Impairment in walking capacity and myocardial function in the elderly: is there a role for nonpharmacologic therapy with nutritional amino acid supplements?

Elderly persons have reduced muscular mass, with consequent deterioration of their daily activities and reduced quality of life. This is more pronounced in elderly patients affected by chronic diseases such as chronic heart failure (CHF). It has been demonstrated that oral amino acid (AA) supplementation improves muscle protein metabolism. A recent study shows that use of oral supplements with a special mixture of AAs for 12 weeks increases (1) 6-minute walk distance (from 212.5 +/- 34 m to 268.8 +/- 34.9 m; p <0.001), (2) maximal isometric muscular strength (from 14.6 +/- 2.2 kg to 20.2 +/- 2 kg; p <0.001), and (3) peak exercise left ventricular ejection fraction (LVEF 0.55 + 0.4 vs 0.67 + 0.7) (0.558 vs 0.67 +/- 0.7; p <0.01). In a pilot observational study, we studied elderly patients with CHF who were clinically stable on standard therapy (age range, 68-76 years; New York Heart Association (NYHA) class II-III; LVEF <0.40; normal body mass index and arm muscle measurements; peak oxygen consumption <15 mL/kg per min). After basal assessment of (1) cardiac function (by 2-dimensional echocardiography), (2) 6-minute walk test, and (3) blood variables, an AA mixture (4 g x 2 die) was orally administered to the patients for 12 weeks in conjunction with standard therapies and a controlled diet. The AA supplements increased 6-minute walk distance significantly (201 +/- 12 m vs 226 +/- 9 m; p < 0.05). Interestingly, urea values were unchanged (31.3 +/- 10.5 mg/dL vs 32.4 +/- 8.1 mg/dL; p = NS). Our results suggest the potential role of a nonpharmacologic therapy with nutrients (ie, AAs) in an attempt to improve muscular metabolism and function in elderly subjects and in hypercatabolic syndromes such as CHF.