Written by Rhiannon Davis. Reviewed by Jenny Wordsworth. 

If you’re training for a marathon (hello, London runners!) you might be wondering how running impacts fertility. Now is as great a time as ever to talk about it. This topic is often discussed in the context of extremes, either as a potential barrier to conception, or as a healthy lifestyle choice that supports reproductive health. The reality, as with most things, lies somewhere in between. While exercise is essential for overall well-being, its impact on fertility depends on factors like intensity, nutrition, and individual health on all parties involved in the conception journey. We’ve worked with ExSeed to bring you a holistic guide to marathon training on your trying to conceive journey, leaning on their expertise for sperm health.

The Role of Exercise in Fertility

Moderate exercise is linked to improved fertility outcomes. It helps regulate insulin levels, reduce inflammation, and support healthy hormone balance, all of which contribute to reproductive health. Running, in particular, can improve cardiovascular fitness and mental well-being, both of which are important when trying to conceive.

However, high-intensity endurance training can have the opposite effect. Excessive running, especially when paired with inadequate nutrition, may lead to disruptions in sperm production, ovulation, irregular periods, or even hypothalamic amenorrhea (a condition where the menstrual cycle stops due to stress on the body). This is more common in those who engage in high mileage without sufficient calorie intake to compensate for energy expenditure.

Maintaining Chromosomal Integrity

While exercise is an essential part of a healthy lifestyle, its impact on fertility is not just about hormones and ovulation, it extends to chromosomal integrity as well. Both egg and sperm quality can be affected by oxidative stress, a process that leads to the production of free radicals which may damage cells, including the DNA within eggs and sperm. These chromosomal abnormalities are a leading cause of infertility, miscarriage, and genetic conditions such as Down's syndrome.

How Exercise Affects Chromosomes and DNA Integrity

• Oxidative Stress and DNA Damage: Intense exercise, especially when done over long periods or without proper recovery, can result in increased oxidative stress. This leads to an imbalance between free radicals and antioxidants in the body, which can damage the DNA in eggs and sperm. For women and people, this damage can cause chromosomal abnormalities in eggs, resulting in poor egg quality or pregnancy complications.

• Hormonal Disruption and Egg Quality: Excessive or extreme exercise can also disrupt hormone levels, particularly oestrogen and progesterone, which are vital for maintaining healthy egg cells. If these hormones are out of balance, egg maturation can be affected, leading to a higher likelihood of chromosomal errors during cell division.

• The Protective Role of Moderate Exercise: Regular, moderate exercise can help regulate hormones, reduce inflammation, and support proper egg maturation, all of which help maintain chromosomal integrity.

Nutrients That Support Chromosomal Integrity

To combat the potential negative effects of oxidative stress and support egg health, it’s important to ensure that the body is getting the nutrients it needs to maintain healthy cells and chromosomes. This is where OVUM's supplements come into play, specifically targeting oxidative stress and mitochondrial function.

• CoQ10: This powerful antioxidant plays a crucial role in supporting mitochondrial function, which is essential for energy production in cells, including eggs. CoQ10 helps to reduce oxidative damage, thereby protecting the DNA in eggs and improving egg quality. Since egg quality declines with age, particularly in terms of mitochondrial function, CoQ10 supplementation is vital for maintaining chromosomal integrity, especially for those trying to conceive later in life.
  

• Optimised Antioxidant Blend: OVUM’s optimised antioxidant blend combines a selection of vitamins and minerals that work synergistically to reduce oxidative stress. Key antioxidants, like Vitamin E, Vitamin C, and Zinc, help neutralise free radicals and protect cells from damage. This antioxidant support is essential for both egg and sperm quality, as it helps maintain the integrity of genetic material and enhances overall reproductive health.
  

• Folic Acid (in the form of Methylfolate): In addition to its well-known role in supporting healthy fetal development, methylfolate also plays a role in protecting DNA integrity during cell division. By supporting healthy chromosomal development in eggs and sperm, methylfolate helps reduce the risk of chromosomal abnormalities.
  

