Is it possible to burn more fat by exercising 20 minutes instead of 40 minutes? The answer is yes, if you do what’s called “high intensity interval training (HIIT).”
HIIT refers to performing maximum or 90% exercise exertion for a few seconds, immediately followed by a rest period of a longer duration. For example, pedaling as fast as you can on a stationary bike for 15 seconds, followed by 45 seconds of light pedaling, and repeating it ten times, for a total of ten minutes. You can apply this principle to many other types of exercises including running, swimming, jumping jacks, plyometrics (jumping), and even weight lifting.
Several studies have confirmed that exercising in shorter bursts with rest periods in between burns more fat than exercising continuously for an entire session. This has been shown to hold true even when the session is not done at an extremely high intensity.
In fact, some leading researchers believe that too much “duration” running, or running at a constant pace for more than 20 minutes can promote fat cell creation. The reasoning is that after 20 minutes of running, metabolism shifts from glucose (blood sugar) burning to body fat burning. But if you do it too often, what it tells the body is that fat is needed for fuel during exercise, so the body takes more dietary fat and stores it in your fat cells.
Dr. Al Sears, M.D. is a leading proponent of shorter, burst type exercise sessions to improve cardiovascular fitness and lung capacity, as well as burning excess body fat. He believes, and the research shows, that following such a regimen can be a strong deterrent to getting a heart attack because this type of exercise increases your heart’s reserve capacity (ability to pump blood) and strengthens your lungs.
One study demonstrated that you can burn more fat exercising for 20 minutes than for 40 minutes!
In the study, women either exercised for 20 minutes, alternating 8 seconds of sprinting on a bike with 12 seconds of exercising lightly, or exercised at a regular pace for 40 minutes. After exercising three times a week for 15 weeks, those who did the 20-minute, alternating routine lost three times as much fat as the other women.
So there you have it, a proven way to exercise less and burn more fat. The other benefit to shorter interval training is that you can still do it even if you don’t have much time in your schedule to exercise. As little as 10 minutes of HIIT a day can have a profound, positive impact on your health. Also, you will incur less microtrauma to your knees by doing shorter high intensity interval training as opposed to running five miles on asphalt three times a week.
A note of caution, however. If you are not well-conditioned, gradually work up to max speed in your interval training. Do not attempt to sprint all out when starting high intensity interval training; the risk of injuring yourself is greater if your muscles, joints, and reflexes are not accustomed to this level of exercise. Seek the help of a personal trainer, and tell him/her that you want to learn HIIT.
This article originally appeared in my previous blog, Weight Loss Mavens.