Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 24
Filter
1.
J Int Soc Sports Nutr ; 21(1): 2341903, 2024 Dec.
Article in English | MEDLINE | ID: mdl-38626029

ABSTRACT

Protein supplementation often refers to increasing the intake of this particular macronutrient through dietary supplements in the form of powders, ready-to-drink shakes, and bars. The primary purpose of protein supplementation is to augment dietary protein intake, aiding individuals in meeting their protein requirements, especially when it may be challenging to do so through regular food (i.e. chicken, beef, fish, pork, etc.) sources alone. A large body of evidence shows that protein has an important role in exercising and sedentary individuals. A PubMed search of "protein and exercise performance" reveals thousands of publications. Despite the considerable volume of evidence, it is somewhat surprising that several persistent questions and misconceptions about protein exist. The following are addressed: 1) Is protein harmful to your kidneys? 2) Does consuming "excess" protein increase fat mass? 3) Can dietary protein have a harmful effect on bone health? 4) Can vegans and vegetarians consume enough protein to support training adaptations? 5) Is cheese or peanut butter a good protein source? 6) Does consuming meat (i.e., animal protein) cause unfavorable health outcomes? 7) Do you need protein if you are not physically active? 8) Do you need to consume protein ≤ 1 hour following resistance training sessions to create an anabolic environment in skeletal muscle? 9) Do endurance athletes need additional protein? 10) Does one need protein supplements to meet the daily requirements of exercise-trained individuals? 11) Is there a limit to how much protein one can consume in a single meal? To address these questions, we have conducted a thorough scientific assessment of the literature concerning protein supplementation.


Subject(s)
Dietary Proteins , Physical Endurance , Humans , Physical Endurance/physiology , Exercise/physiology , Dietary Supplements , Muscle, Skeletal/physiology
2.
J Int Soc Sports Nutr ; 20(1): 2263409, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37800468

ABSTRACT

Position Statement: The International Society of Sports Nutrition (ISSN) presents this position based on a critical examination of literature surrounding the effects of essential amino acid (EAA) supplementation on skeletal muscle maintenance and performance. This position stand is intended to provide a scientific foundation to athletes, dietitians, trainers, and other practitioners as to the benefits of supplemental EAA in both healthy and resistant (aging/clinical) populations. EAAs are crucial components of protein intake in humans, as the body cannot synthesize them. The daily recommended intake (DRI) for protein was established to prevent deficiencies due to inadequate EAA consumption. The following conclusions represent the official position of the Society: 1. Initial studies on EAAs' effects on skeletal muscle highlight their primary role in stimulating muscle protein synthesis (MPS) and turnover. Protein turnover is critical for replacing degraded or damaged muscle proteins, laying the metabolic foundation for enhanced functional performance. Consequently, research has shifted to examine the effects of EAA supplementation - with and without the benefits of exercise - on skeletal muscle maintenance and performance. 2. Supplementation with free-form EAAs leads to a quick rise in peripheral EAA concentrations, which in turn stimulates MPS. 3. The safe upper limit of EAA intake (amount), without inborn metabolic disease, can easily accommodate additional supplementation. 4. At rest, stimulation of MPS occurs at relatively small dosages (1.5-3.0 g) and seems to plateau at around 15-18 g. 5. The MPS stimulation by EAAs does not require non-essential amino acids. 6. Free-form EAA ingestion stimulates MPS more than an equivalent amount of intact protein. 7. Repeated EAA-induced MPS stimulation throughout the day does not diminish the anabolic effect of meal intake. 8. Although direct comparisons of various formulas have yet to be investigated, aging requires a greater proportion of leucine to overcome the reduced muscle sensitivity known as "anabolic resistance." 9. Without exercise, EAA supplementation can enhance functional outcomes in anabolic-resistant populations. 10. EAA requirements rise in the face of caloric deficits. During caloric deficit, it's essential to meet whole-body EAA requirements to preserve anabolic sensitivity in skeletal muscle.


Subject(s)
Amino Acids , Muscle, Skeletal , Humans , Leucine , Amino Acids/pharmacology , Muscle Proteins/metabolism , Dietary Supplements
3.
Clin Nutr ESPEN ; 49: 385-389, 2022 06.
Article in English | MEDLINE | ID: mdl-35623841

