In brief: The contention that amino acids increase secretion of human growth hormone has served as the catalyst for their increased popularity. Although growth hormone has been linked to muscle hypertrophy and its secretion is known to increase with exercise, there is no proof that artificially induced increases combined with weight training contribute to gains in strength and hypertrophy. Further, growth-hormone-induced hypertrophy, as seen in acromegaly, does not follow the same process as work-induced muscle growth. It is possible that growth-hormone-induced muscle hypertrophy lacks corresponding strength properties because of increases in noncontractile protein. Additional research is needed to determine what effect, if any, combining amino acid supplementation with weight training has on muscle strength and hypertrophy.