Dr. Andy Galpin

Now, this is interesting because while we were just starting to get data on lifelong exercisers, almost all of that has been in aerobic or endurance-based exercisers.

We're just starting to come on board with these lifelong strength trainers.

And what that paper found was that that activity,

to strength training basically over your entire life was able to preserve fast twitch fiber concentrations.

However, the endurance training was not.

And so it's not to say that strength training is more important or better for your health at all, but it is simply saying these fiber types are lost.

You're not able to get them back, but you can preserve that or ameliorate that loss by chronic strength training.

Now, you're going to care about these fast twitch fibers for a

While we will acknowledge that both fast and slow fibers are critically important for overall muscle health, what makes fast-twitch fibers unique is a few things.

The first is that, again, they express the greatest capacity for force and power production.

This is obviously critically important for young folks trying to enhance their club head speed on their driver when they're playing golf.

or individuals as they move throughout age.

Think about scenarios in which you need to move your foot in front of you to catch yourself from a fall.

You want to be explosive enough to go upstairs without it fatiguing you.

You need to have power to lift something up overhead quickly before it collapses back down in you, or any number of reasons in which you need to have strength and power as you age.

Now, the way that you regulate force production extends beyond just what the muscle fibers themselves can do.

Unfortunately, I've got to give a little bit of credit back to the neuroscientist folks here, because really this is a combination of nervous system as well as muscle fiber characteristics.

All of your muscle fibers...

are combined into what are called motor units.

So the definition of a motor unit is the motor nerve, as well as all the muscle fibers within that package.