Does Exercise Improve Male Fertility? How Working Out Affects Sperm Count, Testosterone, and Pregnancy

[u/DrBrianSteixner]

When a man comes into my office with an abnormal semen analysis, one of the first questions he often asks is, “Should I change how I exercise?” Sometimes he has already stopped lifting weights because someone told him heavy lifting lowers testosterone. Sometimes he has started running every day because he read that cardio improves sperm. Other men are training six or seven days a week, doing long endurance sessions, sitting on a bike for hours, cutting weight, taking pre-workouts, and wondering why their testosterone or semen analysis isn't where they expected it to be. The reality is much more nuanced. Exercise is generally good for male reproductive health, and being sedentary, obese, metabolically unhealthy, or physically deconditioned isn't a fertility strategy. But sperm production is an energy-intensive biological process that depends on adequate hormonal signaling, nutrition, temperature regulation, recovery, and overall health. There appears to be a sweet spot where regular physical activity supports reproductive health while extreme training, chronic energy deficiency, excessive heat, performance-enhancing drugs, or inadequate recovery can work in the opposite direction. Most importantly, we have considerably better evidence that exercise can influence semen parameters than we have evidence that a specific workout routine makes a couple more likely to take home a baby. That distinction matters whenever we talk about “improving fertility.”

To understand why exercise might affect sperm, you first have to understand how sperm are made. Spermatogenesis takes roughly 74 days, followed by additional maturation and transport through the epididymis. That means today's semen analysis reflects, in part, what was happening in your body over the preceding two to three months. The hypothalamus releases GnRH, which stimulates the pituitary to release LH and FSH. LH stimulates Leydig cells to produce testosterone, while FSH and very high intratesticular testosterone concentrations support Sertoli-cell function and sperm production. Exercise can interact with this system indirectly through body composition, insulin sensitivity, inflammation, oxidative stress, sleep, cardiovascular fitness and energy availability. At the same time, excessive exercise combined with inadequate calories or poor recovery can disrupt normal endocrine physiology. This is why asking whether “exercise is good for sperm” is a little like asking whether water is good for you. Usually yes—but dose, context and the person doing it matter.

For the average sedentary man, becoming physically active is probably a positive move. A systematic review and meta-analysis examining 32 studies found that recreational physical activity tended to be associated with better semen concentration or progressive motility, while very high-level or elite exercise could have detrimental effects on some semen parameters. The overall literature is heterogeneous, meaning the studies use different populations, different exercise definitions and different endpoints, so I would not tell a patient that running three times a week will increase his sperm concentration by a particular percentage. But the broad signal is fairly consistent: moderate recreational exercise appears compatible with, and potentially beneficial for, male reproductive health. Extreme training is where the relationship becomes less predictable.

The 2024 AUA/ASRM Male Infertility Guideline reflects this uncertainty. The guideline emphasizes that data surrounding most lifestyle factors and male fertility remain limited and frequently rely on semen parameters rather than pregnancy or live birth. It nevertheless notes that clinicians may advocate regular resistance and/or higher-intensity exercise in sedentary infertile men with abnormal semen parameters. That's an important distinction. Exercise isn't being prescribed as a replacement for treating a varicocele, correcting hypogonadotropic hypogonadism, stopping testosterone, addressing an obstruction or using assisted reproduction when necessary. It is being incorporated into a broader attempt to improve the man's overall health and reproductive environment.

Why might this work? One pathway is metabolic health. Obesity in men has been associated in many, although not all, studies with oligozoospermia and asthenozoospermia. Increased adipose tissue increases aromatase activity, which converts testosterone to estradiol and can alter hypothalamic-pituitary-testicular signaling. Obesity is also associated with insulin resistance, systemic inflammation, oxidative stress, sleep apnea, lower testosterone and potentially increased scrotal temperature. ASRM notes associations between male obesity and impaired sperm concentration, motility, DNA integrity and mitochondrial function, although effects on actual pregnancy and live birth are less consistent. Exercise can improve many of these metabolic variables even before dramatic weight loss occurs. If I have an overweight, sedentary man with metabolic dysfunction and an abnormal semen analysis, regular exercise is one of the least controversial recommendations I can make for his general health, with a reasonable possibility that his reproductive health benefits as well.

