TheCardioClub.Net

This article appeared in the New York Times and is shared here for your use and enjoyment.

SOME gymgoers are tortoises. They prefer to take their sweet time, leisurely pedaling or ambling along on a treadmill. Others are hares, impatiently racing through miles at high intensity. 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. Eight volunteers in a control group, who did not do any interval training, showed no improvement in endurance. Researchers at McMaster University in Hamilton, Ontario, had the exercisers sprint for 30 seconds, then either stop or pedal gently for four minutes.

Over two weeks, they completed seven interval workouts.  After interval training, the amount of fat burned in an hour of continuous moderate cycling increased by 36 percent, said Jason L. Talanian, the lead author of the study and an exercise scientist at the University of Guelph in Ontario. Cardiovascular fitness — the ability of the heart and lungs to supply oxygen to working muscles — improved by 13 percent.

It didn’t matter how fit the subjects were before. Borderline sedentary subjects and the college athletes had similar increases in fitness and fat burning. “Even when interval training was added on top of other exercise they were doing, they still saw a significant improvement,” Mr. Talanian said.