We all like the idea of getting more bang for our buck, so it would be great if you can burn calories while you exercise but also get extra calorie burning after you finish your session.
As it turns out, you can, and there are more benefits to higher intensity exercise than you might think. The name for this concept is excess post-exercise oxygen consumption – EPOC for short.
Higher intensity exercise also gives an unexpected fat burning benefit that becomes apparent when you do the math.
For years exercisers have been told that the best way to lose weight was to do moderate, long duration workouts keeping the heart rate at 60 per cent (the low end) of the training range.
On most cardiovascular machines today, such as treadmills, bikes and elliptical trainers, you still see heart-rate charts containing this ‘fat-burning zone’ posted on the console. But this is not entirely correct.
It is true that when you keep the pace of your exercise session slow and steady you burn a greater percentage of your calories from fat than when you boost your speed. However, herein lays the rub: your total calorie burn is lower at lower intensities.
Say you walk for 30 minutes and burn a total of 180 calories, you will burn about 135 (75 per cent) of them from fat.
This doesn’t compare to running at a fast clip for 30 minutes and burning a total of 360 calories, because you will burn 180 (50 per cent) of them from fat.
Of course, these percentages will change depending on how hard you exercise. What’s more, research shows low-intensity exercise does not stimulate you metabolism much for the desired delayed calorie after-burn, EPOC. Your metabolism returns to normal within minutes after doing a mild to moderate exercise session.
However, a high intensity session can promote an increase of the number of calories you burn per hour for a period of up to 48 hours. And it’s not just calorie after-burn that occurs with more intense exercise. You also get a beneficial change in hormone regulation that favours healthy weight maintenance, and you start to store greater amounts of carbohydrate in the muscle (called muscle glycogen).
This means that you will start to feel like you have more energy for normal daily activities because you have a ready supply of fuel stored right in the muscle ready to be burned at any given moment.
In one review of the literature, Swain and Franklin (American Journal of Cardiology in 2006) state that there are greater protective benefits to your cardiovascular system from participating in higher intensity aerobic exercise compared to moderate intensity aerobic exercise.
So how do you get this greater calorie burn and increased health benefits? Just increasing your exercising heart rate to the upper range of your training zone (70 to 85 per cent of your maximum heart rate) will do it. This can be done with something called interval training, where short periods of anywhere from 30 seconds to three or four minutes of high intensity are interspersed with similar durations of medium paced recovery exercise.
Sprinting for one minute, followed by a medium paced jog for one minute can be repeated for at least 20-30 minutes or more. The recent craze of exercise boot-camps are another example of this, and weight training can also have this effect if it is done at the appropriate intensity.
That’s not to say that long, easy workouts don’t have a place in a routine. Any calories you burn can help with weight control.
Kerry Senchyna holds a bachelor of science degree in kinesiology. For more, visit www.westcoastkinesiology.com.