We all know that testosterone a key hormone needed to stimulate anabolism and muscle growth.
In a study published in the Journal of Ethnopharmacology, scientists tested the effects of oral tongkat ali supplementation on sexual behavior in sexually sluggish and impotent rats. They hypothesized that the supplement would increase serum testosterone levels thereby boosting sexual performance. Furthermore, the researchers looked at the effects of dose (amount of tongkat ali) and duration of supplementation. They found that treatment with 500 mg/kg/day increased sexual performance after 6 days of treatment when compared to placebo controls. These findings were supported by a nearly 2-fold increase in serum testosterone levels in the supplemented animals!
Zanoli P, Zavatti M, Montanari C, Baraldi M. Influence of Eurycoma longifolia on the copulatory activity of sexually sluggish and impotent male rats. J Ethnopharmacol. 2009 Nov 12;126(2):308-13.