How 30-second bursts of exercise can do more good than 30 minutes

SHORT bursts of exercise may be better than long drawn-out PE classes in combating childhood obesity, new research suggests.

A study of Scottish schoolchildren found that those who did 30-second sprints interspersed with breaks for just a few minutes produced better results than youngsters exercising more moderately for 30 minutes.

Experts believe this approach could be used in schools to improve the fitness of pupils, with the time saved spent teaching them about health and nutrition. Professor Julien Baker and Duncan Buchan, from the University of the West of Scotland, conducted tests with teenagers at Holy Cross High School in Hamilton.

The pupils were split into three groups of 25. One group carried out high intensity activity, exercising three times a week for four minutes, with 30 seconds of sprinting followed by 30 seconds of rest.

The next group carried out moderate activity, exercising three times a week for 30 minutes. The last control group just did their usual PE lessons.

At the start and end of the eight-week study, the researchers measured body fat, blood pressure, activity and agility as well as testing blood for signs of good cardiovascular health.

Prof Baker said the short bursts of exercise appeared more effective at improving health. "The high intensity exercise group exercised for about 80 per cent less time," he said. "But this group improved more than the moderate intensity group.

"There was significantly reduced blood pressure in the high intensity group than the other groups. The blood profiles were better and body fat went down in this group, too."

Prof Baker said that, using this approach, schools could change the curriculum with the extra time available used to teach about nutrition and the benefits of exercise. But he said that moderate exercise over longer periods did also benefit the body, so a mix of the two types of activity might be the best way forward.

"It may be that we work some days high intensity and some days more moderately, or work at a higher intensity for longer, which means that instead of working for four minutes you do ten."

Prof Baker said adults doing exercise should probably follow the same mix of high and moderate intensity activity.

But he warned that people over 40 suffered more stress on their body if working at a high intensity so needed to get a medical check before they did that.

Tam Fry, from the Child Growth Foundation, welcomed the findings and said research had suggested that it was necessary to "huff and puff" to get the best out of exercise.

"The kind of moderate exercise which I think is traditionally followed in PE in schools is more leisurely," he said."High intensity activity really does push the heart and muscles."