre-existing conditions. Effects on gut microbiota are mixed while some studies show anti-inflammatory benefits, others suggest dysbiosis. A key issue is the lack of dosage standardization and individual consultation, increasing misuse risk. SummaryWP supplementation can offer health and performance benefits when used responsibly. Risks, especially for liver and kidneys, must be considered. Individualized guidance and more standardized research are essential to ensure safe and effective use.

Effects of a Blend of Trisodium Citrate, Creatine Monohydrate, Leucine, and Blueberry Extract on Training-Induced Changes in Leg Extension Strength, Endurance, and Muscle Size

2025-06-19
Trevor D. Roberts , Jocelyn E. Arnett , Dolores G. Ortega +6 more | Journal of Dietary Supplements
Although creatine monohydrate (CM), leucine, and polyphenols have been independently researched, there is a lack of research on the effects of a supplementation blend containing trisodium citrate, CM, leucine, and 
 Although creatine monohydrate (CM), leucine, and polyphenols have been independently researched, there is a lack of research on the effects of a supplementation blend containing trisodium citrate, CM, leucine, and blueberry extract (TCLB) on muscle strength, endurance, and size. This study compared the effects of 8 wk of supplementation with TCLB versus CM and placebo (PLA) combined with resistance training on leg extension strength, endurance, and muscle size. Twenty-eight recreationally active men ingested either TCLB (n = 10), CM (n = 10), or PLA (n = 8) during 8 wk of resistance training. Leg extension 1-repetition maximum (1RM), leg extension repetitions-to-failure at ∌80% of pre-training 1RM, individual quadriceps cross-sectional area (CSA) values, and the sum of the CSA values (CSAsum) were assessed at pre-training and post-training. Separate one-way ANCOVAs covaried for pre-training values were used to analyze differences in adjusted post-training means. Separate Chi-squared tests were used to analyze differences between groups in the proportion of subjects that exceeded the minimal important difference (MID). There were no group differences (p > 0.05) for leg extension 1RM, leg extension repetitions-to-failure, rectus femoris CSA, vastus lateralis CSA, or vastus medialis CSA. The TCLB group demonstrated greater (p ≀ 0.05) adjusted post-training means and proportions of subjects who exceeded the MID for the CSAsum and vastus intermedius CSA than the PLA group, but the TCLB group did not differ (p > 0.05) from the CM group for those variables. The CM group (p ≀ 0.05) exhibited a greater proportion of subjects who exceeded the MID for the CSAsum than the PLA group. These findings indicated that 8 wk of supplementation with TCLB and CM combined with resistance training increased the overall quadriceps muscle size greater than the PLA, but TCLB did not differ from CM. Furthermore, the groups did not differ in the training-induced increases in leg extension strength and endurance.

Barriers and enablers to implementing the UEFA Consensus Statement on Nutrition: insights from sport nutrition practitioners in the English Premier League

2025-06-18
Nessan Costello , Stephanie Roe , Susan H. Backhouse +1 more | Science and Medicine in Football
Despite the importance of evidence-based nutrition in elite football, Premier League players often exhibit sub-optimal dietary behaviours, highlighting the need for improved guideline implementation. This study used the COM-B model 
 Despite the importance of evidence-based nutrition in elite football, Premier League players often exhibit sub-optimal dietary behaviours, highlighting the need for improved guideline implementation. This study used the COM-B model and Theoretical Domains Framework (TDF) to explore sport nutritionists' perceived barriers and enablers to applying the UEFA Consensus Statement on Nutrition. Twelve lead sport nutritionists from English Premier League clubs took part in semi-structured interviews (1 hour ± 44 mins). The interviews were structured using the COM-B and TDF and analysed thematically. Six key themes were identified, representing six barriers and two enablers, encompassing all three components of the COM-B model and seven TDF domains. Psychological capability barriers included challenges in changing players' dietary behaviours. Reflective motivation was hindered by doubts regarding the scientific basis of carbohydrate and body composition guidelines, alongside concerns over players' ability to practically adhere to carbohydrate recommendations. Physical and social opportunity barriers involved restricted time and support for ongoing personal and professional development. Practitioners desired greater autonomy over the nutrition service, which was either enabled or constrained by the club' social environment. As an enabler, female practitioners' strong interpersonal skills (psychological capability) supported implementation; however, they also faced gender-related challenges navigating male predominate environments, making the social opportunity for implementation more complex. Implementing nutrition guidelines in elite football is challenging. Overcoming barriers-by boosting practitioner confidence, belief in guidelines, professional development support, and autonomy-is key to improving uptake of UEFA recommendations and enhancing player dietary adherence in the English Premier League.

