Optimising Male Fertility: Why Your Jocks Might Be Sabotaging Your Swimmers

By Saara Jamieson - Founder, Cool Beans Underwear

We talk a lot about women’s health when it comes to fertility. But here’s the thing: up to 50% of infertility cases are due to male factors — and a lot of guys don’t even realise how much their underwear might be working against them.

Sperm health isn’t just about biology. It’s about temperature — and unfortunately, we’ve been sitting on the problem.

Heat: The Quiet Killer of Sperm Health

Sperm production happens best at a temperature a couple of degrees below core body temp. The scrotum exists to regulate that. But tight-fitting underwear, long hours sitting, cycling, driving, or even just warm bedding can raise testicular temperature by 2–3°C — enough to drop fertility by up to 14% or even stop sperm production altogether in some men (Jung & Schuppe, 2007).

And guess what?
Most guys are unknowingly overheating their crown jewels every day.

How Everyday Habits Overheat Sperm

Simple, everyday actions can elevate testicular temperature:

• Wearing tight underwear
• Sitting for prolonged periods
• Sleeping in warm environments

These factors can raise scrotal temperature by 2-3°C — enough to significantly impair sperm production.

Everyday Habits, Unexpected Damage

We’re not talking about extreme environments here. It only takes 20 minutes of sitting on a padded office chair, or 12–13 minutes in a car seat, to heat the testes enough to impair sperm and testosterone production (Mieusset et al., 2007).

Add tight jocks or polyester blends and you’ve got a perfect storm: heat gets trapped, the testes can’t cool down, and your sperm start taking a hit.

The Polyester Problem

Polyester might be great for moisture-wicking — but when it comes to sperm, it’s a dead zone. Studies have shown that polyester underwear can generate electrostatic fields through friction with body hair, which may disrupt sperm production and quality over time (Shafik, 1992). In short: not all “performance” fabrics are doing your body a favour.

How Cool Beans Underwear Helps

We designed Cool Beans Underwear to solve this problem — and we built it from personal experience and scientific research, not marketing trends.

• No polyester, ever. We only use materials that are non-reactive and sperm-safe.
• Patented mesh pouch design that lifts and cools the testes away from the heat of the body.

• Three pouch sizes (Quokka, Koala, Wombat) so your anatomy can actually function the way it’s supposed to — extending and retracting, not being crushed into your groin.

• Recognised as a Class 1 Medical Device and recommended by GPs, urologists, and fertility specialists across Australia.

“Men only need to sit for 20 minutes before testicular temperature rises enough to start shutting down sperm and testosterone production. Cool Beans offers the first wearable, daily solution to counteract this heat and protect male reproductive health.” - Saara Jamieson

The Bottom Line

Fertility isn’t just a women’s issue. And it's not just about supplements or lifestyle either. Sometimes, it's as simple as what you wear every day.

Swapping your jocks could be one of the easiest and most impactful changes you can make on your fertility journey.

Because when it comes to sperm health, cooler is better.

Join the Fertility Movement

Whether you're actively trying to conceive or simply planning ahead, your underwear might be the missing piece in the fertility puzzle. Heat matters — and science shows that even small temperature shifts can make a big difference to sperm health.

Cool Beans is the only underwear designed to actively support male fertility, hormone balance, and testicular comfort, every single day.

👖 Experience next-level comfort. 🔬 Protect your sperm. ❤️ Support your future.

👉 Shop Cool Beans Men's Health Underwear — the most comfortable, fertility-friendly underwear you'll ever wear.

References

• Jung, A., & Schuppe, H. C. (2007). Influence of genital heat stress on semen quality in humans. Andrologia, 39(6), 203–215.
• Mieusset, R., & Bujan, L. (2007). Testicular heating and its effects on male fertility. International Journal of Andrology, 30(6), 339–345.
• Shafik, A. (1992). Effect of different types of textiles on spermatogenesis. European Urology, 21(3), 287–291.