Test Sets, Metabolic States, and Lactate Threshold for Swimmers


When I first read “Swim Coach’s Bible” volume one, I got lost when they started talking about things like VO2 Max and Lactate Thresholds -1 or +1 sets. When I got to volume 2, well that didn’t clear things up either. Application was fairly easy, but I wasn’t sure what theory or premise they were working from.

So, if you are in a similar boat this might be a good place for you. After getting started, I realized that it might take more than one post.

Ok, the chemistry for beginners:

Your body burns ATP –  adenosine triphosphate – because when you break off one of those three phosphates it releases the energy needed to contract your muscles or do any one of a jillion (technical term meaning a lot) of chemical processes in your body. But you can only store a limited concentration of ATP in your blood/muscles/fluids.

So, it’s too bulky for long term storage.

Sugar (glucose) works better.

Glycogen (chains of glucose) work better.

Fat (chains of hydrogen and carbon) can be used to make both sugar and glycogen.

All of these require some break down in order to produce ATP, and all of them are being broken down constantly in our body to keep things running. Depending on the type and duration of any given activity, what gets broken down or used in what quantity all changes.

ATP concentration tries to stay level, but you will burn through strictly ATP in ~10 seconds. After that it goes to sugar, then glycogen, and after an hour and a half fat becomes dominant. Of course all of them are going on all the time, it’s just a matter of which one is dominant and how much of any fuel is getting burned.

Now, here’s the important bit: when processing sugar to make it ATP there are a ton of pathways. Google krebs cycle or citric acid cycle if you want to see some of them. One produces lactate which forms lactic acid.


Well because you need oxygen to break down glucose all the way and get the most ATP out of it. When you don’t have oxygen – jumping to lactate produces extra ATP while waiting for enough oxygen to get there. Lactate offers a few metabolic helps along the way – but that is really a distraction from the main point.

All of this I learned in Biochemistry 101 (it was not a 101 level course).

What it meant for swimming, I couldn’t have told you then. I had to read about what it means not in the swimming books. Instead, why this matters I found on various cycling and running websites. Mostly, I found it on cycling sites.

What it boils down down to is this: your lactate threshold is where you are working so hard you are burning ATP so fast that your body has to create lactate faster than it can be burned off. With regular training, the pace that you go when this happens changes. Pushing past this point is what gets you there – pushing past in measured amounts.

Next time, I’ll offer a couple of my theories regarding test sets (ways to figure out what pace this happens at for you), and why continuing to measure where your lactate threshold is over the course of training is important (one of my college coaches missed this memo).


About Sean Smith

Husband, Father, Pastor, Swimmer, Writer, Reader, and attempted Adventurer!
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