Tribulus terrestris is marketed for unproven testosterone-enhancing capabilities. Very little research is available regarding its ergogenic potential; however, one study in which resistance-trained men consumed an herbal preparation containing 3.21 mg of Tribulus per kg of body weight failed to demonstrate enhancements in body weight and composition, strength, or mood states. In fact, the placebo group outperformed the Tribulus group following supplementation in one measure of strength.