• Vitamin D: Research suggests that Vitamin D may have a direct impact on egg quality by regulating the genes involved in reproductive health. It also helps reduce inflammation and oxidative stress, which further protects chromosomal health.

Supporting Sperm Health and Chromosomal Integrity

Sperm health is equally important in the fertility equation. Sperm DNA quality can be affected by oxidative stress, with increased free radicals damaging sperm chromosomes, leading to conditions like sperm aneuploidy (abnormal chromosome number). Moderate exercise, combined with a nutrient-rich diet, can help reduce oxidative damage and improve sperm health.

ExSeed’s sperm health testing allows men to monitor key sperm parameters, including motility, morphology, and concentration, which can be influenced by exercise and lifestyle factors like diet, stress, and antioxidant intake. Alongside regular exercise, maintaining a healthy weight, avoiding smoking, and reducing alcohol intake can further support sperm DNA integrity.

For more information on sperm health and exercise, check out ExSeed’s blog. 

Finding the Right Balance

For those trying to conceive, a balanced approach to running is key. This doesn’t mean stopping altogether but rather considering factors such as:

• Training Load: High mileage and intense sessions can lead to elevated cortisol levels, which may interfere with reproductive hormones. Reducing overall volume or incorporating more rest days can help reduce oxidative stress without putting excess strain on the body.

• Energy Availability: Ensuring adequate calorie intake is crucial. Ensure a diet rich in antioxidants, healthy fats, and essential nutrients and minerals. Undereating can exacerbate hormonal imbalances and negatively impact egg and sperm quality.

• Menstrual Cycle Monitoring: Regular cycles are a good indicator of hormonal health. If running is causing disruptions, adjusting intensity or volume may be necessary.

• Strength Training and Recovery: Adding resistance training and prioritising recovery can help mitigate the impact of running on reproductive hormones.

What the Research Says

Studies suggest that moderate exercise (around 150 minutes per week) can enhance fertility, particularly for those with conditions like PCOS, where insulin resistance plays a role. Overweight people with PCOS may benefit most from vigorous aerobic exercise or resistance training due to their insulin-sensitising effects. Similar recommendations may apply to lean people with PCOS, though more research is needed to confirm this.

However, for healthy women and people trying to conceive, regular vigorous exercise may sometimes negatively impact fertility by causing anovulation or luteal phase defects. If menstrual irregularities are detected, increasing caloric intake to prevent an energy deficit or temporarily replacing vigorous exercise with moderate-intensity activity may help restore cycle regularity. Despite these potential concerns, the mental and physical health benefits of regular exercise remain significant, and a blanket recommendation against vigorous activity is not advised.

Assisted Reproduction and Exercise

For individuals undergoing assisted reproduction for diagnoses other than PCOS, research suggests that exercise likely has little to no impact on treatment outcomes. This means that individuals can generally continue their regular exercise routine throughout fertility treatments without concern. However, there’s one crucial exception: the lead-up to egg retrieval.

During this part of the process, your ovaries are at their largest and most vulnerable. They’re stimulated to grow multiple follicles, which can cause bloating and discomfort. At this stage, fertility clinics are usually very clear: no high-intensity workouts, no running, no CrossFit. It’s not about being overly cautious – it’s about avoiding ovarian torsion, a rare but serious complication where an ovary twists on itself.

“It is crucial to avoid intense exercise during the week of egg retrieval. At this time, your ovaries are at their most enlarged, and the risk of developing ovarian torsion is higher.”

Gentle movement like walking or swimming is usually encouraged, but always check with your clinic for specific recommendations tailored to your cycle and response.

Practical Considerations and Key Takeaways

For marathoners trying to conceive, small adjustments can make a significant difference. Ensuring adequate nutrition, incorporating lower-impact training, and prioritising recovery can help maintain a balance between fitness and fertility. If there are concerns about menstrual irregularities, sperm production, or ovulation, consulting a healthcare professional can provide further guidance.

Running doesn’t have to be an obstacle to conception, but understanding the relationship between exercise, hormones, and cellular health is essential in making informed decisions. The goal is to find a sustainable approach that supports both physical health and reproductive well-being.