Amino acid supplementation may be one way to improve muscle function and exercise endurance in the elderly, according to research appearing in the American Journal of Cardiology (Volume 101, Issue 11, Supplement 1, 2 June 2008, Pages S104-S110). The subjects of the randomized, double-blind, placebo-controlled study were 95 senior citizens (aged 65-74) with chronic heart failure. Subjects were given either a placebo or 4 g of a mixed amino acid supplement twice per day. An exercise test was given at the beginning of the study and after 30 days of supplementation. The group receiving the amino acids had a significant improvement in exercise capacity and in peripheral oxygen availability.

Another pilot study appearing in the American Journal of Cardiology (Volume 101, Issue 11, Supplement 1, 2 June 2008, Pages S78-S81), showed the value of amino acid supplementation in elderly patients with chronic heart failure. The subjects took 4 g. of a mixed amino acid supplement for 12 weeks. Prior to supplementation the subjects were able to walk an average of 201 meters in six minutes. After 12 weeks of supplementation, the average distance walked increased to 226 meters.