The purpose of this study was to investigate the effect of whey protein (WP) supplementation on muscular strength, hypertrophy, and muscular quality in older women preconditioned to resistance training (RT). In a randomized, double-blind, and placebo (PLA)-controlled design, 31 older women (67.4 ± 4.0 years, 62.0 ± 6.9 kg, 155.9 ± 5.7 cm, and 25.5 ± 2.4 kg/m2) received either 35 g of WP (n = 15) or 35 g of PLA (n = 16) over a 12-week study period while performing an RT program three times a week. Dietary intake, one-repetition maximum test, and skeletal muscle mass by dual-energy X-ray absorptiometry were assessed before and after the intervention period. Both groups showed significant (p < .05) improvements in skeletal muscle mass and total strength, and the WP group realized greater increases (p < .05) in these measures compared with PLA (skeletal muscle mass: WP = +4.8% vs. PLA = +2.3%; strength: WP = +8.7% vs. PLA = +4.9%). Muscular quality increased (p < .05) in both groups (WP = +2.9% vs. PLA = +1.5%) without statistical differences (p > .05) noted between conditions. We conclude that WP supplementation in combination with RT induces higher increases in both strength and hypertrophy in older women preconditioned to RT.
DXA & MRI measures of tissue composition: implications for muscle quality in older women varying in physical activity
