Protein requirements and supplementation in strength sports

Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada.
Nutrition (Impact Factor: 2.93). 07/2004; 20(7-8):689-95. DOI: 10.1016/j.nut.2004.04.009
Source: PubMed

ABSTRACT Daily requirements for protein are set by the amount of amino acids that is irreversibly lost in a given day. Different agencies have set requirement levels for daily protein intakes for the general population; however, the question of whether strength-trained athletes require more protein than the general population is one that is difficult to answer. At a cellular level, an increased requirement for protein in strength-trained athletes might arise due to the extra protein required to support muscle protein accretion through elevated protein synthesis. Alternatively, an increased requirement for protein may come about in this group of athletes due to increased catabolic loss of amino acids associated with strength-training activities. A review of studies that have examined the protein requirements of strength-trained athletes, using nitrogen balance methodology, has shown a modest increase in requirements in this group. At the same time, several studies have shown that strength training, consistent with the anabolic stimulus for protein synthesis it provides, actually increases the efficiency of use of protein, which reduces dietary protein requirements. Various studies have shown that strength-trained athletes habitually consume protein intakes higher than required. A positive energy balance is required for anabolism, so a requirement for "extra" protein over and above normal values also appears not to be a critical issue for competitive athletes because most would have to be in positive energy balance to compete effectively. At present there is no evidence to suggest that supplements are required for optimal muscle growth or strength gain. Strength-trained athletes should consume protein consistent with general population guidelines, or 12% to 15% of energy from protein.

