Sprint training for 60 minutes a week burns the same amount of body fat in men as jogging for seven hours a week, a Sydney study has found.

More than 40 overweight males took part in a short, high-intensity training regimen based on cycle sprints over 12 weeks and measured a significant drop in their abdominal fat and an increase in muscle mass. Lead researcher Steve Boutcher said the training program provided the ideal amount of exercise intensity for health benefits, including weight loss, in a short time frame.

''We've been searching for about 10 years for the minimum amount of exercise you can do with the biggest health impact factor,'' said Professor Boutcher, a exercise physiologist and associate professor at the University of NSW.

By exercising three time a week, those taking part, mostly university students in their mid-20s, lost an average two kilograms of fat and gained 1.1 kilograms of muscle mass, mainly in their trunk and legs.

Other studies have shown men would need to jog for between five and seven hours a week for more than three months to lose the same amount of fat.

Participants sprinted on an exercise bike for eight seconds, and raised their heart rate to between 80 and 90 per cent of its maximum rate, followed by 12 seconds of slow peddling.

''In three 20-minute sessions a week, they're only working hard for eight minutes,'' he said.

Those taking part lost mainly visceral fat, adipose tissue which surrounds internal organs and is linked to cardiovascular disease risk, and reduced their waist circumference.

Previous studies revealed similar results for women, he said.

A control group, who did no exercise, lost no weight during the study. Both groups were asked to consume their regular diets.

Fast sprinting caused the body to release high levels of a specific group of hormones, catecholamines, which drive the release of fat, especially abdominal and visceral fat, from fat stores so it can be burned by working muscles. ''We don't know why, but moving limbs very fast generates high levels of catecholamine,'' the professor, whose findings are published in the Journal of Obesity, said.

Sprinting for eight seconds raised the heart rate while keeping lactic acid release which make muscles tire more quickly to a minimum, he said.

The study, funded by Diabetes Australia, only measured the effect of sprints on an exercise bike. Other activities such as fast running, rowing and stair climbing could also raise the heart rate to a high level for the body to release catecholamines.