Effects of Moderate-Intensity Endurance and High-Intensity Intermittent Training on Anaerobic Capacity and VO2 Max

Title and Abstract

Tabata I. et. al.  Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max.  Med Sci Sports Exerc. (1996) 28(10):1327-30.

This study consists of two training experiments using a mechanically braked cycle ergometer. First, the effect of 6 wk of moderate-intensity endurance training (intensity: 70% of maximal oxygen uptake (VO2max), 60 min.d-1, 5 d.wk-1) on the anaerobic capacity (the maximal accumulated oxygen deficit) and VO2max was evaluated. After the training, the anaerobic capacity did not increase significantly (P > 0.10), while VO2max increased from 53 +/- 5 ml.kg-1 min-1 to 58 +/- 3 ml.kg-1.min-1 (P < 0.01) (mean +/- SD). Second, to quantify the effect of high-intensity intermittent training on energy release, seven subjects performed an intermittent training exercise 5 d.wk-1 for 6 wk. The exhaustive intermittent training consisted of seven to eight sets of 20-s exercise at an intensity of about 170% of VO2max with a 10-s rest between each bout. After the training period, VO2max increased by 7 ml.kg-1.min-1, while the anaerobic capacity increased by 28%. In conclusion, this study showed that moderate-intensity aerobic training that improves the maximal aerobic power does not change anaerobic capacity and that adequate high-intensity intermittent training may improve both anaerobic and aerobic energy supplying systems significantly, probably through imposing intensive stimuli on both systems.


Background

In recent years, training and the Internets have become interval crazy.  Everybody wants to do nothing but interval training all the damn time (with some even proclaiming that any non-interval training is not only useless but downright detrimental).

Now, I’ve written extensively about this in what must be about a 12 part series on Steady State vs. Interval Training here on the site.  I’m not going to rehash the entirety of that series, mind you; go read it.  But simply, both intervals and steady state have their place in training.  Arguments that one is inherently or always superior to the other has more to do with marketing than reality.

But among other aspects of this particular meme, the idea of the Tabata protocol (often abbreviated Tabatas) gets bandied about all the time.  And the problem is that people are using the term to describe something that they don’t really understand.  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.  And most people who think they are doing the Tabata protocol are doing absolutely nothing of the sort.

As a bit of history, 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’ve spent the last 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 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 (VO2 max was roughly 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; 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 (This is maybe 60-65% maximum heart rate).

The two primary tests were VO2 max and the maximal accumulated oxygen deficit (this is a test of anaerobic capacity, basically people with higher anaerobic capacity can generate a larger oxygen deficit) and then subjected to one of two training programs.

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 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.

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.  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.


Results

For group 1, 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 because the paper failed to provide vaules, I’m going by what’s in the graphic 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).  It is worth noting that the interval group was starting with a lower value and may have had more room for improvement.  Also note that they still ended up with a lower Vo2 max than the steady state group.

I’ve put Figure 2 from the paper (showing improvements in VO2 max) below

Click to Enlarge

Click to Enlarge

As I noted, pay attention to the fact that the Tabata group (black line, filled circles) started lower than the steady state group, they also still ended up lower than the steady state group.  As well, note that 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).


My Comments

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 no shock based on the training effect to be expected.  And while the Tabata protocol certainly improved both, not only did the Tabata group still end up with a lower VO2 at the end of the study, they only made progress for 3 weeks before plateauing on VO2 max and 4 weeks for anaerobic capacity.

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.  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.

I’ve asked this question before but for all of the ‘All interval all the time’ folks, if intervals stop working after 3-4 weeks, what are people supposed to do for the other 48-49 weeks of the year.  Should they keep busting their nuts with supra-maximal interval training for no meaningful results?

On that note, it’s worth mentioning that the Tabata group actually did a single steady state workout per week.  Is it at all possible that this contributed to the overall training effect (given that 70% VO2 max training improved VO2 max in the steady state only group)?  Does anybody else find it weird that the Tabata promoters ignore the fact that the Tabata group was doing steady state work too?

It’s also relevant to note that the study used a bike for training.  This is important and here’s why: 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.  The folks suggesting high skill movements for a ‘Tabata’ workout might want to consider that.  Because when form goes bad on cleans near the end of the ‘Tabata’ workout, some really bad things can happen.  Things that don’t happen on a stationary bike.

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.

Finally, I’d note that, as I discussed in Predictors 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.


Summing Up

First, here’s what I’m not saying.  I’m not anti-interval training, I’m not anti-high intensity training.  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.