In recent years, the Internet has gotten a bit crazy for high-intensity interval training, proclaiming it’s superiority overall other forms of conditioning training. And while HIIT can take many forms, one popular one, wholly misrepresented in the fitness industry is what is called the Tabata Protocol.
This describes a very specific approach to HIIT created, originally for speed skaters, by an author named Tabata. Hence the name. It’s even been studied and it is this study that I want to look at today.
HIIT and the Tabata Protocol
The concept of HIIT is fairly general, it describes a method of training where short periods of near maximum training lasting 15-90 seconds (with some variance) are alternated with periods of low intensity activity for some number of rounds. HIIT protocols are effectively endless in how they can be set up and few have a specific name given to them.
The Tabata Protocol is different. This describes a very specific type of training, defined below, which has been shown to generate certain adaptations which I’ll also discuss below. And one of many problems is that this very specific protocol has been bastardized, with similar looking training approaches often being called Tabatas.
And basically a lot of people are using this term or thinking they are using the protocol when they actually have no clue what they are talking about. What has happened is that a bunch of people who don’t really know what they are talking about have written so much about the protocol that what it actually is or accomplishes has been completely diluted.
So I figured I’d undilute it by actually examining the study that the whole set of claims and supposed ‘protocols’ are based on. Because, as is so often the case, what people think they are doing as ‘Tabatas” are nothing like what the actual study did or the actual protocol describes. And most people who think they are doing the Tabata protocol are doing absolutely nothing of the sort.
As I mentioned above, the protocol was actually originally developed by a Japanese speed skating coach and later studied by researchers, I bring this up because speed skating is actually a very peculiar sport in a lot of ways (something that I have insight into as I spent 5.5 years training full time as a skater). But I’m not going to get that into detail here; I simply mention it for completeness.
The Tabata Study
The study set out to compare both the anaerobic and aerobic adaptations (in terms of one parameter only, VO2 max) to two different protocols of training. The study recruited 14 active male students who were, at best moderately trained. Their VO2 max (one of several predictors of endurance performance) was 50 ml/kg/min which is average at best. Elite endurance athletes have values in the 70-80 range).
All work including the pre- and post tests were done on a mechanically braked bicycle ergometer. Just think of it as a stationary bike. This is an important point that is often ignored and I’ll come back to in the discussion. Every test or high-intensity workout was proceeded by a 10 minute warm-up at 50% of VO2 max (which is around 60-65% of maximum heart rate).
The two primary tests were VO2 max and the maximal accumulated oxygen deficit (MAOD). MAOD is just a test of anaerobic capacity. People with a higher capacity can generate a larger oxygen debt. After testing, subjects did one of two training programs.
The Aerobic Training Program
The first program was a fairly standard aerobic training program, subjects exercised 5 days/week at 70% of VO2 max for 60 minutes at a cadence of 70 RPMs for 6 straight weeks. The intensity of exercise was raised as VO2 max increased with training to maintain the proper percentage. VO2 max was tested weekly in this group and the maximal accumulated oxygen deficit was measured before, at 4 weeks and after training.
The Tabata Protocol Training Program
The second group performed the Tabata protocol. For four days per week they performed 7-8 sets of 20 seconds at 170% of VO2 max with 10 seconds rest between bouts, again this was done after a 10 minute warm-up. When more than 9 sets could be completed, the wattage was increased by 11 watts. If the subjects could not maintain a cadence of 85RPM, the workout was ended.
Let me make it clear that this IS The Tabata Protocol. It is 7-8 sets of 20 seconds of maximum work at 170% of VO2 max with 10 seconds rest between bouts after a warm-up. Anything that is not exactly that is not a Tabata and I’ll come back to this below.
On the fifth day of training, they performed 30 minutes of exercise at 70% of VO2 max followed by 4 sets of the intermittent protocol and this session was designed to NOT be exhaustive. So they did the full Tabata protocol 4 days per week along with one short aerobic session and a non-exhaustive partial Tabata workout.
The anaerobic capacity test was performed at the beginning, week 2, week 4 and the end of the 6 week period; VO2 max was tested at the beginning and at week 3, 5 and the end of training.
For the standard aerobic training group, while there was no increase in anaerobic capacity, VO2 max increased significantly from roughly 52 to 57 ml/kg/min. I say roughly as the paper failed to provide the actual values and I had to sort of eyeball it from the data I’ve below. Frankly, given the lack of anaerobic contribution to steady state training, the lack of improvement in this parameter is absolutely no surprise.
For group 2, both the anaerobic capacity and VO2 max showed improvements. VO2 max improved in the interval group from 48 ml/kg/min to roughly 55 ml/kg/min (see graphic below). While it wasn’t statistically significant the Tabata group was starting a little bit lower and may have had more room to improve. They also ended up a little bit lower although that difference was also not statistically significant.
So you can see the results from above, both groups made improvements in VO2 max. But note the pattern of improvement: the Tabata group got most of their improvement in the first 3 weeks and far less in the second three weeks. The steady state group showed more gradual improvement across the entire 6 week period but it was more consistent. As the researchers state regarding the Tabata group
After 3 wk of training, the VO2 max had increased significantly by 5+-3ml.kg/min. It tended to increase in the last part of the training period but no significant changes [emphasis mine] were observed.
Basically, the Tabata group improved for 3 weeks and then plateaued despite a continuingly increasing workload. I’d note that anaerobic capacity did improve over the length of the study although most of the benefit came in the first 4 weeks of the study (with far less over the last 2 weeks).
