How intense is intense? #exercise

In previous posts, I have extolled the virtues of High Intensity Exercise, and in particular High Intensity Intermittent Exercise (HIIE) or High Intensity Interval Training (HIIT). The general concept is that you alternate short bursts (e.g. 30 seconds) of intense exercise with a short rest period (e.g. 15 seconds) over the course of 10 to 30 minutes. The attraction is that you can get a good workout in a limited amount of time; the disadvantage is that the workout is very intense ("the intensity hovers at about an 8 on a discomfort scale of 1 to 10"). As a result, "even a few minutes of training at an intensity approaching your maximum capacity produces molecular changes within muscles comparable to those of several hours of running or bike riding."

I perhaps underestimated the intensity of this type of workout until the other day at the local gym I observed an instructor leading some students through a version of the 7-minute (really 8-minute) workout. The students were simply exhausted barely making it through each exercise. At the end they were totally spent, sprawled on the ground like fish in a pond that had dried up.

This raises the question "How intense is intense?"

On the Peak Fitness website, the author Dr. Mercola recommends

"Exercise as hard and fast as you can for 30 seconds. You should be gasping for breath and feel like you couldn't possibly go on another few seconds."

Basically you are going all out for each exercise for the 30 seconds. On a discomfort scale from 1 to 10 that sounds more like a 10, not an 8.

The number of repetitions for each exercise (e.g. how many pushups) depends on the person and how good shape you are in. However, the idea is to push yourself to do as many as you can, and over time the number should increase.

The moral of the story is that there is no free lunch. If you want to benefit from a high intensity exercise regimen then you have to engage in high intensity exercise. The tradeoff is that the exertion (i.e. suffering) is for a briefer period of time (8 min) compared to more moderate exercise (e.g. jogging) for a longer period of time (30 min) to obtain roughly equivalent health benefit.

Caution: Do not over exert; make sure you warm up beforehand and cool down afterwards. Dr. Mercola recommends a 3 minute warm up period at the beginning and a few minute cool down at the end.

Figure 1. After a high intensity exercise session you should be pretty exhausted.