Dr. Andy Galpin

Well, there's a very specific reason. First of all, it's pretty good. If that's all we can do, I'll take it. That's a win. But your muscles are actually constructed of hundreds of thousands of individual muscle fibers. So think of this like a ponytail. So a ponytail you think of as like one thing, but in reality, it's just a conglomerate of a bunch of individual hairs.

Well, there's a very specific reason. First of all, it's pretty good. If that's all we can do, I'll take it. That's a win. But your muscles are actually constructed of hundreds of thousands of individual muscle fibers. So think of this like a ponytail. So a ponytail you think of as like one thing, but in reality, it's just a conglomerate of a bunch of individual hairs.

That's how your muscles work. You have lots of hair, we call them muscle fibers in there. Each one of those muscle fibers can be broadly categorized as either fast twitch, Or slow twitch. Fast twitch does what it sounds like. Slow twitch has more mitochondria in it. It handles most of your basal physical activity. Right now, you and I are using almost exclusively slow twitch fibers.

That's how your muscles work. You have lots of hair, we call them muscle fibers in there. Each one of those muscle fibers can be broadly categorized as either fast twitch, Or slow twitch. Fast twitch does what it sounds like. Slow twitch has more mitochondria in it. It handles most of your basal physical activity. Right now, you and I are using almost exclusively slow twitch fibers.

Nothing we're doing fast here. Right. And so they're not fatigable. So if I ask you to take your finger, maybe your right finger, left finger, we'll do left finger. and reach up and touch your nose with that left finger. Now, what you just did right there is you activated a set of neurons that said, okay, turn on the muscles in combination to touch that nose.

Nothing we're doing fast here. Right. And so they're not fatigable. So if I ask you to take your finger, maybe your right finger, left finger, we'll do left finger. and reach up and touch your nose with that left finger. Now, what you just did right there is you activated a set of neurons that said, okay, turn on the muscles in combination to touch that nose.

The neurons you just turned on are very low threshold, which means they're easy to activate, they're very energy efficient, but they're gonna activate generally those slow twitch fibers. Now, if I said, grab that can of juice, will you? Or juice, sorry to call it juice. Tea? Yeah, sparkling tea. Yeah, okay, great. Put that back in your left hand.

The neurons you just turned on are very low threshold, which means they're easy to activate, they're very energy efficient, but they're gonna activate generally those slow twitch fibers. Now, if I said, grab that can of juice, will you? Or juice, sorry to call it juice. Tea? Yeah, sparkling tea. Yeah, okay, great. Put that back in your left hand.

Now, do the same exact activity and raise it to your nose Boom. You just did the exact same process, but you needed to produce more force. Why? Because you got an extra eight ounces or something in that. So your body went, wait a minute. I'm assuming nothing was going to be in my hand, but then I realized there's an additional amount of force needed. And so how did it increase force production?

Now, do the same exact activity and raise it to your nose Boom. You just did the exact same process, but you needed to produce more force. Why? Because you got an extra eight ounces or something in that. So your body went, wait a minute. I'm assuming nothing was going to be in my hand, but then I realized there's an additional amount of force needed. And so how did it increase force production?

Your muscle fibers can't squeeze any harder. When they contract, they contract as hard as possible every single time. The only way that you increase force production is to turn on more of those nerves. We just train our nervous system. That's what it is. More of those nerves turned on.

Your muscle fibers can't squeeze any harder. When they contract, they contract as hard as possible every single time. The only way that you increase force production is to turn on more of those nerves. We just train our nervous system. That's what it is. More of those nerves turned on.

If I were to now take that T and we made it 40 kilos, the only way that you can continue to produce more force to lift it up to your nose is to turn on those additional motor neurons, which are going to be your fast-twitch muscle fibers. So if we extend this all out, when you're doing those other activities, you're not ever going to get to that high threshold.

If I were to now take that T and we made it 40 kilos, the only way that you can continue to produce more force to lift it up to your nose is to turn on those additional motor neurons, which are going to be your fast-twitch muscle fibers. So if we extend this all out, when you're doing those other activities, you're not ever going to get to that high threshold.

You're never going to use those muscle fibers. And so one of the things we know happens with aging, when we omit strength training or strength training-like activities, those motor neurons and those muscle fibers die. And this is why we lose strength and power as we age is because we never activate those neurons. I don't care about getting you PRs in the gym right now.

You're never going to use those muscle fibers. And so one of the things we know happens with aging, when we omit strength training or strength training-like activities, those motor neurons and those muscle fibers die. And this is why we lose strength and power as we age is because we never activate those neurons. I don't care about getting you PRs in the gym right now.

We're trying to make sure that we just don't lose any functional capacity 50 years from now. The sprinting that got your legs sore was good. But those nerves are turned on when force is required. We didn't get enough physical force production. This is the exact same reason why things like body weight exercise is great. It's good. It can take people a long way. But eventually...

We're trying to make sure that we just don't lose any functional capacity 50 years from now. The sprinting that got your legs sore was good. But those nerves are turned on when force is required. We didn't get enough physical force production. This is the exact same reason why things like body weight exercise is great. It's good. It can take people a long way. But eventually...

We're going to run out of some options here, especially for our lower body, because we just won't have enough load to activate all the nerves or the motor units rather in the legs to truly get force production to keep them as strong and healthy as possible. So that third category we're talking about, remember category one was kind of physical activity.

We're going to run out of some options here, especially for our lower body, because we just won't have enough load to activate all the nerves or the motor units rather in the legs to truly get force production to keep them as strong and healthy as possible. So that third category we're talking about, remember category one was kind of physical activity.