Post-Exercise Whey Protein Supplementation: Effects on IGF-1, Strength, and Body Composition in Pre-Menopausal Women, a Randomised Controlled Trial

2025-06-18
M. A. F. Murray , Lara Vlietstra , A. Best +3 more | Nutrients
Introduction: The purpose of this study was to evaluate effects of post-exercise protein supplementation with combined resistance and interval training on total insulin-like growth factor-1 (IGF-1) concentration, strength (3RM), and 
 Introduction: The purpose of this study was to evaluate effects of post-exercise protein supplementation with combined resistance and interval training on total insulin-like growth factor-1 (IGF-1) concentration, strength (3RM), and body composition (DXA) in untrained pre-menopausal women. Methods: Twenty-seven women (33.6 ± 9.2 years, 69.4 ± 12.4 kg, 25.5 ± 3.7 kg/m2) were randomised into a control (CON) or moderate protein group (PRO) (3 g, 24 g, resp.) and completed twelve weeks of upper-body resistance (2×/week) and high-intensity interval cycle training (3×/week). Linear mixed-effects model analyses were conducted. Results: PRO had a greater daily protein intake (5.0 ± 16.6 g, 20.5 ± 13.9 g, CON, PRO, resp., p = 0.025), with no change in IGF-1 (-6.0 ± 27.7 ”g/L, -2.1 ± 27.8 ”g/L, CON, PRO, resp., p = 0.920). Total lean mass increased (0.84 ± 0.80 kg, 0.56 ± 1.4 kg, CON, PRO, resp., p = 0.009), and all strength measures increased in both groups (19-113%, p < 0.05). Conclusions: Untrained women can increase strength and lean mass over twelve weeks of combined resistance and interval training. Post-exercise protein supplementation had little effect, despite increasing protein intake by ~20 g/day in the PRO group. IGF-1 was not associated with any outcome measure.

Nutrition and Soccer

2025-06-18
Andrew T. Hulton , D. MacLaren | Routledge eBooks

Nutritional intake, sports nutrition knowledge and energy availability in recreational female football players

2025-06-17
Philip Woodbridge , Kevin Campbell-Karn , Fiona McCormack | Research in Sports Medicine
The study aimed to assess the nutritional intake, sports nutrition knowledge and risk of low energy availability (LEA) and injury in recreational female football (soccer) players, a growing but understudied 
 The study aimed to assess the nutritional intake, sports nutrition knowledge and risk of low energy availability (LEA) and injury in recreational female football (soccer) players, a growing but understudied population. Players were recruited from Tier 4-5 clubs of the female domestic league in England (n = 54) aged 22.7 years ± 6.1, weight 64.7 kg ± 8.4, height 165.9 cm ± 5.7. Nutritional intake was quantified using 3-day food diaries, sports nutrition knowledge was assessed using the 88-item Sports Nutrition Knowledge Low Questionnaire (SNKQ) and the risk of LEA was assessed using the LEA in Females Questionnaire (LEAF-Q). LEA was identified in 55.6% of the players using the cut-off of 30 g/kg fat free mass. Mean energy intake (1730 kcal) was identified as significantly lower than energy intake targets (2195 kcal) (p < 0.001). The mean score for the SNKQ was 55.6% ± 10.6 with 29.6% identified as having poor nutritional knowledge. Nutritional knowledge had a weak positive correlation with energy intake (r = 0.305) and energy availability (r = 0.268). LEAF-Q identified 42.6% of the players as at risk of LEA and therefore injury. The results suggest that recreational female football players may be at risk of developing LEA and injury.

Improvement of sports nutrition knowledge by a dual method education program in track and field athletes: a randomized controlled trial