ABSTRACT

BACKGROUND & AIMS: Protein kinetic responses to nutrition and exercise interventions are commonly evaluated using a primed-constant infusion of stable isotope tracers. While this methodology is state-of-the-art, the required preparation at a certified pharmacy makes the utilization of isotope infusion both expensive and logistically cumbersome. Oral tracer ingestion has been used to quantify 24-h whole-body protein status; however, this does not permit examination of acute interventional effects. Ingestion of a priming bolus, followed by continuous ingestion of stable isotope tracer in a 'sip feeding' fashion may provide a more feasible alternative for quantifying acute kinetic responses. Therefore, the purpose of this study was to evaluate the viability of a primed continuous oral sip-ingestion method of stable isotope tracers for the evaluation of whole-body protein kinetics. METHODS: In a randomized, crossover design, eight healthy adults (63% female; Age: 29.4 ± 5.8 yrs; BMI: 24.3 ± 2.7 kg/m2) completed two, two-period stable isotope oral ingestion studies, consisting of a 3 h basal fasted period, followed by a 4-h post-ingestion period. After the basal period, subjects ingested either 6.3 g (Low) or 12.6 g (High) of an essential amino acid (EAA) enriched whey protein supplement. The continuous oral sip-feed method was initiated with a primed oral bolus dose of L-[ring-2H5]phenylalanine, L-[ring-2H2]tyrosine, and L-[ring-2H4]tyrosine, followed by oral sip doses of L-[ring-2H5]phenylalanine, L-[ring-2H2]tyrosine every 10 min to approximate steady state tracer enrichment. Blood samples were taken throughout the basal and post-meal periods to determine tracer enrichment. Whole-body net protein balance (NB), synthesis (PS), breakdown (PB), and exogenous hydroxylation were calculated for each period. Repeated measure ANOVAs (treatment × time) were used to assess differences in protein kinetics. RESULTS: Using the sip feed method, NB, PS, and hydroxylation were significantly increased with ingestion of protein (p < 0.05) during the postprandial period, regardless of amount of protein ingested; ΔNB from the postabsorptive to postprandial period was significantly greater for high compared to low protein (p = 0.026; low = 6.2 ± 5.1 g protein·240 min-1; high = 11.8 ± 3.9 g protein·240 min-1). CONCLUSION: The current study provides preliminary evidence that continuous oral sip-feeding of stable isotope tracer is a feasible method that provides physiologically relevant measures of protein metabolism. Assessments of variance and individual responses revealed high measurement variability with the sip-feed method compared to previously published constant infusion responses, but ΔNB, ΔPS, and ΔPB were comparable. In situations where constant infusion is not feasible, oral sip-feeding could be used as an alternative method for measurement of acute, postprandial protein metabolism.


Subject(s)
Phenylalanine , Proteins , Adult , Cross-Over Studies , Eating , Female , Humans , Isotopes , Male , Phenylalanine/metabolism , Proteins/metabolism , Tyrosine
4.
Eur J Appl Physiol ; 121(12): 3297-3311, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34427732

ABSTRACT

High-intensity interval training (HIIT) promotes positive cardiometabolic and body composition changes. Essential amino acids (EAA) may support changes associated with HIIT, but evaluation of potential synergistic effects is lacking. The purpose of this study was to compare independent and combined effects of HIIT and EAA on total body composition and metabolism in men and women considered overweight/obese; an exploratory aim was to evaluate the modulatory effects of sex. Sixty-six healthy adults (50% female; Age: 36.7 ± 6.0 years; BMI: 32.0 ± 4.2 kg/m2) completed 8 weeks of: (1) HIIT, 2 days/weeks; (2) EAA supplementation, 3.6 g twice daily; (3) HIIT + EAA; or (4) control. Body composition, resting metabolic rate (RMR), substrate metabolism (respiratory exchange ratio; RER), and cardiorespiratory fitness were measured at baseline, 4 weeks, and 8 weeks; cardiometabolic blood markers were measured at baseline and 8 weeks. Differences between groups were assessed by linear mixed models covaried for baseline values, followed by 95% confidence intervals (CI) on adjusted mean change scores. There were no significant changes in body composition (p > 0.05) for any group. Changes in RER, but not RMR, occurred with HIIT (mean change; [95% CI]: - 0.04; [- 0.07, - 0.02]) and EAA (- 0.03; [- 0.06, - 0.01]) after 8 weeks. Cardiorespiratory fitness increased following 8 weeks of HIIT (+ 5.1 ml/kg/min [3.3,6.8]) and HIIT + EAA (+ 4.1 ml/kg/min [1.0,6.4]). Changes with HIIT + EAA were not significantly different from HIIT. There were no changes in cardiometabolic markers (p > 0.05) and no sex interaction (p > 0.05). HIIT is efficacious for promoting positive changes in cardiorespiratory fitness and resting substrate metabolism in adults considered overweight/obese. Addition of EAA did not significantly enhance HIIT-induced adaptations. ClinicalTrials.gov ID#NCT04080102.


Subject(s)
Amino Acids, Essential/administration & dosage , High-Intensity Interval Training , Obesity/metabolism , Overweight/metabolism , Adult , Biomarkers/blood , Body Composition , Body Mass Index , Cardiorespiratory Fitness , Energy Metabolism , Female , Humans , Male , Middle Aged
5.
Nutrients ; 13(5)2021 May 15.
Article in English | MEDLINE | ID: mdl-34063333

ABSTRACT

Nutritional status is a strong predictor of postoperative outcomes and is recognized as an important component of surgical recovery programs. Adequate nutritional consumption is essential for addressing the surgical stress response and mitigating the loss of muscle mass, strength, and functionality. Especially in older patients, inadequate protein can lead to significant muscle atrophy, leading to a loss of independence and increased mortality risk. Current nutritional recommendations for surgery primarily focus on screening and prevention of malnutrition, pre-surgical fasting protocols, and combating post-surgical insulin resistance, while recommendations regarding macronutrient composition and timing around surgery are less established. The goal of this review is to highlight oral nutrition strategies that can be implemented leading up to and following major surgery to minimize atrophy and the resultant loss of functionality. The role of carbohydrate and especially protein/essential amino acids in combating the surgical stress cascade and supporting recovery are discussed. Practical considerations for nutrient timing to maximize oral nutritional intake, especially during the immediate pre- and post- surgical periods, are also be discussed.


