Going anaerobic

I remember when I was in my twenties, and I knew absolutely nothing about how to train for running. I just thought you ran as fast as you could for 10-20 mins and assumed you’d get faster. Compared to now, there was a dearth of information on how to train although there were books on it; but anyone who was decent learned how to run by the osmosis of running with others at a club.

These days there’s more information, jargon and approaches to getting better than ever before. Although it wasn’t running, I remember meeting some rowers – which as another endurance sport mirrors running – and one of them talking about “going anaerobic” and “oxygen debt”. These phrases were about as technical as people got in those days and while “anaerobic” still gets bandied around; the concept of oxygen debt is one that’s rarely mentioned these days.

My understanding of going anaerobic back then was based on the idea that sprinters use anaerobic energy while distance runners use the aerobic system. It was one-or-another in my head and anaerobic equalled the breathlessness of sprinting. The truth is more complicated as both groups use varying degrees of aerobic and anaerobic energy in their events. This post isn’t going to break that down but it’s taken me some years to get closer to the truth about when we go anaerobic. The fact is any breathlessness, which can happen for an untrained runner at paces as slow as nine or ten minute miles involves anaerobic metabolism. You don’t have to be running at high speeds to go anaerobic.

When you read running books that mention anaerobic training there is much confusion as different authors define it differently. Again, I’m not going to dive too far into that debate other than to say some authors see it as what happens when you exceed V̇O₂max. Others believe it is what happens when you exceed Lactate Threshold / Anaerobic Threshold (or whatever term they use to name the point where you begin to exhale harder and faster). Whereas I believe it starts much earlier than that, back at what may be called the Aerobic Threshold, but is confusingly also called the Lactate Threshold by some groups, and consequently I refer to as the First Threshold to try and avoid confusion. Even then I’m not entirely correct about when it happens – it’s simply a nice approximation.

What I can say with confidence is that going anaerobic happens any time your aerobic system is overwhelmed. If you’ve been sitting quietly on the sofa and suddenly jump up and run upstairs; your heart doesn’t have time to speed up to supply more oxygen so you have to go anaerobic to meet the demand. For a while you go into “oxygen debt” until the body is able to handle the exertion – which is partly about getting to the top of the stairs and stop the high intensity work; and partly because the heart races and you breath hard in response. Another example is the start of a run, you’ll be using anaerobic energy until the body can meet the demand; once you’re settled in every thing steadies up but if you come to a hill and start to get out of breath going up it – yep, you’ve gone anaerobic again.

All of this is simply background information setting up my next post on how the body responds to going anaerobic. It’s very easy to get bogged down in the detail, I’m trying to keep it simple but if you have questions please do ask in the Comments.