2025-06-17
Ranil Jayawardena , Kalani Weerasinghe , Indumathie Nanayakkara +3 more | Journal of the International Society of Sports Nutrition
Athletes with strong sports nutrition knowledge are believed to have sound nutritional practices and better performance. This study aimed to evaluate the effectiveness of a dual-method personalized nutrition education program 
 Athletes with strong sports nutrition knowledge are believed to have sound nutritional practices and better performance. This study aimed to evaluate the effectiveness of a dual-method personalized nutrition education program in improving sports nutrition knowledge (SNK) among Sri Lankan track and field athletes. This parallel-group, randomized controlled trial recruited national-level track and field athletes aged 18 and above. The intervention group (IG) received personalized sports nutrition consultations at 0, 4th, and 8th weeks, along with online educational materials via WhatsApp from weeks 10 to 16, while the control group (CG) did not receive any intervention. A per-protocol analysis was followed, and t-tests were used to compare the means. Of the 30 participants enrolled, 13 from IG and 14 from CG completed the study. Following the 16-week intervention, the IG demonstrated significant improvements in total nutrition knowledge (TNK) relative to the CG (IG: 34.41 ± 4.15 vs. CG: 20.96 ± 4.38; p = 0.01), with significant increases in general nutrition knowledge (GNK) (IG:24.54 ± 3.66 vs. CG:15.64 ± 2.33; p = 0.004) and SNK (9.87 ± 3.87 vs. 5.32 ± 4.07; p = 0.006). Changes in TNK were also significantly greater in the IG compared to the CG; (IG:9.45 ± 0.10 vs. CG: -2.63 ± 0.37; p < 0.0001), GNK (IG:4.47 ± 0.08 vs. CG: -1.28 ± 0.09; p < 0.0001), and SNK (IG:4.99 ± 0.72 vs. CG: -1.25 ± 0.74; p < 0.0001). The 16-week dual-method nutrition education intervention was effective in improving TNK, GNK, and SNK among track and field athletes in Sri Lanka. This trial is registered at the Sri Lanka Clinical Trials Registry (SLCTR/2024/013), Universal Trial Number (UTN): U1111-1304-8890 on 10 April 2024.

Dietary Behaviors in Gaelic Football: A Mixed-Methods Exploration of Physical, Psychological, and Environmental Influences

2025-06-16
M. Renard , Fiona Lavelle , David T. Kelly +2 more | Research Square (Research Square)
<title>Abstract</title> <bold>Background</bold> Gaelic football is a high-intensity, intermittent team sport played at an amateur level, though its training demands often resemble those of professional sport. Previous research has indicated suboptimal 
 <title>Abstract</title> <bold>Background</bold> Gaelic football is a high-intensity, intermittent team sport played at an amateur level, though its training demands often resemble those of professional sport. Previous research has indicated suboptimal energy and carbohydrate intake among players, which may impair performance and recovery.<bold>Objective</bold> This study aimed to explore the behavioural determinants of dietary intake in Gaelic football players, using the COM-B model to identify modifiable factors to inform future nutrition interventions.<bold>Methods</bold> A mixed-methods, cross-sectional design was used. An online questionnaire captured sociodemographic data, nutrition knowledge, and cooking and food skills confidence. Semi-structured interviews explored dietary influences, and a 5-day estimated food diary assessed dietary intake. Data were integrated to provide a comprehensive understanding of dietary behaviours.<bold>Results</bold> A purposive sample of 20 players (mean age 27.1 ± 5.5 years) participated. The mean nutrition knowledge score was 54.7 ± 10.5%, cooking skills confidence was 62.3 ± 18.9, and average daily energy intake was 2482 ± 788 kcal. Carbohydrate intake averaged 3.8 ± 0.9 g/kg/day, protein 1.9 ± 0.5 g/kg/day, and fat 31.7 ± 4.8% of total energy. Thematic analysis identified seven key influences on dietary behaviour, including performance-driven motivation, variability in applying nutrition knowledge, time and resource constraints, and the influence of social and environmental support.<bold>Conclusions</bold> Findings emphasise the need for holistic, context-sensitive strategies to improve dietary behaviours. Recommended approaches include enhancing food skills, tailoring support from nutrition staff, and integrating practical education into training settings. These findings may apply to other amateur and high-level recreational athletes.

The Impact of Endurance Running Training on the Lipid Profile in Professional and Amateur Athletes: A Comprehensive Review

2025-06-16
Adam Zarzycki , Dominika Nowak , Magdalena PrĂłchnicka +7 more | Quality in Sport
Endurance running is one of the most popular forms of physical activity, influencing many aspects of health, including lipid metabolism. Regular endurance exercise positively affects the lipid profile, which plays 
 Endurance running is one of the most popular forms of physical activity, influencing many aspects of health, including lipid metabolism. Regular endurance exercise positively affects the lipid profile, which plays a key role in preventing cardiovascular diseases (CVD). Dyslipidemia, characterized by abnormal levels of cholesterol and triglycerides, is a significant risk factor for the development of these diseases. The purpose of this study is to analyze the impact of endurance running on the lipid profile of amateur and professional athletes, considering the differences in metabolic adaptations resulting from training intensity and lifestyle. A review of the available literature was conducted by searching official databases such as Pubmed and Google Scholar using the following keywords: dyslipidemia, endurance running, cardiovascular, lipoprotein lipase. The results indicate that regular endurance running enhances LPL activity, fatty acid oxidation, and cholesterol transport. Both moderate and high-intensity training lower LDL-C and triglycerides, while raising HDL-C. Lipid responses vary between amateur and professional athletes due to differences in training and lifestyle. Overall, endurance running with a healthy lifestyle effectively improves lipid profiles and reduces cardiovascular risk.

