Leading a healthy lifestyle is often said to be one of the most important factors when it comes to fertility.

However, it seems that too much of a good thing can actually has the opposite effect, according to a new study. Certainly when it comes to male fertility, some new research points out. Some sports done to the extreme can have a negative effect on fertility, and depending on the duration, type and intensity of the exercise, researchers found that sports can affect sperm quality and concentration. Biking is an increasingly popular sport among men in their 20s, 30s and 40s. But for very active cyclists, this could be bad news for their fertility, as a recent study found that men who ride their bike more than 20 hours per week had a lower sperm count. Too hot down there Tight bike pants and the shape of the bike seat can lead to the testes warming up to body temperature – and this is bad news, as ideally, for sperm production, the testes should be two degrees cooler than the body, which is why they hang lower. Another study by the European Society of Human Reproduction and Embryology on triathletes showed that cycling, the activity needing the most training, reduced sperm quality the most when compared with the 42km run and 3km swim. In fact, the more cycle training in both time and kilometres, the worse their reproductive health.