English Title: Effect of branched-chain amino acid supplementation on human growth hormone and cortisol secretion after exercise.
Personal Authors: Tang FuChun
Author Affiliation: Graduate Institute of Nutrition and Hospitality, Department of Human Development and Family Studies, National Taiwan Normal University, Taipei, Taiwan.
Editors: No editors
Document Title: Nutritional Sciences Journal, 2004 (Vol. 29) (No. 2) 97-104
Abstract:
A double-blind, counter-balanced study was conducted to investigate the effects of branched-chain amino acid (BCAA) supplementation on human growth hormone (HGH) and cortisol secretion before, during and after swimming. 19 male physical education students (aged 19-22 years) were recruited into the study [Taiwan; date not given]. Based on the swimming score in a 600-m crawl stroke, the students were divided into 2 groups: placebo (n=9; BMI, 24.2±2.1 kg/m2; 12 g of glucose/day in capsules) and BCAA (n=10; BMI, 22.7±1.5 kg/m2; 12 g of BCAA/day in capsules: leucine 54%, isoleucine 19% and valine 27%) groups. The participants maintained a regular dietary intake and exercise activity at a moderate/low intensity (60-70% HRRmax, swimming and rowing, ~1.5 h/day) for 2 weeks. Plasma glucose and serum HGH concentrations were not affected by 14 days of dietary supplementation in either group, but serum cortisol concentration decreased significantly (P<0.05) regardless of dietary treatment. On day 15, after 25 minutes of breast stroke exercise and a 600-m crawl stroke competition, plasma glucose concentrations significantly decreased (P<0.05), whereas serum HGH and cortisol concentrations significantly increased (P<0.05) in both groups. Before exercise, the concentrations of the 2 hormones in the BCAA group were significantly higher than those in the placebo group (P<0.05). After either form of exercise, HGH secretion in the BCAA group was significantly enhanced (P<0.05). Both exercise and BCAA supplements significantly affected serum HGH concentration. The cumulative effects of exercise and BCAA supplements increased serum HGH concentration. It is concluded that in the case of BCAA supplementation, moderate/low intensity exercise induces high levels of HGH and cortisol secretion. The effect of HGH on body composition requires further investigation.
Publisher: Nutrition Society in Taipei