Dr. Andy Galpin

I would love to see that.

Interpreting your VO2 max is more interesting in my opinion because there's a lot of components to it.

And so in order to truly understand this, let's talk about how we calculate VO2 max to begin with.

The easiest way in my opinion is to think about VO2 max equals your cardiac output multiplied by what's called your AVO2 difference.

Now, as I've stated, cardiac output is simply your stroke volume multiplied by your heart rate.

So if we were to combine this entire thing, we would say your heart rate

multiplied by your stroke volume, which says, okay, how much blood am I getting out per pump?

How many pumps am I getting?

And I multiply that by what's called your AVO2 difference.

Now the A stands for arterial, V stands for venous, and the O2 is oxygen.

So what literally this means is what's the difference in oxygen concentrations between the arterial side and the venous side?

Remember, arteries generally go away from your heart, which means they're going to exercising tissue and veins come back.

And so what we're really looking at is saying, okay, how much blood, how much oxygen is in the blood when it leaves the heart?

This is going to be the highest concentration of oxygen possible.

And how much is in the blood when it comes back, having passed through muscle?

This then directly tells you how much oxygen your tissue extracted in the process.

So to give you some numbers here to make this easy, these are not accurate, just representing the math here.

If you had 100 molecules of oxygen that left your heart and went into your quadriceps,

And then once it's gone to the capillaries that surround all the muscles and tissues and fibers in your quadriceps, and it went in as 100, and then it came back out the other side and went back to the heart and lungs to be reoxygenated, if it went in at 100 and came out as 75, the difference between the arterial and the venous side is 100 minus 75, which would give you a score of 25.

Now, what that means, and again, I'm using those round numbers to make this simple.