Sex Drive and Training: The Frightening Facts

How Chronic Exercise Affects Men and Women

Sex Drive and Training

Ever wonder why you don't see any baby CrossFitters? You know, shirtless infants who try to learn to walk on their hands before they walk on their feet and who strip down their mobiles to make crude TRX straps?

It's because adult CrossFitters, at least the males, are sexually dysfunctional and can't reproduce. They've either got low testosterone that lead to prostatic fluid that's as free of sperm as the South Pacific Gyre is of fish, or they can't get it up.

And female CrossFitters? The only eggs they drop every 28 days are the ones they drop on the kitchen floor while making the breakfast-egg muffins. They may also suffer from something called "pelvic hypertonicity," which can make the act of procreation painful, if they should even feel like trying.

Most of this applies to long-distance bicyclists, too. You never see any toddlers dressed in head-to-toe Spandex like their space-alien mimicking parents. Neither do you see any baby marathoners eating bananas and chugging breast-milk electrolyte drinks. And it's all because their would-be parents are infertile, all of them! That, or they have non-existent libidos.

Okay, maybe I'm poking fun a bit too hard, but the science does appear to be on my side as far as the effects of chronic overtraining on libido and sexual function.

A few years ago, some scientists from the University of North Carolina in Chapel Hill set about to examine the role of endurance exercise and sexual libido in healthy young men.

This was no five-guys-they-found-playing-Ultimate Frisbee-in-the-commons study, either. Nope, their study involved over 1300 men between the ages of 18 and 60, of which 1077 met the final cut (met all the study criteria).

The study was based on questionnaires – which are often prone to a number of problems – but the researchers went to great lengths to ensure the integrity of the answers.

The questions they compiled were culled from a variety of sources: Those concerning exercise were based on the International Physical Activity Questionnaire and the Baecke Questionnaire and followed the advice of the American Heart Association. The questions about libido were adopted from the Androgen Deficiency in the Aging Male Questionnaire, the Sexual Desire Inventory 2, and the Aging Males Symptoms Scale, all of which are commonly used in research/clinical settings.

The intent was to find correlations between exercise duration, intensity of the workouts, age, and total libido score.

The survey was repeated every four months over a period of a year and targeted men who were involved in various sporting activities (running, bicycling, swimming, weight lifting, etc.) and many of whom were associated with organizations associated with endurance-training activities.

There were a whole lot of statistics to correlate and interpret, but the main points were as follows:

  • Training intensity and duration of training were most significantly associated with libido. Participants with the lowest and mid-range intensities had greater odds of high/normal libido state than those with the highest training intensity.
  • Participants with the shorter and mid-range training durations as their current intensity also had greater odds of high/normal libido score than those with the greatest duration.

Loosely interpreted, training 1 to 16 hours a week (low "chronic duration") makes you 4 times more likely to be in the normal or high libido range than those who train over 20 to even 40 hours a week (like some marathoners).

Of course if you throw intensity in the mix, the results get murkier. If your intensity is high, the lower your training frequency and duration should be, at least in the long run. Your libido can handle short periods of balls-out training, but if it persists for weeks or months, say goodbye to libido.

The underlying message, as stated by lead researcher Anthony Hackney, is this: If you're male and train for a large number of hours or it's at a high intensity, your libido will decrease."

In practical terms, this means that training for marathons (races), training CrossFit style for months or years, or even 5 days a week of your classic cardio sessions is going to wipe out your libido.

The Hackney study didn't pay much attention to the effects of training or overtraining on testosterone, but researchers have long reported an association with overtraining and low resting levels of the hormone (and thus a low libido).

Even though the phenomenon has long been reported, organizations like the IOC have renewed interest in it, even coming up with a new term to describe it: Relative Energy Deficiency in Sports.

It's a benign way of saying that exercise has mucked up the reproductive health of men and women who overtrain. It's most often an acute syndrome, but there are those for whom it becomes a long, hard, persistent hormonal slog. Males who fall into this category are now said to suffer from "Exercise Hypogonadal Male Condition."

The phenomenon also occurs in women who overtrain, but their pathology, as I'll lay out below, is a little more complex.

"Yeah-but-yeah-but-yeah-but other studies say that working out increases testosterone levels!"

That's true. Working out generally increases testosterone levels. It also elevates sexual responsiveness in men and women. The magnitude of these increases in testosterone depend heavily on number of sets, number of reps, the order of exercise, and perhaps most importantly, choice of exercises.

For instance, a set of jump squats will increase testosterone levels more than a set of bench press (15% increase compared to a 7% increase). Generally, working bigger muscle groups elicits a greater increase.

The trouble is, this elevation of testosterone is often woefully short, especially in men who lift heavy. Then, to make matters even more puzzling, post-testosterone levels often dip below baseline, sometimes for days.

