Increased prevalence of androgen deficiency in endurance-trained male runners across the life span

Increased levels of physical activity are associated with many positive health outcomes in men including reproductive health as recently reported by Vieira et al. [1] in The Aging Male. However, the existence of “Relative Energy Deficiency in Sports” (RED-S) health problems and the “Exercise Hypogonadal Male Condition” have alerted endocrinologists to the fact that high-volume, endurance-based exercise training programs are associated with suppressed testosterone in men [2,3]. These health conditions are primarily reported in young-to-middle-aged athletic men. Based upon the work of Vieira et al. [1], we wondered whether these exercise-related reductions in testosterone reached the clinical diagnostic threshold for androgen deficiency (AD) and occurred across the life span of runners. Thus, we conducted pilot work examining the prevalence of AD in cohorts of endurance-trained men (18–57 years old) and age-matched control men.

Habitual, competitive runners (≥10 km events; n = 196) who trained ≥7 h/week (≥80 km/week, ≥1 year) were recruited for this observational, cross-sectional (case-control) study. Each runner was matched with a healthy, non-exercising control subject. Matching factors were: age (±1 year), BMI (±1 kg/m⁻²), and ethnicity. All subjects were required to be in a stable body weight (no body mass changes >3% during the last 4 months) and medically screened to ensure excellent health status. All runners were in a period of normal, stable training during the last 6 weeks and had not experienced a major injury curtailing their training during the last 12 months. All subjects provided a morning (0700–0900 h) resting blood sample after fasting (≥8 h), having had no sexual activity (>24 h before), and for runners ≥18 h absence from training. Blood samples were analyzed for total testosterone using standard clinical bioanalytical techniques. A threshold testosterone cut-point of ≤300 ng/dl was used to determine AD based upon literature recommendations [4].

Prevalence of AD was 15.3% in runner and 5.6% in control (9.7% difference; 95% CI 3.67–15.91, p < .002) cohorts, respectively. The odds ratio for AD was 2.73 for runners versus controls (95% CI 1.33–5.60, p < .007). Prior evidence suggests years of exercise training influences testosterone reduction in runners [5], as does advancing age after ∼45 years for AD in all men [4]; hence, prevalence calculations were stratified by these factors [N.B., training stratification = 1 year, 2 years (±1), 5 years (±2), 10 years (±2), ≥15 years (±2)]. Increasing years of training did escalate the prevalence of AD in runners (<10 years = 6.2% versus ≥10 years = 32.8%, p < .0001), as did being older within both cohorts (<45 years = 7.2% versus >45 years = 14.3%, p < .03; between cohort comparison, p = NS).

These findings are preliminary due to the small sample size. Nonetheless, outcomes point to the possible existence of greater occurrences of AD in men habitually engaged in endurance-based exercise training over a longer period of time (i.e., hence also typically older). The cause of this occurrence is unclear, but research points to intensive or prolonged exercise training exposure leads to a hypothalamic–pituitary–testicular axis dysregulation [3]. We recommend clinicians working in male androgenic health be mindful of the existence of the relationship reported here for habitual exerciser which may differ from men who are just beginning exercise programs [1].

Anthony C. Hackney and Amy R. Lane
Human Movement Science Curriculum, University of North Carolina, Chapel Hill, NC, USA
[email protected]

Disclosure statement

No potential conflict of interest was reported by the authors.