Here’s yet another reason for coach potato guys to turn off the TV and start exercising.  A new study shows that men who watch 20 hours of TV a week had sperm counts significantly lower than guys who watched less TV.

Dr. Jorge Chavarro, an assistant professor of nutrition and epidemiology at the Harvard School of Public Health, led a recent study that measured TV’s effect on sperm by asking 189 young men, aged 18 to 22, about their TV watching and exercise habits.  The subjects were also asked about other habits, such as smoking and diet, and if they had any reproductive health conditions or suffered from stress.

Dr. Chavarro found that men who sat in front of the boob tube for 20 hours or more a week had sperm counts 44 percent lower than men who watched less TV.

Researchers say the reason why TV was associated with a lower sperm count is unclear, and it may be that TV is a signal for other factors.

The study also found that men who exercised 15 or more hours a week also had higher sperm counts than their less active male counterparts. The researchers noted that this was only among men whose exercise routine was considered moderate to vigorous. 

“The associations of TV watching and physical activity with sperm counts were independent of each other,” Dr. Chavarro said.

"What we cannot rule out entirely is that our finding for TV watching is specific to TV or sedentariness in general," Chavarro added.

“Guys, turn off the TV and put on the running shoes. Adopting a less sedentary lifestyle may have a positive impact on sperm counts,” Dr. Chavarro advised.

The study was published in the British Journal of Sports Medicine.