Are HIIT Workouts Wearing You Out? Rethinking The Popular But Often Exhausting Workout Strategy

(First article in a three-part series)

Fitness is booming like never before, but the industry continues to promote dated, ineffective, and even dangerous training methods through manipulative marketing messages and enthusiastic but unqualified teachers/presenters. There are many fantastic elements to the endurance craze (marathon, triathlon, CrossFit, Hyrox, obstacle course racing, and so on) and to group and home-based high-intensity interval training (HIIT) programming. However, there continues to be a problem with people suffering from trying to do the right thing, but with a flawed approach. It’s no secret that exhaustion, breakdown, burnout, illness, injury, and failed weight loss efforts are commonplace, even among the most hard-core fitness enthusiasts.

Today, forward-thinking coaches, trainers, and researchers are helping right the wrongs of the fitness boom, generally rejecting the "more is better" approach in favor of one that respects the importance of balancing stress and rest and adopts an intuitive approach to workout planning. We are now implementing strategies to maximize workout return on investment and minimize the risk of injury and burnout that comes with an indiscriminate approach.

For example, many evolved endurance athletes are driving a revolution by rejecting the narrowly focused, overly stressful chronic cardio approach in favor of emphasizing aerobic development at lower heart rates, becoming fat-adapted instead of sugar-addicted, and embracing the importance of strength training and explosive sprinting (all detailed in the Primal Endurance mastery course and the Born To Walk book). Hopefully you have escaped the disastrous consequences of chronic cardio to embrace a more sensible approach to fitness.

When it comes to the very popular high-intensity interval training (HIIT) found in many group classes or branded workouts, these sessions are quite often too stressful and exhausting to deliver the intended fitness boost they promise: chronic HIIT in a similar realm to chronic cardio. When you complete a killer HIIT session at morning boot camp or spin class, at home on your Peloton bike, or with the Tuesday night track group, you get a tremendous sense of accomplishment and a flood of feel-good endorphin chemicals into your bloodstream. But when these workouts are conducted too frequently with insufficient rest between them, they can lead you right to a general state of overtraining, chronic HIIT echoing chronic cardio.

The problem with many HIIT sessions is that they are too strenuous: too many repetitions of hard effort, each lasting too long, with insufficient rest between hard efforts. This results in cumulative fatigue during the workout, a diminishing quality of performance over the course of the workout, increased cellular damage due to this cumulative fatigue, and extended recovery time afterward. A great term to summarize comes to mind: sufferfest.

Sufferfests are a great source of satisfaction and personal growth when you high five your fellow bootcamp classmates after an hour of power, or cross the finish line of a big event you've been training for. But having sufferfests as a prominent and recurring element of your training program is a really bad idea.

Unfortunately, the sufferfest mentality is incredibly common these days, perhaps suggesting that ego has more influence than strategic planning and intuitive, informed decision making. It doesn't have to be that way. The post "Should You HIRT Instead of HIIT?" explains how you can redesign some of your high-intensity workouts to minimize the risk of fatigue and breakdown, and become more powerful and explosive.