Branched-chain amino acid supplementation during trekking at high altitude. The effects on loss of body mass, body composition, and muscle power.
To investigate the influence of a branched-chain amino acid (BCAA) supplementation on chronic hypoxia-related loss of body mass and muscle loss, 16 subjects [age 35.8 (SD 5.6) years] participating in a 21-day trek at a mean altitude of 3,255 (SD 458) m, were divided in two age-, sex- and fitness-matched groups and took either a dietary supplementation of BCAA (5.76, 2.88 and 2.88 g per day of leucine, isoleucine and valine, respectively) or a placebo (PLAC) in a controlled double-blind manner. Daily energy intake at altitude decreased by 4% in both groups compared with sea level. After altitude exposure both groups showed a significant loss of body mass, 1.7% and 2.8% for BCAA and PLAC, respectively. Fat mass had decreased significantly by 11.7% for BCAA and 10.3% for PLAC, whereas BCAA showed a significantly increased lean mass of 1.5%, as opposed to no change in PLAC. Arm muscle cross-sectional area tended to increase in BCAA, whereas there was a significant decrease of 6.8% in PLAC (P < 0.05 between groups). The same tendency, although not significant, was observed for the thigh muscle cross-sectional area. On the whole it seemed that PLAC had been catabolizing whereas BCAA had been synthesizing muscle tissue. Single jump height from a squatted position showed a similar tendency to increase in both groups. Lower limb maximal power decreased less in BCAA than in PLAC (2.4% vs 7.8%, P < 0.05). We concluded that BCAA supplementation may prevent muscle loss during chronic hypobaric hypoxia.
Schena
F
F
Institute of Human Physiology, University of Verona, Italy.
Guerrini
F
F
Tregnaghi
P
P
Kayser
B
B
D000328:Adult; D000531:Altitude; D000597:Amino Acids, Branched-Chain / Q000008:administration & dosage*; D001823:Body Composition; D002149:Energy Intake; D005260:Female; D006801:Humans; D007532:Isoleucine / Q000008:administration & dosage; D007930:Leucine / Q000008:administration & dosage; D008297:Male; D009132:Muscles / Q000502:physiology*; D010919:Placebos; D014633:Valine / Q000008:administration & dosage; D016138:Walking
D000597:Amino Acids, Branched-Chain; D010919:Placebos; D007532:Isoleucine; D007930:Leucine; D014633:Valine