The Hidden Heat Holding Athletes Back: What Every Sports Executive Should Know

By Saara Jamieson

Discover how testicular heat impacts athlete performance, hormone health, and recovery. Learn why Cool Beans Underwear is disrupting the game at the NRL Magic Round Tech Sprint.

Cool Beans Underwear Takes the Field at NRL Magic Round Tech Sprint

Cool Beans is proud to be one of just eight startups selected to present at the NRL Magic Round Tech Sprint — a program showcasing innovation designed to improve the game and the lives of those who play it.

This opportunity brings Cool Beans Underwear onto one of the biggest innovation stages in Australian sport — the NRL Magic Round Tech Sprint — where only eight startups were selected to pitch game-changing solutions to the league’s top executives.

Founder and medical researcher Saara Jamieson will take the stage to share a simple yet overlooked opportunity to support athletes:

If you're looking for that no-effort, extra edge for your athletes, reducing compounding testicular heat is the answer.

Testosterone. Performance. Recovery. Fertility.

They’re not just buzzwords in the sports world. They’re the biological foundation of male health, and for athletes, they can make or break a season.

But there’s one crucial factor influencing all of them — and no one’s talking about it: testicular heat.

At Cool Beans Underwear, we’re pulling the curtain back on an invisible performance killer affecting athletes from the grassroots to elite level — and it all starts below the belt.

What Is Compounding Testicular Heat?

Compounding testicular heat occurs when the testes are repeatedly exposed to elevated temperatures throughout the day and night — both on and off the field. For athletes, this is a constant threat:

• On the field: the testes are held tightly against the body, absorbing core body heat during games and training.
• Off the field: prolonged sitting (travel, meetings, recovery chairs, even sleeping positions) further traps heat in the groin region.

The result? Little to no opportunity for the testes to return to their optimal temperature range — leading to cellular stress, hormone disruption, and suppressed testosterone and sperm production (Durairajanayagam et al., 2015).

Just 20 minutes of sitting can raise testicular temperature beyond safe levels. For athletes, that means:

• Reduced testosterone
• Slower recovery
• Increased long-term health risks

The Science Behind the Heat

Testes function best when they’re 3°C to 5°C cooler than core body temperature. Even a 1°C rise can reduce sperm and testosterone production by up to 14%, while a 2–3°C increase can halt production entirely (Durairajanayagam et al., 2015).

Shockingly, this level of heat exposure can happen in everyday scenarios:

• 20 minutes on a padded chair
• 13 minutes in a car (Koskelo et al., 2005)

These stats aren’t just relevant to fertility — they reflect broader issues with hormonal balance, muscle recovery, energy levels, mood, and athletic output.

Testicular heat not only suppresses testosterone but also disrupts other critical hormones like luteinising hormone (LH) and follicle-stimulating hormone (FSH), while increasing oxidative stress in the testes. These disruptions can cascade into issues with energy, motivation, muscle integrity, and fertility.

Sperm health has declined by over 50% in the last 50 years, and testosterone levels are falling along the same path. Without immediate attention to testicular health, natural conception may become increasingly difficult — even for elite athletes.

Athletes Are Especially Vulnerable

Elite athletes are particularly susceptible to testicular heat due to:

• Physical exertion elevating core body temperature
• Compression gear limiting ventilation
• Minimal recovery time for the testes to cool down

Research shows they can experience up to 25% lower testosterone than the general population — directly linked to ongoing heat exposure (Hackney, 2020).

This contributes to:

• Decreased physical performance
• Longer recovery times
• Mood and motivation changes
• Declining fertility and hormone function

Why It Matters Beyond the Game

Testosterone is about more than sport. It affects:

• Bone and muscle health
• Mental wellbeing and motivation
• Sexual and reproductive health
• Long-term vitality and ageing

Athletes may retire from the game — but not from their bodies. Supporting their hormone health today shapes their future health tomorrow.

The Cool Beans Solution

Cool Beans Underwear is the world’s first registered medical device designed to passively regulate testicular temperature while providing ergonomic support. Created by Saara and her husband Jordan Jamieson after their own 3.5-year infertility journey, Cool Beans is based on peer-reviewed science and engineered to:

• Reduce daily heat load on the testes
• Create space for proper thermoregulation
• Support testosterone and sperm production
• Offer comfort during recovery, travel, downtime, and sleep

Already recommended by urologists, oncologists, and fertility specialists, Cool Beans is now stepping onto the field — ready to support athletes and clubs prioritising long-term health outcomes.

We’re honoured to represent not just innovation in men’s health — but the future of athlete support — at this year’s Magic Round. This is just the beginning.

Want to give your players a performance edge on and off the field?

Explore Cool Beans at coolbeansunderwear.com or reach out to discuss custom athlete solutions.

Because when you control the heat, you elevate the game.

 

References:

Durairajanayagam, D., Agarwal, A., & Ong, C. (2015). Causes, effects and molecular mechanisms of testicular heat stress. Reproductive BioMedicine Online, 30(1), 14–27. https://doi.org/10.1016/j.rbmo.2014.11.013

Koskelo, R., Varpula, M., & Varpula, T. (2005). Effect of sitting on testicular temperature. International Journal of Andrology, 28(4), 227–231.

Hackney, A. C. (2020). Exercise as a stressor to the human neuroendocrine system. Medicine & Science in Sports & Exercise, 52(8), 1851–1857.