Sports Nutrition in

Adult Men and Women of All Ages

  • Endurance
  • Ergogenic Effects
  • Strength Training


Effect of Eurycoma longifolia Extract on Anabolic Balance During Endurance Exercise

Talbott S, Talbott J, Negrete J, Jones M, Nichols M, and Roza J. SupplementWatch, Inc. Draper, UT

Background. 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.

Purpose. 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 water-soluble 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.

Clinical Trials


S. Hamzah, A. Yusof.

Department of Exercise Physiology, Sports Centre, University of Malaya, 50603 Kuala Lumpur, Malaysia

Eurycoma longifolia Jack (ELJ), which contains quassinoids such as eurycomalacton, eurycomanon, and eurycomanol, has been reported to have aphrodisiac properties and to increase testosterone levels in men.

Previous studies have established that the testosterone supplementation increases fat free mass, muscle strength, and muscle mass, which are important for physical function and athletic performance.

Thus, the objective of this study was to investigate the effect of the increase in testosterone levels, obtained by administration of ELJ, on body composition and muscle strength and size in men. Fourteen healthy men performed an intense strength training program with initial load of 60% RM (2 sets of 10 repetitions with 1 minute rest between, for 10 stations) on alternate days for five weeks.

Simultaneously, seven men were randomly selected to consume 100 mg/day ELJ water soluble extract, and seven men received placebo. The intensity of the exercise was increased by 10% RM/week. Body composition, arm circumference, one repetition maximum (1 RM), and surface electromyography (sEMG) activity were measured and recorded one day before and after the five weeks of supplementation and intervention. The lean body mass of the treatment group showed a significant increment, from 52.26 (7.18) kg to 54.39 (7.43) kg (p = 0.012), but no significant changes in fat free mass were observed in the placebo group. Percentage body fat was significantly decreased in the treatment and placebo group, from 31.30 (5.48)% to 28.44 (6.43)% (p = 0.01) and from 22.83 (2.43)% to 21.33 (2.35)% (p = 0.001) respectively. The 1RM test showed a significant increase from 73.71 (16.63) to 78.71 (17.0) kg (p = 0.006) in the treatment group and from 77.29 (8.9) to 79.43 (8.8) kg (p = 0.011) in the placebo group. The increase in strength in the treatment group was larger than in the placebo group (6.78% and 2.77% respectively). The mean frequency of sEMG on the biceps in the treatment and placebo groups decreased significantly, from 121.77 (40.0) to 90.47 (64.6) μV (p = 0.012) and from 127.95 (30.9) to 98.8 (50.1) μV (p = 0.036) respectively. The treatment produced 2.92% greater reduction in electrical activity of the muscle measured at the end of the experiment compared with placebo.

The mean arm circumference of the treatment group increased significantly by 1.8 cm after the supplementation, from 30.87 (1.88) to 32.67 (1.96) cm (p = 0.011), but there was no significant increase in the placebo group. The results suggest that water soluble extract of Eurycoma longifolia Jack increased fat free mass, reduced body fat, and increased muscle strength and size, and thus may have an ergogenic effect.

Further investigations are warranted.

  1. Ismail MTM. Proceedings paper: Asian Congress of Sexology. 2002.
  2. Bhasin S, Storer TW, Berman N, et al. The effects of supraphysiologic doses of testosterone on muscle size and strength in men. N Engl J Med 1996;335:1–7.
  3. Brodsky IG, Balagopal P, Nair KS. Effects of testosterone replacement on muscle mass and muscle protein synthesis in hypogonadal men: a Clinical Research Center Study. J Clin Endocrinol Metab 1996;81:3469–75.

Strength Training

Effects of strength training and Tongkat Ali (Eurycoma Longifolia) supplementation on physical functions and muscle size in middle-aged women

Sarina Md. Yusof Zaiton Zakaria’, PhD, MD., Aminuddin Abd Hamid Karim, MD., Nor Azmi Kamaruddin, MD., & Azizol Abdul Kadir, Phd.

Faculty of Sports Science & Recreation, UiTM, Shah Alam., ‘Physiology Department,

Medical Faculty, National University of Malaysia (UKJ.1), “Endocrine Department,

Medical Faculty, National University of Malaysia (UKM), 4Phytes Biotek Sdn. Bhd.


Background: Aging is associated with decline in muscle strength. Loss in physical function leads to disability. Tongkat Ali (Eurycoma longifolia) is known for its aphrodisiac property. Tongkat Ali supplementation may enhance the effects of strength training in middle-aged women.

Objectives: To evaluate the effect of strength training and Tongkat Ali supplementation on physical functions and muscle size in middle-aged women.

Method: A double blind randomized control study was conducted on a sample of 31 middle-aged women (aged 45 – 59 years) who were screened and randomized to treatment (n= l7) and control groups (n= l4). Treatment group consumed 100 mg emycoma longifolia extract. Both groups followed 12 weeks of 60% of l RM strength training (twice weekly). Subjects were encouraged to maintain their physical activities and usual diet over the course of the study. Measurements were conducted at baseline and after 12 weeks. Physical functions were measured by muscular strength (bench press, leg press, and handgrip) power (vertical jump), balance, flexibility and endurance (push up). Muscle size represented by rectus femoris cross sectional area measured by ultrasound.

Results: Significant improvements were observed in bench press (67% and 58%, p < 0.05), leg press (33% and 27%, p < 0.05), upper body power (21% and 25%), balance (effect size of0.39 vs 0.31) following strength training in both groups; Greater gains in handgrip strength ( effect size of 0.71 vs 0.43, p < 0.05), flexibility (28.56 ± 6.45 to 31.91 ± 7.70, p < 0.05, effect size of0.60) cm, muscular endurance (effect size of 0.64 vs 0.35, p < 0.05) and rectus femoris cross-sectional area (effect size of 0.59 vs 0.31, p < 0.05) were observed. There was no significant change in leg power.

Conclusion: In conclusion, strength training counteracted the age-related decline in physical functions. Tongkat Ali supplementation enhanced handgrip strength, flexibility, muscular endurance and muscle size gain in middle-aged women during a strength training program.

Other Clinically-Proven Health Benefits

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