Virtual boxing, tennis and dancing along with video game systems may not be helping children meet daily exercise requirements, according to a US study.
Researchers from Baylor College of Medicine in Houston, Texas found that children who were given so-called active video games to play on a Nintendo Wii didn't end up logging any more moderate or vigorous physical activity than those given games they could play sitting on the couch.
Some public health researchers have hoped that active video games might be an alternative to outdoor play and sports for at least some of the physical activity children need, especially for those who live in unsafe neighbourhoods where playing outside isn't always an option.
"We expected that playing the video games would in fact lead to a substantial increase in physical activity in the children," said Tom Baranowski and colleagues at Baylor.
"Frankly, we were shocked by the complete lack of difference."
For the study, they passed out Wii consoles to 78 children who didn't already have one. Half were given their choice of an active game, such as Wii Sports or Dance Dance Revolution-Hottest Party 3, and the other half their choice of inactive game, such as Disney Sing-It Pop Hits or Super Mario Galaxy.
Halfway through the study, which was published in Paediatrics, the children - all 9 to 12-years-old and above average weight - got their choice of a second game from the same category as their first.
Baranowski and his colleagues tracked the children for 13 weeks, testing their physical activity levels with a motion-measuring device called an accelerometer.
Participants wore the devices on a belt during four different week-long periods throughout the study, which allowed the research team to determine when they were sedentary, lightly exercising, or engaged in moderate-to-vigorous exercise.
Accelerometer logs showed that throughout the study period, children with the active games didn't get any more exercise than those given inactive video games.
At weeks one, six, seven and 12, children in the active game group got an average of 25 to 28 minutes of moderate or vigorous physical activity each day, compared to between 26 and 29 minutes for those in the inactive video game group.
There was also no difference in the time spent doing light physical activity or being sedentary during any week the researchers monitored.
Baranowski said his team couldn't tell if children just didn't exert much energy playing the active games, or if they compensated for exercise they got playing Wii with less exercise at other points in the day.
Nintendo was not available for comment and other researchers said that while the games were no substitute for the real thing, they might be better than no exercise at all.
It's possible that children playing active Wii games burned a few extra calories that the movement device didn't pick up on - for instance, if they were moving their arms a lot in a boxing game, said Jacob Barkley, an exercise scientist from Kent State University in Ohio who didn't take part in the study.
"Maybe the Wii isn't going to increase physical activity a whole heck of a lot," Barkley told Reuters Health.
"But it might increase caloric expenditure a bit more than a traditional sedentary video game, and if you do that on a daily basis that could have a cumulative effect that might be beneficial."