Want to get healthy? Exercise 7 minutes a week

After two weeks, the young men had a 23 percent improvement in how effectively their body used insulin to clear glucose, or blood sugar, from the blood stream, Timmons said.

The effect appears to last up to 10 days after the last round of exercise, he added in a telephone interview.

"The simple idea is if you are doing tense muscle contractions during sprints or exercise on a bike you really enhance insulin's ability to clear glucose out of the bloodstream," Timmons said.

The findings highlight a way for people who do not have time to work out a few hours each week as recommended to improve their health, he added.

His team did not look for other important benefits to health that come from exercise, such as lowered blood pressure or weight control, but said another study had shown similar benefits to heart function.

But Timmons said getting people to exercise even a little could translate into big savings for health systems that spend hundreds of million of dollars treating diabetes.

(Reporting by Michael Kahn; Editing by Maggie Fox)