It’s a tale of two passions: one for the trail, the other for the bedroom. But what happens when one starts to eclipse the other?
That’s the concern raised by a candid post on Reddit, where one woman shared that her husband, an ultra-trail runner averaging 110–120 kilometres a week in training for a 160K race, has all but lost interest in sex. “Our sex life has gone drastically downhill ever since he started running this much,” she wrote. “He’s never in the mood.”
The responses flooded in, and many echoed the same sentiment: you’re not alone. From hormone fluctuations to under-fueling and fatigue, the discussion offered both empathy and practical advice. But beyond anecdotal evidence, is there scientific truth to the idea that high-volume endurance training can tank a person’s libido?
The Hormonal Toll of Endurance Sports
The connection between high-volume endurance exercise and reduced libido isn’t just locker room lore—it’s backed by science. A 2017 study published in Medicine & Science in Sports & Exercise by researchers from the University of North Carolina found that men who engaged in prolonged endurance training had lower libido scores than their less active peers. The study surveyed over 1,000 male endurance athletes and concluded that “higher training volumes and intensities were strongly correlated with decreased libido.”
The lead author, Dr. Anthony Hackney, noted that the effect stems from disruptions to the hypothalamic-pituitary-gonadal (HPG) axis, the hormonal system that regulates testosterone production. When the body undergoes prolonged physical stress without adequate recovery, testosterone—essential for sexual desire—can plummet.
For female athletes, the effects are similarly well-documented, though they often present differently. The “Female Athlete Triad,” a syndrome involving low energy availability, menstrual dysfunction, and decreased bone density, can lead to a diminished sex drive due to estrogen suppression.
In both cases, the root cause tends to be the same: overtraining without proper nutritional and hormonal balance.
It’s Not Just About Testosterone
Hormones are a huge piece of the puzzle, but they’re not the whole story. One Redditor shared that after experiencing a loss of libido during intense training, his hormone panel revealed chronically low testosterone. But it wasn’t just that—he also felt more emotionally distant and less confident, underscoring how the effects of endurance training extend beyond biology.
Others pointed to nutrition as a hidden saboteur. “Once I started eating more carbs and timing intake deliberately with my runs, my libido came back,” wrote another person. This lines up with recommendations from experts like performance dietitian Scott Tindal, who emphasizes that endurance athletes often suffer from Relative Energy Deficiency in Sport (RED-S)—a condition where calorie intake doesn’t meet energy expenditure, leading to fatigue, hormonal disruption, and yes, a lower sex drive.
A Shift in Perspective: Seduction vs. Systemic Health
Back on Reddit, the original poster tried everything from sexy lingerie to initiating more often—classic moves in many relationships. But one user noted, “It’s not lingerie. It’s testosterone management.”
He wasn’t being glib. Many suggested scheduling intimacy around rest days, adding strength training into the mix to boost hormone levels, and ensuring proper recovery. Others recommended supplements like zinc and magnesium, which play a role in testosterone production and nervous system recovery.
Still, the underlying message was clear: this isn’t a failing of attraction or emotional connection—it’s biology. And like any training program, it can be managed.
What Can Be Done?
If you or your partner are training for an ultra (or even just putting in a lot of weekly mileage), here are evidence-based steps to keep the fire alive:
Get a hormone panel. Bloodwork can reveal imbalances in testosterone, thyroid hormones, and nutrient levels like vitamin D and B12 that influence energy and libido.
Eat more (especially carbs and fats). Sex hormones are made from cholesterol, so don’t fear fat. And if you’re constantly in a calorie deficit, your body will prioritize survival, not reproduction.
Lift heavy things. Resistance training is a proven testosterone booster. Two sessions a week can balance out the hormonal toll of long cardio sessions.
Supplement wisely. Zinc, magnesium, and vitamin D can support endocrine function, particularly for sweaty, sun-deprived endurance athletes.
Recover like it’s your job. Sleep, stress management, and rest days aren’t optional. They’re the secret sauce to staying strong—and sexy.
Talk about it. Shame and guilt only make things worse. Framing the conversation as one of health and connection, not failure, can bring couples closer—even in dry spells.
The Serious Side of a Funny Topic
Yes, the idea that running can kill your sex life might seem funny on the surface. But for many, the emotional toll is very real. One commenter shared how low libido tied to endurance running exacerbated depression and nearly derailed his marriage. “It caused no end of issues. I felt at fault… and it even drove me to contemplate suicide.”
That sobering reminder shows that this isn’t just a bedroom issue—it’s a well-being issue. And one that deserves compassion, open dialogue, and a few smart adjustments to the training plan.
The Bottom Line
Running an ultramarathon may take you to the mountaintop, but if your libido disappears somewhere along the trail, you’re not alone—and you’re not broken. You’re just out of balance.
The good news? Whether it’s dialing in nutrition, lifting some weights, or penciling in some intimacy on rest day, there are plenty of ways to recalibrate. Because chasing a finish line shouldn’t mean losing touch with the person waiting for you at home.
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