Subject(s)
Malnutrition/prevention & control , Muscular Atrophy/prevention & control , Postoperative Care , Preoperative Care , Amino Acids, Essential/administration & dosage , Dietary Carbohydrates/administration & dosage , Dietary Proteins/administration & dosage , Humans , Muscle Strength , Nutritional Requirements , Nutritional Status , Orthopedic Procedures
6.
J Gerontol A Biol Sci Med Sci ; 76(7): 1184-1191, 2021 06 14.
Article in English | MEDLINE | ID: mdl-33475727

ABSTRACT

We have investigated the hypothesis that nutritional supplementation of the diet in low-physical-functioning older individuals with a specially formulated composition based on essential amino acids (EAAs) would improve physical function as compared to supplementation with the same amount of whey protein. A third group of comparable volunteers were given nutrition education but no supplementation of the diet. After 6 weeks of whey protein supplementation (n = 32), there was no effect on the distance walked in 6 minutes, but the distance walked improved significantly from the pre-value after 12 weeks of whey supplementation. EAA consumption (n = 28) significantly improved walking distance at both 6 and 12 weeks. The distance walked at 12 weeks (419.0 ± 25.0 m) was 35.4 m greater than the pre-value of 384.0 ± 23.0 m (p < .001). The increase in distance walked by the EAA group was also significantly greater than that in the whey group at both 6 and 12 weeks (p < .01). In contrast, a decrease in distance walked was observed in the control group (n = 32) (not statistically significant, NS). EAA supplementation also improved grip strength and leg strength, and decreased body weight and fat mass. Plasma low-density lipoprotein concentration was significantly reduced in the EAA group, as well as the concentration of macrophage migration inhibitory factor. There were no adverse responses in any groups, and compliance was greater than 95% in all individuals consuming supplements. We conclude that dietary supplementation with an EAA-based composition may be a beneficial therapy in older individuals with low physical functional capacity. Clinical Trials Registration Number: This study was registered with ClinicalTrials.gov: NCT03424265-"Nutritional interventions in heart failure."


Subject(s)
Amino Acids, Essential/administration & dosage , Cardiovascular Diseases/physiopathology , Physical Functional Performance , Whey Proteins/administration & dosage , Aged , Aged, 80 and over , Dietary Supplements , Double-Blind Method , Female , Geriatric Assessment , Humans , Male
7.
J Int Soc Sports Nutr ; 18(1): 4, 2021 Jan 07.
Article in English | MEDLINE | ID: mdl-33413462

ABSTRACT

BACKGROUND: The effects of ingesting varying essential amino acid (EAA)/protein-containing food formats on protein kinetics during energy deficit are undetermined. Therefore, recommendations for EAA/protein food formats necessary to optimize both whole-body protein balance and muscle protein synthesis (MPS) during energy deficit are unknown. We measured protein kinetics after consuming iso-nitrogenous amounts of free-form essential amino acid-enriched whey (EAA + W; 34.7 g protein, 24 g EAA sourced from whey and free-form EAA), whey (WHEY; 34.7 g protein, 18.7 g EAA), or a mixed-macronutrient meal (MEAL; 34.7 g protein, 11.4 g EAA) after exercise during short-term energy deficit. METHODS: Ten adults (mean ± SD; 21 ± 4 y; 25.7 ± 1.7 kg/m2) completed a randomized, double-blind crossover study consisting of three, 5 d energy-deficit periods (- 30 ± 3% of total energy requirements), separated by 14 d. Whole-body protein synthesis (PS), breakdown (PB), and net balance (NET) were determined at rest and in response to combination exercise consisting of load carriage treadmill walking, deadlifts, and box step-ups at the end of each energy deficit using L-[2H5]-phenylalanine and L-[2H2]-tyrosine infusions. Treatments were ingested immediately post-exercise. Mixed-muscle protein synthesis (mixed-MPS) was measured during exercise through recovery. RESULTS: Change (Δ postabsorptive + exercise to postprandial + recovery [mean treatment difference (95%CI)]) in whole-body (g/180 min) PS was 15.8 (9.8, 21.9; P = 0.001) and 19.4 (14.8, 24.0; P = 0.001) greater for EAA + W than WHEY and MEAL, respectively, with no difference between WHEY and MEAL. ΔPB was - 6.3 (- 11.5, - 1.18; P = 0.02) greater for EAA + W than WHEY and - 7.7 (- 11.9, - 3.6; P = 0.002) greater for MEAL than WHEY, with no difference between EAA + W and MEAL. ΔNET was 22.1 (20.5, 23.8; P = 0.001) and 18.0 (16.5, 19.5; P = 0.00) greater for EAA + W than WHEY and MEAL, respectively, while ΔNET was 4.2 (2.7, 5.6; P = 0.001) greater for MEAL than WHEY. Mixed-MPS did not differ between treatments. CONCLUSIONS: While mixed-MPS was similar across treatments, combining free-form EAA with whey promotes greater whole-body net protein balance during energy deficit compared to iso-nitrogenous amounts of whey or a mixed-macronutrient meal. TRIAL REGISTRATION: ClinicalTrials.gov, Identifier no. NCT04004715 . Retrospectively registered 28 June 2019, first enrollment 6 June 2019.


Subject(s)
Amino Acids, Essential/metabolism , Exercise/physiology , Nutrients/metabolism , Postprandial Period , Proteins/metabolism , Whey/metabolism , Adult , Amino Acids, Essential/administration & dosage , Amino Acids, Essential/blood , Body Mass Index , Cross-Over Studies , Dietary Proteins/administration & dosage , Dietary Proteins/metabolism , Double-Blind Method , Energy Intake , Female , Food, Fortified , Humans , Insulin/blood , Male , Meals , Muscle Proteins/biosynthesis , Nutrients/administration & dosage , Phenylalanine/administration & dosage , Time Factors , Tyrosine/administration & dosage , Whey/administration & dosage , Whey/chemistry , Young Adult
8.
Nutrients ; 12(12)2020 Dec 02.
Article in English | MEDLINE | ID: mdl-33276485