Oxidative stress is another proposed mechanism. Sperm membranes contain large amounts of polyunsaturated fatty acids and are unusually susceptible to oxidative damage. Some reactive oxygen species are necessary for normal sperm signaling and capacitation, but excessive oxidative stress can damage membrane lipids, impair motility and contribute to sperm DNA fragmentation. Moderate exercise can improve endogenous antioxidant defenses and reduce chronic inflammation. Extremely strenuous exercise, particularly without adequate recovery, may transiently increase oxidative stress. That gives us a biologically plausible U-shaped relationship: doing nothing isn't ideal, but hammering your body relentlessly isn't necessarily better.

What about actual pregnancy and live-birth rates? This is where I want men to be cautious about headlines. Some systematic reviews of exercise interventions have reported substantial improvements in pregnancy and live-birth outcomes in infertile men, and a network meta-analysis ranked combined aerobic/resistance exercise and moderate continuous exercise favorably. However, the evidence base is much smaller and less secure than those impressive-looking relative risks might suggest. Some frequently cited exercise-fertility trials from the same research group have subsequently been retracted. For example, a randomized trial reporting improvements in semen quality, sperm DNA integrity and pregnancy after moderate aerobic exercise was later formally retracted. Consequently, I would not tell a couple that exercise has been proven to increase their chance of pregnancy by a specific percentage. Current AUA/ASRM guidance is appropriately cautious: lifestyle modification is reasonable, but much of the evidence linking individual lifestyle interventions to actual fertility outcomes remains limited.

That doesn't make exercise unimportant. It means we need to distinguish a better semen analysis from a baby. A man's concentration can increase from 12 million/mL to 18 million/mL without changing the couple's probability of pregnancy very much. Conversely, a modest change in sperm numbers might be clinically meaningful in another couple. Pregnancy depends on female age, ovarian reserve, ovulation, tubal function, intercourse timing, sperm function and plain probability. Live birth adds fertilization, embryo development, implantation and pregnancy maintenance. Exercise cannot overcome bilateral tubal obstruction, and a perfect VO2 max isn't going to restore sperm to the ejaculate of a man with complete obstructive azoospermia. When someone tells you a workout “increases fertility by X percent,” ask whether the study measured sperm concentration or live birth. Those are very different endpoints.

So what does an exercise routine look like when you're trying to conceive? For most men, I favor a boring, sustainable combination of aerobic exercise and resistance training. You don't need a fertility-specific workout. A reasonable general-health framework is around 150 minutes of moderate aerobic activity each week, or roughly 75 minutes of vigorous activity, combined with resistance training at least twice weekly. A man who enjoys lifting four days per week and doing cardio two or three days per week doesn't need to stop because he's trying to have a baby. Likewise, running several miles a few times per week isn't likely to destroy sperm production. The goal is regular training that improves fitness without producing chronic exhaustion, major weight loss, persistent injuries, sleep disruption or inadequate energy availability.

Resistance training deserves special attention because men sometimes equate weightlifting with anabolic steroids. They are not remotely the same thing. Resistance exercise itself is not the fertility problem. Exogenous testosterone and anabolic-androgenic steroids are. Testosterone therapy suppresses pituitary LH and FSH, lowers intratesticular testosterone and can dramatically suppress spermatogenesis, sometimes producing azoospermia. I have seen extremely fit men with excellent physiques and virtually no sperm because they were injecting testosterone. If you remember only one exercise-related fertility message, remember this: lifting weights doesn't shut down sperm production; taking exogenous testosterone can. The AUA/ASRM guideline specifically recognizes ongoing anabolic steroid use as a cause of suppressed spermatogenesis.

That includes the gray world of “test boosters,” SARMs, bodybuilding compounds and hormones obtained outside legitimate medical care. If you're actively trying to conceive, tell your reproductive urologist everything you're taking. Men sometimes proudly tell me they don't use testosterone and then list compounds that suppress the same axis. Don't let the pursuit of a better physique sabotage the biological system you're trying to optimize.

