Interval Vs. Endurance Training

A new study suggests that doing intense interval training for 20 minutes three times a week is just as effective at boosting strength and endurance as five to six hours of jogging or moderate cycling.

It's a technique that's been used for years by sports teams and athletes. But is it useful to an average overweight person? Probably not. It doesn't burn many calories.

And it requires so much suffering that you're almost destined to quit, one expert said.

The study, published this month in the Journal of Applied Physiology, was done by researchers at McMaster University in Hamilton, Ontario.

It looked at 16 college students who exercised regularly, but are not competitive athletes, said Martin Gibala, associate professor of kinesiology. Half of the volunteers did two-week sprint interval training, cycling in 30-second bursts going "all out" in four to seven sessions. Each burst of cycling was followed by four minutes of rest. The workout was done three times a week for two weeks.

The other half of the test group did no specific training, but continued their normal activities, including basketball, jogging or aerobics, depending on the individual.

Endurance capacity in the sprint group nearly doubled from an average of 26 minutes to 51 minutes. They also showed a significant increase in the enzyme citrate synthase in their leg muscles, indicating an increased ability to use oxygen, Gibala said.

The control group that did no interval training showed no change.

"From a muscle perspective, when you do long, slow endurance training, you are only recruiting part of your muscle fibers to do the work," Gibala said. "In high intensity exercise, you call upon all of your muscle fibers. They respond and adapt."

Gibala, who has worked with the NHL's Buffalo Sabres, says more research has to be done to determine what effects interval training can have on boosting heart, lung and blood flow capacity.

"We don't know all the other adaptations" someone's body makes after interval training, Gibala said. "Does heart size change? Is there more blood going to the muscles? Do your vessels become more elastic? Those studies have to be done."

An idea that's been around for about 80 years, interval training has been a mainstay of competitive athletes like cyclists and middle distance runners, said Ed Coyle, a professor of kinesiology at the University of Texas who has helped six-time Tour de France champion Lance Armstrong and the NBA's San Antonio Spurs.

Such training, he said, is not without its drawbacks.

"It involves a lot of suffering and requires high motivation," said Coyle, a former runner at Queens College in New York. "Unless it's done with a coach or teammates to ensure motivation and positive feedback it's hard to not quit. It's almost impossible not to quit."

He said it's not the best type of exercise for general health and fitness because it doesn't burn as many calories as exercise done over longer periods of time.