Athletes and backpackers who spend longer periods in the mountains lose muscle mass, probably because of the lower air pressure and lack of oxygen in the atmosphere. Taking a daily supplement containing about 12 g BCAAs can help prevent this, and may even result in an increase in muscle mass, according to a study published by Italian sports scientists in 1992 in the European Journal of Applied Physiology.
The Italians did an experiment with 16 participants, who trekked through the Andes mountains for three weeks at heights of 2,500 to 4,000 metres.
Every day during the trek half of the participants were given a placebo and the other half took a supplement containing BCAAs. That meant they ingested 5.76 g leucine, 2.88 g isoleucine and 2.88 g valine daily.
The researchers examined the participants before they set off on their trek and just after they finished.
The participants who took BCAAs gained a little lean body mass while they were in the mountains â€“ whereas the placebo group lost a small amount of lean body mass. The BCAA group gained a little muscle mass in their arms and legs, while the placebo group lost muscle mass.
Both groups lost large amounts of fat.
“The present study confirmed previous reports describing loss of mass and muscle loss during high altitude exposure,” the researchers wrote. “In addition, it was shown that these changes can be prevented with a supplementation of BCAA.”
“Taking extra BCAA was found to be beneficial during trekking at high altitude, but may be of greater value during climbing at extreme altitude. Whether BCAA supplementation could play a relevant role in hypoxia-related muscle loss at sea level is still matter for investigation.”
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.
PMID: 1425642 [PubMed - indexed for MEDLINE]