Was doing search on zinc and zma and found these abstracts. Conte’s research showed it worked (no surprise there, but this seemingly unbaised research shows otherwise. How could athlete training level change results? Is the benefit enough for the recovery aspect? Thoughts?
1: J Int Soc Sports Nutr. 2004 Dec 31;1(2)
Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism.
Wilborn CD, Kerksick CM, Campbell BI, Taylor LW, Marcello BM, Rasmussen CJ, Greenwood MC, Almada A, Kreider RB.
Exercise & Sport Nutrition Lab, Baylor University, Waco, TX.
ABSTRACT : This study examined whether supplementing the diet with a commercial supplement containing zinc magnesium aspartate (ZMA) during training affects zinc and magnesium status, anabolic and catabolic hormone profiles, and/or training adaptations. Forty-two resistance trained males (27 +/- 9 yrs; 178 +/- 8 cm, 85 +/- 15 kg, 18.6 +/- 6% body fat) were matched according to fat free mass and randomly assigned to ingest in a double blind manner either a dextrose placebo (P) or ZMA 30-60 minutes prior to going to sleep during 8-weeks of standardized resistance-training. Subjects completed testing sessions at 0, 4, and 8 weeks that included body composition assessment as determined by dual energy X-ray absorptiometry, 1-RM and muscular endurance tests on the bench and leg press, a Wingate anaerobic power test, and blood analysis to assess anabolic/catabolic status as well as markers of health. Data were analyzed using repeated measures ANOVA. Results indicated that ZMA supplementation non-significantly increased serum zinc levels by 11 - 17% (p = 0.12). However, no significant differences were observed between groups in anabolic or catabolic hormone status, body composition, 1-RM bench press and leg press, upper or lower body muscular endurance, or cycling anaerobic capacity. Results indicate that ZMA supplementation during training does not appear to enhance training adaptations in resistance trained populations.
1: Eur J Clin Nutr. 2007 Sep 19. [Epub ahead of print]
Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement.
Koehler K, Parr MK, Geyer H, Mester J, Schänzer W.
1Institute of Biochemistry, German Research Centre of Elite Sport, German Sport University Cologne, Cologne, Germany.
Objectives:To investigate whether the administration of the zinc-containing nutritional supplement ZMA causes an increase of serum testosterone levels, which is an often claimed effect in advertising for such products; to monitor the urinary excretion of testosterone and selected steroid hormone metabolites to detect potential changes in the excretion patterns of ZMA users.Subjects:Fourteen healthy, regularly exercising men aged 22-33 years with a baseline zinc intake between 11.9 and 23.2 mg day(-1) prior to the study.Results:Supplementation of ZMA significantly increased serum zinc (P=0.031) and urinary zinc excretion (P=0.035). Urinary pH (P=0.011) and urine flow (P=0.045) were also elevated in the subjects using ZMA. No significant changes in serum total and serum free testosterone were observed in response to ZMA use. Also, the urinary excretion pattern of testosterone metabolites was not significantly altered in ZMA users.Conclusions:The present data suggest that the use of ZMA has no significant effects regarding serum testosterone levels and the metabolism of testosterone in subjects who consume a zinc-sufficient diet.European Journal of Clinical Nutrition advance online publication, 19 September 2007; doi:10.1038/sj.ejcn.1602899.