Effects of L-arginine and L-citrulline Supplementation on Muscle Respiration

This study is a randomized, double-blind, cross over trial of L-arginine and L-citrulline supplementation, L-arginine supplementation alone and placebo supplementation in healthy men. The intervention period will be 8-11 weeks for each participant and a minimum of 15 individuals will be recruited and enrolled to complete the trial. Subjects will complete the experimental protocol described below over 3 individual 10 day supplementation periods, separated by washout periods of approximately 2 weeks. Subjects will ingest corn-starch as a placebo, L-arginine (3g/day) or L-arginine (1.5 g/day) + L-citrulline (1.5g/day). On day 7 of the supplementation period, a skeletal muscle biopsy and blood sample will be obtained from the subjects to investigate mitochondrial function and blood amino acid and nitric oxide levels. On day 10 of the supplementation period, subjects will complete a performance test on a cycle ergometer to investigate their endurance performance. These assessments will be performed to determine the effects of co-ingesting L-arginine and L-citrulline compared to L-arginine alone and placebo administration.