Relationship between Balanced Nutrition and Sports Performance in Swimmers

2025-06-16
Ioana Bardan , Elena Vizitiu Lakhdari | Bulletin of the Transilvania University of BraƟov Series IX Sciences of Human Kinetics
The study investigates the relationship between balanced nutrition and sports performance in swimmers, analyzing the impact of nutritional intake on physical development, exercise capacity, and post-training recovery. Methodology: 50 swimmers 
 The study investigates the relationship between balanced nutrition and sports performance in swimmers, analyzing the impact of nutritional intake on physical development, exercise capacity, and post-training recovery. Methodology: 50 swimmers aged 8 to 14 were assessed by a questionnaire applied to parents, targeting the frequency of meals, intake of macronutrients and micronutrients, hydration, and use of supplements. The results emphasize the importance of a diet adapted to the metabolic requirements of swimmers, highlighting the need for personalized nutritional diaries to optimize sports performance and prevent dysfunctions associated with intense effort.

Effect of rumen-protected guanidinoacetic acid provision as a dietary supplement on the growth, slaughter performance, and meat quality in simmental bulls

2025-06-15
Jing Zhang , Chao Xue , Joshua M. Lang +2 more | Meat Science

Effect of Low‐To‐Moderate Exogenous Carbohydrate Supplementation on Time to Exhaustion During Constant Load Intense Cycling in Healthy Individuals. A Double‐Blind, Randomised and Placebo‐Controlled Crossover Trial

2025-06-14
Janis Schierbauer , Oscar Altenberg , Thomas VoĂŻt +2 more | European Journal of Sport Science
ABSTRACT Exogenous carbohydrate (CHO) supplementation during exercise is an efficient strategy to enhance endurance performance. However, the effects of low‐to‐moderate amounts of exogenous CHO on time to exhaustion (TTE) have 
 ABSTRACT Exogenous carbohydrate (CHO) supplementation during exercise is an efficient strategy to enhance endurance performance. However, the effects of low‐to‐moderate amounts of exogenous CHO on time to exhaustion (TTE) have not been fully investigated. Nineteen healthy moderately active participants (26.2 ± 1.7 years and BMI: 22.4 ± 2.3 kg·m −2 ) performed four TTE tests at the second lactate turn point (LTP2) in a double‐blind, randomised and placebo‐controlled setting consuming either 20, 40 and 60 g·L −1 ·h −1 of a glucose and fructose combination (CHO 20, CHO 40 and CHO 60 ) or a placebo (PLA). Glucose [Glu − ] and lactate concentrations [La − ] as well as ventilatory, heart rate (HR) and rating of perceived exertion (RPE) values were recorded during the tests. There were no statistically significant differences in TTE (PLA: 32.5 ± 9.6 min, CHO 20 : 35.9 ± 14.5 min, CHO 40 : 35.1 ± 12.9 min, CHO 60 : 38.0 ± 17.5 min and p = 0.11). Within each trial arm, no statistically significant differences were found between pre‐ and post‐exercise [Glu − ] ( p &gt; 0.05). Post‐exercise [Glu − ] for CHO 60 were significantly higher when compared to PLA ( p = 0.03). Lastly, mean ventilatory parameters as well as HR and RPE during exercise showed no statistically significant differences between trial arms ( p &gt; 0.05). Low‐to‐moderate amounts of exogenous CHO do not increase TTE in healthy moderately active individuals when compared to a placebo. Therefore, when exercising for less than 60 min at high intensities, exogenous CHO supplementation is not necessary if a CHO rich diet is followed prior to exercise. Trial Registration DRKS‐ID: DRKS00030531

Standardized Amino Acid Digestibility Estimates of Individual Ingredients from Precision-Fed Cecectomized Roosters Are Additive

2025-06-14
Meredith A Smola , P.L. Utterback , C.M. Parsons +1 more | Animals
It is important to determine whether amino acid (AA) digestibility values from individual ingredients are additive and predictive for mixed diets. This study had two objectives: (1) measure the AA 
 It is important to determine whether amino acid (AA) digestibility values from individual ingredients are additive and predictive for mixed diets. This study had two objectives: (1) measure the AA concentrations and digestibilities of individual protein ingredients and their mixtures and (2) determine whether the AA digestibilities of the individual ingredients were additive in their mixtures. Forty-two cecectomized roosters were randomly allotted to one of seven ingredients: dehydrated egg (EGG); pea protein (PP); corn-gluten meal (CGM); a mixture of PP and EGG at a 25:75 ratio (PP25); a mixture of PP and EGG at a 75:25 ratio (PP75); a mixture of CGM and EGG at a 25:75 ratio (CGM25); and a mixture of CGM and EGG at a 75:25 ratio (CGM75). Endogenous loss corrections were made using five fasted additional cecectomized roosters. All ingredients had indispensable AA digestibilities &gt;85% except histidine for CGM. Amino acid digestibilities were typically the highest for EGG, PP25, and CGM25. There were no differences between measured and predicted AA digestibility values, except for histidine and serine in CGM25 (p &lt; 0.05). Our results suggest that all protein-based ingredients tested were highly digestible and that the AA digestibilities obtained from individual ingredients are additive in ingredient mixtures when using the precision-fed cecectomized rooster model.

