I hope this is almost the last post on the subject, because I seem to have been getting aerobic running wrong for quite a long time.
And I think what’s got in the way is ego — these are v slow runs, circa 7:30/8 min / km — and the fact that running quite slowly is really quite difficult. Obviously it’s not as lung-bustingly hard as a fast / threshold run, but it’s difficult nonetheless, but it tests your willpower in a different way.

(Chart that shows physical efficiency degradation during a run, measured in metres per heart beat. The aim is to keep it to a drift of 5% or less by the last quarter of the run for maximum aerobic efficiency.)
The key thing that seems to have fixed it, possibly, is:
- An understanding of how exactly I should be trying to run if I’m doing true aerobic running.
- Nasal breathing as a way of regulating pace / effort.
The idea of aerobic or Zone 2 running has long fascinated me. Partly, I suppose, because you just can’t go out every time and run at threshold.
And secondly, because the theory is there and seems to be legitimate: that you can run slowly and make lots of gains. In other words, if you run at the pace at which your Type I slow-twitch muscles are using their energy reserves—namely, fat stores in the muscles—at their optimum, then you improve the ability to draw energy from those fat stores, and you build mitochondria most effectively (mitochondria being the cells that generate the power in your body). And that therefore, you become more efficient at running, with an aerobic base that can use fuel stores to their best and can also help with processing lactate at higher paces.
Trying an HR cap
So early this year, I hadn’t really run for about two years, and wanted to get back into it. And doing most of my running at a slow pace is obviously really attractive from the point of view of just getting on my feet and getting moving.
Initially, I set a heart rate cap at 130 bpm. Which doesn’t sound like a lot to many people, but for me is probably halfway up my aerobic/lactate zone. In other words, I’m well above the level where I’m only using fat as a fuel and well into the area where I’m using type II muscle fibres (fast twitch), using oxygen as a fuel, generating lactate and having to deal with processing it.
I realized that a few months ago and I dropped it down to about 120. This is all obviously using a heart rate figure as a proxy and 120 is more like where it should be.
But I’ve been doing a few runs lately, and by analysing runs using R and with the help of Gemini as sounding board, I’ve been discovering that my runs haven’t been that efficient because my efficiency at the beginning of the runs has been—sometimes, most times in fact—tailing off quite substantially as I’ve gone through the run.
Paying through the nose
Gemini had suggested elsewhere in our conversations that nasal breathing was a good idea. And I’ve tried it once or twice on runs, and it does, to a large extent, limit you in your pace and therefore your heart rate.
But I hadn’t really tried it all the way through runs until last week where I explored my efficiency over the course of a run. How we measure this is metres per heart beat. What we do is it split a run into four quarters (I’m doing all this analysis in the background using R) and then measure each quarter against the baseline first quarter when you’re at your most fresh.
What we should aim for, is a degradation—a drift in your aerobic efficiency (ie, of metres per heart beat) —of 5%. That’s considered to be a good, efficient run. If you’re going above that, then you’re probably working too hard and going into lactate production territory and building fatigue too quickly.
Nasal breathing early on in the run means you can put a very clear limitation against that happening.
So you spend the most part of the run operating in the most efficient zones from the point of view of creating mitochondria and building your efficiency in terms of using fat as a store.
So, that’s how I’m going to do aerobic runs from now on: with nasal breathing from the start .
We’ll see how it goes. This experiment started in March; it’s now August. So that’s about six months where I’ve kind of been doing it wrong. I’m sure not all of the running I’ve done has been a complete waste of time, but as far as aerobic running has been concerned, I have certainly been operating less than efficiently.
I’ve got no great desire to change the approach that I have, which at the moment is kind of an 80/20 thing—I spend 80% of my time running very slowly and 20% doing threshold. I’m not aiming at any races; I just want to get more efficient and stay able to run for as long as possible. So I’ll probably keep this experiment going into the autumn and winter, maybe early next year. So I have a few months of being able to see what real aerobic running can do for me.
We’ll check back in a few months and see how all that’s gone, especially when the cool weather comes back and I’m not having to deal with the overhead of dealing with higher temperatures.





















Leaving aside the ridiculous ball-in-the-net-that-wasn’t incident . . .
The Blades had a lot of possession (53%), of which a lot was relatively high up the pitch (see average line stats left) and which resulted in a higher final third pass count than Villa (deep completions 20 vs 15).











