Can you calculate % of V02 max at which you're working using pulse ox readings?

Question

Can you calculate % of V02 max at which you're working (assuming it's >100%) by measuring change in blood oxygenation with a pulse ox?

My understanding is that working at >100% VO2 max means you're not absorbing enough oxygen to fully re-oxygenate your arterial blood (ie going hypoxic, which, I believe, is what a pulse ox is often used to detect). It would seem, then, that by measuring the rate at which your blood oxygen level is decreasing, that "oxygen deficit" could be quantified.

Am I missing something? Would this actually be feasible? (I don't have any sense of how much blood oxygenation level would change and how sensitive/accurate the readings are from a pulse ox)

Thanks!

Edit

What first got me curious about this question was trying to experiment with the original Tabata HIIT regimen (the "IE1 protocol": 8 intervals of 20s at 170% VO2 max, followed by 10s of rest). I realize that actually paying attention to readings during the exercise is likely unfeasible, but was wondering if looking at pulse ox data after the fact could give a sense of whether the intensity goals were met.

Answer 1

While it's an interesting question, it would be a very short lived time anyway.

VO2 max is the maximum oxygen your body can use at a given (usually fairly intense) activity level. If you exceed this work level, then you are working anaerobically, and the energy pathways for that are short lived at best. Up to VO2 max, your normal readings should be in the 95-100% range anyway.

For example, about the maximum distance you could probably work anaerobically (Depending on your own efficiency and speed while running) is not much more than 200m. After that, your anaerobic energy pathways are pretty much spent, and you have to start relying again on aerobic methods. This would force you to slow down, as you couldn't sustain the workload. So, by the time you can even really pay attention to your oximeter levels, your body is already putting on the brakes for you.

That being said, VO2 max is not that great of an indicator/metric to use. It's basically a number that is a predictor of possible performance, and doesn't really mean that you will perform at that level. You can increase your VO2 max simply by losing weight. A much better metric to use is VVO2, or Velocity (speed) at VO2 max.