Can Too Much Exercise Lead to Infertility?

Exercise is great for your health, can help you maintain a healthy body weight, can reduce stress, and can even help you sleep better. Research published in the journal Sports Medicine even found that 30-60 minutes of vigorous exercise every day could reduce the risk of infertility in women. But too much of a good thing can also be hazardous to your health and to your fertility.

Before we move forward, let’s be clear: in most cases, exercise is a good thing and can improve fertility. If you’re obese, vigorous exercise is consistently recommended to improve health and to improve fertility. If you’re planning to begin an I.V.F. cycle, research published in Reproductive BioMedicine Online found that women who spent at least 2.8 hours per week involved in aerobics, rowing, or working out on a stair machine, ski machine, or doing other types of vigorous physical activity saw higher probabilities of getting pregnant and seeing that pregnancy to term. This led the researchers to conclude that certain kinds of vigorous physical activity can potentially lead to positive I.V.F. outcomes.

But what happens when individuals take a good thing too far? Research indicates that certain elite athletes experience declines in their fertility and there is a belief that overtraining could be linked to these issues. Studies in women and men also suggest that athletic overtraining can have negative reproductive consequences. How much exercise is too much? What effects does athletic overtraining have on the body? Let’s explore

How Much Exercise is Too Much? When Does Training Become Overtraining?

We live in a culture where healthy eating and regular exercise is celebrated. Some women and men who engage in daily vigorous exercise might think that they’re doing what it takes to stay healthy. It can sometimes be difficult to judge when your weekly tough workout becomes too tough for your body to handle. The journal, Sports Health, notes that overtraining syndrome “remains a clinical diagnosis with arbitrary definitions.” Basically, this means that there isn’t a clear definition of what exactly overtraining means. However, the medical literature does seem to provide some information about warning signs individuals can watch for.

Marathon runners, long-distance cyclists, swimmers, ballet dancers, and other athletes who participate in regular heavy exercise could be at higher risk of harming their fertility and stressing their bodies in a way that can harm their musculoskeletal system, cardiovascular system, and reproductive system. While some of these effects can be reversed by reducing the intensity and time spent exercising, those who have been overtraining for years (especially elite athletes) could be causing their bodies potentially irreversible damage.

What are the signs that you’re overtraining?

Here are a few:

• If you’re a woman and have irregular menstruation or have stopped menstruating since you’ve been training, this is the biggest red flag that indicates you’re training too hard.
• Overtraining in women can lead to a condition known as hypothalamic amenorrhea, where the hypothalamus stops releasing hormones needed for reproduction and menstruation stops.
• If you are engaging in extremely heavy exercise for more than 60 minutes every day, you could be at risk.
• If you often feel fatigued or sore after every workout, you may be training too hard.
• If you have no body fat or very low body fat, you may not be eating enough calories to support your workouts.
• If you’re a man and are an endurance runner, resistance trainer, or if you cycle more than 300 kilometers a week (186 miles), you could be at risk of lower sperm count and lower testosterone.

Part of the challenge with athletic overtraining is that individuals may not realize that they’re harming their bodies. Our culture puts a premium on thinness, healthy eating, and exercise, and individuals who train hard may be celebrated for their hard work, commitment, and thin or muscular appearance. According to Endocrine News, treating women who have developed hypothalamic amenorrhea can be challenging because convincing women that their diet and lifestyle isn’t healthy can be difficult. Sometimes women only change their lifestyle once they see the physical consequences. That is, some women might only agree to make changes when they have difficulty conceiving. Other times, a team of doctors including nutritionists, psychologists, and physicians is required. Treatment is further complicated if the woman is suffering from an eating disorder.

Exercise associated with athletic overtraining includes marathon running, long-distance running, ballet, swimming, figure skating, and cycling. But as more women engage in diverse sports and activities, including weight training, CrossFit, and as younger women push themselves to elite levels to get college sports scholarships, it is possible that athletic overtraining and fertility will only grow as an area of concern for physicians.

What are the Health Consequences of Athletic Overtraining?

Too much exercise can impact various body systems, including the reproductive systems of both women and men. In a review of the available research on the impact of athletic overtraining on health, researchers at the Harokopio University of Athens Greece found that excessive exercise could result in musculoskeletal injuries and muscle damage; too much exercise could lead to negative cardiovascular effects. Overtraining could also result in lowered immunity, reproductive dysfunction, negative energy balance, sleep disorders, and osteoporosis. In men, excessive exercise could impact the hypothalamic-pituitary-testicular axis. Exhaustive exercise in men was associated with lower testosterone levels, lowered sperm count, and changes in sperm quality. Researchers also found a link between excessive bike riding and erectile dysfunction. Too much exercise in women affected the hypothalamic-pituitary axis, which could lead to delayed puberty in girls, as well as luteal phase deficiency (failure of the uterus to build up a thick enough endometrium to promote embryo implantation), infrequent menstruation, and failure to ovulate.

According to the National Institutes of Health, athletic overtraining in women can lead to a condition known as hypothalamic amenorrhea, where the hypothalamus stops releasing gonadotropin-releasing hormone, the hormone required to start the menstrual cycle. The Journal of Endocrinological Investigation found that this condition can impact fertility, but also could include other health risks including risks to cardiovascular health, mental health, and the risk of skeletal problems. In hypothalamic amenorrhea, women experience reduced (GnRH) secretion, impairment of follicle-stimulating hormone, and luteinizing hormone (translation to English: women may have no ovulation or irregular ovulation, no period or irregular periods, and endometrial thickness might be low).

Research performed at the Norwegian Institute of Science and Technology found that elite sports women were more likely to be infertile than women in the general population. The study followed 3,000 women who engaged in frequent and intense training. When the women reduced the frequency and intensity of their exercise, they saw their fertility improve. The researchers surveyed women between 1984 and 1986, and then followed up with the women between 1995 and 1997. They found that women in two groups in particular experienced more infertility: women who trained every day and women who trained until they were exhausted. 24% of women who trained to exhaustion had fertility problems and 11% of women who trained every day experienced fertility problems. When all other factors were taken into account, women who trained every day had a 3.5 times greater risk of having fertility problems than women who didn’t train daily.

Men also could be affected by athletic overtraining. Researchers writing in the Open Reproductive Science Journal found that physically active men had better semen parameters and better hormone levels than sedentary men, but when exercise became excessive, researchers noted changes in sperm count, testosterone levels, and even saw cases where men experienced erectile dysfunction. Increased training alone wasn’t enough to impact sperm count and testosterone, but in elite athletes, endurance training athletes, and cyclists who biked more than 186 miles a week, saw changes in their reproductive health. The research indicates that endurance runners, high-mileage runners, cyclists, and elite athletes were most at risk. The journal, Sports Medicine noted that endurance runners in particular had changes in their reproductive hormones. Cycling was also associated with erectile dysfunction.

Why do men suffer from fertility problems with athletic overtraining? Theories include the idea that excessive exercise can lead to hormonal imbalances and the fact that heavy training can elevate the temperature of the scrotum, which could interfere with sperm production (the scrotum needs to remain cool to produce sperm). Another theory is just that men who overtrain are simply too exhausted to maintain an erection.

What You Can Do

If you’re having difficulty conceiving, you might want to talk to your doctor about your exercise regimen to see if it might be having an impact on your reproductive system. Making sure you’re taking in enough calories to support your workouts is important, and taking a daily wellness supplement can potentially help. But, if you’re a woman and have stopped menstruating, or if you’re a man and have noticed erectile dysfunction or are concerned for your sperm health, speaking to a doctor and nutritionist about your workout schedule might be a good idea, especially if you plan to have a baby soon.

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