During the warmer months, many men notice that their testicles tend to hang lower and appear more pendulous—a phenomenon humorously dubbed “summer long balls” online. While this phrase might sound like casual locker-room banter, the change actually reflects an important biological mechanism that helps protect male fertility.
The testicles’ main functions are to produce sperm and release testosterone, both of which require a temperature slightly cooler than the body’s core. Unlike ovaries, which remain inside the pelvis, testicles descend into the scrotum to maintain this cooler environment. This descent happens typically during puberty, marking a critical stage known as the “balls dropping.”
However, the testicles don’t just stay put. They actively regulate their position in response to changes in temperature, ensuring sperm production can proceed optimally. When it’s cold, muscles such as the cremasteric and dartos contract to pull the testicles closer to the body to preserve heat. Conversely, in hot weather, these muscles relax, allowing the testicles to hang lower, increasing their surface area and facilitating cooling.
Temperature control is vital. Prolonged overheating of the testicles can impair sperm quality and reduce fertility. That’s why an undescended testicle—one that fails to move into the scrotum—often requires surgical correction.
Men trying to conceive are often advised to avoid overheating the testicles. Recommendations include wearing loose-fitting underwear instead of tight briefs, minimizing time in hot baths, and being cautious with cycling shorts and saddle pressure, which can trap heat in the groin area. Although research is ongoing, the general consensus is that excessive heat and compression can negatively impact sperm production.
Another key player in temperature regulation is the pampiniform plexus, a network of veins surrounding the testicular artery. It acts like a natural radiator, cooling arterial blood before it reaches the testes. When these veins become swollen—a condition called varicocele—it can disrupt this cooling system, potentially causing discomfort and contributing to fertility problems.
The visible loosening and dropping of the testicles in warm weather is therefore not just a quirky seasonal oddity but an elegant example of the body’s ability to protect reproductive function. Men who notice this should understand it as a healthy, normal physiological response rather than a cause for concern.
Understanding this natural temperature regulation can also empower men to make lifestyle choices that support their reproductive health year-round. Supporting testicular health through appropriate clothing, avoiding overheating, and seeking medical advice for persistent discomfort or fertility issues remain important.
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