High Intensity Interval Training

I prefer to do HIIT (High Intensity Interval Training) for my “cardio” exercise.  ["Cardio" is a poor choice of terms because it implies that weight lifting doesn't work the heart, but that's another story for another day.]  HIIT has been studied and shown to be a more efficient style of “cardio” exercise than Low Intensity Steady State (LISS).  Obviously there are many different “cardio” styles, some of which may be more efficient than LISS, but the benefit of HIIT resides in its short time requirement and long-lasting effects on metabolism. 

 Researchers (see citation at bottom of post) enrolled 17 subjects in a 20-week program.  The subjects were first assigned to a 5-week conditioning phase on a recumbent cycle, after which one group was assigned to do sprints on the cycle (HIIT) while the other group continued with a more traditional low-intensity endurance regimen.  The HIIT group exercised for 30 minutes at a time, while the endurance group started at 30 minutes and increased to 45 minutes. 

Despite not utilizing as much energy during the actual workouts, the HIIT group lost significantly more body fat (3 times as much) as measured by skinfold measurements.  Thus, HIIT gives you more “bang for your buck” – shorter workouts, but more fat loss.  This finding suggests that HIIT rev’s up one’s metabolism for longer periods than a typical endurance workout. 

My HIIT regimen is on the elliptical and can certainly be carried over to any exercise, e.g. walking, running, stair-climbing, treadmill, bicycling.  Here’s a brief overview of my strategy:

3-4 minutes warmup 50% effort

[1 minute 90% effort]

[1 minute 50% effort]

{Repeat above 2}

2 minutes cooldown 40-50% effort

 It’s a tough workout.  You certainly need to build up a certain level of fitness before you can make it through a 20 minute HIIT workout, but it is definitely worthwhile.  I recommend some good motivational music to help keep you “pumped” through the workout.

I especially like being able to fit in a shorter workout into my crazy day without feeling guilty about not doing a 45-60 minute endurance workout.  I will still incorporate those workouts once in a while as well to keep my body guessing, but most days I can’t wake up early enough to spend an hour on the elliptical. 

 See this Wikipedia article on HIIT for more information and some other references if you are interested in reading more about it.

Trembblay A, Simoneau JA, Bouchard C. (1994). Impact of Exercise Intensity on Body Fatness and Skeletal Muscle Metablism, Metabolism. 43(7): 814-818.