Effect of Aerobic Exercise Training and Essential Amino Acid Supplementation for 24 Weeks on Physical Function, Body Composition, and Muscle Metabolism in Healthy, Independent Older Adults: A Randomized Clinical Trial

Abstract

Background: Essential amino acids (EAA) and aerobic exercise (AE) acutely and independently stimulate skeletal muscle protein anabolism in older adults.

Objective: In this Phase 1, double-blind, placebo-controlled, randomized clinical trial, we determined if chronic EAA supplementation, AE training, or a combination of the two interventions could improve muscle mass and function by stimulating muscle protein synthesis.

Methods: We phone-screened 971, enrolled 109, and randomized 50 independent, low-active, nonfrail, and nondiabetic older adults (age 72 ± 1 years). We used a 2 × 2 factorial design. The interventions were: daily nutritional supplementation (15 g EAA or placebo) and physical activity (supervised AE training 3 days/week or monitored habitual activity) for 24 weeks. Muscle strength, physical function, body composition, and muscle protein synthesis were measured before and after the 24-week intervention.

Results: Forty-five subjects completed the 24-week intervention. VO2peak and walking speed increased (p < .05) in both AE groups, irrespective of supplementation type, but muscle strength increased only in the EAA + AE group (p < .05). EAA supplementation acutely increased (p < .05) muscle protein synthesis from basal both before and after the intervention, with a larger increase in the EAA + AE group after the intervention. Total and regional lean body mass did not change significantly with any intervention.

Conclusions: In nonfrail, independent, healthy older adults AE training increased walking speed and aerobic fitness, and, when combined with EAA supplementation, it also increased muscle strength and EAA-stimulated muscle protein synthesis. These increases occurred without improvements in muscle mass.

Trial registration: ClinicalTrials.gov NCT00872911.

Keywords: Body composition; Exercise; Nutrition; Physical performance.

© The Author(s) 2018. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Figures

Figure 1.

CONSORT flow diagram.

Figure 2.

Muscle protein fractional synthetic rate (FSR) in the basal state and in response to acute treatment with the nutritional supplement [essential amino acids EAA, or placebo placebo supplementation (PLA)] with or without aerobic exercise (AE), before (A) and after (B) 24 weeks of chronic treatment with the same intervention. Treatment effect, *p < .05 compared to basal; time effect, †p < .05 compared to pre-intervention.