Body Composition and Strength Changes in Women with Milk and Resistance Exercise

Abstract

We aimed to determine whether women consuming fat-free milk versus isoenergetic carbohydrate after resistance exercise would see augmented gains in lean mass and reductions in fat mass similar to what we observed in young men. Young women were randomized to drink either fat-free milk (MILK: n = 10; age (mean +/- SD) = 23.2 +/- 2.8 yr; BMI = 26.2 +/- 4.2 kg x m(-2)) or isoenergetic carbohydrate (CON: n = 10; age = 22.4 +/- 2.4 yr; BMI = 25.2 +/- 3.8 kg x m(-2)) immediately after and 1 h after exercise (2 x 500 mL). Subjects exercised 5 d x wk(-1) for 12 wk. Body composition changes were measured by dual-energy x-ray absorptiometry, and subjects' strength and fasting blood were measured before and after training. CON gained weight after training (CON: +0.86 +/- 0.4 kg, P < 0.05; MILK: +0.50 +/- 0.4 kg, P = 0.29). Lean mass increased with training in both groups (P < 0.01), with a greater net gain in MILK versus CON (1.9 +/- 0.2 vs 1.1 +/- 0.2 kg, respectively, P < 0.01). Fat mass decreased with training in MILK only (-1.6 +/- 0.4 kg, P < 0.01; CON: -0.3 +/- 0.3 kg, P = 0.41). Isotonic strength increased more in MILK than CON (P < 0.05) for some exercises. Serum 25-hydroxyvitamin D increased in both groups but to a greater extent in MILK than CON (+6.5 +/- 1.1 vs +2.8 +/- 1.3 nM, respectively, P < 0.05), and parathyroid hormone decreased only in MILK (-1.2 +/- 0.2 pM, P < 0.01). Heavy, whole-body resistance exercise with the consumption of milk versus carbohydrate in the early postexercise period resulted in greater muscle mass accretion, strength gains, fat mass loss, and a possible reduction in bone turnover in women after 12 wk. Our results, similar to those in men, highlight that milk is an effective drink to support favorable body composition changes in women with resistance training.