Relationship between Aerobic Training and Testosterone Levels in Male Athletes Siu Yuen Ng Biology 493 13 th December, 2010
Abstract Salivary testosterone levels of 11 athletes and 15 non athletes were studied to test for the effects of 20 hours per week of aerobic training on the levels of testosterone. The samples were taken in the 13 th week of the 21 week basketball season. Athletes had a significant (84.4%) higher level of testosterone when compared to non athletes. The correlation between testosterone concentration and aerobic training suggest that 20 hours of aerobic training per week was sufficient for elevation of testosterone levels. Introduction Testosterone is an androgenic hormone that stimulates protein synthesis and cell growth (Malm et al. 2004). Resistance training has been shown to increase testosterone concentrations in men (Kraemer & Ratamess 2005). Linnamo et al. (2005) showed that serum testosterone increased significantly during heavy resistance exercise in men, with no significant changes in women. Ahtiainen et al. (2004) determined that the concentrations of testosterone increased significantly after heavy resistance training in athletes. Testosterone elevation was influenced by the volume of total work in a heavy resistance exercise protocol. A high intensity resistance training protocol using three sets stimulated higher magnitudes of postexercise elevations in circulating concentrations of testosterone than did a one set protocol (Gotshalk et al. 1997). Baker et al. (2006) demonstrated testosterone concentrations were significantly higher in males age 20 to 26 than in males 38 to 53 or 59 to 72 year old test subjects. Similar relative increases in testosterone among these three groups suggested aging did not attenuate hormone responses. Increases in testosterone were found immediately following resistance exercise (Baker et al. 2006). Kraemer & Ratamess (2005) reported that basal testosterone concentrations were also elevated after an exercise bout. Ahtiainen et al. (2003) reported significant increases in basal testosterone concentrations after a fourteen week high volume resistance training program. Twenty one weeks following the exercise program, testosterone Page 1
levels returned to the base line. This study suggested no chronic effects of strength training on testosterone levels. Ari et al. (2004) found significantly higher testosterone levels in elderly male athletes, who exercise regularly, than in sedentary elderly males. There are few reports on changes in testosterone levels as a result of aerobic exercise training. Malm et al. (2004) found that after two soccer games on two consecutive days, there was a significant decrease in testosterone levels six hours after the second game, and 72 hours later it was still below the resting concentration levels. A recent study (Martinez et al. 2010) showed that 35 hours per week of basketball training increased the testosterone levels significantly after five months. The purpose of this research was to determine whether 20 hours per week aerobic training protocol increased testosterone concentrations in college age males. Methods The research proposal was approved by BYU Hawaii Institutional Review Board for Human Subjects. A total of 15 athletes from the BYU Hawaii men s basketball team were recruited as subjects. Also, 15 sedentary males were recruited as the control group. Each subject was asked to sign an informed consent agreement to participate in the study. The athletes trained aerobically for four hours per day, five days per week, for a total of 20 hours per week, beginning six weeks prior (mid September) to the end of the basketball season (November to March). Saliva samples were collected with oral swabs. Samples of the non athlete control subjects (male students who had been sedentary for at least one month) were collected on 26 th January, 2010. Samples of the athletes were collected during a training session in the 13 th week Page 2
of the 21 week basketball season, on 5 th February, 2010. Samples were all taken in the afternoon (between 1500 and 1800 hours). All salivary samples were analyzed for testosterone by Enzyme Immunoassay (Salimetrics). Testosterone concentrations from athletes were compared to non athletes to determine the effect of aerobic training on the concentration of testosterone. The data were analyzed by Mann Whitney U test, and p values of less than 0.05 were considered significant. Results Due to insufficient quantity of saliva, only 11 athlete samples were analyzed. An Anderson Darling normality test was performed on the raw data. Data obtained from nonathletes showed a normal distribution (p = 0.559) but the data from the athletes showed a nonnormal distribution (p < 0.005). Since the data were nonparametric, they were evaluated by the Mann Whitney U test. The mean testosterone levels for athletes was 198 pg/ml (SD = 149 pg/ml). Non athletes had a mean of 107.4 pg/ml (SD = 36.0 pg/ml) (Table 1). The P value for Mann Whitney U test was 0.0031. (Table 1 & Figure 1). Table 1. The mean, SD, SE Mean and median values for the non athletes (control) and athletes. *p < 0.05 Groups Mean ± SD (pg/ml) SE Mean Median (pg/ml) Athletes (n=11) 198 ± 149* 45 163.7 Control (n=15) 107.4 ± 36.0 9.3 107.7 Page 3
