While we're happy that the Nintendo Wii has inspired so much fitness among the traditional couch potatoes among us, just remember that since many of its games are physically interactive, you have to be careful. Such is the case of Jerry Marlin over at Nashville, Tennessee, who blew out his knee after taking a bad spill during an intense game of Wii tennis at a church social gathering in his local community.

"I landed on my feet and my knees buckled," said Marlin, whose knee suffered torn ligaments and cartilage. Marlin has subsequently undergone knee surgery, and will be required to wear a knee brace for two months.

"It's addictive. People don't play tennis for four hours without taking a break," said Dr. Barry Callahan, director of Premier Hand and Microsurgery Center in Nashville. Callahan further commented that most of the Wii-related injuries he regularly saw at the clinic were similar to those seen in competitive sports. "They make the same motions that they would in real sports. When they swing they really swing," He said regarding players who used the Wiimote.

The good news is that Wii gaming still appears to be perceived as a healthy thing among doctors. As of the Dr. Steve Samudrala  of America's Family Doctors said: "Anything to get people up and moving is a good thing."

Now, before the parents start getting nostalgic about their college sports days and start teaching their kids about the proper backhand, Dr. Callahan notes that the most Wii-related injuries he's observed are on...middle-aged adults (the age range of most parents, FYI). There you have it - always remember to stretch before you play (jogging's also good), always take breaks between games, and always remember the golden rule: Kids have far more flexible joints than the oldies do.