ABSTRACT

Ingesting protein-containing supplements and foods provides essential amino acids (EAA) necessary to increase muscle and whole-body protein synthesis (WBPS). Large variations exist in the EAA composition of supplements and foods, ranging from free-form amino acids to whole protein foods. We sought to investigate how changes in peripheral EAA after ingesting various protein and free amino acid formats altered muscle and whole-body protein synthesis. Data were compiled from four previous studies that used primed, constant infusions of L-(ring-2H5)-phenylalanine and L-(3,3-2H2)-tyrosine to determine fractional synthetic rate of muscle protein (FSR), WBPS, and circulating EAA concentrations. Stepwise regression indicated that max EAA concentration (EAACmax; R2 = 0.524, p < 0.001), EAACmax (R2 = 0.341, p < 0.001), and change in EAA concentration (ΔEAA; R = 0.345, p < 0.001) were the strongest predictors for postprandial FSR, Δ (change from post absorptive to postprandial) FSR, and ΔWBPS, respectively. Within our dataset, the stepwise regression equation indicated that a 100% increase in peripheral EAA concentrations increases FSR by ~34%. Further, we observed significant (p < 0.05) positive (R = 0.420-0.724) correlations between the plasma EAA area under the curve above baseline, EAACmax, ΔEAA, and rate to EAACmax to postprandial FSR, ΔFSR, and ΔWBPS. Taken together our results indicate that across a large variety of EAA/protein-containing formats and food, large increases in peripheral EAA concentrations are required to drive a robust increase in muscle and whole-body protein synthesis.


Subject(s)
Amino Acids, Essential/biosynthesis , Amino Acids, Essential/pharmacology , Muscle Proteins/biosynthesis , Muscle Proteins/pharmacokinetics , Protein Biosynthesis , Aging/physiology , Amino Acids/metabolism , Amino Acids/pharmacokinetics , Dietary Supplements , Eating , Food , Humans , Kinetics , Male , Metabolism , Muscle, Skeletal/metabolism , Phenylalanine , Postprandial Period , Whey Proteins
9.
Nutrients ; 12(8)2020 Aug 15.
Article in English | MEDLINE | ID: mdl-32824200

ABSTRACT

Protein intake recommendations to optimally stimulate muscle protein synthesis (MPS) are derived from dose-response studies examining the stimulatory effects of isolated intact proteins (e.g., whey, egg) on MPS in healthy individuals during energy balance. Those recommendations may not be adequate during periods of physiological stress, specifically the catabolic stress induced by energy deficit. Providing supplemental intact protein (20-25 g whey protein, 0.25-0.3 g protein/kg per meal) during strenuous military operations that elicit severe energy deficit does not stimulate MPS-associated anabolic signaling or attenuate lean mass loss. This occurs likely because a greater proportion of the dietary amino acids consumed are targeted for energy-yielding pathways, whole-body protein synthesis, and other whole-body essential amino acid (EAA)-requiring processes than the proportion targeted for MPS. Protein feeding formats that provide sufficient energy to offset whole-body energy and protein-requiring demands during energy deficit and leverage EAA content, digestion, and absorption kinetics may optimize MPS under these conditions. Understanding the effects of protein feeding format-driven alterations in EAA availability and subsequent changes in MPS and whole-body protein turnover is required to design feeding strategies that mitigate the catabolic effects of energy deficit. In this manuscript, we review the effects, advantages, disadvantages, and knowledge gaps pertaining to supplemental free-form EAA, intact protein, and protein-containing mixed meal ingestion on MPS. We discuss the fundamental role of whole-body protein balance and highlight the importance of comprehensively assessing whole-body and muscle protein kinetics when evaluating the anabolic potential of varying protein feeding formats during energy deficit.


Subject(s)
Amino Acids, Essential/administration & dosage , Diet , Dietary Proteins/administration & dosage , Muscle Proteins/metabolism , Protein Biosynthesis/drug effects , Amino Acids, Essential/metabolism , Digestion , Gastrointestinal Absorption , Humans , Leucine/metabolism , Meals , Muscle, Skeletal/metabolism , Signal Transduction/drug effects , Whey Proteins/administration & dosage
10.
Physiol Rep ; 8(16): e14529, 2020 08.
Article in English | MEDLINE | ID: mdl-32845565

ABSTRACT

Understanding human physiological responses to high-fat energy excess (HFEE) may help combat the development of metabolic disease. We aimed to investigate the impact of manipulating the n-3PUFA content of HFEE diets on whole-body and skeletal muscle markers of insulin sensitivity. Twenty healthy males were overfed (150% energy, 60% fat, 25% carbohydrate, 15% protein) for 6 d. One group (n = 10) received 10% of fat intake as n-3PUFA rich fish oil (HF-FO), and the other group consumed a mix of fats (HF-C). Oral glucose tolerance tests with stable isotope tracer infusions were conducted before, and following, HFEE, with muscle biopsies obtained in basal and insulin-stimulated states for measurement of membrane phospholipids, ceramides, mitochondrial enzyme activities, and PKB and AMPKα2 activity. Insulin sensitivity and glucose disposal did not change following HFEE, irrespective of group. Skeletal muscle ceramide content increased following HFEE (8.5 ± 1.2 to 12.1 ± 1.7 nmol/mg, p = .03), irrespective of group. No change in mitochondrial enzyme activity was observed following HFEE, but citrate synthase activity was inversely associated with the increase in the ceramide content (r=-0.52, p = .048). A time by group interaction was observed for PKB activity (p = .003), with increased activity following HFEE in HF-C (4.5 ± 13.0mU/mg) and decreased activity in HF-FO (-10.1 ± 20.7 mU/mg) following HFEE. Basal AMPKα2 activity increased in HF-FO (4.1 ± 0.6 to 5.3 ± 0.7mU/mg, p = .049), but did not change in HF-C (4.6 ± 0.7 to 3.8 ± 0.9mU/mg) following HFEE. We conclude that early skeletal muscle signaling responses to HFEE appear to be modified by dietary n-3PUFA content, but the potential impact on future development of metabolic disease needs exploring.


