Last week I (Tim) went to get a VO2 max test on a treadmill. It involved running for a certain amount of time – well, technically til I fell off – at ever increasing speeds and inclines. I lasted all of 6 minutes before it all fell apart, which, apparently is about right. Anything over 7 minutes and you probably haven’t started fast enough, and anything under 5 minutes, you’ve probably overestimated your fitness.
I quite like the scientific rigmarole of having a face mask and a Heart rate monitor, and lots of stats being pumped out of a computer…. But why did I need to do it?
Well, let us be totally honest, I don’t NEED to do this, much in the way we don’t need to know exactly how fast we run, but it is an interesting set of statistics to know. In the past I have done various heart rate tests to try to work out my zones – all of them based on various formulae connected to my age. I have also done a load of races and runs, short to long, with a heart rate monitor on. I kind of know where my point of no-return is, I know to within a few bpm where I start to feel really ill, and I know when I am not pushing as hard as I could.
Those numbers are of less interest to me at this point. I am much more interested at the other end of the scale. The zone where I am burning less carbohydrate and more fat. The efficiency part of the scale. Again, there are a number of formulae for working this out. My concern is that I really don’t know how accurate these numbers are in terms of my physiology. I’m fairly sure I run “too fast” when in the efficiency range, but have no real way of knowing. Unless I start to go down the route of the gas exchange testing.
This is where my inner geek comes out. I like this kind of stuff because it gives me numbers to think about when training, not only that, but numbers based on my physiology that have been tested through cunning and exciting gadgetry. Yes. I am that sad.
So – after the ramp test, how do the numbers compare to the various other ways of calculating my zones, and what did I learn?
This gets a little number intensive…
According to the Karvonen Formula (the gold standard, if you will), my zones look like this….
50%-70% Aerobic Fat burning – 122-146
70%-80% Aerobic – 146-158
80%-90% Anaerobic 158-171
90%+ Redline 171 onwards.
The Maffetone formula – which is essentially to get a heart rate which you should run at, and NOT over in order to maximise your fat burning efficiency comes out at 149 or 154, depending on how generous I am being about how “active” I am.
Basically, I was always wondering if I was meant to be running at a max of 154 to keep my in the efficiency zone, or if I was going too fast and if I should be slower etc. All that wondering tended to get out of hand, I’d decide that it wasn’t really worth worrying about, because if I was doing it wrong, I might as well enjoy myself anyway, and I’d go off and forget about the whole thing.
Not terribly useful.
So, after the VO2/gas exchange test, what did that say?
Aerobic Base – 119-139
Aerobic 2 140-155
Aerobic 3 156-166
Anaerobic capacity 174-184
Interestingly, the point at which I totally stop burning any type of fat and rely totally on carbohydrate is 153bpm – right in the midst of the Maffetone numbers.
You’ll notice that my Aerobic 3 is therefore totally carb based, which is why I need to eat a fair amount when I’m out on things like the Old County Tops (a 37 mile fell race). I might not be running fast, but I’m only burning carbohydrate all day.
So the differences between the tests are only a few beats out. At the upper end, that really isn’t going to make a huge amount of difference. When I’m busting a gut in a threshold session there isn’t enough mental capacity to wonder if I’m at 172 or 173bpm. At the other end, jogging along on a fasted run I don’t want to be thinking… am I going to fast or hard? I want to know that I’m doing it right, and have plenty of mental capacity to worry about it. Those few beats are crucial to me in the plan.
From the test it is evident that my fat burning ability is pretty rubbish. I knew that (or at least suspected that was the case) anyway, but it is nice to have it in black and white. I have numbers to work with, and I have some work to do.
That being said, I am not going to spend the entire next few months as a slave to a monitor. Running and cycling for fun is just as valid, and I don’t want people going away thinking that this is going to be a chore. Anything but! I can’t wait to get stuck in.