Written by Dr Katherine Joseph. Reviewed by Dr Phoebe Howells.

Introduction: Getting the dose of exercise ‘right’?

Exercise is a wonder drug. If it came in a pill form, we would all be on a lifelong prescription, but unfortunately, only a minority of us manage to achieve our recommended weekly intake. 

The NHS recommends 150 minutes of moderate intensity exercise and two strength-training sessions per week, something only around a third of us reportedly achieve. Exercise improves your cardiovascular system, metabolic health, and supports weight management. It also enhances well-being, sleep, and longevity.

Like many things, there is an optimal dose, and excessive duration or intensity of training can tip the balance to become a negative. A 2024 study highlighted when exercise can become problematic: exercising for 2 hours a day, 5 days a week, at above 80% VO2 max was enough to put a dent in the fertility of participants. Overtraining can impair the hypothalamic-pituitary-gonadal axis, potentially overheating the testicles and increasing oxidative stress, which can lead to worse sperm parameters. 

So, what are the impacts of cycling on male fertility? 

High-level cyclists are a special breed. Long cycling sessions in Lycra, which apply saddle pressure around the male fertility organs, can be particularly problematic. There are two related but separate considerations: fertility (sperm parameters) and erectile dysfunction (from pressure-related nerve damage to the penis). 

1. Fertility Considerations

The Concern: 

Research that directly evaluates fertility outcomes in cyclists is extremely limited. The largest and most recent study to do so, involving over 5,200 British cyclists, bears good news. For the average cyclist, there does not appear to be a link between cycling and fertility, erectile dysfunction or prostate cancer. The study found no association between cycling and infertility, even among those riding up to 8.5 hours per week, the highest duration assessed. 

Interestingly, men who cycled between four and six hours per week actually had roughly half the odds of being infertile compared with non-cyclists.

However, as we discussed at the start, exercise is a case of moderation, and professional cycling is a different matter. The science is not entirely settled, but cycling consistently demonstrates issues for endurance athletes. A recent systematic review found that four articles reported a decrease in semen quality, with potential clinical consequences, including a reduced number of sperm cells exhibiting normal morphology, in cyclists and triathletes. 

Further, a study from the 1990s on Spanish professional cyclists found that compared to runners, triathletes and sedentary controls, the cyclists had worse sperm morphology. Now, it is worth noting these are Tour de France-calibre cyclists, and these were men training 9 times a week for at least 8 years; it might not be surprising their sperm morphology wasn’t perfect. The study itself examined only semen quality and not fertility, but concluded that those cycling more than 185 miles a week had sperm that is less “normal looking”. 

Looking towards more moderate levels of cycling, a 10-year observational study conducted in Boston looked at the relationship between cycling and sperm counts among men from various backgrounds. The researchers analysed 4,500 semen samples from 2,261 participants. Interestingly, men who cycled for more than five hours per week had sperm concentrations around 90% lower than those who reported no exercise. However, no links were observed between semen quality and other common risk factors such as age or obesity. 

It’s worth noting that all participants were infertile men whose partners were undergoing IVF treatment, which limits how broadly the results can be applied. The study did not directly assess fertility outcomes.

The Solution:

Going back to the NHS guidelines, ‘moderate intensity’ exercise is the key phrase here. Moderate intensity exercise is associated with improved semen parameters (sperm count, motility, morphology, and DNA integrity) through beneficial effects on hormonal balance, reduced oxidative stress, and better metabolic control. 

A 2025 analysis of 14 studies found that for infertile men, any form of regular exercise enhanced sperm motility and total sperm count, with outdoor aerobic exercise also increasing sperm volume. 

2. Erectile Dysfunction and Pelvic Numbness

The Concern:

Are you suffering from pelvic numbness? This is a cause for concern, and it’s probably time to consider a new saddle. Pelvic numbness after long rides is a hallmark of compression damage to the pudendal nerve and/or the blood vessels that run with the nerve. This isn’t a cause for concern for fertility. Still, it is much more of a concern for erectile function as repeated trauma from the saddle, on the nerves and arteries, can lead to erectile dysfunction. 

The Solution:

A seat where the middle of the saddle is largely absent, so the ischial tuberosities (your sit bones) are doing the supporting, but nothing else. The best saddle is flat or gel in the back, cut out in the middle, with some kind of lean in. 

More and more bike seats have this central cutout or indentation to reduce pressure on these pudendal nerves and vessels. A US study of bicycle patrol police officers found that “no nose” cycling seats reduced pudendal pressure by 65%, with over 80% of riders reporting no numbness when using these seats. 

Bike seat choice is a highly personal decision, influenced by riding position, anatomy, and the type of riding. There is a range of noseless seats available, such as the ISM P2, which is pictured below. Short-nosed saddles with larger central cut-outs are more popular among competition cyclists who need to balance speed, overall seat comfort, and pudendal numbness (e.g., some Tour de France riders use seats such as the Fizik Vento Argo 00 short-nosed saddle or the S-Works Power with Mirror - a wallet warning on these options!). 

We recommend people try three different saddles, as brands are usually happy to offer them on a trial basis, to learn which is the most comfortable for you. Alternatively, brands will send you a pressure pad to ascertain where your sit bones land (or talk you through how to DIY this at home), you send it back, and they’ll measure the width of the saddle you need. 

The Key Takeaways

• Regular moderate exercise is one of the most important habits you can develop for overall health and longevity, as well as for optimising your fertility. So, keep up the cycling!

• Some endurance and elite athletes can harm their fertility temporarily through overtraining, and cycling appears to be particularly problematic with the added effects of neurovascular damage to the pudendal area. 

• Moderate levels of cycling (4-6 hours/week) still appear to be net positive for fertility, and there are seat and position adjustments you can consider to reduce the pressure effects. With no nose seats, the most pudendal nerve-friendly option is available.