Protein requirements and supplementation in strength sports.
Nutrition. 2004 Jul-Aug;20(7-8):689-95.
Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada. email@example.com
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.
PMID 15212752 [PubMed - indexed for MEDLINE]
Full text: Elsevier Science
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