Long-term endurance running training and testosterone daily variation in ageing men; a comparative cross-sectional...

The aim of this study was to assess the relationship between long-term endurance running training and daily variation in testosterone, which is known to diminish during ageing, in a comparative, cross-sectional study. We recruited 45 male participants into four groups [young athletes (YA), young sedentary (YS), master athletes (MA) and elderly sedentary (ES)] and performed anthropometry, strength and ergometry tests. Morning (AM) and afternoon (PM) venous blood samples were collected to evaluate testosterone daily variation, sex hormone binding globulin (SHBG), cortisol and estradiol, and we calculated free testosterone, bioavailable testosterone and the free androgen index. Two-way and three-way ANOVAs followed by Bonferroni's multiple comparisons tests were performed. The free testosterone and free androgen index showed a significant PM decrease in the MA group (P = 0.0009 and 0.0021, respectively), comparable to YA and YS; however, in the ES group there was no difference between AM and PM values (both P > 0.9999). SHBG levels were significantly increased by both the age (P = 0.0001) and activity (P = 0.0016) factors, leading to a significant decrease in free testosterone, bioavailable testosterone and free androgen index. In the peak power output parameters of ergometry, expressed in both absolute and relative values, MA achieved values comparable to YS, significantly higher than ES (P = 0.0020 and P < 0.0001, respectively) and lower than YA (P < 0.0001). In conclusion, long-term endurance running training in elderly men might be associated with the presence of daily variation in free testosterone and higher performance levels in comparison to sedentary counterparts, but it might contribute to age-related changes in SHBG and related testosterone fraction levels.