It’s tricky to put a price on feeling, and looking, your fittest. A set of one-on-one PT sessions? Makes sense. Half the supplements in a Priceline stockroom? As long as payday’s on the horizon. Your sex life? Er, what? Yes – the true cost of peak fitness may not be financial, but sexual. It could be as simple as ditching Ben from Bumble for a class at Barry’s Bootcamp. Or following your training runs with a shake and a sleep, rather than any shenanigans in bed.
In 2017, when the University of North Carolina took 1077 men and studied their long-term exercise habits and self-reported libido levels, a clear but rarely talked about trend emerged.
“If you’re male and train for a large number of hours or at a high intensity, your libido will decrease,” reveals study author Anthony Hackney, professor of exercise physiology and nutrition. “And while there’s no solid research as yet, there’s no reason to suspect that women would be any different.”
Why does exercise impact your sex drive?
Let’s take a look at what we know about the relationship between working out and your sexual desires. Unlike Hackney’s research, studies into female arousal tend to focus on your body’s immediate genital response to a single sweat session. And findings suggest the flush in your face is repeated down below.
“Genital arousal is dependent on blood flow to that area,” says sex researcher Dr Tierney Lorenz. “So it stands to reason that anything that promotes blood flow – exercise included – will boost sexual feeling.”
Back in 1996, Dr Cindy Meston, now director of the Sexual Psychophysiology Laboratory at the University of Texas at Austin, asked 15 women to cycle for 20 minutes before showing them an erotic film. This short burst of activity triggered the women’s sympathetic nervous systems (SNS) to arouse their sweet spots, where, come porn time, researchers found an increase in “vaginal pulse amplitude”, the measure of vaginal engorgement specific to sexual arousal. Lorenz reproduced these findings in 2012, swapping bikes for treadmills.
“Moderate levels of SNS activity prime a woman’s body to experience higher genital arousal than if she is at very low or very high levels of SNS activity,” she says. “So you’ll experience a difference from when you’re at rest or in a state of high physical stress.” And it’s here where the argument that too much high-intensity exercise could affect your mojo really starts to take off.
How much exercise is too much?
The 20 minutes of moderate exercise participants did in the aforementioned research – recording an energy expenditure level of about 70 per cent of maximum heart rate – doesn’t quite do justice to the average fitness-lover’s schedule these days. Whether it be short, sweaty HIIT sessions or multiple weights workouts every week, there’s nothing chilled about it. Link this back to sex and it’s not as simple as getting hot in a spin class leading to things heating up in the bedroom.
Instead, Hackney presents the “inverted U”. Up to a point, exercise will increase your sex drive, thanks to that SNS boost, but train beyond this and your libido is likely to tank. We also tend to be more sensitive to overexercising than men.
“When women exercise to an extreme or endurance level, hypopituitarism (an under-functioning of the pituitary gland) can develop, leading to low levels of testosterone and oestrogen,” says professor Peter Sönksen of the Society for Endocrinology. Lisa Dawn Hamilton, an associate professor of psychology, adds, “Women need a certain level of body fat for the reproductive system – with all its hormones – to work effectively. So, if overexercising leads to low body fat, your body shuts down its capacity to become pregnant. It would make sense for this to extend to the desire for sex, too.”
Plus, between early alarms, skipped lunch breaks and delayed bedtimes in the name of training, it’s no wonder many women are often too shattered to even consider sex.
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Your pelvic floor is at play, too
Another sexual player in all this is the pelvic floor. Being too fit can tighten these muscles so much that intercourse becomes challenging.
“Athletes typically have a high level of tone in their pelvic floor – called hypertonicity – and this tends to [link] with pain during penetration,” explains Julia Di Paolo, a pelvic health physiotherapist. “There’s just no give. The vagina is designed to close down on itself when there’s nothing in it ... but force-stretch a tissue that is mega toned and the brain will interpret that as pain.”
Di Paolo admits that we lack the exact science to explain why hypertonicity is seen so commonly in heavy exercisers, but it’s likely down to the fact that your pelvic floor is the internal equivalent of a good sports bra.
“It has to shock absorb and decelerate motion while simultaneously supporting the pelvic organs, similar to your quads when running downhill,” she says. And tense muscles elsewhere don’t help. “Tight calves can pull down on your hamstrings, tilting your pelvis and tightening the floor.”
It’s why maintaining a groin prepped for good times is no longer simply about teaching the right muscles to contract, but also learning to relax them.
“We call it down training or reverse Kegel,” explains Di Paolo.
Imagine picking up a blueberry with your vagina and anus as you exhale, then fully let the blueberry go as you inhale. Eye roll, sure, but it’s worth unwinding: research in the International Urogynecology Journal linked optimum pelvic floor function to increased arousal and orgasms. But beyond the science, what does working out to the max really mean for your sex life? While widely acknowledged, the training tipping point that kills libido faster than the familiar ringtone of your parents on FaceTime remains undefined.
“It should be possible to learn more ... but no one’s done it yet,” says Sönksen. Until then, Pete McCall, a fitness educator, suggests a 45-minute session cap. “To protect the libido, limit high-intensity exercise to 40-45 minutes, two or three times a week,” he advises. Hackney, the academic behind the surprising libido results in men, is now calling for research into the opposite sex, too.
“It’s crucial,” he says. “We know a lot about the development of reproductive dysfunction, athletic amenorrhoea [lack of periods], but other consequences, such as lowered libido, need to be addressed to ensure overall health.” Until that intel is nailed down, it’s up to you to reach a happy state between the thrill of scoring a PB and, well, just scoring.