Dr. Andy Galpin

Within the population of participants that we analyzed, there was no relationship whatsoever between their physical strength and their muscle mass.

In fact, there was also no relationship at all between their amount of muscle mass they had and their physical activity background.

What this tells us is in this population alone, they accrued their muscle mass from non-exercise pathways.

What we did actually find was a strong relationship between muscle strength and cognitive function, but that's something we'll talk about in a further episode.

So my point here is when you look at the relationship between, again, muscle mass and strength, they can overlap.

They can also not.

We can see further evidence of this when we look at things like mitochondrial health, testosterone concentrations, range of motion.

A lot of these things are somewhat linked to muscle size, but not necessarily.

In the last example, think about this as if you were to take somebody who has more muscle mass, that will tell you actually very little about their range of motion or flexibility, right?

If that extends to a certain point, of course, excessive amounts of muscle mass may start contributing.

And so again, there's an overlap there, but there's so much distinction between the two.

I think it's important that we actually treat them as almost separate variables.

We're going to start off with muscle quantity or muscle size.

The gold standard here in research would be to use something like an MRI or an ultrasound to get a high-resolution cross-sectional image of an individual muscle or muscle groups.

Think, again, the quadriceps, hamstring muscles, elbow flexors, etc., etc.

The benefit of this, of course, is high fidelity, accuracy, and precision.

The downside is it's really only telling you about that individual muscle or muscle group.

It's really only covering that portion of it.

So where the MRI is shot, it may necessarily cover, say, the part of the quadricep that's close to your hip or close to your knee if the MRI was taken at, say, the midpoint of it.

It doesn't really allow you to access or compare the right leg to the left leg unless you also image that leg.