I was recently investigating a fancy new stationary bike that came on the market not that long ago. It uses a variation of High-Intensity Interval Training (HIIT). It’s a slick-looking bike, which appeals to my fashionista side. It also includes some interesting machine learning, which appeals to my inner nerd. And it boasts some pretty phenomenal health study results, which appeals to my inner coach. But despite all that, I still find myself scratching my head.
This is where the stumbling block starts for me. The bike’s website claims that the device is "clinically proven to give you the same cardio benefits of a 45-minute jog in under 9 minutes, with only 40 seconds of hard work."
Really? On a stationary bike? Where you aren’t using your arms at all, your skeleton is supported by a seat, and your legs are only moving through a biomechanically repetitive and limited range of motion? I find that claim dubious at best.
Before we get into some of the problems with HIIT, let’s clarify what it is.
What is High-Intensity Interval Training (HIIT)?
HIIT involves alternating brief bouts of high-intensity exercise (30 seconds to five minutes) with shorter rest periods during a single exercise session. For most people, the allure of this type of training is that it promises shorter workouts, which still provide results that are equal to (or greater than) more traditional moderate-intensity training. HIIT is versatile enough to be used in all types of settings. It also packs a punch that can take some extra time to recover from.
Arguably, the most popular form of HIIT is the Tabata method. I wrote about that in an article called How to Use Tabata Training for More Than Just HIIT Workouts. Although the article you’re reading right now may seem like it’s putting HIIT down, I stand by my previous claims. Tabata training, if done correctly (and that’s a big if), is very demanding. The body responds to the stress of this workout by rapidly increasing its capacity to increase oxygen uptake, which is an important measure of fitness.
As I hinted at earlier, you do not need to do HIIT more often than once or twice per week. Doing it more often than two or three times a week can actually be counterproductive. If you are doing these workouts correctly, your body will need time to recover between sessions. The key to making any interval training effective is in the intensity. Which leads me back to the problems with HIIT.
HIIT Problem #1
Cardiovascular fitness based on one particular activity is not the same as cardiovascular health in everyday life.
In biomechanist Katy Bowman’s book, Move Your DNA, she explains that “cardiovascular health comes when the entire circulatory system is used in a variety of ways to deliver oxygen to 100 percent of all cells of the body.” So, with that in mind, let’s think about this bike. A stationary cyclist’s cardiovascular fitness may allow them to pump a lot of blood to their legs for several hours (or just a few minutes on this device.) But at the same time, that cyclist’s body may be providing lower blood supply to other parts of the body that remain still and supported during this short-but-intense exercise session. And that’s a problem.