How long a HIIT workout should be is one of the most frustrating fitness questions to answer, primarily because the definition of what constitutes a HIIT workout tends to vary depending upon who is offering the description.
For my money, there are certain workouts referenced as HIIT that are decidedly not HIIT, and other workouts that are designed to be HIIT, but that become something else entirely over the course of their execution. Either way, before we get into matters of length, we should start off by evaluating what the HIIT category was designed to include, what falls neatly into that category and where everything begins to get muddy. Then, we can talk about how much time your body should be in motion.
Anything that follows the Coe regimen definitely qualifies as HIIT. This regimen was named after its developer, Peter Coe, who designed a training regimen that allowed for only 30 seconds of rest for his son Sebastian “Seb” Coe after the latter completed 200-meter sprints. I’m willing to bet there isn’t a runner, swimmer, speedskater or other sprint athlete alive who hasn’t incorporated some variation of this workout style into their regular training. Most athletes quickly hit a wall when attempting to maximize the number of all-out sprints of a competitive distance that they can complete at any true quality level when given only 30 seconds rest.
The same holds true of any training that follows the Tabata regimen. The training protocol of Izumi Tabata minted the original gold standard of HIIT, which demonstrated how a group of athletes that regularly completed a series of all-out, 20-second sprints with only 10 seconds rest in between them, for four straight minutes, experienced similar aerobic gains as a group that trained for 60 minutes at a steady state. The Tabata group also achieved far greater anaerobic gains than the steady-state group.
These structured HIIT workouts are almost certainly designed to be completed in 10 minutes or less, with again, the Tabata regimen possessing a definitive four-minute cutoff.
The Zuniga regimen seems to have been configured in order to help design an optimal, prolonged workout for HIIT practitioners. This is also where the purity of HIIT begins to get called into question, inasmuch as HIIT was originally built around explosive bursts of 100 percent effort. Former Creighton professor Jorge Zuniga — a true hero who now develops prosthetic limbs for children at the University of Nebraska at Omaha — designed a fitness regimen that asked subjects to exert themselves at a level of 90 percent for 30 seconds, followed by 30 seconds of rest, because this formula was supposedly the key to lengthening workout time and maximizing oxygen consumption while also incorporating sprints that were of relatively high intensity, albeit not all-out intensity. The only element being called into question here is the requirement to give everything you have as opposed to giving 90 percent.
This is where the goals of the training protocol need to be considered, because lengthening workout time isn’t necessarily the same as maximizing the degree to which the body can perform at its peak capacity. Therefore, if you’re training on your own with a specific sprint in mind and want to ensure that your body performs at its optimal level, you’ll want to replicate the conditions of the actual race in your training as best you can, and that will absolutely require you to thrash your way through some all-out sprints. In this case, if you never exceed 90 percent effort, it’s not gonna cut it.
Probably Not HIIT
The Vollaard regimen of Niels Vollaard was seemingly devised to provide a counterpoint to the notion that several all-out sprints during HIIT sessions were required to maximize performance. Participants were asked to cycle easily for the bulk of a 10-minute training session, with two 20-second sprints thrown in. According to the results of the study, these participants tested at the same ability levels as cyclists who performed six to 10 30-second sprints over similar spans of time.
While this information is both interesting and probably useful for anyone looking to maximize results while minimizing the accumulation of overuse injuries — not to mention, it does contain an all-out-effort component — it doesn’t maintain the spirit of the traditional HIIT protocol. In essence, it seems closer to an anti-HIIT protocol in its execution, with recovery periods several times longer than the explosive periods, and with no obvious attempts to push the limits of the training subjects while they’re nearing peak levels of exertion. This may be a case where a training regimen got shoehorned into a category because there was no other pre-existing category to neatly place it.
Absolutely Not HIIT
It’s story time, folks! The first client-acquisition strategy I was ever taught as a personal trainer at Bally Total Fitness involved taking newly-signed club members through an arduous, custom-tailored workout, all for the sake of proving to them how desperately they needed to purchase the expertise of a trainer (aka me).
The formula was this: Instruct the client to perform one exercise per body part with a relatively strenuous weight for as many reps as they could complete in one go, and fill the space between each weight-bearing exercise with 30 seconds to one minute of a calisthenic movement like stepback lunges, forward lunges, jumping jacks or occasionally push-ups if you were working with a particularly beastly member. Over the course of 30 minutes to an hour, the prospective client’s muscles were completely broken down, and that’s when we made our pitch and posited the unavoidable breakdown of their muscles as the unmistakable evidence for how badly they required our services.
Did it work?
Occasionally, it worked like a charm. But that’s not the point. The point is, what I just described is not a HIIT workout; it’s simply a workout with an active rest that’s of a decidedly different nature than the key movement of the workout. I could manipulate the client’s exertion during the “rest period” to cause whatever level of fatigue I wished.
This method of money-motivated torture does not qualify as a true HIIT workout for a few key reasons: First, it isn’t truly structured or goal-oriented, save for my goal of selling fitness sessions to enervated club members. All my regimen was intended to do was create as much fatigue and discomfort for the trainee as I could. Second, in every HIIT workout we’ve reviewed, the rest period consisted of either an outright rest, or a version of the primary training movement that was drastically scaled down in its intensity.
In fact, let’s say I took the same principles of the aforementioned workout, made all of the primary movements into leg exercises and then decided that the active rest would be either bodyweight squats or stepback lunges. Many of you would easily recognize that as supersetting, and you’d be correct. Supersetting adds an additional element of fatigue induction to a training routine, but no component of it is typically construed as either a rest period, or a reduced-intensity execution of the core exercise. These are essential hallmarks of every true HIIT workout we’ve discussed, so I don’t know why we should go making any exceptions now.
Okay, Trainer Man, Enough with the Stalling — How Long Should a HIIT Workout Be?
Honestly, if you continue the workout for longer than 10 minutes, you’re outside the bounds of almost every workout regimen that’s credited with establishing the framework for what a HIIT workout was intended to be, as instituted by the true pioneers of HIIT. Therefore, it would probably be best not to refer to your training session as a true HIIT workout if it extends beyond this time window, or even if it consists of more than one foundational training movement.
Please remember, this doesn’t mean your workout is defective or ineffective in any way. It’s simply not a HIIT workout routine. Don’t blame me — blame Coe and Tabata!
Another good thing to remember: If either your workout or your sprint intervals are too long, you’ll eventually lose the “high intensity,” and you’ll simply be left with “interval training.” When that happens, you’ll find yourself locked into a plodding form of steady-state cardio as you fill the remaining minutes and seconds of every extended interval with low-quality, low-intensity movement.
Generally speaking, you can train long, or you can train hard, but you can’t truly train both long and hard without sacrificing the true meaning of at least one of those things.