Protein supplementation before and after exercise does not further augment skeletal muscle hypertrophy after resistance training in elderly men

Abstract

Background:Considerable discrepancy exists in the literature on the proposed benefits of protein supplementation on the adaptive response of skeletal muscle to resistance-type exercise training in the elderly.Objective: The objective was to assess the benefits of timed protein supplementation on the increase in muscle mass and strength during prolonged resistance-type exercise training in healthy elderly men who habitually consume adequate amounts of dietary protein.Design: Healthy elderly men (n = 26) aged 72 ± 2 y were randomly assigned to a progressive, 12-wk resistance-type exercise training program with (protein group) or without (placebo group) protein provided before and immediately after each exercise session (3 sessions/wk, 20 g protein/session). One-repetition maximum (1RM) tests were performed regularly to ensure a progressive workload during the intervention. Muscle hypertrophy was assessed at the whole-body (dual-energy X-ray absorptiometry), limb (computed tomography), and muscle fiber (biopsy) level.Results: The 1RM strength increased ≈25–35% in both groups (P < 0.001). Dual-energy X-ray absorptiometry and computed tomography scans showed similar increases in leg muscle mass (6 ± 1% in both groups; P < 0.001) and in the quadriceps (9 ± 1% in both groups), from 75.9 ± 3.7 and 73.8 ± 3.2 to 82.4 ± 3.9 and 80.0 ± 3.0 cm2 in the placebo and protein groups, respectively (P < 0.001). Muscle fiber hypertrophy was greater in type II (placebo: 28 ± 6%; protein: 29 ± 4%) than in type I (placebo: 5 ± 4%; protein: 13 ± 6%) fibers, but the difference between groups was not significant.Conclusion: Timed protein supplementation immediately before and after exercise does not further augment the increase in skeletal muscle mass and strength after prolonged resistance-type exercise training in healthy elderly men who habitually consume adequate amounts of dietary protein. This trial was registered at clinicaltrials.gov as NCT00744094.