Cambridge, Mass. - A new Harvard University study suggests there may be a link between television habits and lower-quality sperm concentration.

Scientists asked 189 volunteers questions about how much they exercise -- and how often they watch T-V.

They then took semen samples from each of the men.

Volunteers who said they exercise 15 hours or more per week had much higher sperm concentration.

By contrast, those who watched more than 20 hours of T-V had just half as many sperm cells as those who watch no T-V.

The study's authors say more research is needed because of their small group sample size.