Comparison of the influence of pre‐exercise BCAA supplementation on serum HMB level between endurance and resistance exercises

Abstract

AimsBranched‐chain amino acids (BCAA) play the certain beneficial roles on the resistance exercise‐induced muscle damage and soreness, and are also metabolized for energy production in the skeletal muscle during endurance exercise. In addition to the acetyl‐CoA production in the mitochondria of skeletal muscle, leucine is also metabolized in the cytoplasm to β‐hydroxy‐β‐methylbutyrate (HMB), which enhances protein synthesis through mTOR activation. However, it is unclear whether HMB is synthesized from the supplemented leucine by any kinds of exercises. This study investigated the influence of pre‐exercise BCAA supplementation on serum HMB level after exercises by comparison between endurance and resistance exercises.MethodsStudy 1) BCAA (3.2g) or placebo supplementation were given after every meal from a day to immediately before a full‐marathon race (N=14/group). Blood was collected at two days, immediately after and one day after the race.Study 2) BCAA (3.2g) or placebo supplementation were given after every meal for three days prior to a repeated eccentric resistance exercise in the upper arm (N=5/group). Blood was collected at before supplementation, immediately after the exercise, and everyday for three days after the race. Serum concentrations of HMB and valine intermediate β‐hydroxyisobutyrate (HIB) that is a marker of BCAA catabolism for energy production were measured by LC‐MS/MS system.ResultsStudy 1) Both HMB and HIB concentrations in serum immediately after the marathon race were significantly increased, and then, were returned to the base levels at next day. At the immediately after the race, the increased levels of the both BCAA metabolites were significantly higher in the BCAA group than in the placebo group. Study 2) Serum HMB concentration was significantly increased immediately after the eccentric resistance exercise only in the BCAA group but not in the placebo group, and was returned to the base level at next day. There was no change in serum HIB concentration in the both groups during the experiment.ConclusionThe resistance exercise after the BCAA supplementation may activate the HMB metabolism from leucine, while HMB is also synthesized in the endurance exercise accompanied with BCAA catabolism for energy production. The beneficial effects of BCAA supplementation on the exercise‐induced muscle damage and soreness might be partly contributed by HMB derived from the supplemented leucine.Support or Funding InformationThis study was supported in part by an educational grant from the Seikatsu Bunkasya Co. Inc. (Tokyo, Japan), and by Kakenhi grants (25750334, 16K01734, 15J00614, 16K16571) from the Japan Society for the Promotion of Science.