BOSTON -- It was one of the hottest holiday gifts for fun and fitness. Doctors are even using it for physical therapy.

But as NewsCenter 5's Heather Unruh reported Tuesday, the Nintendo Wii may cause more harm than anyone expected.

Most people use Nintendo's Wii for fun and fitness. But a growing number of Wii-users are getting hurt.

"We bowled for a good hour or two, and I felt strains in my arm," said Christine Fisher, of Peabody, Mass.

"I was playing on the Wii, and I just continued playing until it was a little too late. And then I was in pain," said Joe Saenz, of Danvers.

According to The Massachusetts Chiropractic Society, there has been an increase in Wii-itis. Chiropractor Laura Godfrey has seen it firsthand. She said the injuries associated with the Wii are very real.

"I am concerned about the Wii for people. They won't stretch. They won't warm up. And then that leads to a level of repetitiveness. Then you see those strain, sprain types of injuries," Godfrey said.

Excessive playing can cause carpel tunnel and back pain, knee, shoulder and elbow pain. Godfrey said the Wii-related injuries can become serious, because it mimics an activity you would play in real life without the limitations.

"When you spend a weekend in front of the TV playing tennis for a handful of hours at a time, we're not used to that," she said.

She advises her patients to warm up and cool down. And if they're new to exercising, she says start slowly.

"It helps to actually stretch. People think it's not what you should do before playing a video game, but it helps," Fisher said.