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
+44.6% (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)
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