It could be because of cortisol's antagonistic relationship with testosterone: Rising levels of cortisol induced by a tough workout bring testosterone levels down. That might well explain the chronic low libido seen throughout Hackney's study.

However, there are a couple of other theories that might explain acute (but not chronic) post-workout dips in testosterone. After a hard workout, several things happen.

For one, testosterone converts to its metabolite, DHT, at a much faster rate, which would affect the total testosterone seen in a blood test. Not to worry, though, DHT is more anabolic than testosterone, so no harm, no foul in that regard.

Secondly, increases in testosterone increase the receptivity and responsiveness of androgen receptors (it's this "androgen complex" that initiates muscle protein synthesis). That means that more testosterone would park its butt into the welcoming laps of androgen receptors, which would also show up as reduced testosterone levels in any blood test.

So that might explain the transient dips in testosterone often seen in strength athletes. However, it's not the same thing that happens in chronically overtrained athletes, the type Hackney evaluated in his study.

Female Libido

Hackney's study involved the effect of overtraining on the libidos of men but there's no reason to think the results don't apply to women too.

However, most studies on female libido and arousal focus on the effects of a single exercise session. Their goal is usually to determine how female genitals respond to a workout and generally speaking, anything that increases blood flow to the area increases sexual responsiveness.

Likewise, short bouts of exercise trigger a female's sympathetic nervous system (SNS), resulting in increased "vaginal pulse amplitude," which is a polite way of saying that exercise makes women more likely to grow a female boner (an increase in vaginal engorgement).

But all of that pertains to short periods of exercise (usually less than 45 minutes) and not the hours long, 5 to 7 days a week training sessions often associated with CrossFitters, marathoners, or the exercise addicted in general.

When females chronically overtrain, the most commonly seen problem is a disruption of the normal function of the pituitary/hypothalamic axis (just like in men) that manifests itself through lower levels of testosterone and estrogen.

And, once body fat drops below a certain percentage (around 11%), the reproductive system goes on sabbatical. Menses generally cease and desire for sex is replaced by a desire for one of those Vyper 2.0 vibrating foam rollers, which, sadly, these women will probably use only for therapeutic purposes.

But there's another factor, this one a musculo-skeletal one, that can affect a chronic female overtrainer's sex life – the pelvic floor. Sometimes after childbirth, a woman can experience a loosening or slackening of what Women's Health described as a "hammock" of muscles. This loosening can make sex less pleasurable, especially if her partner's girth comes nowhere near approximating that of a fireplug.

Conversely, training too much can cause the pelvic floor to over tighten. As mentioned above, it's called "hypertonicity" and it can make sex painful. Normally, the vagina is designed to stretch when something is inserted into it, but if there's no give (as seen in cases of hypertonicity), the brain interprets it as pain.

Tight muscles elsewhere compound the problem. According to leading pelvic floor physiotherapist Julia Di Paolo, as quoted in Women's Health, "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."

Di Paolo explains that these women should imagine picking up a blueberry with their vagina and anus as they exhale and then fully letting the blueberry drop as they exhale.

Okay then.

Once the pelvic floor starts to loosen, presumably through a combination of down training the body and the pelvic floor, sexual pleasure increases.

If your libido is suffering as a result of too much (and too intense exercise), the most obvious solution is to take it down a notch. Dr. Hackney reminds us that up to a point, exercise increases libido, but train beyond that point often enough, and you'll experience a drop in libido. He calls it the "inverted U."

A general rule of thumb, at least according to the people who study such things, is to limit the real high-intensity, full-fledged CrossFit stuff to maybe three times a week.

You might also consider taking a week off to reset the hypothalamic/pituitary axis, but that's probably like telling a two-pack a day smoker to lay off the smokes for a week.

Alternately, there are probably things you can do to at least ameliorate the libido-lowering effects of obsessive, you can take my barbell when you pry it from my cold, dead fingers, overtraining. There's sleep and good nutrition, which should be painfully obvious.

Men might also consider a testosterone booster like Alpha Male®. It's not as powerful as true testosterone replacement therapy (TRT) but it'll give most males a decent boost in T levels.

Both men and women could also try a workout formula like Surge® Workout Fuel, which, among a long list of workout-potentiating things, decreases stress hormone levels following exercise.

Regardless, it all comes down to making a decision about whether the obsessive pursuit of some hazily defined definition of physical perfection is worth being a walking contradiction: a body seemingly built for sex but is mentally and, to a point, physically, neutered.

  1. Hackney AC et al. Endurance Exercise Training and Male Sexual Libido. Med Sci Sports Exerc. 2017 Jul;49(7):1383-1388. PubMed.
  2. Lost Your Sex Drive? Why Fitness Lowers Libido. Women's Health. 01/15/2018.
  3. Ahtianinen JP et al. Heavy resistance training and skeletal muscle androgen receptor expression in younger and older men. Steroids. 2011 Jan;76(1-2):183-92. PubMed.