Each approach offers similar health benefits: lower risk of heart disease, protection against Type 2 diabetes, and weight loss.

But new findings suggest that for at least one workout a week it pays to be both tortoise and hare — alternating short bursts of high-intensity exercise with easy-does-it recovery.

Weight watchers, prediabetics and those who simply want to increase their fitness all stand to gain.

This alternating fast-slow technique, called interval training, is hardly new. For decades, serious athletes have used it to improve performance.

But new evidence suggests that a workout with steep peaks and valleys can dramatically improve cardiovascular fitness and raise the body’s potential to burn fat.

Best of all, the benefits become evident in a matter of weeks.

“There’s definitely renewed interest in interval training,” said Ed Coyle, the director of the human performance laboratory at the University of Texas at Austin.

A 2005 study published in the Journal of Applied Physiology found that after just two weeks of interval training, six of the eight college-age men and women doubled their endurance, or the amount of time they could ride a bicycle at moderate intensity before exhaustion.