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    • "The collective agreement among reviewers is that a protein intake of 1.2-2.2 g/kg is sufficient to allow adaptation to training for athletes whom are at or above their energy needs [23-28,35-38]. However, bodybuilders during their contest preparation period typically perform resistance and cardiovascular training, restrict calories and achieve very lean conditions [2-6,17-21]. "
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    ABSTRACT: The popularity of natural bodybuilding is increasing; however, evidence-based recommendations for it are lacking. This paper reviewed the scientific literature relevant to competition preparation on nutrition and supplementation, resulting in the following recommendations. Caloric intake should be set at a level that results in bodyweight losses of approximately 0.5 to 1%/wk to maximize muscle retention. Within this caloric intake, most but not all bodybuilders will respond best to consuming 2.3-3.1 g/kg of lean body mass per day of protein, 15-30% of calories from fat, and the reminder of calories from carbohydrate. Eating three to six meals per day with a meal containing 0.4-0.5 g/kg bodyweight of protein prior and subsequent to resistance training likely maximizes any theoretical benefits of nutrient timing and frequency. However, alterations in nutrient timing and frequency appear to have little effect on fat loss or lean mass retention. Among popular supplements, creatine monohydrate, caffeine and beta-alanine appear to have beneficial effects relevant to contest preparation, however others do not or warrant further study. The practice of dehydration and electrolyte manipulation in the final days and hours prior to competition can be dangerous, and may not improve appearance. Increasing carbohydrate intake at the end of preparation has a theoretical rationale to improve appearance, however it is understudied. Thus, if carbohydrate loading is pursued it should be practiced prior to competition and its benefit assessed individually. Finally, competitors should be aware of the increased risk of developing eating and body image disorders in aesthetic sport and therefore should have access to the appropriate mental health professionals.
    Journal of the International Society of Sports Nutrition 05/2014; 11(1):20. DOI:10.1186/1550-2783-11-20 · 1.91 Impact Factor
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    • "The Recommended Daily Allowance for protein is 0.8 gm●kg body weight −1●day−1[100]. However, summaries of studies indicated that the daily average intake of protein among strength-trained athletes was 2.1 gm●kg−1●day−1[101] while that among endurance athletes was 1.8 ± 0.4 gm●kg−1●day−1 for men and 1.2 ± 0.03 gm●kg−1●day−1 for women [102]. A recent consensus statement on the efficacy of protein supplementation in military personnel recommended 1.5 to 2.0 gm●kg−1●day−1 for service members involved in substantially increased metabolic demand and 1.2 to 1.5 gm●kg−1●day−1 for older service members [103]. "
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    ABSTRACT: Background Although a number of studies have been conducted on the prevalence of dietary supplement (DS) use in military personnel, these investigations have not been previously summarized. This article provides a systematic literature review of this topic. Methods Literature databases, reference lists, and other sources were searched to find studies that quantitatively examined the prevalence of DS use in uniformed military groups. Prevalence data were summarized by gender and military service. Where there were at least two investigations, meta-analysis was performed using a random model and homogeneity of the prevalence values was assessed. Results The prevalence of any DS use for Army, Navy, Air Force, and Marine Corps men was 55%, 60%, 60%, and 61%, respectively; for women corresponding values were 65%, 71%, 76%, and 71%, respectively. Prevalence of multivitamin and/or multimineral (MVM) use for Army, Navy, Air Force, and Marine Corps men was 32%, 46%, 47%, and 41%, respectively; for women corresponding values were 40%, 55%, 63%, and 53%, respectively. Use prevalence of any individual vitamin or mineral supplement for Army, Navy, Air Force, and Marine Corps men was 18%, 27%, 25%, and 24%, respectively; for women corresponding values were 29%, 36%, 40%, and 33%, respectively. Men in elite military groups (Navy Special Operations, Army Rangers, and Army Special Forces) had a use prevalence of 76% for any DS and 37% for MVM, although individual studies were not homogenous. Among Army men, Army women, and elite military men, use prevalence of Vitamin C was 15% for all three groups; for Vitamin E, use prevalence was 8%, 7%, and 9%, respectively; for sport drinks, use prevalence was 22%, 25% and 39%, respectively. Use prevalence of herbal supplements was generally low compared to vitamins, minerals, and sport drinks, ≤5% in most investigations. Conclusions Compared to men, military women had a higher use prevalence of any DS and MVM. Army men and women tended to use DSs and MVM less than other service members. Elite military men appeared to use DSs and sport drinks more than other service members.
    BMC Complementary and Alternative Medicine 05/2014; 14(1):143. DOI:10.1186/1472-6882-14-143 · 2.02 Impact Factor
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    • "selected to represent the current sport nutrition guidelines (Lemon, 1998; Phillips, 2012; Rennie & Tipton, 2000; Rodriguez, Di Marco, & Langley, 2009; Tarnopolsky, 2004), a typical composition of athletes (Phillips, 2004) as compared to the current RDA (Institute of Medicine, 2005). It was hypothesized that supplementing a daily diet with a whey protein isolate would cause a greater increase in certain amino acids (e.g. "
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    ABSTRACT: The purpose was to investigate the effects of a controlled typical one day diet supplemented with two different doses of whey protein isolate on blood amino acid profiles and hormonal concentrations following the final meal. Nine males (age: 29.6 ± 6.3 yrs) completed four conditions in random order: a control (C) condition of a typical mixed diet containing ~10% protein (0.8 g·kg-1), 65% carbohydrate and 25% fat; a placebo (P) condition calorically matched with carbohydrate to the whey protein conditions; a low dose condition of 0.8 grams of whey protein isolate per kilogram body mass per day (g·kg-1·d-1; W1) in addition to the typical mixed diet; or a high dose condition of 1.6 g·kg-1·d-1 (W2) of supplemental whey protein in addition to the typical mixed diet. Following the final meal, significant (p<0.05) increases in total amino acids, essential amino acids (EAA), branch-chained amino acids (BCAA), and leucine were observed in plasma with whey protein supplementation while no changes were observed in the control and placebo conditions. There was no significant group difference for glucose, insulin, testosterone, cortisol, or growth hormone. In conclusion, supplementing a typical daily food intake consisting of 0.8 g of protein·kg-1·d-1 with a whey protein isolate (an additional 0.8 or 1.6 g·kg-1·d-1) significantly elevated total amino acids, EAA, BCAA, and leucine but had no effect on glucose, insulin, testosterone, cortisol, or growth hormone following the final meal. Future acute and chronic supplementation research examining the physiological and health outcomes associated with elevated amino acid profiles is warranted.
    International Journal of Sport Nutrition and Exercise Metabolism 11/2013; 24(2). DOI:10.1123/ijsnem.2013-0136 · 2.44 Impact Factor
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