Cycling and Male Fertility

Excessive training combined with energy deficiency can cause hypogonadism, according to the American College of Sports Medicine, with evidence suggesting that this condition can impair fertility 1, 2
The European Association of Urology notes that training at higher intensities with increased loads is associated with more profound changes in semen quality, including decreased sperm concentration, motility, and morphology 1, 2

Clinical Implications for Cyclists

The American Society for Reproductive Medicine recommends that men engaging in intense cycling training consider semen analysis if attempting conception, particularly during heavy training blocks, as some parameters may require more than 30 days to normalize after intense training 1, 2
The International Society of Sports Nutrition suggests monitoring for signs of energy deficiency, as low energy availability combined with intense training can cause hypogonadism and further impair fertility 1, 2

The European Society of Human Reproduction and Embryology notes that while the evidence on heat exposure from cycling position/clothing is insufficient to draw conclusions, scrotal temperature elevation remains a theoretical concern requiring further study 3

Male cyclists with severely reduced energy availability (as low as 8 kcal/kg/FFM/day) can experience reproductive effects, including impaired fertility, according to the British Journal of Sports Medicine 4

The evidence linking heat exposure from cycling to fertility problems is insufficient, with many studies failing to demonstrate actual effects on semen parameters or fertility outcomes, as reported in Human Reproduction Update 5, 6, 7
Studies that show heat-related reductions in semen parameters often report values still within normal ranges, and the quality of evidence is very low, with no RCTs, mostly retrospective data, small sample sizes, and significant confounding factors, according to Human Reproduction Update 5, 7
There is insufficient evidence to conclude that heat exposure from cycling position or clothing affects semen quality or male fertility, as stated in Human Reproduction Update 7

The quality of human evidence linking heat exposure from cycling to fertility problems is insufficient and very low quality, with studies showing heat-related reductions often reporting values still within normal ranges, according to the Human Reproduction Update 8, 9
Scrotal temperature elevation remains a theoretical concern requiring further study, although the evidence is limited to animal studies and low-quality human evidence 8, 9

The evidence base has significant limitations, including a lack of randomized controlled trials, reliance on retrospective data with small sample sizes, and uncontrolled confounding factors such as lifestyle, energy availability, and saddle type, as noted in the Human Reproduction Update 8, 9