December 10, 2010
Men Who Bicycle Have Poorer Sperm Quality
A study said that most exercise appears to have little relationship with the quality or quantity of sperm, but men who bike at least five hours a week have fewer and less active sperm than men who did not exercise.
Lauren Wise at Boston University, who led the study, said that research among competitive athletes has linked biking to genital or urinary problems and poor semen quality.
"However, we were uncertain whether we would find an association among a sample of men engaged in more moderate levels of physical activity," she told Reuters Health, warning it is still too early to say regular biking caused the sperm problems.
Previous studies have found that competitive athletes may have issues with their sperm. However, the study looked at the relationship between sperm health and exercise in 2,200 average men attending fertility clinics.
Each man that took part in the study provided a semen sample and answered questions about their general health and physical activity.
The authors found that men who exercised regularly were no more likely to have problems with the quality or quantity of their sperm than men who had never exercised.
When Wise and her colleagues looked at specific types of exercise they saw that men who said they spent at least five hours every week biking were twice as likely to have both a low sperm count and relatively poor sperm mobility.
The men who did not get regular exercise had a 23 percent lower sperm count, but so did over 31 percent of those who biked at least five hours each week.
About 40 percent of frequent bikers had low numbers of sperm with good motility, versus 27 percent of men who did not exercise.
Wise said that trauma or temperature increases in the scrotum may explain the relationship between biking and semen health.
She also said that it was possible that men included in the study may not be representative of the general population, since they were all attending a fertility clinic and were more likely to have problems with their sperm.
"More studies are needed to replicate our findings before they can be considered causal," she said.
Results of this study were published in the journal Fertility and Sterility.
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