"If you watch late-night television, or look in the backs of magazines, you'll see magical ads saying you need just 10 minutes a day or five minutes a day of exercise to stay fit. And for those of us in the medical field, we just rolled our eyes at that.
But surprisingly, they may actually be right and that's what this research shows," says co-principal investigator Richard Lewanczuk, a researcher with the Faculty of Medicine & Dentistry at the U of A.
"Our research showed children don't need a lot of intense physical activity to get the health benefits of exercise -- seven minutes or more of vigorous physical activity was all that was required. But the seven minutes had to be intense to prevent weight gain, obesity and its adverse health consequences. And most kids weren't getting that."
Lewanczuk worked on this study with Jonathan McGavock, his co-principal investigator, and former post-doctoral fellow, who now works with the Manitoba Institute of Child Health.
They collaborated with Black Gold Regional Schools in Leduc and surrounding communities just south of Edmonton, as well as researchers from the University of Manitoba, Queen's University, the University of Newcastle, and U of A researchers from the Faculty of Medicine & Dentistry, the School of Public Health, Physical Education and Recreation, and Agricultural, Life and Environmental Sciences.
The team's findings were recently published in the peer-reviewed journal Archives of Pediatrics & Adolescent Medicine.
More than 600 children, between the ages of nine to 17 from Leduc and surrounding areas, wore monitors that tracked their physical activity levels for seven days. These children also had their weight, waist circumference and blood pressure regularly monitored.
Researchers reviewed the data collected through the Healthy Hearts program via Black Gold Regional Schools and determined the children spent almost 70 per cent of their time doing sedentary activities; nearly 23 per cent was devoted to light physical activity; almost seven per cent to moderate physical activity and 0.6 per cent to vigorous physical activity.
Overall, boys were less sedentary than girls. And the more vigorous the physical activity, the less apt the children were to be overweight.
Children who were overweight had improved fitness levels and shrinking waist lines when they increased the amount of time spent doing vigorous activities.
Lewanczuk said the team made some other notable findings including the following: there weren't the expected health benefits from doing only mild or moderate activity even if the time spent doing this type of activity increased.
What seemed to be critical was taking part in intense physical activity. For kids who took part in vigorous physical activity that lasted longer than seven minutes, their health benefits were significantly better. And the whole notion of being overweight but fit? The team's data didn't support that finding in children. If children were overweight, they were also unhealthy, Lewanczuk says.