If you don’t have the time to spend hours working out at the gym, you may want to consider intense interval training. New studies suggest you may be able to get fit in as little as 6 minutes per week if you exercise at the right intensity.

That’s the surprising conclusion by a growing number of sports scientists. New research suggests much shorter, more intense exercise could provide the same benefit as longer, less strenuous workouts.

The effectiveness of interval training has been known for years. Athletes have been incorporating one or two interval sessions a week into their regular exercise routine. What’s new is that many researchers now believe you only need a few minutes of strenuous exercise per week to do the job.

One of the leading proponents of shorter, more intense workouts is Dr. Martin Gibala at McMaster University in Ontario, Canada. In one recent study, Gibala had one group of healthy but not athletic college students ride a stationary bike at a moderate level for between 90 and 120 minutes. A second group of students completed a series of short, very intense intervals by cycling for 20 to 30 seconds for as hard as they could. These students would then rest for 20 to 30 seconds and repeat the cycle four to six times.

Each group exercised three times a week, but while the first group spent up to two hours on the bike, the second group only spent 2 to 3 minutes pedaling. After two weeks, researchers found that both groups had achieved nearly identical increases in their endurance. Researchers also found both groups exhibited molecular changes in mitochondria that signal increased fitness.

Another benefit of the intense interval sessions studied by Gibala was weight loss. High-intensity exercise increases energy expenditure well into the recovery phase. Other scientists have found interval training also improves cardiac health, even for those with heart disease.

To get these results, however, researchers say you have to go all out during training. It’s going to hurt and you’ll be out of your comfort zone. You also need to be in relatively good shape before starting a program like this as it can take a toll on your body.

One established interval method to try is called Tabata, developed by a Japanese scientist who did research in the field. You can check out this New York Times article for more information on intensity training.