Cyclists who cycle for at least 5 hours a week have less active sperm than men who do not exercise, according to a study published in the journal Fertility and Sterility. Scientists at Boston University studied cyclists with regard to genital or urinary problems and poor sperm quality. Each participant in the study had a sperm sample taken. The athletes answered questions related to their health status and physical activity, the researchers said. After accounting for data on multivitamin use, body weight, blood pressure, and the respondents’ choice of underwear, the authors found that men who were active in sports were more likely to have problems with sperm quality or quantity , compared to men who never exercised. However, when scientists looked at different types of exercise, it became clear that those who cycled at least five hours a week were twice as likely to have a reduced sperm count. 23% of men who do not do regular physical exercise have low sperm count. The condition also affects 31% of those who cycle at least five hours a week. Trauma or an increase in temperature in the scrotum may explain the link between cycling and sperm health. The researchers note that it is possible that the causes are due to another problem, as the participants were patients of sterility clinics.