Action video games, including Wii Fit games, certainly promote themselves as a form of exercise, but can they really make you fit?

Yes, experts say, but with some important caveats.

The games need to be intense enough to elevate your heart rate to a certain degree. And they need to be played long enough, and frequently enough, to make a difference.

The games more likely serve to augment a fitness regimen rather than supply the basis for it, some experts say.

And while they're probably not good training for an Ironman triathlon, they do get people moving. In an era in which most people live an all-too sedentary lifestyle , that's a big deal.

"What we're trying to get people to do is, get people to be more active," said Allan Goldfarb, a professor of exercise and sport science at the University of North Carolina, Greensboro. "If this is one way that can encourage people, great," Goldfarb said.

But for those at a high fitness level, the games might, in some instances, be counterproductive. "If it's taking away from something that they would have done that's more strenuous, then they're moving in the wrong direction," he said.

Intensity, duration, frequency

To benefit from a cardiovascular activity, you need to get your heart rate up to 70 percent of its maximum, said Richard Lampman, associate professor in the department of physical medicine rehabilitation at the University of Michigan. You also need to perform the activity for at least 30 minutes, three times a week, Lampman said.

"If the games accomplish those three things, you can benefit from them," he said.

Can the games achieve this? The latter two requirements are up to the consumer, and studies on the exercise benefit of the games are lacking. A 2010 study from researchers in England found heart rates of individuals playing Wii aerobics fell below the level needed to maintain cardiovascular fitness. And another 2010 study from researchers in Wisconsin found aerobic and balance Wii Fit games can elevate heart rates of older adults to about 43 percent of their maximum rate.

But, if you pick the right games, you can reach a level of moderate or vigorous activity, said Ernie Medina a preventive care specialist at Beaver Medical Group in Redlands, Calif, and chief executive officer of MedPlay Technologies, a fitness company that incorporates action video games, or exergames, into its fitness program. Examples of these games include Wii Boxing, Running and Cycling, Medina said. Some high-intensity games, such as Sportswall, require a large space and are found in fitness centers rather than sold to consumers.

What you get out of the games also depends on your individual fitness level. For someone who is out of shape, the games are "a great place to start," Medina said. But someone who is already fit will have fewer choices in terms of games that will keep him or her in shape, Medina said. A game such as EA Sports Active 2, which is designed to be like a workout video, would cater to someone at a higher fitness level, he said.

Can they help you lose weight?

Studies in this area are too scant to say whether playing action video games can lead to weight loss . And Goldfarb notes that you still have to take into account the calories in and calories out.

If the Wii is helping people expend calories "that's great," Goldfarb said. But if they're snacking on junk food while they're playing, or in between games, that's counterproductive, he said.

Goldfarb said that action video games would likely be only part of an exercise program , and that other activities, including strength training, could complete the program.

But Medina thinks that exergames can be a person's sole source of exercise, if that's the only activity he or she wants to do. "The heart doesn't care," whether you're playing an exergame or running on a treadmill or outdoors, he said. "Whatever works and whatever gets their heart rate up and whatever gets them moving," he said.

Medina is starting a national exergame league in which teams will compete against each other playing action video games in recreational centers. Children on the teams will keep in shape with exergames and traditional exercise, he said.

Pass it on: Wii games and other action video games can make you fit if they meet specific requirements.

Follow MyHealthNewsDaily staff writer Rachael Rettner on Twitter @RachaelRettner.