Is this a case of “damned if you do, damned if you don’t? No! It is a matter of moderation.
Given the number of infertility issues which are directly related to the rising problem of obesity, we are certainly not in the game of dissuading women from exercise. Exercise is a good thing for anyone considering their fertility status. It promotes blood flow and makes you feel good. Moreover, a study in Obstetrics & Gynaecology concluded that women who exercised 30 minutes or more daily, had a reduced risk of infertility due to ovulation disorders.
However, too much exercise may impede fertility in both men and women. But how much is too much and how might too much lead to fertility issues?
In some epidemiological studies, more than 7 hours of aerobic exercise per week has been associated with ovulation problems. The effects of strenuous exercise can be related to reduced progesterone (affecting the ability of a fertilised egg to implant) and rising testosterone levels; changes in reproductive hormone regulation affect ovulation. It's also possible that women who exercise more than 7 hours per week are more likely to restrict their diet - not eating enough healthy fats, losing weight rapidly, or weighing below the recommended weight guidelines for your height, can affect ovulation.
In men, a healthy sperm count supports the chances of conception. However any activity, such as cycling, that presses the testicles against the body may cause a decrease in the number of sperm available to vie for fertilization of the female egg: the temperature of the region simply becomes too hot to support optimal sperm counts. The same may also be said of sitting in extreme temperatures of a sauna or steam room - an activity often associated with post exercise habit.
So, in conclusion we need to stress that the link between exercise and fertility is at best an association. There are a number of causal relationships such as general health, diet, body weight (both obesity and underweight), smoking and alcohol consumption, but that’s for another blog.