Health: Does cycling make you infertile?

How saddles affect your sperm

Long hours in the saddle won’t ruin your sex life, despite the press’s recent claims to the contrary

‘Long-distance cycling may seriously damage fertility,’ said The Scotsman. ‘Fertility goes downhill for endurance cyclists,’ reported the Press Association. ‘Cycling saddles men with dodgy sperm,’ decried The Sun.


In time for the start of the 2009 Tour de France, the health editors of the British press warned once again that mankind was cycling towards a childless oblivion.

These latest stories were based upon research presented to the European Society of Human Reproduction and Embryology, carried out by Professor Diana Vaamonde at the University of Cordoba Medical School, Spain.

However, this study isn’t the first to look into the issue of how the saddle affects our sperm. Back in 1997, Dr Irwin Goldstein, an impotence specialist at Boston University, released data suggesting that saddle-soreness was pretty much a precursor to infertility. Since then, the reporting of such studies has followed a well-worn path.

And so, once again, cyclists have been warned that time in the saddle could reduce their sperm count, even though the results of the Cordoba study came not specifically from cyclists, but from 15 elite male triathletes.

Admittedly, triathletes do a lot of cycling, but in the case of this small, very elite sample, they’d been training nine times a week for at least eight years. Crucially, it’s this volume and intensity of exercise that the study’s data suggests could be the major cause of misshapen sperm – not simply cycling too much.

“Not only was the sample group not made up solely of cyclists, but when the story was reported, the links to Lycra and the temperature of the testicles were brought up once again,” says Dr Allan Pacey, a senior lecturer in andrology at the University of Sheffield. “And yet there remains no solid scientific data to suggest that cycling in close-fitting garments is a cause of infertility in men.”

Iron men?

In the study, the triathletes tested were found to have less than 10 percent of normal looking sperm (most fertile men have around 15-20 percent). Then Vaamonde’s team broke down the athletes’ training schedules and looked at the sperm of those who cycled over 300km a week, discovering a further drop to four percent.

Yet Vaamonde’s study wasn’t able to find a reason for this. Instead, the report speculated that it could be due to irritation and compression caused by friction of the testes against the saddle, or tight clothing, which raises the temperature around the testes.

However, she also maintained that reactive oxygen species – small molecules that are a natural byproduct of very high-end exertions – could play a significant part. These molecules react to the ‘stress’ the body undergoes during endurance sports in a way that can damage cell structures and alter the shape of sperm.

Dr Pacey insists that cyclists need not be alarmed by these results, maintaining that the link between cycling and infertility should be treated with caution. “In the ’20s, ’30s and ’40s through to the ’60s, cycling was much more common,” says Pacey, “and yet the real concerns over the fall in fertility among men have only come about in the last couple of decades.”

Instead, he suggests that a combination of factors may be to blame: “The fact that these particular athletes are pushing themselves to physical extremes may have a lot more influence on their sperm count than cycling does. When the body is under extreme duress – when you’re seriously ill, say – such ‘luxuries’ as sperm production get shut down by the body as blood and oxygen are focused on the key survival organs.”

So, does that mean that all but the ultra cyclists, those clocking up over 300km a week, are in the clear?

The shock factor

No, not quite. Pacey adds a caveat to his findings, citing a study from 1999 by Ferdinand Frauscher, from the department of uroradiology at University Hospital, Innsbruck. Frauscher discovered, through scrotal ultrasounds, that up to 96 percent of heavy-duty mountain bikers – those in the saddle for 12 hours a week or more – showed irregularities including swelling, cysts and even benign tumours.

According to Dr David Ralph, a consultant urogenital surgeon at the London Clinic, the trauma experienced by many rough terrain cyclists’ nether regions should be a matter for concern for us all. “Mountain biking can shock the testicles and even compress some of the nerves, leading to cysts and twisted veins,” he says. “While this shouldn’t directly link to fertility problems, cyclists should take action to avoid increasing the trauma.”

Dr Ralph advocates the use of saddles with anatomically designed cutouts in them and insists that cyclists should avoid slamming on the brakes. “Without doubt,” he said, “the chief cause of infertility and erectile dysfunctional problems in men these days stems from a lack of exercise and failure to engage in the kind of cardiovascular training that cycling certainly provides.”

So for the sake of your sperm, carry on cycling. 

I’m too sexy for my saddle

Dr Ralph is not the only expert to recommend cycling as a way to improve sexual function. Researchers from the Lancisi Heart Institute in Ancona, Italy, found that cycling helped counter the erection-hindering side effects of medication on male heart patients.

Meanwhile, the University of California found that men who engaged in regular cardiovascular-based exercise programmes recorded a 30 percent rise in the frequency of sex with their partners.


It seems that saddle choice has a large role to play. US policemen who switched to no-nose cycle saddles recorded ‘significant’ improvements in erectile function, according to research from the National Institute for Occupational Safety and Health in Cincinnati.