L. R. Brilla, Western Washington University, Bellingham, WA 98225, and V. Conte, BALCO Laboratories, Burlingame, CA 94010.

A double-blind, randomized study was conducted to determine the effect of a novel zinc and magnesium formulation (ZMA) on anabolic hormone levels and strength in athletes. Members of the University football team (n=27) had blood collected at the beginning and end of an 8 week period of intensive training. Subjects were supplemented with ZMA (n=12) or placebo (n=15) for the 8 weeks. The ZMA group took 3 capsules nightly that contained a total of 30 mg of ZN as monomethionine/aspartate, 450 mg of Mg as aspartate and 10.5 mg of vitamin B-6. The plasma Zn and Mg levels increased in the ZMA group by 29.1% (.804 to 1.038 mcg/ml) and 6.2% (19.43 to 20.63 mcg/ml), respectively, while levels decreased in the placebo group by 4.4% (.836 to .799 mcg/ml) and 9.2% (19.68 to 18.04 mcg/ml), respectively. The total and free testosterone levels in serum increased in the ZMA group by 32.4% (567.9 to 752.7 ng/dl) and 33.5% (132.1 to 176.3 pg/mL), respectively, in contrast to the placebo group which decreased by 10.5% (588.8 to 526.8 ng/dL) and 10.2% (141.0 to 126.6 pg/mL), respectively. The serum, IGF-1 levels increased in the ZMA group by 3.6% (424.2 to 439.3 ng/mL) and decreased in the placebo group by 21.5% (437.3 to 343.3 g/mL). All comparisons were statistically significant (P<0.001). Pre and post isokenetic strength determinations in newton meters were made using a Biodex dynamometer. Subjects (ZMA n=10; placebo n=11) were measured for maximum quadricep strength on the right leg at 180 degrees per sec (strength) and 300 degrees per second (functional power). The ZMA strength group change at 180 degrees per second was +11.6% (189.9 to 211.8) compared to the placebo group change of +4.6% (204.2 to 209.1) and the ZMA group change at 300 degrees per sec. was +18.2% (316.5 to 373.7), in contrast to the +9.4% (369.5 to 404.3) for the placebo group (P<0.05). These findings suggest that nightly supplementation with ZMA significantly increases Zn and Mg levels, anabolic hormone levels as well as strength and power in athletes.

Sports Medicine, Training and Rehabilitation Journal, November 1998 (in press)