Sex files: Running, sexual function and fertility

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First, the situation for men. Weight and, in particular, a high body mass index have been shown to have a significant effect on both sperm count and the chances of erectile dysfunction. Research shows the more fat you carry, the greater your chances of suffering from these issues. Happily, increasing your running can improve matters, especially in middle age: a Harvard University study found that men over the age of 50 who run for at least three hours a week have a 30 per cent lower risk of impotence than those who do little or no exercise.

‘However, don’t overdo it,’ says Federico Febbraro, lead physiotherapist at The London Clinic. ‘Athletes who regularly undertake gruelling endurance events such as marathons can have problems with fertility. Why? ‘Firstly, lowering your body fat too far can affect the quality and quantity of your sperm,’ says Febbraro. ‘Secondly, men who do a lot of mileage running in tight shorts, like compression kit, that squeeze around the reproductive area can sometimes develop varicocele.’ This is an enlargement of the veins around the penis caused by compression of the arteries around the perineal region (between the scrotum and anus). The resulting lack of blood flow to the area affects sufferers’ ability to achieve and sustain erections. Febbraro recommends wearing compression around the groin area either for training or recovery but not both, and not sleeping in recovery tights except after really hard sessions.

And for women? The same doctrine of moderation applies when it comes to female fertility. According to NHS guidelines regular moderate exercise is key for promoting a healthy prepregnancy state. The benefits of running – such as less stress, increased circulation, greater strength and flexibility, and detoxification – all help to increase the chances of conception. But if you’re trying to get pregnant, Febbraro recommends that you limit your training to three 30-minute mid-intensity runs per week, plus two half-hour strength-training sessions. Pushing yourself too hard, the evidence shows, can have a negative impact on your chances of conceiving. A Norwegian study of 3,000 women of child-bearing age found only a ‘moderate exercise’ protocol was beneficial to fertility, while those who were either sedentary, trained almost every day, or regularly trained to exhaustion, all experienced problems. Those who did little or no exercise were found to be at greater risk of ailments such as polycystic ovary syndrome, diabetes and hypertension, all of which can reduce chances of conception.

At the other end of the scale, the study (along with numerous others) suggested low levels of body fat (less than 17 per cent) are related to fertility issues. ‘This is a problem that can be quite prevalent among elite female athletes,’ says Febbraro. ‘There are two issues: low body fat can lead to irregular periods or the menstrual cycle stopping altogether because of decreased production of oestrogen and progesterone, two hormones essential to fertility. In addition, studies on athletic women have shown that their cortisol [the stress hormone] levels are constantly elevated and their thyroid hormone levels tend to drop, which leads to greater adrenal stress and can cause poor reproductive function.’ The good news, though, is that the scales can be reset if you make sensible changes to your exercise regime. ‘All the evidence shows that if you cut back to a moderate level of exercise your stress levels will drop and your periods should go back to normal within a couple of months,’ says Febbraro.