Males concerned with fertility might want to step off the bike and supplement with other forms of physical activity. A report published in Fertility and Sterility (2011; 95 , 1025-30) linked frequent cycling and diminished sperm production. The study included 2,261 men who were attending Boston-area fertility clinics. The men completed a questionnaire on general health, medical history and physical activity. At the end of the study, the researchers found little correlation between generalized physical activity and sperm count. However, respondents who cycled at least five times per week presented with low sperm concentration and low total mobile sperm. But before you suggest to your male clients that they ditch the bike altogether,note that the study authors suggested further research was necessary to confirm a causal link.