Boosts Testosterone & Decreases Estradiol  A key ingredient in Muscle Builder PM has been shown in a double-blind, placebo-controlled study to increase free testosterone and reduce estradiol in only 7 days! Naghii et al., 2011. Journal of Trace Elements in Medicine and Biology. 25:54-58. Improve Muscular Recovery To aid in muscular recovery, Muscle Builder PM also includes a clinical dose of tart cherry, which has been shown in scientific research to improve recovery through the reduction of muscle soreness post-workout. Connolly et al., 2006. British Journal of Sports Medicine. 40:679-683. With GABA, Melatonin & L-Theanine Muscle Builder PM includes a comprehensive blend of nighttime ingredients, such as melatonin, GABA, L-theanine, Valeriana officinalis, magnesium, and more. ‡Based on AC Nielsen xAOC combined total sales for MuscleTech® & Six Star® powder & pill supplements.