Phoenix (November 4, 2016)—Twelve weeks of aerobic exercise significantly boosted testosterone levels in overweight and obese men, with the greatest increases seen among vigorous exercisers, according to research presented today at the Integrative Biology of Exercise 7 meeting in Phoenix.

Researchers from Tsukuba University and Ryutsu Keizai University in Japan previously found that a combination of diet and exercise was effective in increasing the testosterone in this population. For this study, however, they looked specifically at the effect of regular aerobic exercise on testosterone levels.

“Testosterone is a male sex hormone, and low circulating testosterone levels lead to various health disorders in men. Obesity, one of the biggest problems in the world, results in reduction in circulating testosterone levels in men,” the research team wrote. Fatigue, decreased sex drive and decreases in muscle and bone mass are some of the common symptoms of low testosterone in men.

The research team compared 16 normal weight men to 28 overweight/obese men. None of the men were regular exercisers. At baseline, the overweight/obese men had significantly lower total, free and bioavailable testosterone level than normal weight men. All of the study volunteers completed a 12-week aerobic exercise plan that entailed 40–60 minutes of walking or jogging on one to three days per week. Testosterone levels were also recorded at the end of the study.

While their testosterone was still at lower levels than the normal weight men at baseline, overweight and obese men saw a significant increase in all measured testosterone levels. This effect was particularly evident among the men who exercised vigorously. However, the exercise intervention had no significant effect on testosterone levels in the normal weight men.

Normal Weight Men
Pre-Exercise InterventionPost-Exercise Intervention
Total Testosterone21.2 ± 1.3 nnol/l21.1 ± 1.3 nmol/l
Free Testosterone0.47 ± 0.04 nnol/l0.48 ± 0.05 nmol/l
Bioavailable Test.11.65 ± 0.76 nnol/l11.88 ± 1.11 nmol/l

Overweight/Obese Men
Pre-Exercise InterventionPost-Exercise Intervention
Total Testosterone15.4 ± 1.0 nnol/l18.1 ± 1.1 nmol/l
Free Testosterone0.33 ± 0.02 nnol/l0.40 ± 0.02 nmol/l
Bioavailable Test.8.07 ± 0.53 nnol/l9.63 ± 0.55 nmol/l

Body weight also significantly decreased following the exercise intervention in the overweight/obese cohort. “I think decrease in body mass is one of the factors for increasing serum testosterone levels,” said Hiroshi Kumagai, lead researcher on the study. “However, the degree of weight loss is small, and we found that the increase in vigorous physical activity was independently associated with the increase in serum testosterone levels. So, it seems the increase in physical activity, especially vigorous physical activity, is the main factor for increasing serum testosterone levels.”

Kumagai will present “Habitual Aerobic Exercise Increases Serum Testosterone Levels in Overweight and Obese Men” at a poster session on Friday, Nov. 4, from 1 to 3 p.m. in the Hyatt Regency Phoenix Atrium Lobby.

NOTE TO JOURNALISTS: The Integrative Biology of Exercise 7 meeting will be held in Phoenix, Nov. 2–4, 2016. Read the full program. To schedule an interview with the conference organizers or presenters, contact the APS Communications Office or call 301-634-7209. Find more research highlights in the APS Press Room.

Physiology is the study of how molecules, cells, tissues and organs function in health and disease. Established in 1887, the American Physiological Society (APS) was the first U.S. society in the biomedical sciences field. The Society represents more than 11,000 members and publishes 14 peer-reviewed journals with a worldwide readership.