Monday, July 23, 2007

Turn Your Fat Burning Mechanism into High Gear with Interval Training

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I’ve recently experimented with High Intensity Interval Training (HIIT) and have received amazing results. HIIT is, undisputedly, the single most effective factor involved in breaking weight loss plateaus and burning fat. HIIT consists of short bursts of exercise at high intensity levels – near or around your maximum heart rate. This is also referred to as anaerobic exercise and includes exercises such as sprinting. Aerobic training, on the other hand, consists of endurance type exercises at lower intensity levels like jogging, power walking etc.

For the last couple of decades and longer, it was believed that fat burning was best achieved by endurance training - exercise at longer durations (cardio training). The argument was that (according to research) the body begins to burn fat beyond the 20 minute mark of continuous aerobic exercise. Although this still holds true, many recent studies have shown that training at very high intensities burns higher amounts of calories and fat.

HIIT may be responsible for burning up to 50% more body fat than lower intensity exercise. It has been documented that exercising at 65% of maximum heart rate (cardio-endurance) burns more calories from fat than from carbohydrates. HIIT, however will burn more total calories which will amount to more TOTAL fat burned even though it’s at a lower percentage.

When exercising at lower intensities for longer periods (duration), your body goes into a “steady state”. In this state, the body has adjusted to the speed and intensity and attempts to conserve energy (calories). This is one factor that may be responsible for reaching weight loss plateaus when performing cardio exercise. This could be avoided if you added HIIT to your workouts.

While doing steady – rate cardio for longer periods the body burns fat for fuel but also goes into a catabolic state. This means that the body begins to break down muscle to use as fuel. So, as it burns fat it also uses up muscle. And as we know, muscle increases the metabolic rate – and as muscle mass decreases so does the metabolism. Short bouts of training associated with interval training, however, have been shown to prevent the body from entering the catabolic phase.

In fact, interval training increases the body’s resting metabolic rate causing the body to burn more calories well after the exercise session – up to 48 hours after training.

Benefits of High Intensity Interval Training:

- Increases metabolism

- Increases calorie and fat burning capacity

- Helps to overcome weight loss plateaus

- Improves aerobic capacity – increasing the ability to train longer with higher intensity

- Keeps you from getting bored with exercise – By mixing in exercise at higher intensity for shorter durations you’re adding more variety to your workout.

- Special equipment is not required – all you need to do is modify your current training method.

- Improves your body composition.

- Improves eating and sleeping habits as the body adjusts to meet the new demands of exercise.

- The short power bursts of HIIT may often boost your energy level causing you to feel more upbeat and energetic.

- Increases athletic performance for athletes.

- Improves excess post - exercise oxygen consumption (EPOC) – oxygen intake is increased for a certain period, following high intensity exercise, which has shown to increase fat burning by up to 9 times during periods of rest.

Are there any risks involved with HIIT?

HIIT is not for everyone. If you have a chronic health condition or not accustomed to regular exercise, you should consult your doctor before trying any type of high intensity exercise.

The other thing is you should start slow. Don’t rush into high intensity training before your body is ready. You may run the risk of hurting yourself, which may include bone, tendon-ligament and muscle damage.

Keep in mind that HIIT workouts need more recovery time than aerobic workouts. They should be performed no more than 3 times a week and should be on non weight-training days.

Here is an HIIT program for beginners:

Total Workout: 12 Minutes in Duration

Warm – Up -First 4 Minutes:

Jog at around 50% effort

1st Interval -5th Minute:

Sprint at maximum effort for 30 seconds – follow with jogging/walking for 30 seconds

2nd Interval – 6th Minute:

Sprint at maximum effort for 30 seconds – follow with jogging/walking for 30 seconds

3rd Interval - 7th Minute:

Sprint at maximum effort for 30 seconds – follow with jogging/walking for 30 seconds

4th Interval - 8th Minute:

Sprint at maximum effort for 30 seconds – follow with jogging/walking for 30 seconds

Cool Down – Minutes 9-12:

Jog at 50% effort


You can gradually increase the number of intervals in the workout as your body adapts to high intensity and frequency. A good pace would be to add an interval after every 2-3 workouts, until you reach 10 intervals per workout session.

HIIT workouts can also be performed on machines such as steppers, elliptical trainers and stationary cycles. Research suggests, however, that the closer one gets to their maximum oxygen uptake (VO2 max) during training, the more efficiently they burn fat. And sprinting is the most efficient form of exercise for optimizing VO2 max.

I hope not too many of you, who are trying to lose weight (and not very excited about the exercise part), hate me too much for this article.


1. - University of Guelph, “Interval Training Burns More Fat, Increases Fitness, Study Finds”

2. Tremblay, A., Simoneau, J-A., Bouchard, C., “Impact of Exercise Intensity on Body Fatness and Skeletal Muscle Metabolism, Vol. 43 #7 (July), 1994: pp 814-818.






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