Guys may now have another reason to get off the couch: Watching TV has been linked to lower sperm counts, a new study suggests.
During the study, which involved 189 healthy 18- to 22-year-olds, men who watched the most TV (20 or more hours a week) had sperm counts that were 44 percent lower than men who did not watch television.
The findings held after the researchers took into account factors that could affect sperm count, such as smoking, body mass index (BMI) and calorie intake.
Men who watch a lot of TV may have a more sedentary lifestyle, which in turn may affect sperm count, the researchers said. Indeed, the men in the study who exercised the most — doing 15 or more hours a week of moderate to vigorous physical activity — had sperm counts that were higher than those of guys who exercised less than 5 hours a week.
The findings suggest that having a more physically active lifestyle may improve sperm quality, said study researcher Audrey Gaskins, a doctoral student at Harvard School of Public Health. Previous studies have found that being obese and eating a high-fat die are risk factors for lower sperm counts.
However, the new study only found an association, and cannot prove that a sedentary lifestyle lowers sperm count. The researchers also don't know if the lower sperm counts seen in the study would have an effect on the men's fertility.
Given the benefits of a healthy lifestyle, the findings make sense, said Dr. Andrew Kramer, a urologist at the University of Maryland Medical Center, who was not involved in the study. But future studies will be needed to determine if increasing exercise in sedentary men will actually improve their sperm counts, Kramer said.
All the men involved in the study were enrolled at the University of Rochester in N.Y. in 2009 and 2010. They were asked about their levels of physical activity and TV watching during the previous three months. More than half of the men were of normal weight, and 75 percent were nonsmokers.
The study is published on Feb. 4 in the British Journal of Sports Medicine.
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