High Intensity Interval Training: Why is it So Effective?

High Intensity Interval Training: Why is it So Effective?
by Aaron Ivey ATC, CSCS

The comparisons between high intensity short duration exercise (HIT) and low to moderate intensity long duration exercise (LSD) continue to spark conversation and controversy. While there is no doubt that research suggests long, slow endurance type training does have some benefits, can high intensity training be more effective for the average person?

This article is meant to outline why high intensity interval training workouts are the effective alternative to long, slow exercise. I will outline 6 reasons why interval training is so effective for fat loss, increased cardiovascular conditioning and general health.

1.    Muscle changes: As the intensity of a particular activity increases, more muscle fibers are needed to perform the activity. The highly intense nature of HIT elicits rapid changes in muscle chemistry to be able to tolerate such an increase in recruitment.
2.    Increase fat utilization: HIT contractions stimulate nerve pathways that increase the amount of energy producing structures (mitochondria) in muscle fibers. These are the structures responsible for burning fat.
3.    Time efficient: Some studies have used training protocols as short as 4 minutes of total workout time and produced similar, if not better, results than LSD training. The average HIT workout usually lasts about 20 minutes. That is 40 minutes less than the recommended time to complete an LSD workout. I do not about you but I would rather be finished in 1/3 of the time and get even better results.
4.    After burners: HIT has been shown to increase metabolism for hours after the workout ended. LSD effects usually stop after you are done with your workout. Though it is difficult to get an exact number, some research suggests that even more calories are burned in the hours after a workout than were burned during the workout.
5.    Range of populations: HIT can be performed by a range of populations from the elite athlete to someone recovering from coronary artery disease. Research is now showing effective results for cardiac rehabilitation by using HIT. Granted the intensity is not going to be the same for the cardiac patient and the elite athlete, but the principle remains. Even the out of shape, obese person is more likely to tolerate 30 seconds of high intensity than 60 minutes of running on a treadmill.
6.    Long-term adherence: Because HIT workouts can be done quickly and show results within as little as 2 weeks, those that use HIT are more likely to continue a training program than those who start an LSD training program. Not to mention, there are more exercise possibilities to reduce boredom with HIT program.

HIT has been shown consistently to effectively reduce fat, get in shape, and make necessary changes within the muscles to allow for greater well being. HIT can be used by nearly everyone in one form or another and provides enough variety to prevent boredom and increase the likelihood of long term adherence.

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