Effects of Branched‐Chain Amino Acid Supplementation on Exercise Performance and Recovery in Highly Endurance‐Trained Athletes

Abstract

Branched‐chain amino acid (BCAA) supplementation has recently entered the spotlight as a potentially key nutritional component to skeletal muscle recovery during periods of high training volume in endurance athletes. The purpose of this study was to examine the effects of BCAA supplementation on anaerobic and aerobic performance, substrate utilization during constant‐load exercise to exhaustion, and plasma creatine kinase and lactate dehydrogenase levels during post‐exercise recovery. Nine well‐trained cyclists (5 male, 4 female) underwent a morning session and an afternoon session of exercise testing under BCAA or Placebo conditions. Morning tests included two 15‐second Wingates to determine peak and mean anaerobic power output, followed by an incremental test to exhaustion to determine peak oxygen consumption (VO2peak). Afternoon tests included two 15‐second Wingates, followed by a constant‐load exercise to exhaustion at 75% VO2peak, during which only water was provided. During the latter test, pulmonary gas exchange, blood lactate and blood glucose were periodically measured to monitor substrate utilization. Pre‐ and post‐exercise blood tests were conducted to quantify plasma creatine kinase and lactate dehydrogenase levels as biomarkers for muscle damage. Post‐exercise ratings of perceived soreness were also collected. Subjects were then instructed to continue training for at least 2000 MET‐min/week for the next four weeks while supplementing with either a BCAA (5 g amino acids + 56 g carbohydrates) or Placebo (56 g carbohydrates) powdered drink during each workout. At the completion of the four weeks, subjects repeated two 15‐second Wingates and an incremental test to exhaustion to determine any differences in anaerobic and aerobic power due to BCAA or Placebo supplementation. There were no differences in VO2peak pre‐ and post‐training between BCAA and placebo conditions. Peak anaerobic power was slightly improved when athletes supplemented their training with the BCAA drink. The total energy expenditure achieved during the constant‐load exercise test was not different between conditions. Post‐exercise plasma creatine kinase levels were significantly reduced with BCAA compared with Placebo, while there were no differences in plasma lactate dehydrogenase levels. Post‐exercise leg muscle soreness was slightly lower with BCAA supplementation, although not significant. In conclusion, BCAA supplementation with endurance training may augment adaptations in muscle anaerobic power and post‐exercise recovery in well‐trained athletes.Support or Funding InformationThis research was supported by the Saint Mary's College Faculty Development Fund and a gift from GU Energy Labs, Berkeley, CA.