ZMA is a supplement promoted to aid recovery. One of the claims of the product is it boosts anabolic hormone production. I know many people in the Jiu Jitsu community that have taken it to help recover from their training. A very common strength training supplement too. I was one of them for several months. However, I wanted to do my own research to see if it really boosted testosterone.
"enhance recovery by improving sleep efficiency.....significantly increase anabolic hormone production in trained athletes. ZMA® is an advanced formulation designed to significantly improve muscle strength and endurance as well as accelerate healing and tissue repair.......research has demonstrated that rigorous exercise and stress result in significant body losses of zinc and magnesium"
It's a supplement I have used on and off. I will say that personally I do sleep quite deeply when taking ZMA although I've never tested whether it boosted anabolic hormones, recovery and muscular strength and endurance. All of which you would want to improve if you're strength training for Jiu Jitsu. So does it live up to its claims?
Here's what I found:
Study 1: split 42 men into two groups and gave them either a commercially recommended dose of ZMA before bed each day or a placebo. They were then tested at 0, 4 and 8 weeks for serum levels of zinc, levels of several anabolic markers (e.g. testosterone, free testosterone and growth hormone) and also tested across several exercises (e.g. One rep max bench and leg press, muscle endurance tests and anaerobic tests) after being placed on a standardised training program for 8 weeks. Conclusion; results showed a marginal yet not significant increase in serum levels of zinc for the ZMA group and no significant difference any of the other tests, including testosterone levels or strength and endurance tests.
Study 2: split 14 men into two groups and gave them a commercially recommended dose of ZMA or a placebo. They tested for serum levels of zinc and testosterone and its motabilites. They did find a significant increase of zinc in the urine excretion, although no significant increase in testosterone and free testosterone or its motabilites.
Does this mean ZMA doesn't live up to its claims?
Not necessarily, all this means is that these two studies showed ZMA did not help increase strength, strength endurance and testosterone. Just like we should always be wary of positive claims, we should also be wary of contradictory claims. Hormone production is a highly complex subject, there could be several other factors at play with the use of ZMA that could result in benefits that are not measured here in these studies. For example, these studies do not measure impact on sleep and if that in turn improves recovery. Sleep is a key factor in recovering from Jiu Jitsu and strength training. So that could be a benefit.
However, it does teach a valuable lesson to always check the research behind the claims and do your own searches (I quickly and easily found these via PubMed) then make your own informed decisions about what you put in your body.
Study 1: C. D. Wilborn, C. M. Kerksick, B. I. Campbell, L. W. Taylor, B. M. Marcello, C. J. Rasmussen, M. C. Greenwood, A. Almada & R. B. Kreider. 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, 2004.
Study 2: K Koehler, MK Parr, H Geyer, J Mester & W Scha¨nzer. Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement. European Journal of Clinical Nutrition (2009) 63, 65–70.