Subject(s)
Diet, High-Fat/adverse effects , Fatty Acids, Omega-3/metabolism , Hyperphagia/metabolism , Muscle, Skeletal/metabolism , AMP-Activated Protein Kinase Kinases , Adolescent , Adult , Ceramides/metabolism , Humans , Male , Oxidative Stress , Phospholipids/metabolism , Protein Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism
11.
J Int Soc Sports Nutr ; 17(1): 9, 2020 Feb 10.
Article in English | MEDLINE | ID: mdl-32041644

ABSTRACT

BACKGROUND: We have determined the acute response of protein kinetics to one or two servings (6.3 g and 12.6 g) of a proprietary composition containing free-form essential amino acids (EAA) (3.2 g EAA per serving) and whey protein (2.4 g per serving), as well as the response to consumption of a popular whey-based protein supplement (Gatorade Recover) (17 g; 12.6 g protein). METHODS: Whole-body rates of protein synthesis, breakdown and net balance (taken to be the anabolic response) were determined using primed-constant infusions of 2H5-phenylalnine and 2H2-tyrosine. Muscle protein fractional synthetic rate (FSR) was also determined with the 2H5-phenylalanine tracer. RESULTS: Plasma EAA levels increased following consumption of all beverages, with the greatest response in the high-dose EAA/protein composition. Similarly, the increase in net balance between whole-body protein synthesis and breakdown was greatest following consumption of the high-dose EAA/protein composition, while the low-dose EAA/protein composition and Gatorade Recover induced similar increases in net balance. When the net balance response was normalized for the total amount of product given, the high- and low-dose EAA/protein beverages were approximately 6- and 3-fold more anabolic than the Gatorade Recover, respectively. The greater anabolic response to the EAA/protein composition was due to greater increases in whole-body protein synthesis with both doses, and a markedly greater suppression of whole-body protein breakdown in the high-dose group. Muscle protein FSR after beverage consumption reflected changes in whole-body protein synthesis, with the larger EAA/protein dose significantly increasing FSR. CONCLUSION: We conclude that a composition of a balanced EAA formulation combined with whey protein is highly anabolic as compared to a whey protein-based recovery product, and that the response is dose-dependent. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03502941. This trial was registered on April 19, 2018.


Subject(s)
Amino Acids, Essential/pharmacology , Dietary Supplements , Muscle Proteins/metabolism , Protein Biosynthesis , Whey Proteins/pharmacology , Adult , Amino Acids, Essential/blood , Cross-Over Studies , Healthy Volunteers , Humans , Male , Young Adult
12.
Int J Med Sci ; 11(2): 116-26, 2014.
Article in English | MEDLINE | ID: mdl-24465156

ABSTRACT

In this prospective, randomized, double-blind, trial conducted in two parts, we examined the effects of a multi-ingredient pre-exercise workout supplement blend of creatine, betaine and a dendrobium extract (MMP) on safety, performance, and body composition in healthy men and women undergoing a supervised program of resistance exercise. Part 1 was an acute hemodynamic safety study wherein forty young, healthy men and women (26.2 ± 5.3 years, 70.4 ± 3.3 inches, 83.7 ± 14.9 kg, 26.0 ± 3.2 kg●m(-2)) ingest one dose of either the MMP or comparator in a randomized, double-blind, comparator controlled, crossover fashion before having their resting heart rate, blood, ECG and comprehensive blood chemistry and blood counts completed. Systolic (SBP) and diastolic (DBP) blood pressures were generally raised (3.0-5.4 mm Hg, p<0.01) following supplementation with MPP whereas in the comparator group SBP was marginally reduced by 0.3 to 1.2 mm Hg, p>0.05 at all time points) and DBP was increased (3.0 - 3.9 mm Hg, p<0.05 at all time points). No changes in EKG-corrected QT interval were observed, and no serious adverse events were reported. Part 2 was a six-week training study wherein forty-three young, healthy men and women (24.3 ± 2.9 years, 70.5 ± 3.1 inches, 83.8 ± 9.6 kg, 26.1 ± 2.7 kg●m(-2)) supplemented with daily pre-workout doses of either the MPP or a comparator in a randomized, double-blind, comparator-controlled fashion while following a standardized resistance training program for six weeks. MPP and the comparator were isocaloric and delivered the same amount of caffeine. Significant improvements in visual analog scale (VAS) scores for energy (p<0.024) and concentration (p<0.041) were found along with consistently higher levels of focus accompanied by less fatigue when MPP was consumed in comparison to comparator during upper body muscular strength-endurance tests at weeks 3 and 6. MPP supplementation for 6 weeks did not improve dual-energy x-ray absorptiometry (DEXA) measures of body composition or objective assessments of exercise performance. Overall, MPP use and administration was well tolerated. Self-reported scores for energy and concentration were significantly greater. Over a six-week training and supplementation period, MPP use was not associated with improvements in performance or body composition. Future studies should confirm these effects over a more prolonged training period.


