The current mania for high-intensity interval training has some runners wondering if they’re wasting their time “jogging.”
Written by: Matt Fitzgerald
The fields of personal training and strength and conditioning coaching are dominated by men and women with backgrounds in bodybuilding and team sports. The typical personal trainer or strength and conditioning coach has little knowledge of or appreciation for endurance sports. That’s not to say these fields are not influenced by endurance training methods, however.
High-intensity interval training is a method that was developed originally by swimmers and was then adopted by runners, cyclists and every other kind of endurance athlete. Interval training is now universally practiced by competitive athletes because it is a very powerful fitness builder. However, it’s optimal role in the training of true endurance athletes is limited. Swimmers can perform high-intensity intervals until they’re blue in the face, in part because they are really sprinters and in part because high-intensity intervals are physiologically much less stressful in the pool than they are on the bike or in running shoes. Runners and cyclists seem to perform best when they limit their interval training to one or two sessions per week and put these in the context of a high-volume training regimen that is dominated by moderate-intensity work.
Personal trainers and strength coaches were late to adopt the use of high-intensity interval training with their clients, but they have since fallen madly in love with it, to the point of declaring it “superior” to steady-state aerobic training—full stop, no qualifications—and scorning those, including endurance athletes, who continue to practice the latter. The trainers’ declaration of the superiority of HIIT (as they have renamed interval training, perhaps to disguise its origins in endurance sports) is based on a bunch of impressive studies showing that overweight and sedentary individuals shed body fat and gain aerobic fitness much faster through HIIT than they do through steady-state aerobic training. These studies are interesting and valid, but they do not support the conclusion that HIIT is just plain superior to steady-state aerobic training, full stop, no qualifications. Here’s why:
1. Intensity limits volume.
High-intensity interval training is very taxing on the neuromuscular system. One can do only so much HIIT without creating a chronic recovery deficit that eventually causes results to diminish, then cease, then reverse. The human body’s tolerance for moderate- to moderately high-intensity aerobic training is significantly greater. Thus, while the individual who does only HIIT gets more results per minute of exercise, the greater overall potential for fat burning and aerobic fitness development lies with steady-state aerobic training, because you can do so much more of it without becoming overtrained.
It’s no accident that the leanest athletes in the world are elite marathoners, about 80 percent of whose training is of moderate intensity. Elite marathoners have body fat levels that professional bodybuilders would kill for, yet the runners often get there without having to exercise any restraint in their diet, while the bodybuilders, who rely on HIIT, have to practically starve themselves to get that lean.
2. It’s possible to go fast and long.
Last year I visited a friend who works in the strength and conditioning world. He took me to his gym for a workout. I hopped on a treadmill and ran while he lifted weights. An hour after we had started our respective workouts, he came to the cardio room to fetch me. I stepped off the treadmill and announced, “I just burned 1,200 calories. Let’s eat!” His jaw dropped.
Most trainers and strength coaches have no idea how many calories well-trained endurance athletes are able to burn in their workouts, because they assume that all steady-state aerobic workouts are low-intensity workouts. They make this assumption for two reasons. First, the research on HIIT trains them to think this way, as it always compares very high-intensity intervals to pitifully low-intensity steady-state aerobic training, as if going both fast and far is not an option. Second, most trainers and strength coaches have very low aerobic fitness levels and cannot themselves go both fast and far, so how are they supposed to know others can?
Competitive endurance athletes routinely perform workouts that entail prolonged work at high intensities—tempo runs, lactate intervals, etc. A well-trained runner can sustain a work output level for 40 straight minutes in a hard tempo run that is only marginally lower than the intensity level he could sustain in a set of 1-minute intervals and is in many cases higher than the intensity level that your typical gym exerciser could sustain in a set of 1-minute intervals.
To cite a research example, a recent study required elite rugby players (who are strength/speed/power athletes, obviously) to cycle at 90 percent of VO2max as long as they could. They lasted 12 minutes, on average. A well-trained runner can last five times that long at that same intensity. The more aerobically fit you get, the longer you can go fast and the faster you can go long, and it’s traditional endurance training that maximizes aerobic fitness and the calorie-burning capacity that comes with it, not all-HIIT programs.
To give an example involving myself, last year in training for the Boston Marathon I performed a peak tempo run consisting of 10 miles at 5:41 per mile. That works out to 80 seconds per 400 meters, which is not a hell of a lot slower than the pace I was running in my interval workouts at that time. What the trainers and strength coaches don’t understand is that well-trained endurance athletes really don’t have to slow down much as they increase the duration of their efforts. We are not the folks reading magazines on elliptical trainers!
3. Enjoyment matters.
Trainers and strength coaches are fond of pointing out that HIIT workouts are much more time efficient than steady-state cardio workouts, which is great, because lack of time is the most often-cited reason for not exercising. This notion is highly problematic, because in fact everyone has time to exercise. The time excuse indicates a lack of motivation to work out, not a lack of time. Now, it so happens that HIIT is very painful. So, do you think that people who are so unmotivated to work out that they create a time excuse are going to be more motivated to suffer greatly in their workouts? Not a chance. The time excusers are the very last people who are going to tolerate immoderate agony in exercise.
If lack of time really were the reason most people did not exercise, then HIIT might present a legitimate solution, but it’s not, and it doesn’t.
The trainers and strength coaches underestimate the importance of enjoying exercise. New research by exercise psychologists shows that the more people enjoy exercise, the more likely they are to adhere to it, and they are more likely to enjoy exercise when they are able to freely choose a comfortable exercise intensity.
“But they’re not getting as much bang for their buck when they do that!” cry the meatheads.
Yes, but at least they’re still at it a year later.
Every personal trainer is forcing HIIT on new clients these days. What percentage of those clients continues to do HIIT on their own later? Not much more than zero, I would guess, because HIIT sucks.
Now, don’t get me wrong. I am a big fan of suffering in workouts, and I believe that developing a taste for real exertion is important. But for those who are not already committed to exercise, enjoyment should be prioritized in workout formatting, not narrow physiological rationales.
4. Motivation matters.
Research in exercise psychology has also shown that people are more motivated to exercise when their workouts have a clear external purpose. This phenomenon is probably a legacy of our ancestral environment, in which all exercise was task-oriented work. Fifty thousand years ago we only worked up a sweat when there was food at stake. Consequently, even today we are only motivated to huff and puff when we feel we are getting something done.
I believe this is one reason that running marathons is so incredibly popular these days. The goal of running a marathon is a mission, a quest, and a journey one can share with many other people. Compare that to the traditional vanity-motivated, health club-based fitness program where one literally goes nowhere. If adhered to, such a program can produce great results, but it just doesn’t speak to the animal in us nearly as well as running a marathon does.
No, training for a marathon is probably not the most efficient way to get fit and lose weight, but in the all-important context of reality that is so often forgotten by the HIIT proselytizers, it is very likely the most effective way.