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


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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    ABSTRACT: Skeletal muscle mass is regulated by a balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). In healthy humans, MPS is more sensitive (varying 4-5 times more than MPB) to changes in protein feeding and loading rendering it the primary locus determining gains in muscle mass. Performing resistance exercise (RE) followed by the consumption of protein results in an augmentation of MPS and, over time, can lead to muscle hypertrophy. The magnitude of the RE-induced increase in MPS is dictated by a variety of factors including: the dose of protein, source of protein, and possibly the distribution and timing of post-exercise protein ingestion. In addition, RE variables such as frequency of sessions, time under tension, volume, and training status play roles in regulating MPS. This review provides a brief overview of our current understanding of how RE and protein ingestion can influence gains in skeletal muscle mass in young, healthy individuals. It is the goal of this review to provide nutritional recommendations for optimal skeletal muscle adaptation. Specifically, we will focus on how the manipulation of protein intake during the recovery period following RE augments the adaptive response.
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    Full-text · Article · May 2014 · Journal of the International Society of Sports Nutrition
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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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    Full-text · Article · May 2014 · BMC Complementary and Alternative Medicine
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