BOB ZUNINO ¦¦ Personal Trainer

We’ve all heard the claim that the best type of cardiovascular training for burning fat is lower-intensity exercise, which keeps the exerciser in the so-called “fat-burning zone.”  Thompson and colleagues (1998) have confirmed that at lower intensities (50% VO₂max), a greater percentage of energy comes from fat than at higher intensities (70% VO₂max).  However, as long as workouts are the same length, the total energy expenditure will be greater, and a person will almost always burn at least as many fat calories (if not more), at a higher training intensity than at a lower training intensity.  In other words, the selective use of fat as fuel that occurs in low-intensity exercise does not translate into greater fat loss.  For weight loss plans, fitness professionals should focus on the exercise regime that yields the greater total volume of calories expended.

To further substantiate this association, I conducted a simple experiment.  A 191-pound physically fit male student performed 30 minutes of treadmill exercise under two conditions: (1) at 55% of his heart rate maximum (HRmax) and (2) at 85% of his HRmax.  The results of this experiment were as follows:

At the higher intensity, the subject burned more total calories, more fat calories and more carbohydrate calories.  But not everyone can exercise the way this very fit student can.  For people who are sedentary or at orthopedic, cardiac or health risk, high-intensity exercise may be contraindicated.  For their weight loss exercise plans, low- to moderate-intensity exercise should be performed for progressively longer durations.  In fact, since most people can’t do high-intensity exercise on a daily basis, owing to potential overtraining and overuse concerns, perhaps the best strategy is to integrate and balance the low- to moderate-intensity, long-duration workouts with high-intensity workouts for optimal fat-calorie burning.