There are numerous benefits of HIIT. Such as increased fat burning, shorter workouts, aerobic benefit, etc. I even did a blog post on that last benefit. The list can be long of potential benefits. Like any type of exercise over the years, things come and go. So has HIIT hit the wall so to speak in terms of the evolution of training?
A study was done by the University of British Columbia shows that in fact doing too much HIIT can have negative consequences on your health. The results of the studywere published in the Official Journal of the Federation of American Studies for Experimental Biology.
12 untrained or decently active men with ages in their 20’s, performed upper body and lower body, arm and leg exercises, for 30seconds at an intense level and then rested for four minutes. The men would perform 4-6 total sets of this workout for seven days out of a fifteen day period.
After the exercises their muscle tissue displayed oxidative stress. The mitochondria (the powerhouse of the cells) of the cells was weakened and damaged. That damage was up to 45%, which is pretty significant. That could lead over time to disease through the creation of free radicals which can be created as a byproduct of exercise. This could be more rapid aging, or even cancer.
This does not mean that you have to now drop HIIT from your training or from adding in into your training arsenal. If you already are in shape and regularly exercise intensely your body could contain more enzymes that actually can help your body fight off and remove the free radicals from your body.
I think the take home message needs to be that HIIT does have a place in your training and can be a valuable piece of the fitness puzzle. Just like LSD running, long steady or slow distance running all the time is not good for you, or only strength training, HIIT can be incorporated into a program where not all your eggs will be in one basket. I think the key should be moderation of all the above as well as being sure to have a solid base of fitness.
At the very least this should at least cause you to analyze your own training routine and be sure to have a healthy balance.