11) Journal of Exercise Physiology Online 3(4):26-36 · October 2000

Effects of a novel zinc-magnesium formulation on hormones and strength

1. R Brilla

Abstract

Muscle attributes and selected blood hormones of football players were assessed in response to a nightly supplementation regimen during spring football, over an 8-week period, with pre-post measures. A double-blind randomized study was conducted with ZMA (30 mg zinc monomethionine aspartate, 450 mg magnesium aspartate, and 10.5 mg of vitamin B-6) and placebo (P), n=12 and n=15, respectively. Plasma zinc and magnesium levels were ZMA (0.80 to 1.04 mg/ml; 19.43 to 20.63 mcg/ml) and P (0.84 to 0.80 mg/ml; 19.68 to 18.04 mg/ml), respectively (P<0.001). Free testosterone increased with ZMA (132.1 to 176.3 pg/mL), compared to P (141.0 to 126.6 pg/mL) (P<0.001); IGF-I increased in the ZMA group (424.2 to 439.3 ng/mL) and decreased in P (437.3 to 343.3 ng/mL) (P<0.001). Muscle strength via torque measurements and functional power were assessed with a Biodex dynamometer. Differences were noted between the groups (P<0.001): ZMA (189.9 to 211 Nm at 180°/s and 316.5 to 373.7 Nm at 300°/s) and P (204.2 to 209.1 Nm at 180°/s and 369.5 to 404.3 Nm at 300°/s). The results demonstrate the efficacy of a Zn-Mg preparation (ZMA) on muscle attributes and selected hormones in strength-trained, competitive athletes.