Subject(s)
Biomarkers/blood , Dietary Supplements , Exercise , Muscle Strength/physiology , Adipose Tissue , Adult , Body Composition , Body Mass Index , Caffeine , Creatine/blood , Female , Humans , Male , Middle Aged , Muscle Strength/genetics , Muscle, Skeletal
13.
J Nutr ; 143(11): 1852S-1856S, 2013 Nov.
Article in English | MEDLINE | ID: mdl-24027188

ABSTRACT

Special operations are so designated for the specialized military missions they address. As a result, special operations present some unique metabolic challenges. In particular, soldiers often operate in a negative energy balance in stressful and demanding conditions with little opportunity for rest or recovery. In this framework, findings inferred from the performance literature suggest that increased protein intake may be beneficial. In particular, increased protein intake during negative caloric balance maintains lean body mass and blood glucose production. The addition of protein to mixed macronutrient supplements is beneficial for muscle endurance and power endpoints, and the use of amino acids improves gross and fine motor skills. Increasing protein intake during periods of intense training and/or metabolic demand improves subsequent performance, improves muscular recovery, and reduces symptoms of psychological stress. Consumption of protein before sleep confers the anabolic responses required for the maintenance of lean mass and muscle recovery. A maximal response in muscle protein synthesis is achieved with the consumption of 20-25 g of protein alone. However, higher protein intakes in the context of mixed-nutrient ingestion also confer anabolic benefits by reducing protein breakdown. Restricted rations issued to special operators provide less than the RDA for protein ( ∼ 0.6 g/kg), and these soldiers often rely on commercial products to augment their rations. The provision of reasonable alternatives and/or certification of approved supplements by the U.S. Department of Defense would be prudent.


Subject(s)
Dietary Proteins/administration & dosage , Dietary Supplements , Military Personnel , Amino Acids/administration & dosage , Body Mass Index , Energy Intake , Energy Metabolism , Humans , Muscle Proteins/biosynthesis , Muscle, Skeletal/metabolism , Recommended Dietary Allowances
14.
Clin Nutr ; 29(1): 18-23, 2010 Feb.
Article in English | MEDLINE | ID: mdl-19419806

ABSTRACT

BACKGROUND & AIMS: Older individuals are more likely to experience extended hospitalization and become protein malnourished during hospitalization. The concomitant compulsory inactivity results in functional decline. Increasing protein intake in hospitalized patients improves nitrogen balance, but effects on function are unknown. In the present study, we examined the effects of increasing protein intake by essential amino acid (EAA) supplementation in older individuals subjected to 10 d bed rest on LBM and muscle function. METHODS: Subjects were given a placebo (n=12, 68+/-5 (SD) yrs, 83+/-19 kg) or 15 g of EAA (n=10, 71+/-6, 72+/-8 kg) 3 times per day throughout 10d of bed rest. LBM, muscle protein synthesis, and muscle function were determined before and after bed rest. Due to an imbalance in randomized gender distribution between groups, gender and beginning functional and LBM measures were utilized for analyses by repeated measures analysis of covariance (RMANCOVA). RESULTS: Analyses revealed the potential for the preservation of functional outcomes with EAA supplementation. CONCLUSIONS: Increasing protein intake above the RDA may preserve muscle function in the elderly during compulsory inactivity. EAA supplementation is potentially an efficient method of increasing protein intake without affecting satiety.


Subject(s)
Aged/physiology , Amino Acids, Essential/therapeutic use , Bed Rest , Dietary Supplements , Muscle, Skeletal/drug effects , Muscle, Skeletal/physiology , Nitrogen/metabolism , Absorptiometry, Photon , Aging , Amino Acids, Essential/administration & dosage , Analysis of Variance , Body Composition/drug effects , Female , Hospitalization , Humans , Male , Muscle Proteins/biosynthesis , Muscle Proteins/drug effects , Protein-Energy Malnutrition/prevention & control
15.
Nutrition ; 25(3): 281-8, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19041223

ABSTRACT

OBJECTIVE: Hypertriglyceridemia is a risk factor for coronary heart disease. The aim of this study was to determine the effect of amino acid (AA) supplementation on plasma, liver, and muscle lipid concentrations and insulin sensitivity in the elderly. METHODS: Twelve impaired glucose tolerant elderly (mean +/- SD 67.0 +/- 5.6 y of age, seven women and five men) ingested 11 g of essential AAs plus arginine twice a day for 16 wk, after a 7-wk control run-in. Diet and activity were not otherwise modified. Plasma lipid concentrations and oral glucose tolerance were measured every fourth week and tissue lipid concentrations (magnetic resonance spectroscopy) every eighth week. RESULTS: No changes in plasma lipids were observed during the control run-in. AA supplementation lowered plasma triacylglycerol (TG; P < 0.001), total cholesterol (P = 0.048), and very low-density lipoprotein cholesterol (P < 0.001) concentrations. Plasma TG decreased approximately 20% from the initial value of 1.45 +/- 0.18 mmol/L (mean +/- SE, 128 +/- 16 mg/dL), with the greatest decrease in the subjects starting out with the highest concentrations (r = -0.83). Similarly, liver fat content (liver TG/Intralipid standard) decreased approximately 50% from the initial value of 0.34 +/- 0.06 (P = 0.021, n = 8), with the greatest decrease in the subjects who initially had the highest values (r = -0.86). Intramuscular fat content and insulin sensitivity did not change. CONCLUSION: Diet supplementation with AAs lowers plasma TG, total cholesterol, and very low-density lipoprotein cholesterol concentrations and liver lipid content in impaired glucose tolerant elderly. AA supplementation may have a potential role in the treatment of hypertriglyceridemia or hepatic steatosis.


