The fashion for men’s “maxxing” has propelled
saunas very hot and
ice baths among rituals supposed to boost testosterone, recovery and even the chances of becoming a father. On social media, some swear that a daily sauna plus ice bath combo is enough to improve sperm quality. So the researchers asked a simple question: What do extreme heat and freezing water really do to sperm and sperm? male fertility ?
The available data paints a nuanced picture. Repeated heat seems to be able to degrade certain parameters of a spermogram, while no study shows that cold water improves fertility. Another common pitfall: confusing testosterone with the ability to conceive. The American Urological Association and the American Society for Reproductive Medicine point out that testosterone treatments can reduce sperm production and are not recommended for men who want a child.
Heat, testicles and male fertility: the threshold that must not be crossed
The testicles are placed outside the body to stay a little cooler than the body’s internal temperature, a key condition for spermatogenesis (the process leading to the formation of sperm). “The testicles are located outside the body because they work better when they are cooler. If you hatch them in a sauna, they don’t perform as well“, explains Professor Colin Duncan, fertility specialist at the University of Edinburgh, quoted by the British daily The Guardian in May 2026.
Assistant lecturer in the Faculty of Health Sciences at the University of Canterbury, Colin Duncan is reassuring for moderate use. “The testicles are designed to produce far more sperm than is actually needed for fertility. If you do a sauna every once in a while, it’s going to make absolutely no difference“, he explains. But “if you do extreme saunas for a long time every day, it will reduce your sperm count“. He summarizes his advice: “If you’re doing anything to excess, anything, it’s probably worth moderating“.
Sauna, extreme heat and spermogram: what the studies show
In an Italian study, ten healthy men did two weekly 15-minute Finnish sauna sessions at 80 to 90°C for three months. Their concentration and motility of spermatozoa have significantly decreased. Six months after stopping the sauna completely, their sperm count had returned to baseline values, which argues for a primarily reversible effect.
A 2024 Chinese study of 15,112 men and 28,267 semen samples, published in Environmental Researchlinked exposure to extreme ambient temperatures to lower concentration, lower total counts and reduced motility, consistent with the idea that the testes do not cope well with repeated heat.
Research in the United States observed couples trying to conceive. Hot baths and jacuzzis, considered separately, had minimal impact on pregnancy rates. However, men subjected to multiple heat sources repeatedly showed a slight decrease in their chances of conceiving.
Ice baths and scrotal cooling: little evidence
Australian systematic reviews find that cold water immersion mainly helps recovery and well-being, with no demonstrated effect on testosterone, sperm count or pregnancy. As for targeted scrotal cooling, it remains experimental for male infertility and the method used is very different from immersing the entire body in cold water.
But following multiple wellness trends without real evidence of effectiveness is likely not to improve your health and even in certain cases, particularly in matters of fertility, you risk obtaining the opposite effect from that sought.