Effect of lean red meat combined with a multicomponent exercise program on muscle and cognitive function in older adults: a 6-month randomized controlled trial

Abstract

Background: Exercise and increased dietary protein have been linked to improved muscle and cognitive health, but the combination may be more effective.

Objective: In this study performed in community-dwelling older adults undergoing a 3-d/wk resistance-based exercise training program, we investigated whether those who consumed lean red meat compared to carbohydrates on the 3 training days per wk would experience greater exercise-induced improvements in total body and leg lean mass (LM), muscle strength, and executive function (multiple primary outcomes), as well as muscle size and density, functional performance, cognition, inflammatory and neurotrophic markers, blood pressure, and lipid concentrations.

Design: In a 24-wk, 2-arm parallel randomized controlled trial, 154 adults aged ≥65 y participated in a multicomponent 3-d/wk resistance-based exercise program with random allocation to either a lean red meat group (two 80-g servings of cooked red meat), the exercise plus lean red meat (Ex + Meat) group (n = 77) or a control group receiving carbohydrates in the form of one-half cup (approximately 225 g cooked weight) of rice or pasta or 1 medium potato, the exercise plus carbohydrate control (C + Ex) group (n = 77), on the training days.

Results: Exercise-induced improvements (mean within group changes) did not significantly differ between groups for the primary outcomes of total body LM (0.6 to 0.8 kg), leg LM (0.1 to 0.2 kg), thigh muscle cross-sectional area (3.7% to 4.9%), leg and back muscle strength (26% to 40%), and executive function (z-score SD: 0.33 to 0.39), nor the secondary outcomes of global cognition function (0.17 to 0.23 SD), fat mass (-0.65 to -0.75 kg), physical function measures (sit-to-stand, both 15%; 4-square step test, 2% to 7%), or systolic blood pressure (-3.2 to -4.1 mm Hg). The Ex + Meat group experienced greater improvements than the C + Ex in arm LM (0.07 kg; 95% CI: 0.01, 0.14; P = 0.029), gait speed (0.05 m/s; 95% CI: 0.00, 0.11; P = 0.042), muscle density (1.0%; 95% CI: 0.2, 1.9; P = 0.015), and appendicular LM in the per-protocol analysis (0.21 kg; 95% CI: 0.02, 0.40; P = 0.03). The C + Ex group had greater net improvements in working memory/learning after 12 wk (SD: 0.24; 95% CI: 0.05, 0.43; P = 0.011) and 24 wk (SD: 0.27; 95% CI: 0.06, 0.49; P = 0.007). Inflammatory and neurotrophic markers did not change in either group.

Conclusion: In healthy community-dwelling older adults undertaking resistance-based exercise training 3-d/wk, participants who consumed lean red meat in line with current Australian dietary recommendations did not experience any significant additional benefits in the primary outcome measures of muscle mass, strength, or cognitive function compared to participants consuming carbohydrates.This trial is registered with the Australian and New Zealand Clinical Trials Registry as ACTRN12613001153707.

Keywords: cognitive function; dietary protein; exercise; lean red meat; muscle mass; muscle strength; older adults.