Os efeitos das prĂĄticas nutricionais em atletas de alta performance e seus impactos na longevidade

2025-06-14
Henrique Vilas Boas , Ralph Lugon , Ana Cristina de Castro Pereira Santos | Research Society and Development
Atletas de alta performance utilizam diversas estratĂ©gias nutricionais com o objetivo de maximizar o desempenho esportivo, muitas vezes por meio de manipulaçÔes agressivas de macronutrientes, desidratação e cortes rĂĄpidos de 
 Atletas de alta performance utilizam diversas estratĂ©gias nutricionais com o objetivo de maximizar o desempenho esportivo, muitas vezes por meio de manipulaçÔes agressivas de macronutrientes, desidratação e cortes rĂĄpidos de peso. Embora essas abordagens possam favorecer resultados imediatos em competiçÔes, evidĂȘncias cientĂ­ficas indicam que seu uso crĂŽnico pode comprometer a saĂșde metabĂłlica, renal, hormonal e intestinal, afetando negativamente a longevidade. A relação entre nutrição, microbiota, ciclo circadiano e resposta fisiolĂłgica do atleta Ă© complexa e interdependente, o que reforça a necessidade de estratĂ©gias personalizadas. Assim, o objetivo deste estudo foi discutir as prĂĄticas nutricionais utilizadas na preparação de atletas de alta performance, bem como seus impactos na longevidade. Trata-se de uma revisĂŁo da literatura que reuniu e interpretou evidĂȘncias cientĂ­ficas nacionais e internacionais publicadas entre 2007 e 2025, das bases de dados SciELO, Pubmed, MDPI, Google AcadĂȘmico, The Psychological Society e European Journal of Sport Science. Observou-se que, enquanto protocolos como jejum estratĂ©gico, ciclos de macronutrientes, crononutrição e dieta mediterrĂąnea demonstraram benefĂ­cios duradouros, mĂ©todos extremos de perda de peso e desequilĂ­brio alimentar expuseram o organismo a disfunçÔes inflamatĂłrias e metabĂłlicas. Concluiu-se, portanto, que o equilĂ­brio entre performance e longevidade depende de um planejamento nutricional individualizado, adaptado Ă  fisiologia e Ă s demandas competitivas de cada atleta.

The sports nutrition knowledge of large language model (LLM) artificial intelligence (AI) chatbots: An assessment of accuracy, completeness, clarity, quality of evidence, and test-retest reliability

2025-06-13
Thomas P. J. Solomon , Matthew J. Laye | PLoS ONE
Background Generative artificial intelligence (AI) chatbots are increasingly utilised in various domains, including sports nutrition. Despite their growing popularity, there is limited evidence on the accuracy, completeness, clarity, evidence quality, 
 Background Generative artificial intelligence (AI) chatbots are increasingly utilised in various domains, including sports nutrition. Despite their growing popularity, there is limited evidence on the accuracy, completeness, clarity, evidence quality, and test-retest reliability of AI-generated sports nutrition advice. This study evaluates the performance of ChatGPT, Gemini, and Claude’s basic and advanced models across these metrics to determine their utility in providing sports nutrition information. Materials and methods Two experiments were conducted. In Experiment 1, chatbots were tested with simple and detailed prompts in two domains: Sports nutrition for training and Sports nutrition for racing . Intraclass correlation coefficient (ICC) was used to assess interrater agreement and chatbot performance was assessed by measuring accuracy, completeness, clarity, evidence quality, and test-retest reliability. In Experiment 2, chatbot performance was evaluated by measuring the accuracy and test-retest reliability of chatbots’ answers to multiple-choice questions based on a sports nutrition certification exam. ANOVAs and logistic mixed models were used to analyse chatbot performance. Results In Experiment 1, interrater agreement was good (ICC = 0.893) and accuracy varied from 74% (Gemini1.5pro) to 31% (ClaudePro). Detailed prompts improved Claude’s accuracy but had little impact on ChatGPT or Gemini. Completeness scores were highest for ChatGPT-4o compared to other chatbots, which scored low to moderate. The quality of cited evidence was low for all chatbots when simple prompts were used but improved with detailed prompts. In Experiment 2, accuracy ranged from 89% (Claude3.5Sonnet) to 61% (ClaudePro). Test-retest reliability was acceptable across all metrics in both experiments. Conclusions While generative AI chatbots demonstrate potential in providing sports nutrition guidance, their accuracy is moderate at best and inconsistent between models. Until significant advancements are made, athletes and coaches should consult registered dietitians for tailored nutrition advice.