Testosterone Concentration (pg/ml) 400 350 300 250 200 150 100 50 * Athletes Non athletes 0 Groups Figure 1. A histogram of testosterone concentration in athletes (left) and non athletes (right). Athletes had a higher mean and standard deviation. *p < 0.05 Athletes had a higher median concentration than the non athletes. The distribution of data for testosterone concentration for the athletes was not normal (Figure 2). Figure 2. A boxplot of testosterone concentration in the two groups. Athletes had a higher median. A mean connecting line is drawn to show mean differences. Page 4
Discussion The basketball players had a significantly (p < 0.05) greater mean testosterone level than the non athletes. Their difference was 84.4% higher when compared to the non athletes. However, there was a greater standard deviation among athletes than non athletes. Previous studies focused on anaerobic exercise induced increase of testosterone concentrations (Gotshalk et al. 1997, Ahtiainene et al. 2003, Kraemer & Ratamess, 2005). Basketball training was found to exert the same influence as resistance training. The higher testosterone levels found in basketball players resulted from frequent aerobic training. Martinez et al. (2010) demonstrated that 35 hours of basketball training per week induced an increase of testosterone levels. This study found that 20 hours of training could also increase testosterone levels. The standard deviation of the athlete group was quite high, and the increase in hormone levels varied among the basketball players. One possible reason for the variance may be due to the diet of the individuals since it was not monitored during the study. Intensity of exercise during practice for each individual was also not monitored. Some individuals may have worked harder than others during practice. The difference in intensity may have increased the variance. Testosterone levels decline over an individual s lifespan (Morley et al. 2006). Male hypogonadism may result in osteoporosis, raising the percentage of body fat, high blood pressure, heightened risk of heart attack brought about by the dilation of arteries, blood clots, lessened libido, depression, increased irritability, and mental fatigue. Booth et al. (1999) suggested that testosterone supplementation reduced depression. One way to treat male Page 5
hypogonadism is to boost the natural testosterone production in the body. This study suggested that exercise could be used as a prescription for low testosterone concentration in males as they age. In conclusion, this study demonstrated that basketball training elevated testosterone levels. Furthermore, 20 hours of training per week was sufficient to illicit the increase. The minimal amount of training time needed to cause the elevation is unknown and remains to be examined. Future studies might determine whether or not 10 hours of training per week creates the same response. This would delineate the minimal amount of training time. Acknowledgments All materials for this study were supported by the Department of Biology of Brigham Young University Hawaii. I would like to thank Dr. Randy Day, Professor at the Department of Biology at the Brigham Young University Hawaii, for mentoring this study. Works Cited Ahtiainen, J.P., A. Pakarinen, M. Alen, W.J. Kraemer & K. Hakkinen. 2003. Muscle hypertrophy, hormonal adaptations and strength development during strength training in strengthtrained and untrained men. European Journal of Applied Physiology 89: 555 563. Ahtiainen, J.P., A. Pakarinen, W.J. Kraemer & K. Hakkinen. 2004. Acute hormonal responses to heavy resistance exercise in strength athletes versus nonathletes. Canadian Journal of Applied Physiology 29: 527 543. Ari, Z., N. Kutlu, B.S. Uyanik, F. Taneli, & G. Buyukyazi. 2004. Serum testosterone, growth hormone, and insulin like growth factor 1 levels, mental reaction time, and maximal Page 6
aerobic exercise in sedentary and long term physically trained elderly males. International Journal of Neuroscience 114: 623 637. Baker, J.R., M.G. Bemben, M.A. Anderson & D.A. Bemben. 2006. Effects of age on testosterone responses to resistance exercise and musculoskeletal variables in men. Journal of Strength and Conditioning Research 20: 874 881. Booth, A., Johnson, D.R. & Granger, D.A. 1999. Testosterone and men s depression: the role of social behavior. Journal of Health and Social Behavior 40: 130 140. Gotshalk, L.A., C.C. Loebel, B.C. Nindl, M. Putukian, W.J. Sebastianelli, R.U. Newton, K. Hakkinen & W.J. Kraemer. 1997. Hormonal response of multiset versus single set heavy resistance exercise protocols. Canadian Journal of Applied Physiology 22: 244 255. Kraemer, W.J. & N.A. Ratamess. 2005. Hormonal responses and adaptations to resistance exercise and training. Sports Medicine 35: 339 361. Linnamo, V., A. Pakarinen, P.V. Komi, W.J. Kraemer & K. Hakkinen. 2005. Acute hormonal responses to submaximal and maximal heavy resistance and explosive exercise in men and women. Journal of Strength and Conditioning Research 19: 566 571. Malm, C., Ö. Ekblom & B. Ekblom. 2004. Immune system alteration in response to two consecutive soccer games. Acta Physiologica Scandinavica 180: 143 155. Martinez, A.C., J.S. Calvo, J.A.T. Mari, L.C.A. Inchaurregui, E.E. Orella & A.P. Biescas. 2010. Testosterone and cortisol changes in professional backetball players through a season competition. Journal of Strength and Conditioning Research 24: 1102 1108. Morley, J.E., Perry, H.M. III, Patrick, P., Dollbaum, C.M. & Kells, J.M. 2006. Validation of salivary testosterone as a screening test for male hypogonadism. The Aging Male 9: 165 169. Page 7