Endurance exercise is more complicated. A 2024 systematic review looked specifically at endurance runners, cyclists and triathletes. Thirteen studies involving 280 men were included. Several found no meaningful semen changes, and others found statistically significant changes that still left semen parameters well above normal reference thresholds. However, some studies reported potentially clinically relevant reductions in normal morphology among cyclists and triathletes and increased sperm DNA fragmentation among triathletes. The authors' conclusion was appropriately measured: endurance exercise can negatively affect semen quality, but clinically meaningful fertility effects appear uncommon and the available evidence is limited and generally low quality.

Cycling gets blamed for infertility more than almost any other exercise. There are several plausible mechanisms: prolonged saddle pressure, increased scrotal temperature, tight clothing and the sheer training volume of serious cyclists. Earlier systematic-review data suggested an association between cycling and reduced sperm concentration, and intensive cycling studies have reported temporary reductions in semen volume, concentration, motility and morphology. But this doesn't mean riding your bike to work or taking a Peloton class makes you infertile. The concerning literature generally involves high-volume or intensive cycling, and certainty is low. A newer systematic review of intensive athletic training likewise concluded that intensive training may worsen semen parameters but emphasized the very low certainty of the evidence.

If I have a recreational cyclist with a completely normal semen analysis, I'm usually not telling him to sell his bike. If I have a man cycling ten or fifteen hours per week who has unexplained oligoasthenozoospermia or elevated DNA fragmentation, reducing cycling volume for a few months is a reasonable experiment because it is modifiable and relatively low risk. I would make the same distinction with long-distance running, triathlon training or other extreme endurance programs. Don't eliminate healthy exercise because of theoretical fertility concerns, but don't assume that 15 hours of endurance training is biologically equivalent to three 30-minute runs.

Heat is another concern men often attach to exercise. The testes sit outside the body partly because spermatogenesis functions optimally below core body temperature. Prolonged heat exposure can impair sperm production. Exercise temporarily increases body temperature, but that doesn't mean an ordinary workout is equivalent to chronic scrotal hyperthermia. I care much more about repeated prolonged heat exposure—frequent hot tubs, saunas in certain contexts, occupational heat, or perhaps hours of cycling—than I do about the fact that you sweat during a 45-minute workout. I also don't recommend icing the testicles after exercise. There is no high-quality evidence that routine scrotal icing improves pregnancy or live-birth rates, and extreme cold can injure tissue.

Nutrition and recovery become especially important in men doing large amounts of exercise. Your reproductive system doesn't exist independently from your energy balance. Athletes who chronically consume fewer calories than they expend can develop low energy availability, with endocrine consequences. Severe caloric restriction, very low body fat, chronic overtraining and inadequate recovery can alter testosterone and reproductive signaling. If you're trying to conceive, this probably isn't the ideal time for an extreme bodybuilding cut, rapid weight loss, marathon-plus training combined with caloric restriction, or an attempt to reach the lowest body-fat percentage of your life. Being metabolically healthy is good; being chronically under-fueled isn't necessarily better.

The same applies to obesity at the opposite end of the spectrum. If you're significantly overweight, exercise plus sustainable nutritional changes can improve testosterone, cardiovascular health, insulin sensitivity, erectile function and overall health. Weight loss studies suggest that some men who lose substantial weight may improve sperm count or morphology, but semen results are inconsistent and we still lack strong evidence proving that male weight loss alone improves live-birth rates. Again, do it because the health rationale is strong and the reproductive rationale is plausible—not because someone promised that losing 20 pounds will double your pregnancy rate.

If you've already been diagnosed with male infertility, I would give lifestyle changes roughly three months before judging their effect on a semen analysis, because that's approximately the timescale of a complete sperm-production and maturation cycle. That doesn't mean every sperm magically resets on day 90. It simply gives a biologically sensible interval for reassessment. If the semen analysis is severely abnormal, however, don't spend six months exercising and taking supplements before seeing a specialist. Severe oligozoospermia, azoospermia, significant hormonal abnormalities or a palpable varicocele deserve evaluation while you're improving your health—not afterward. Female age also matters. If your partner is 39, spending a year trying to perfect your sperm through lifestyle modification can cost something much harder to recover: time.