The Effects of Ingesting a Single Bolus of Hydrolyzed Collagen versus Free Amino Acids on Muscle Connective Protein Synthesis Rates

2025-06-13
Thorben Aussieker , Jeremias Kaiser , Floris K. Hendriks +7 more | Medicine & Science in Sports & Exercise
ABSTRACT The suggested anabolic properties of hydrolyzed collagen on connective tissue may be attributed to the delivery of amino acids as precursors or to anabolic signaling properties of bioactive peptides. 
 ABSTRACT The suggested anabolic properties of hydrolyzed collagen on connective tissue may be attributed to the delivery of amino acids as precursors or to anabolic signaling properties of bioactive peptides. Purpose To assess the impact of ingesting a single bolus of hydrolyzed collagen or free amino acids on myofibrillar and muscle connective protein synthesis rates. Methods In a randomized, double-blind, parallel design, 45 young male ( n = 21) and female ( n = 24) adults (age: 23 ± 3 y; BMI: 22.3 ± 2.2 kg/m 2 ) received intravenous infusions with L-[ ring - 13 C 6 ]-phenylalanine. Following unilateral resistance exercise, participants ingested either 30 g hydrolyzed collagen (COLL, n = 15), 30 g free amino acids reflecting the collagen amino acid profile (AA, n = 15), or a non-caloric placebo (PLA, n = 15). Blood and muscle tissue samples were collected over 6 h to assess myofibrillar and muscle connective protein synthesis rates and associated signaling responses. Results Both collagen and free amino acid ingestion substantially increased circulating plasma amino acids concentrations and effected collagen turnover proteins. Collagen and free amino acid ingestion did not significantly increase myofibrillar protein synthesis rates in the rested (0.039 ± 0.011, 0.037 ± 0.010, and 0.036 ± 0.015%·h −1 in PLA, COLL and AA, respectively) or the exercised (0.049 ± 0.010, 0.048 ± 0.011, and 0.045 ± 0.013%·h −1 ) leg ( P &gt; 0.05). Similarly, both collagen and free amino acid ingestion did not significantly increase muscle connective protein synthesis rates in the rested (0.065 ± 0.014, 0.063 ± 0.017, and 0.061 ± 0.025%·h −1 in PLA, COLL and AA, respectively) or the exercised (0.098 ± 0.023, 0.092 ± 0.028, and 0.085 ± 0.024%·h −1 ) leg ( P &gt; 0.05). Conclusions Ingestion of a single bolus of collagen hydrolysate or free amino acids substantially increases circulating amino acids concentrations, particularly glycine, but does not further increase myofibrillar or muscle connective protein synthesis rates at rest or during recovery from exercise in healthy, recreationally active young men and women.

Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer players

2025-06-13
Alireza Niknam , Kamran Tahmasebi , Mohammad Hemmatinafar +5 more | Frontiers in Nutrition
Background Purple grape juice (PGJ), a natural carbohydrate- and polyphenol-rich supplement, may enhance exercise performance. This study, incorporating individual response analysis, examined the acute effects of PGJ ingestion on endurance, 
 Background Purple grape juice (PGJ), a natural carbohydrate- and polyphenol-rich supplement, may enhance exercise performance. This study, incorporating individual response analysis, examined the acute effects of PGJ ingestion on endurance, explosive power, and perceived fatigue in elite male soccer players. Methodology Twenty-two U-20 male soccer players [Age: 19.7 ± 0.3; height: 178 ± 4 cm; body mass: 72 ± 5 kg; body mass index (BMI): 22.6 ± 0.9 kg/m 2 ] participated in an equally allocated, double-blind, crossover design study. Participants were allocated to one of two conditions: (1) purple grape juice (PGJ, n = 11) or (2) placebo (PLA, n = 11). The PGJ or placebo was ingested in four equal portions (10 ml/kg of body mass PGJ or PLA diluted with water) starting 4 h before the test and continuing every hour, with the final ingestion 60 min before the 30-15 Intermittent Fitness Test (IFT). The placebo consisted of a calorie-free, grape-flavored liquid designed to match the taste and appearance of the PGJ. A 7 days washout period was maintained between the two conditions. Perceived fatigue and standing long jump (SLJ) performance were assessed at baseline, immediately and 5 min after the IFT. Maximum oxygen consumption (VO 2 max ), time to exhaustion (TTE), and final velocity in the IFT (VIFT) were recorded during the test. The smallest worthwhile change (SWC) analysis was used to evaluate individual responses. Results Purple grape juice improved VIFT ( P &amp;lt; 0.001, Cohen’s d = 0.58), TTE ( P &amp;lt; 0.001, Cohen’s d = 0.69), and VO 2 max ( P &amp;lt; 0.001, Cohen’s d = 0.56) compared to PLA. No effects were found for SLJ or perceived fatigue ( P &amp;gt; 0.05), SWC analysis revealed that 77% of participants showed improvements in VIFT and VO 2 max , and 54% showed improvements in SLJ 5 min post-IFT. Conclusion Purple grape juice supplementation enhanced endurance performance parameters in most participants, with significant individual variability in response. These findings highlight the potential benefits of PGJ, particularly for athletes more responsive to its effects, emphasizing the need for personalized supplementation strategies.

