Marathon Running and Sexual Libido in Adult Men: Exercise Training and Racing Effects.

We examined whether endurance training for a standard marathon (42.2 km) had a greater influence on male libido than more generalized endurance exercise training. We surveyed adult men (>1000) who regularly engaged in endurance running to evaluate exercise training histories-patterns and libido characteristics. Our participants were primarily recruited from North America and Europe. Results indicate men conducting marathon training had lower libido scores (p<0.05; ~20%, d=0.44) than those not doing such specific training. Factors most related to libido were: 1) the number of years of training, and 2) the proportion of high-intensity effort conducted in training (inverse relationships); regardless of whether marathon training was performed or not. Our survey approach did not allow us to determine the cause of the reduced libido, but we speculate it could relate to: 1) chronic physical fatigue from high volumes of exercise training, 2) behavioral accommodations in energy expenditure, or else 'Relative Energy Deficiency in Sport' (RED-S) syndrome, and/or 3) endocrinological adaptations as a result of the exercise training (i.e., low testosterone). From a practical perspective, we recommend couples attempting conception should inform their healthcare providers of the male partner's exercise habits concerning endurance running as this may be a factor relative to potential infertility.