Monthly Archives: December 2013
I just found this post, fully-formed, in my drafts folder. I wrote it in April, which shows just how badly I’ve neglected this blog. Sorry about that, but to tide you over, have a little post on fitness. This post is shamelessly stolen from myself, from a totally different blog. I’m re-posting it here because I think it makes points about critical thinking and evidence that fit with this blog’s ethos pretty well, and also carry on the theme of questioning what you’re told about health and fitness that I started a few weeks ago. Without any further hesitation, here’s what to bear in mind when you hear the word “Tabata”…
I have a bugbear. I’m going to use it to hopefully produce a blog post that’s useful and informative, but first I’m going to get something off my chest.
If you work out regularly, or even if you don’t, the chances are you’ve heard of the Tabata protocol. Named after Izumi Tabata, the chap who first published an academic journal on the subject, the protocol is very simple:
- 20 seconds of work, immediately followed by 10 seconds of rest
- performed 8 times without any pauses or interruptions, for a total of 4 minutes
- with the working phases performed at 170% of VO2max
If you deviate from this on any point, you’re not doing Tabata, you’re doing interval training. You may even be doing High Intensity Interval Training (HIIT), but it’s still not Tabata. Does it matter? Well, yes. Just because you’re doing intervals on a 20:10 split doesn’t mean you’re working to the same intensity as the Tabata protocol, and that means you can’t necessarily expect to get the results of the Tabata protocol. As an example, depending how hard you’re working it’s a little bit like the difference between doing a class like Body Pump, and training with Olympic weightlifting; both might make you sore the next day, and help you get stronger, but it’s evident that in the long-term, and arguably the short- and medium-term too, the results are very different.
That’s my pet peeve (more-or-less) off my chest, so on to the useful part. Points one and two on the list above seem straightforward, but what’s VO2max?
Simply put, it’s the maximum volume of oxygen that your body is capable of using. It’s usually expressed in litres per minute (L/min), or in millilitres per kilogram of bodyweight per minute (mL/kg/min). Men generally have a higher VO2max than women, and it tends to increase as you get fitter (and also decrease as you get older).
The next obvious question is, if VO2max is the maximum volume of oxygen your body can use, how can you reach more than 100% of it? That’s because your body has two energy systems. Let me expand
- The aerobic energy system uses oxygen to produce energy. It uses glucose, which goes through a series of chemical reactions to produce energy molecules like ATP, with CO2 and water as the waste products, and a few other things that are important to your body (but not to this blog post).
- The anaerobic system can produce energy in the absence of oxygen, by using up molecules like ATP, and by breaking down glucose and glycogen in the absence of oxygen. This produces by-products like lactic acid. Once you’re at rest, your body will use some of the oxygen it’s consuming to metabolise these by-products and return your muscles to peak condition. This is sometimes referred to as the “oxygen debt”, because you’re paying back oxygen for energy you’ve already used.
What this means for you is that you can work at a rate that is higher than your VO2max; your aerobic system will consume as much oxygen as it can, and your anaerobic systems will also kick in, but you’ll have an oxygen debt to pay off once you’re finished. Back in the 1990s Tabata decided to test what effect using both of these systems at once would have on fitness, so he took the now-familiar 20:10 protocol (which was already being used by the Japanese speed skating team in training) and compared it to steady-state cardio.
A summary of the results is available for anyone to read if they want to, but the gist of it is this:
- The study was quite small, with a total of 23 men who were already physically active – no women were tested. Only 7 men completed the interval training experiment. All athletes trained 5 times per week in total.
- Athletes performing cardiovascular exercise at steady state (70% of VO2max) for an hour significantly improved their VO2 max.
- Athletes performing intervals of 20 seconds of work at 170% VO2max interspersed with 10 seconds rest (with one 30 minute session per week at steady-state 70% VO2max) increased their VO2 max by a similar amount to the other group, but also increased their anaerobic capacity by 28%. In reality this group performed 7-8 sets of high-intensity work in each session; the session was terminated if their pedalling speed dropped below 85RPM. If they were able to do 9 sets, the difficulty was increased the next time. This means that the workout was always varying, and it’s likely both that no two men ever did the same workout, and that no man ever did an identical workout more than a few times.
One really important point to take away from all of this is that working at 170% of your VO2 max is hard. Really hard. Joe Bloggs can’t do it, at least not without falling over or being sick (or both). It takes a trained athlete, someone who pushes their limits most days to achieve this kind of intensity. And since this is the only protocol that was tested, this is the only protocol that we can make claims about. Even them the claims aren’t particularly strong if you look at this trial in isolation – the results for seven men who were already quite fit aren’t likely to generalise very well to a larger population of diverse individuals. Crucially, if you work at less than 100% VO2max (which most people will), you certainly shouldn’t expect anaerobic benefits of this magnitude, if any.
So what was my point again? A large part of this is my belief that language should be used accurately – call a spade a spade. The Tabata protocol is a very specific thing, which has been found to produce very specific results. Calling your workout Tabata when it’s not is at best pointless, and at worst misleading (or, if you’re a fitpro selling your services, false advertising).
There’s no doubt that doing almost any form of HIIT is beneficial (and I don’t mean to discourage it), so please don’t stop doing it, but – to keep me sane – please do stop calling it Tabata? Cheers 😉