The quality of intestinal microbiota and its influence on the sports performance of long-distance runners

2025-06-13
Justyna ƚnieĆŒek , Natalia Wittek-Smorąg | Polish Journal of Sports Medicine
<ns3:p>The content of the intestinal microbiota is not only a determinant of metabolic efficiency, but also has an impact on the regulation of immunological processes, which is particularly important in 
 <ns3:p>The content of the intestinal microbiota is not only a determinant of metabolic efficiency, but also has an impact on the regulation of immunological processes, which is particularly important in the context of intense physical effort, such as ultramarathon running. The article discusses the specifics of runners’ nutrition, pointing out their unique energy needs and the risk of dysbiosis. The role of fatty acids and probiotics as potential tools in optimizing sports performance is emphasized, paying attention to supplementation and nutritional strategies that can support gut health and energy efficiency in long-distance runners.</ns3:p>

Resistance exercise and skeletal muscle: protein synthesis, degradation, and controversies

2025-06-13
Fujue Ji , Hae Sung Lee , Jong-Hee Kim | European Journal of Applied Physiology

What renal outcomes occur in athletes using creatine supplementation?

2025-06-13
Daniel Cohen , David Cubbler , Sarah Davis | Evidence-Based Practice

Effects of Pork Protein Ingestion Prior to and Following Performing the Army Combat Fitness Test on Markers of Catabolism, Inflammation, and Recovery

2025-06-13
Drew E. Gonzalez , Kelly M. Hines , Ryan Sowinski +7 more | Nutrients
Tactical athletes and military personnel engaged in intense exercise need to consume enough quality protein in their diet to maintain protein balance and promote recovery. Plant-based protein sources contain fewer 
 Tactical athletes and military personnel engaged in intense exercise need to consume enough quality protein in their diet to maintain protein balance and promote recovery. Plant-based protein sources contain fewer essential amino acids (EAAs), while pork loin contains a higher concentration of EAAs and creatine than most other animal protein sources. This study aimed to determine whether the ingestion of plant-based or pork-based military-style meals ready-to-eat (MREs) affects recovery from and subsequent Army Combat Fitness Test (ACFT) performance. Methods: Twenty-three (n = 23) University Corps of Cadets members participated in a randomized, double-blind, placebo-controlled, and crossover-designed study. Diets were prepared by a dietitian, food scientist, and chef to have similar taste, appearance, texture, and macronutrient content. The chef also labeled the meals for double-blind administration. Participants refrained from intense exercise for 48 h before reporting to the lab in a fasted condition with a 24 h urine sample. Participants donated a blood sample, completed questionnaires and cognitive function tests, and consumed a pre-exercise meal. After four hours, participants performed the ACFT according to military standards. Participants were fed three MREs daily while returning to the lab in a fasted condition at 0600 with 24 h urine samples after 24, 48, and 72 h of recovery. On day 3, participants repeated the ACFT four hours after consuming an MRE for breakfast. Participants resumed normal training and returned to the lab after 2–3 weeks to repeat the experiment while consuming the alternate diet. Data were analyzed using general linear model statistics with repeated measures and percent changes from baseline with 95% confidence intervals. Results: Results revealed that 3 days were sufficient for participants to replicate ACFT performance. However, those consuming the pork-based diet experienced less muscle soreness, urinary urea excretion, cortisol, inflammation, and depression scores while experiencing a higher testosterone/cortisol ratio and appetite satisfaction. There was also evidence of more favorable changes in red and white blood cells. Conversely, blood lipid profiles were more favorably changed when following a plant-based diet. Conclusions: These findings suggest that protein quality and the availability of creatine in the diet can affect recovery from intense military-style exercise. Minimally, plant-based MREs should include 6–10 g/d of EAA and 2–3 g/d of creatine monohydrate to offset dietary deficiencies, particularly in military personnel following a vegetarian diet. Registered clinical trial #ISRCTN47322504.

