Testosterone is a male reproductive hormone that is also produced in smaller amounts by women. Testosterone determines male sexual characteristics and plays a role in some of the female signs of puberty, such as hair growth in the genitals and underarm area. Testosterone also helps prevent osteoporosis in women. Low testosterone can cause fatigue, problems sleeping, decreased muscle mass and decreased libido in both men and women. Exercise has effects on testosterone.
Testosterone levels normally drop as people age. A low testosterone level in men is a level of less than 250 nanograms/deciliter, according to St. John Providence Health Center. Low testosterone in young men is usually the result of a genetic condition, radiation or chemotherapy, trauma to the testicles or tumors of the pituitary gland. Some medications, such as narcotic pain medications, cortisone and steroids, can also cause low testosterone. There is no generally accepted low level for women, according to Dr. Michael Werner, an urologist who specializes in male infertility and male sexual dysfunction.
Testosterone and Weight Lifting
In a study published in the June 2011 "Journal of Sports Medicine and Physical Fitness," researchers analyzed the effect of resistance training on 10 men who trained for recreational purposes. The study participants completed two resistance training protocols of different intensity seven days apart. Testosterone increased for both protocols. An older study published in the December 1993 "Medicine and Science in Sports and Exercise" found that both moderate and light intensity weight lifting caused a similar increase in serum testosterone levels.
Testosterone and Over-Training
A study reported in the April 2003 "Medicine and Science in Sports and Exercise" found testosterone did not change at differing levels of resistance exercise. Although Dr. Mark Jenkins of Rice University notes that over-training can cause decreased testosterone levels, the available research seems to indicate otherwise. Over-training is an imbalance between training or competition and recovery. Short-term over-training is called over-reaching. Among the normal physiological responses to over-reaching are an increased testosterone to cortisol ratio, increased resting heart rate and increased creatine kinase levels – a sign that microscopic muscle damage has occurred.
The research on bodybuilding and testosterone is limited to relatively small studies, but the available data indicate that bodybuilding increases testosterone slightly, at least in the short term. No long-term studies of excessive body-building and its effects on testosterone are available. If you have a low testosterone level and are concerned that bodybuilding may have caused or influenced changes in your testosterone, consult a health-care professional.
- St. John Providence Health Center: Male Menopause
- Michael A. Werner, M.D.: Low Testosterone
- Healthy Women: Androgen
- Journal of Sports Medicine and Physical Fitness: Acute Effect of Resistance Training Volume on Hormonal Responses in Trained Men
- Medicine and Science in Sports and Exercise: Acute Effects of Different Intensities of Weight Lifting on Serum Testosterone
- Medicine and Science in Sports and Exercise: Hormonal Responses After Various Resistance Exercise Protocols
- Curtin University: Overtraining