If your kids play "active" video games, like Wii Fit Plus or Dance, Dance Revolution, they may not be getting as much physical exercise as you think.

A new study in "Pediatrics" says there is no evidence children playing those games become more active than those who play stationary ones.

Researchers tracked nearly 80 children using a motion-measuring device.

The goal was to see if the games would help them meet their daily exercise requirements.

Researchers say they were stunned by the results.

They expected to see a substantial increase in physical activity.

The team's lead researcher says he could not tell if the kids were playing less energetically or if they became sedentary later in the day to compensate for working out with the games.