People who say they don't have time to exercise may be out of excuses: A new study finds that just 1 minute of sprinting, along with 9 minutes of light exercise, leads to similar improvements in health and fitness as a 50-minute workout at a moderate pace.

The findings suggest the benefits of so-called sprint interval training, in which people go "all out" for a short period, then recover at a slow pace for a longer period and then repeat the cycle. Such exercise may be an option for people who want to boost their fitness, but don't have a whole lot of time to commit to regular exercise, the study suggests.

"Most people cite 'lack of time' as the main reason for not being active", study co-author Martin Gibala, a professor of kinesiology at McMaster University in Ontario, said in a statement. "Our study shows that an interval-based approach can be more efficient — you can get health and fitness benefits comparable to the traditional approach, in less time."

In the study, 25 men who previously did no exercise were randomly assigned to either a sprint interval workout or an endurance workout. They performed the exercise three times a week for 12 weeks on a stationary bicycle. A smaller group of men did no exercise at all for the 12 weeks, to serve as a control.

The sprint workout consisted of warming up for 2 minutes, sprinting all-out for 20 seconds, recovering at a slow pace for 2 minutes, sprinting for 20 seconds, recovering again for 2 minutes, sprinting for a last 20 seconds and cooling down for 3 minutes. The endurance workout consisted of warming up for 2 minutes, riding at a moderate pace for 45 minutes and cooling down for 3 minutes. [9 Healthy Habits You Can Do in 1 Minute (Or Less)]

After the 12-week program, the two training groups showed similar improvements in aerobic fitness. Specifically, both groups had a 19 percent improvement on a test called VO2 peak, which measures the peak amount of oxygen consumed by the body per 30 seconds of exercise.

The two groups also had similar improvements in a test of insulin sensitivity, which measures how well the body responds to insulin, a hormone that regulates blood sugar. Finally, a biopsy of participants' muscle tissue revealed similar improvements in markers of muscle function in the two groups.

The new findings, which were published yesterday (April 26) in the journal PLOS ONE, agree with previous studies that have looked at the health effects of interval training. But the new study tested an even shorter interval training period — just 10 minutes, compared to a previous study that tested the effects of a 25-minute interval workout.

The researchers note, however, that even though interval training workouts are shorter, the type of interval training tested in the current study is very intense. It "requires a very high level of motivation and is clearly not suited for everyone," the researchers said.

It's important, too, to note that the researchers did not look at long-term benefits of interval training, only at short-term fitness improvements.

Future studies should look at whether internal training that doesn't involve such an "all out" effort would still lead to improvements like those seen in the new study, the researchers said.

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