High Intensity Interval Training: A Better Way to Exercise?

By Michael Lasalandra
BIDMC Correspondent

It is one of the hottest methods of getting fit these days. High Intensity Interval Training (HIIT) involves alternating short bursts of anaerobic exercise with recovery periods of less intense activity.
Supporters of the exercise regime say it is more effective and less time consuming than normal aerobic exercise regimens like jogging, for example.
“It involves a hard, focused workout for short bursts of time, involving activities that require near maximum effort,” says Dr. Joseph DeAngelis, orthopedic surgeon and Director of Sports Medicine Research in the Division of Sports Medicine and Shoulder Surgery at Beth Israel Deaconess Medical Center.
“You sprint, then walk. HIIT has been shown to be an effective way to burn calories in contrast to slower, stamina and endurance exercises that we’ve done for years. These are fundamentally different ways of thinking about aerobic and anaerobic activity,” says DeAngelis, who participates in HIIT training himself.
“Historically, we have not wanted our heart rate to be at, or near, the max. We just wanted to keep it elevated for long periods, to just keep moving,” he says.
With HIIT, the idea is to go all out for a burst of time, ranging from 3 to 10 minutes, followed by a period of rest. It is much like a program on an exercise bike where you go all out while climbing a hill, then peddle at a more comfortable pace until the next hill. “Going all out” means you can’t carry on a conversation while running or bicycling or whatever you are doing because you are just too winded.
When compared to people participating in a normal exercise routine, like jogging, research has shown those doing interval training can double their endurance, improve their oxygen utilization and strength by more than 10 percent and their speed by at least five percent. Even studies in the elderly and in cardiac patients found they had more efficient oxygen use and greater fitness after doing interval training.
How to balance the intense periods of activity with the periods of rest is a matter of debate, according to DeAngelis. Some people say the intense exercise should cover 90 percent of your exercise time, with 10 percent rest time. Others say it should be half and half. Still others say the intense exercise should only cover 10 percent of the workout period, with 90 percent of the time devoted to rest or maintaining a normal heart rate.
“There’s not a lot of science to the matter of the ratios,” he says.
DeAngelis says the concept is similar to the way basketball players train and play during games. They run up and down the court at maximum effort for several minutes, with rest periods in between, during TV timeouts or other breaks in the action.
Officials recommend that people get about two and a half hours of moderate exercise per week, but these guidelines target a mostly sedentary population and are intended to help with weight control and heart health, not boosting strength, endurance or overall fitness levels. With intensity training, people might be able to get better results in half the time.
DeAngelis says most people respond well to interval training because of its compactness and its results, especially when combined with a healthy diet. The workouts can also be varied, with running, bicycling, weight lifting, calisthenics, yoga and any number of other calorie-burning activities involved.
The time involved is shorter than conventional exercise. For example, if you were to walk a mile it might take you 15 minutes. To walk at a very brisk pace might allow you to finish the mile in 10 minutes. But to run the mile might only take six minutes. “The distance is the same but how you expend the energy is different,” he says. “It all depends on the intensity.”
How hard you work will depend on what you are looking to get out of the program, he says.
“It all depends on your goals,” DeAngelis says. “Some use it to lose weight, some to gain muscle. There are different forms of becoming fit. Some want better cardiovascular health. It depends on who you are talking to. A young, fit person who is looking to become more muscular has a different goal than someone who is trying to lose a few pounds and stay heart healthy. You need to know why you are doing this.”
However, he warns that intense interval training is only safe for those who are in good shape to start with.
“This is not the first thing you want to do to start to get in shape,” he says. “You have to ease into it and should start by talking to your doctor.”
Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.