Pre-workout multi-ingredients or carbohydrate alone promote similar resistance training outcomes in middle-aged adults: a double-blind, randomized controlled trial

2025-06-13
Joel Puente-Fernández , Eneko Larumbe‐Zabala , Justin Roberts +1 more | Journal of the International Society of Sports Nutrition

Insect Protein to Support Human Skeletal Muscle Anabolism: A Systematic Review of Randomised Controlled Trials

2025-06-13
JC Rutherford , Ruan Elliott , Geoffrey Knott +2 more | Nutrition Reviews
Abstract Context A global shift toward sustainable food sources is emerging due to the immense environmental pressure from the production of animal foods. Insects present a novel source of sustainable 
 Abstract Context A global shift toward sustainable food sources is emerging due to the immense environmental pressure from the production of animal foods. Insects present a novel source of sustainable dietary protein, due to their high protein content and favourable amino acid profile. Objectives The aim of this systematic review was to establish the effects of insect protein compared with animal protein on skeletal muscle anabolism and adaptation. This review also explores the usefulness of insects for supporting the protein needs of population groups with high protein requirements. Data Sources Database searches were performed using the search terms “edible insects” and “insect protein,” plus the key words “human health,” “exercise,” “anabolic response,” “muscle protein synthesis,” “skeletal muscle,” “muscle adaptation,” “lean mass,” and “bioavailability.” Studies had to be randomised controlled trials conducted with adult human participants (aged &amp;gt;18 years) that measured protein bioavailability, anabolic response, or skeletal muscle adaptation, with direct comparison between insect and animal protein. Data Extraction Four studies (n = 100 participants) were included in the review. Of the two studies that assessed only postprandial blood amino acid concentration, one reported higher aminoacidemia from cricket compared with beef protein ingestion, and the other reported higher aminoacidemia from whey compared with lesser mealworm protein ingestion. Two studies also directly assessed the postprandial skeletal muscle anabolic response after exercise. Both reported lower peak plasma amino acid concentration from cricket or lesser mealworm protein compared with whey or milk protein, but there was no difference in skeletal muscle anabolism between the insect and animal protein sources. Conclusion Insects are a viable protein source that can likely support skeletal muscle anabolism to the same extent as conventional animal protein but with a considerably lower environmental impact. Insects could be an effective protein source to facilitate skeletal muscle during challenging life circumstances or for those with physically demanding occupations.

Insights into carboxymethyl cellulose enhances the stability of myofibrillar protein aqueous solution modulated by charge density

2025-06-12
Jiale Chai , Ye Tao , Xue Zhao +2 more | Food Research International

Trends in Protein Supplement Use Among Non-Professional Athletes: Insights from a Survey in Greece

2025-06-12
Panagiota Athanasopoulou , Georgia-Eirini Deligiannidou , Paraskevi Basdeki +7 more | Physiologia
Objective: Protein supplements (PSs) are widely consumed by professional and non-professional athletes, yet research on non-athletic PS users’ perceptions, motivations, and health risk awareness is limited. This study aimed to 
 Objective: Protein supplements (PSs) are widely consumed by professional and non-professional athletes, yet research on non-athletic PS users’ perceptions, motivations, and health risk awareness is limited. This study aimed to investigate non-professional athletes’ PS patterns of use, motivations, and safety. Methods: A cross-sectional study was conducted using a constructed questionnaire reporting on PS usage trends, exercise habits, and demographic factors. Adult respondents were recruited from gyms, athletic organizations, amusement parks, and playing fields. Results: We received 1100 responses, and 327 were PS users. From the total of PS users, there was a prevalence of PS use in males [(203 (62%)]; adults in the age group of 25–34 [136 (42%)], p &lt; 0.001; and participants with a normal BMI (189, 58%), p &lt; 0.001. Following high-intensity fitness exercise sessions and engagement with more than two types of physical activity were associated with more than doubled odds of PS consumption (p &lt; 0.001). The main reasons for PS intake were for muscle mass increase (35%) and recovery (18%), and protein powder was the most popular PS (279; 64%). The main channels of information for PS use were Web/social media (50, 40%) and coaches (54, 43.2%), while one out of two [35 (49%); p = 0.008] of those engaged in more than two types of physical exercise declared that PSs are good for health. Conclusion: The findings highlight demographic, behavioral, and informational factors shaping PS consumption in non-professional athletes. Despite the perceived benefits, reliance on non-expert sources and unregulated products raises concerns about consumer awareness and safety, while educational initiatives to promote evidence-based supplementation practices are deemed crucial.