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guy working bicepTribulus terrestris is an herbal ingredient that has been included in countless testosterone boosting supplements as it is popularly believed to increase testosterone levels and muscle mass. A 5-week study published in the Journal of Strength and Conditioning Research examined the effects of Tribulus terrestris supplementation on rugby players participating in heavy resistance training as a part of their pre-season training.

There were 22 male subjects aged 18-22 years old. The subjects were divided into two groups, a tribulus group and a placebo group. The tribulus group consumed 450 mg of Tribulus terrestris once daily for 5 weeks, and the placebo group consumed a placebo capsule once daily for 5 weeks.

Both groups, as expected, made improvements in muscle size and strength. There was no significant difference in strength or muscle size gains between the tribulus group and the placebo group. When the testosterone to estrogen ratio was tested by urinalysis both before and after supplementation, the tribulus group showed no difference in testosterone to estrogen ratio from the placebo group. Basically, supplementation with 450 mg of Tribulus terrestris for 5 weeks did absolutely nothing for testosterone levels, muscle gains, or strength gains!

The dosage used in this study was on the lower end of what is typically recommended for boosting testosterone levels and Tribulus terrestris is typically taken multiple times per day rather that all at once. Still, at 450 mg daily there should have been a statistically significant difference in the urinary testosterone to estrogen ratio. Many users of Tribulus concur that they never really experienced much in the way of muscle gains from the herb. Tribulus terrestris may have other benefits, but it has shown itself to be pretty useless for boosting testosterone and muscle gains!



Rogerson S, Riches CJ, Jennings C, Weatherby RP, Meir RA, & Marshall-Gradisnik SM. (2007). The effect of five weeks of Tribulus terrestris supplementation on muscle strength and body composition during preseason training in elite rugby league players. Journal of Strength and Conditioning Research / National Strength & Conditioning Association. 21(2), 348-53.

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

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