First and foremost, there’s no doubt that while the steady state group only improved VO2 max, it did not improve anaerobic capacity. This is absolutely no surprise given the training that was done. Nobody would expect steady state aerobic training to improve anaerobic capacity. Endurance athletes use a variety of training methods and that’s because no single intensity can possibly improve everything important to their performance.
And while the Tabata protocol certainly improved both factors, they only made progress for 3 weeks before plateauing on VO2 max and 4 weeks for anaerobic capacity. Basically Tabata training gave some nice short improvements that tapered off quickly.
Interestingly, the running coach Arthur Lydiard made this observation half a century ago. After months of base training, he found that only 3 weeks of interval work were necessary to sharpen his athletes. More than that was neither necessary nor desirable. The German Track Cycling team tops off months of aerobic training with as little as 10 days of anaerobic training for the 4000m time trial so this isn’t an uncommon pattern.
Other studies using cycling have found similar results: intervals improve certain parameters of athletic performance for about 3 weeks or 6 sessions and then they stop having any further benefit.
This raises an important practical question for all of the “All HIIT all the time” or “HIIT only
” zealots which is this. If HIIT training gives it’s maximal benefits after 3-4 weeks of training, what are people supposed to do the other 48-49 weeks of the year? Should they keep busting their nuts with supra-maximal interval training for no meaningful results? I daresay not.
In that vein, I think it’s worth re-mentioning that the Tabata group did do a single steady state workout per week (admittedly with a half-volume Tabata protocol). It’s worth considering that at least some of the training effect came from this workout? It’s worth noting that I’ve never seen any of the Tabata-zealots mention that the study subjects also did a steady state workout during the week.
The Importance of Doing it on a Bike
I mentioned explicitly above that the Tabata training was done on a bike ergometer and this is actually critically important. Mainly from a safety standpoint. On a stationary bike, when you start to get exhausted and fall apart from fatigue, the worst that happens is that you stop pedalling. You don’t fall off, you don’t get hurt, nothing bad happens.
As part of their bastardized “Tabatas, many are recommending high skill movements. Not only is it not possible to achieve 170% VO2 max in this way, when fatigue invariably sets in and technique suffers bad things often happen. This is not an issue on a stationary bike (or elliptical or rower).
The Tabata Protocol is Very Specific
As well, I want to make a related comment: as you can see above the protocol used was VERY specific. The interval group used 170% of VO2 max for the high intensity bits and the wattage was increased by a specific amount when the workout was completed. Let me put this into real world perspective.
My VO2 max occurs somewhere between 300-330watts on my power bike, I can usually handle that for repeat sets of 3 minutes and maybe 1 all out-set of 5-8 minutes if I’m willing to really suffer. That’s how hard it is, it’s a maximal effort across that time span.
For a proper Tabata workout, 170% of that wattage would be 510 watts (for perspective, Tour De France cyclists may maintain 400 watts for an hour). This is an absolutely grueling workload. I suspect that most reading this, unless they are a trained cyclist, couldn’t turn the pedals at that wattage, that’s how much resistance there is.
If you don’t believe me, find someone with a bike with a powermeter and see how much effort it takes to generate that kind of power output. Now do it for 20 seconds. Now repeat that 8 times with a 10 second break. You might learn something about what a Tabata workout actually is.
My point is that to get the benefits of the Tabata protocol, the workload has to be that supra-maximal for it to be effective. Doing thrusters or KB swings or front squats with 65 lbs fo 20 seconds doesn’t generate nearly the workload that was used during the actual study. Nor will it generate the benefits (which I’d note again stop accruing after a mere 3 weeks). You can call them “Tabatas” all you want but they assuredly aren’t.
That is, just doing something hard for 20 seconds and easy for 10 second and repeating it 8 times is not The Tabata Protocol. And calling it a Tabata doesn’t make it so. If you can’t hit the 170% of max intensity that is seen in the study, it doesn’t qualify.
A Pedantic Note about Vo2 Max
Finally, as I discussed when I talked about the determinants of endurance performance, VO2 max is only one of many components of overall performance, and it’s not even the most important one. Of more relevance here, VO2 max and aerobic endurance are not at all synonymous.
Many people confuse the two because they don’t understand the difference between aerobic power (VO2 max) and aerobic capacity (determined primarily by enzyme activity and mitochondrial density within the muscle).
Other studies have shown clearly that interval work and steady state work generate different results in this regards, intervals improve VO2 max but can actually decrease aerobic enzyme activity (citrate synthase) within skeletal muscle.
The basic point being that even if the Tabata group improved VO2 max and anaerobic capacity to a greater degree than the steady state group, those are not the only parameters of relevance for overall performance. To improve actual endurance means performing actual aerobic work.
First, here’s what I’m not saying. I’m not anti-interval training, I’m not anti-high intensity training. I’m not. I’ve done more HIIT workouts over my athletic career than I care to think about. They are an important part of athletic performance for many sports and research clearly shows they can have important benefits.
I am anti-this stupid-assed idea that the only type of training anyone should ever do is interval training, based on people’s mis-understanding and mis-extrapolation of papers like this.
High-intensity interval training and the Tabata protocol specifically are one tool in the toolbox but anybody proclaiming that intervals can do everything that anyone ever needs to do is cracked. That’s on top of the fact that 99% of people who claim to be doing ‘Tabatas” aren’t doing anything of the sort.
Because 8 sets of 20″ hard/10″ easy is NOT the Tabata protocol and body-weight stuff or the other stuff that is often suggested simply cannot achieve the workload of 170% VO2 max that this study used. It may be challenging and such but the Tabata protocol it ain’t.