Efficacy of L-leucine Supplementation Coupled With Resistance Training in Untrained Midlife Women

Abstract

Objective: This study investigated the effects of leucine supplementation with resistance training (RT) in untrained peri- and postmenopausal women on fat free mass, strength, and select anabolic-related hormones. Method: This was a randomized, double-blind, placebo-controlled trial, in which 36 untrained women were randomly assigned to either a leucine or placebo supplement group coupled with 10 weeks of RT, performed thrice weekly, while ingesting either 5 g of placebo or leucine. Before and after RT, body composition and muscle strength were assessed and venous blood samples obtained to determine the levels of estradiol, testosterone, insulin-like growth factor-1, growth hormone, and cortisol. Data were analyzed by utilizing separate 2 × 2 [group × time (pretest and posttest)] factorial analyses of variance with repeated measures (p ≤ .05). Results: There were no significant changes or differences between groups in fat free mass or with any of the serum hormones assessed in response to supplementation. However, there were significant increases in strength in both groups in response to RT, but not supplementation. Conclusions: Peri- and postmenopausal women had significant increases in strength following 10 weeks of RT, with no additional effects from supplementing with leucine. There were no significant changes in either group regarding fat free mass or serum hormones.