Eurycoma longifolia, commonly known as “Tongkat Ali” or “Longjack,” is often touted as a testosterone “booster” and marketed to athletes as a training aid and performance enhancer. Rodent studies have shown oral delivery of Eurycoma extract to improve sexual performance and increase serum testosterone levels. Open-label human trials have suggested that Eurycoma extract may help prevent age-associated androgen deficiency, improve sexual function, and increase psychological parameters such as mood, energy, and sense of well-being. The purpose of this study was to determine the effects of Eurycoma longifolia on testosterone and cortisol levels during intense endurance exercise.

 

Methods

We used a freeze dried extract of Eurycoma longifolia (E) standardized to 22%

eurypeptides and 40% glycosaponins. Male subjects (N=30) were recruited from a 24-hour mountain biking event and asked to provide a saliva sample before and after each lap for measurement of cortisol and testosterone by enzyme immunoassay (Salimetrics, State College, PA). Subjects completed 4 laps (14.91 miles/lap) and provided 8 saliva samples over a 24h period. Subjects consumed 100mg of E (N = 15) or a look-alike placebo (P, N = 15) approximately 30 minutes prior to endurance exercise.

 

Results

 

 

 

 

Cortisol levels were 32.3% lower in E compared to P (0.552+0.665 versus 0.816+0.775 ug/dL, P < 0.05). Testosterone levels were 16.4% higher in E compared to P (86.72+40.90 versus 72.47+33.77 pg/mL, P < 0.05).

 

Conclusions

These results suggest that Eurycoma longifolia extract may help to maintain normal levels of cortisol (low) and testosterone (high) and thus promote an overall “anabolic” hormonal state (versus a “catabolic” state characterized by elevated cortisol and suppressed testosterone) during intense endurance exercise.

 

 

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