Effect of amino acid supplementation on muscle mass, strength and physical function in elderly.

Background & Aims: With advancing age there is a gradual decline in muscle mass, strength and function. The aim of this study was to determine if regular intake of a nutritional supplement containing essential amino acids (EAA)+arginine could reverse these responses in elderly subjects.

Methods: Twelve glucose intolerant subjects (67.0+/-5.6 (SD) years, 7 females, 5 males) ingested 11 g of EAA+arginine two times a day, between meals for 16 weeks. Diet and activity were not otherwise modified. Lean body mass (DEXA) was measured every fourth week. Maximal leg strength was tested and functional tests were performed at week 0, 8, 12, and 16.

Results: Lean body mass (LBM) increased during the study (p=0.038). At week 12, the average increase in LBM was 1.14+/-0.36 (SE) kg (p<0.05 vs baseline), whereas at week 16, the increase was 0.60+/-0.38 kg (NS vs baseline). The lower extremity strength measure score (sum of individual knee flexors and extensors' one repetition maximum, n=10) was 127.5+/-21.8 kg at baseline, and average increase during the study was 22.2+/-6.1% (p<0.001). Improvements were also observed in usual gait speed (p=0.002), timed 5-step test (p=0.007), and timed floor-transfer test (p=0.022).

Conclusion: Supplementation of the diet with EAA+arginine improves lean body mass, strength and physical function compared to baseline values in glucose intolerant elderly individuals.