Endocrine Abstracts

Background: Physical exercise represents the first-line therapy in the management of metabolic diseases, considering its beneficial properties on blood pressure, glyco-lipid profile, body composition and hormonal imbalances. On the other hand, testosterone is largely investigated in the setting of competitive sport, representing the main doping source. Although endogenous testosterone levels are demonstrated to be affected by both acute exercise and resistance training, the dynamic regulation of androgen production after physical activity is still a matter of debate.

Aim of the study: This meta-analysis was designed to assess whether physical exercise acutely affects testosterone levels in men.

Methods: The literature search was conducted to identify longitudinal trials evaluating the acute change of testosterone levels after physical activity in adult men published in English language until October 2019 (PROSPERO registration ID: 157348). Data were extracted using testosterone levels before and after exercise as primary endpoint, considering sex hormone binding globulin (SHBG) and free testosterone (fT) as secondary endpoints. Sensitivity analyses were performed considering the sample collected (i.e. blood or saliva), the intensity of the physical exercise (mild, moderate or high, considering either the intensity reported in the manuscript or the percentage of the maximal exercise intensity described), and the interval between the end of the exercise and the sample collection (0–2 minutes, 3–30 minutes, and 31–60 minutes after the activity).

Results: Forty-eight studies were included in the analysis, accounting for 126 trials. A total of 569 patients were enrolled (mean age 29.7 + 13.1 years).The physical activity increased acutely total testosterone levels, considering both serum and saliva samples (P < 0.001, respectively). In particular, testosterone levels significantly increased after moderate (P < 0.001) and high intensity (P < 0.001) exercises, but not after mild physical activity (P = 0.190). Moreover, the testosterone increase was evident when measured immediately at the end of the exercise and within 30 minutes (P < 0.001), but not after 30 minutes (P = 0.930). Similar significant results were obtained considering fT, while SHBG did not change after physical activity (P = 0.090).

Conclusion: Albeit considering the high heterogeneity of included studies, the comprehensive evaluation of the acute physical activity effect on testosterone levels identified a clear increase after exercise, irrespective of the sample collected. The main determinant of this fluctuation was the exercise intensity, with a mechanism that seems to be mostly SHBG-independent. In particular, moderate/intense physical activity resulted able to increase endogenous androgenic production, albeit acutely and transitory.