Subject(s)
Amino Acids, Essential/pharmacology , Hypertriglyceridemia/drug therapy , Insulin/metabolism , Liver/drug effects , Muscle, Skeletal/metabolism , Triglycerides/blood , Aged , Amino Acids, Essential/administration & dosage , Arginine/administration & dosage , Arginine/pharmacology , Cholesterol/blood , Cholesterol, VLDL/blood , Dietary Supplements , Female , Glucose Intolerance/blood , Humans , Hypertriglyceridemia/blood , Hypertriglyceridemia/complications , Liver/metabolism , Male , Muscle, Skeletal/drug effects , Muscle, Skeletal/pathology , Treatment Outcome , Triglycerides/metabolism
16.
Essays Biochem ; 44: 85-98, 2008.
Article in English | MEDLINE | ID: mdl-18384284

ABSTRACT

Muscle mass is critical for athletic performance and, perhaps more importantly for most, health and survival. The metabolic basis for a change in muscle mass is an increase in net muscle protein balance (termed NBAL). NBAL is the difference between MPS (muscle protein synthesis) and MPB (muscle protein breakdown). Thus an increase in MPS and/or a decrease in MPB are necessary for NBAL to increase, leading to accretion of muscle proteins. In particular, accretion of myofibrillar proteins is necessary. NBAL responds to exercise, feeding and other factors. In healthy, weight-stable adults, muscle mass remains constant because periods of positive balance following feeding are countered by periods of negative balance during fasting. A combination of resistance exercise and nutrition is a potent anabolic stimulus through stimulation of MPS from amino acids and attenuation of MPB by carbohydrates. Increased muscle mass results from the accumulation of small amounts of protein in response to each bout of exercise combined with nutrient intake. The magnitude of the response may be influenced by factors other than just the amount of a nutrient ingested. Timing of ingestion, co-ingestion of nutrients and the type of protein may all influence protein accretion. Testosterone is a potent anabolic stimulus primarily through improvement in re-utilization of amino acids from MPB. There is a general lack of efficacy in studies assessing the potential for growth hormone, androstenedione and dehydroepiandrostenedione to increase muscle mass. Creatine supplementation is clearly an effective means to increase muscle mass, especially in combination with resistance exercise, however the mechanisms remain unclear. Results from acute metabolic studies provide useful information for estimation of the efficacy of anabolic agents.


Subject(s)
Anabolic Agents/administration & dosage , Exercise/physiology , Muscle, Skeletal/metabolism , Nutritional Physiological Phenomena , Dietary Supplements , Food/standards , Humans , Muscle, Skeletal/drug effects , Muscle, Skeletal/growth & development
17.
Clin Nutr ; 27(2): 189-95, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18294740

ABSTRACT

BACKGROUND & AIMS: With advancing age there is a gradual decline in muscle mass, strength and function. The aim of this study was to determine if regular intake of a nutritional supplement containing essential amino acids (EAA)+arginine could reverse these responses in elderly subjects. METHODS: Twelve glucose intolerant subjects (67.0+/-5.6 (SD) years, 7 females, 5 males) ingested 11 g of EAA+arginine two times a day, between meals for 16 weeks. Diet and activity were not otherwise modified. Lean body mass (DEXA) was measured every fourth week. Maximal leg strength was tested and functional tests were performed at week 0, 8, 12, and 16. RESULTS: Lean body mass (LBM) increased during the study (p=0.038). At week 12, the average increase in LBM was 1.14+/-0.36 (SE) kg (p<0.05 vs baseline), whereas at week 16, the increase was 0.60+/-0.38 kg (NS vs baseline). The lower extremity strength measure score (sum of individual knee flexors and extensors' one repetition maximum, n=10) was 127.5+/-21.8 kg at baseline, and average increase during the study was 22.2+/-6.1% (p<0.001). Improvements were also observed in usual gait speed (p=0.002), timed 5-step test (p=0.007), and timed floor-transfer test (p=0.022). CONCLUSION: Supplementation of the diet with EAA+arginine improves lean body mass, strength and physical function compared to baseline values in glucose intolerant elderly individuals.


Subject(s)
Amino Acids, Essential/administration & dosage , Arginine/administration & dosage , Body Composition/drug effects , Muscle Strength/drug effects , Muscle, Skeletal , Absorptiometry, Photon , Aged , Aging/physiology , Amino Acids, Essential/pharmacology , Arginine/pharmacology , Body Composition/physiology , Dietary Supplements , Female , Gait/physiology , Glucose Intolerance/metabolism , Humans , Lower Extremity/physiology , Male , Muscle Strength Dynamometer , Muscle, Skeletal/drug effects , Muscle, Skeletal/physiology , Treatment Outcome
18.
Aviat Space Environ Med ; 78(6): 608-12, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17571663

ABSTRACT

INTRODUCTION: Hypokinesia is associated with spaceflight and prolonged illnesses and may lead to secondary immune deficiency. METHODS: The distribution of immunocytes in whole blood, mitogen-induced cytokine secretion in vitro, Epstein-Barr virus (EBV) reactivation, and plasma cortisol levels were studied in 13 healthy volunteers subjected to a horizontal bed rest (BR) regime for 28 d. Samples were collected before the study, weekly during BR, and then 3-5 d after the regime ended. Additionally, subjects were treated with hydrocortisone on the 1st and 27th d of BR to simulate the hypercortisolemia that occurs during stress. RESULTS: The factors of 28-d BR regime accompanied by acute hypercortisolemia significantly decreased the relative and absolute number of total lymphocytes, CD3+ T-cells, T-helper subset, and monocytes, but increased the percentage of the CD8+ T-cells, and NK cells at the 4th wk compared with the baseline. A significant decrease in mitogen-activated secretion of IL-2, IFN-gamma, TNF-beta, IL-6, and IL-10 was registered at the same interval. Also, secretion of IL-2 and IFN-gamma declined at the 2nd week of the BR regime. Secretion of IL-4 was significantly higher at the 2nd and 3rd weeks compared with the baseline. A significant increase in the shedding of EBV DNA in saliva was observed as early as the 3rd wk of BR. CONCLUSIONS: Stress factors associated with BR significantly alter immune responsiveness in vitro and in vivo. Changes in the cytokine secretion and cytokine imbalance precede latent EBV reactivation. PHA/LPS-activated cytokine secretion in whole blood can be used as a test system for predicting latent virus activation.