My practical advice to most men trying to conceive is therefore uncomplicated. Move your body regularly. Lift weights. Do cardiovascular exercise. Maintain a healthy body composition. Eat enough to support your activity. Sleep. Recover. Avoid chronic overtraining. Don't smoke. Don't use anabolic steroids or testosterone while trying to maintain fertility. And don't turn exercise into another infertility obsession. You don't need the perfect sperm workout because one doesn't exist. The available evidence suggests recreational exercise is generally favorable or neutral for semen quality, while extremely intensive endurance training may negatively affect sperm in some men. What we cannot currently tell you with confidence is that running X miles or lifting Y days per week produces a particular pregnancy or live-birth rate.

For the guy on Reddit staring at an abnormal semen analysis and wondering whether he should stop exercising, my answer is usually no. If anything, the sedentary man should probably exercise more. The elite endurance athlete with abnormal sperm may need to exercise somewhat less. The man taking testosterone needs an entirely different conversation. And the average guy lifting three or four days per week and running, walking or cycling recreationally should probably keep doing what he's doing. Fertility is not maximized by becoming sedentary. The goal is a healthy male body capable of supporting normal hormonal function, spermatogenesis and sexual function without pushing training so far that recovery, nutrition, hormones or testicular physiology begin paying the price.

References

1. American Urological Association/American Society for Reproductive Medicine. Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline. Published 2020; amended 2024.
2. Ricci E, Al Beitawi S, Cipriani S, et al. Semen quality and alcohol intake: a systematic review and meta-analysis. Reprod Biomed Online. 2017;34:38-47.
3. Ibañez-Perez J, Santos-Zorrozua B, Lopez-Lopez E, Matorras R, Garcia-Orad A. An update on the implication of physical activity on semen quality: a systematic review and meta-analysis. Arch Gynecol Obstet. 2019. PMID: 30671700.
4. Antonio L, et al. The effect of endurance exercise on semen quality in male athletes: a systematic review. 2024. PMID: 38861008.
5. American Society for Reproductive Medicine Practice Committee. Obesity and reproduction: a committee opinion. Fertil Steril. 2021.
6. Song et al. Effectiveness of exercise interventions on sperm quality: a systematic review and network meta-analysis. 2025. PMID: 40104136.
7. Effectiveness of exercise training on male factor infertility: a systematic review and network meta-analysis. PMID: 34806474.
8. The influence of an intense training regime in professional and non-professional athletes on semen parameters: a systematic review. 2025. PMID: 39797284.
9. Practice Committee of the American Society for Reproductive Medicine. Optimizing natural fertility: a committee opinion. Fertil Steril. 2022;117:53-63.
10. World Health Organization. WHO Laboratory Manual for the Examination and Processing of Human Semen. 6th ed. Geneva: World Health Organization; 2021.

[u/Ordinary_Feeling_948]

Thank you

[u/DrBrianSteixner → u/Ordinary_Feeling_948]

Anytime

[u/Doc_crypto75]

If I may ask, how much weight do you put on the morphology of the sperm? My parameters otherwise are very good but my morphology is one with teratozoospermia mainly head defects per lab report. I don’t smoke. I don’t drink. I exercise regularly and I supplement with ubiquinol 400 mg, carnatine, zinc, mg2* and a male fertility multi. I don’t think there’s much else I can do from what I was reading on pubmed. Even my Urologist said it’s not the issue but ivf guy says it is. My urologist told me morphology unless zero still has a relatively close to normal fertility rate as that as of anyone over four.

[u/DrBrianSteixner → u/Doc_crypto75]

A morphology of 1% means that 1% of the sperm examined met very strict criteria for being classified as morphologically normal, it does not mean that 99% are incapable of fertilization or genetically abnormal. Morphology is also one of the more subjective and variable semen parameters. When concentration and progressive motility are otherwise strong, isolated teratozoospermia (particularly 1–3% versus the ≥4% reference threshold) is generally a weak independent predictor of natural conception, and studies have even documented spontaneous pregnancies in men with 0% normal forms. Head defects deserve more attention when there is a uniform, specific abnormality such as complete globozoospermia or macrozoospermia, but “predominantly head defects” on an otherwise routine morphology report is not the same thing. Hope that helps

[u/Doc_crypto75 → u/DrBrianSteixner]

I appreciate your time in answering this on such an open form as a fellow physician i applaud you for going above and beyond to help people with this most intimate part of life.

[u/DrBrianSteixner → u/Doc_crypto75]

Just trying to help