In my recent article Intervals Don’t Work I discussed the scientific evidence surrounding the use intervals for fat loss.  By why, if science says intervals aren’t that much better than endurance exercise, does everyone report such great success with intervals?

In my mind, there are a few possible reasons for this:

1.  Actually Doing Cardio

Before interval training became en vogue, many people weren’t doing much (if any) cardio.  Whether it was due to fear of cardio burning off hard earned muscle (which it doesn’t), boredom from endurance style cardio, or lack of the “cool factor” associated with intervals people just weren’t getting it done.  The additional calories from doing something instead of nothing could easily account for the “success” of intervals for those that were previously doing nothing for conditioning.

2.  Working Intensely

Many who were actually doing cardio before considered walking on a treadmill sufficient to burn calories.  Of course, exercising at this intensity is hardly different than sitting on the couch watching Gilligan’s Island reruns so it should come as no great surprise that doing high intensity interval work brings about greater results.  Had they done higher intensity steady state work the result would likely have been similar.

3.  Efficiency

Those that were doing cardio before and doing it with success (i.e., busting ass and burning kcals) realized that it takes time and hard work to lose extra fat via cardiovascular exercise.  Intervals (even if not technically better in terms of fat loss) were a welcome addition since they made achieving the same results possible with less of a time commitment.  So not better, but faster.

4.  Appetite Supression

While everyone knows that it is quite possible to burn off the same number of calories from endurance or interval training, intervals have the added bonus of appetite supression.  This could lead to less eating for those who are doing intervals and not consciously dieting.  It could also result in greater ease in sticking to a nutrition plan for those who need a more formal eating plan.  Personally, I lean slightly toward this as the most likely player for the relative success of intervals because the calorie deficit from any exercise is fairly dismal compared to the calorie deficit that can be achieved with food.

What do you think?

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