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muscled guy double dumbbell curlingZMA (zinc magnesium aspartate) is often marketed to increase testosterone levels, improve sleep quality, and help the user gain muscle and strength. A study published in the Journal of the International Society of Sports Nutrition examined the effects of ZMA on a wide variety of measures relating to athletic performance and body composition.

42 males with previous resistance training experience were given either ZMA or a placebo supplement before bed daily for 8 weeks. Before, mid-way through, and after the 8 week supplementation period the subjects were tested for strength, endurance, and anaerobic capacity. Body composition was measured and blood samples were taken to test for levels of anabolic and catabolic hormones.

The researchers found that just about the only difference between the groups was that the ZMA group had elevated serum zinc levels, which is certainly to be expected. There was no significant difference in body composition, anabolic or catabolic hormones, strength, endurance, or anaerobic capacity between the two groups. Other research has found that ZMA also does not boost testosterone levels in healthy young individuals as claimed. Anecdotally, many people find that they have improved sleep quality when using ZMA, but apparantly that improved sleep quality is not significant enough to translate to enhanced gains in muscle size or strength. Thinking of trying ZMA as a performance enhancing supplement? Your money is probably better spent elsewhere.



Wilborn CD, Kerksick CM, Campbell BI, Taylor LW, Marcello BM, Rasmussen CJ, Greenwood MC, Almada A, & Kreider RB. (2004). Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism. Journal of the International Society of Sports Nutrition. 1(2), 12-20.

ABOUT THE AUTHOR: Cassie is a chemistry major and national level bodybuilder. Questions or comments? Talk to Cassie on the FORUM or on FACEBOOK.

DISCLAIMER: The information on this website reflects the opinion of our staff and manufacturer’s and should not be interpreted as medical advice. The information is not unbiased or independent and is the opinion of the owners of The descriptions and statements accompanying these products and vitamin supplements have not been evaluated by the FDA. These products are not intended to diagnose, treat, cure or prevent any disease.

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