Subject(s)
Cytokines/metabolism , Herpesvirus 4, Human/immunology , Immobilization/adverse effects , Immobilization/physiology , Virus Activation/immunology , Adult , Amino Acids, Essential/immunology , Amino Acids, Essential/metabolism , Anti-Inflammatory Agents/immunology , Anti-Inflammatory Agents/pharmacology , Cytokines/drug effects , Dietary Supplements , Humans , Hydrocortisone/blood , Hydrocortisone/immunology , Middle Aged , Saliva/virology , Space Simulation/adverse effects , Stress, Psychological/immunology , Stress, Psychological/virology , Virus Latency/immunology , Virus Latency/physiology
19.
J Nutr ; 135(7): 1809S-1812S, 2005 Jul.
Article in English | MEDLINE | ID: mdl-15987870

ABSTRACT

Muscular inactivity is inherent in many circumstances, including convalescence from serious illness or injury, spaceflight, and the progression of aging. Inactivity in a healthy individual leads to a decrease in whole-body protein turnover composed primarily of a decrease in muscle protein synthesis. The decrease in muscle protein synthesis leads to a substantial loss of lean body mass. We have demonstrated that this loss of lean mass is greater when inactivity is accompanied by stress, specifically hypercortisolemia. During convalescence from trauma or injury, the anabolic stimulus provided by nutrient ingestion represents a primary means of ameliorating the loss of muscle protein. We have previously demonstrated that ingestion of essential amino acids (EAAs), formulated to mimic the proportion of EAAs in muscle, provides a potent anabolic stimulus for muscle protein. Recently, we demonstrated that EAA supplementation throughout 28 d of bed rest stimulated net muscle protein synthesis. The repeated stimulation translated to maintenance of lean body mass and an amelioration of functional decrement compared to a placebo treatment. We have also demonstrated that this EAA supplement stimulates net protein synthesis during acute hypercortisolemia and are currently testing the effects during prolonged inactivity. Although EAAs promote muscle anabolism during hypercortisolemia, it is unlikely that a nutritional intervention alone would be effective in maintaining lean body mass during severe stress. It may be necessary to concomitantly reduce the catabolic influence of cortisol or provide another anabolic stimulus.


Subject(s)
Amino Acids/administration & dosage , Bed Rest/adverse effects , Dietary Supplements , Muscular Diseases/drug therapy , Amino Acids/therapeutic use , Humans , Muscle, Skeletal/drug effects , Muscle, Skeletal/pathology
20.
Am J Physiol Endocrinol Metab ; 288(4): E761-7, 2005 Apr.
Article in English | MEDLINE | ID: mdl-15572657

ABSTRACT

We sought to determine whether ingestion of a between-meal supplement containing 30 g of carbohydrate and 15 g of essential amino acids (CAA) altered the metabolic response to a nutritionally mixed meal in healthy, recreationally active male volunteers. A control group (CON; n = 6, 38 +/- 8 yr, 86 +/- 10 kg, 179 +/- 3 cm) received a liquid mixed meal [protein, 23.4 +/- 1.0 g (essential amino acids, 14.7 +/- 0.7 g); carbohydrate, 126.6 +/- 4.0 g; fat, 30.3 +/- 2.8 g] every 5 h (0830, 1330, 1830). The experimental group (SUP; n = 7, 36 +/- 10 yr, 87 +/- 12 kg, 180 +/- 3 cm) consumed the same meals but, in addition, were given CAA supplements (1100, 1600, 2100). Net phenylalanine balance (NB) and fractional synthetic rate (FSR) were calculated during a 16-h primed constant infusion of L-[ring-2H5]phenylalanine. Ingestion of a combination of CAA supplements and meals resulted in a greater mixed muscle FSR than ingestion of the meals alone (SUP, 0.099 +/- 0.008; CON, 0.076 +/- 0.005%/h; P < 0.05). Both groups experienced an improvement in NB after the morning (SUP, -2.2 +/- 3.3; CON, -1.5 +/- 3.5 nmol x min(-1) x 100 ml leg volume(-1)) and evening meals (SUP, -9.7 +/- 4.3; CON, -6.7 +/- 4.1 nmol x min(-1) x 100 ml leg volume(-1)). NB after CAA ingestion was significantly greater than after the meals, with values of 40.2 +/- 8.5 nmol x min(-1) x 100 ml leg volume(-1). These data indicate that CAA supplementation produces a greater anabolic effect than ingestion of intact protein but does not interfere with the normal metabolic response to a meal.


Subject(s)
Amino Acids, Essential/administration & dosage , Dietary Proteins/administration & dosage , Dietary Supplements , Muscle Proteins/metabolism , Muscle, Skeletal/drug effects , Adult , Amino Acids, Essential/blood , Amino Acids, Essential/metabolism , Dietary Carbohydrates/administration & dosage , Dietary Carbohydrates/metabolism , Dietary Proteins/metabolism , Eating/physiology , Feeding Behavior/physiology , Humans , Male , Middle Aged , Muscle, Skeletal/metabolism
SELECTION OF CITATIONS
SEARCH DETAIL