Dr. Andy Galpin

but the left ventricle pumps it out of your heart in throughout the entire rest of your body, down to the tip of your toes, and then all the way back up into your heart.

So it has to have enough force to have all of that blood moving up against gravity, fighting through muscular contractions to get blood all the way to return.

Now you have some ways that you can help that blood return along the way, but primarily that's what the left ventricle has to be able to do.

And so because it is asked to have a higher function, in other words, produce more force,

it actually is larger.

There is an association at all times between muscle size and muscle strength, though that is not linear, and we'll discuss that in other episodes.

And so globally, the left ventricle is larger.

What's also unique about the heart is that the way that the muscle fibers themselves are made up.

And so you see your heart, like any muscle, is just a composite of many hundreds, if not thousands, of individual muscle fibers.

And we will talk again about the nature of those in the skeletal muscle episodes.

But for now, we need to think that they are actually quite different.

And so while you think of muscle, your biceps muscles or hamstrings muscles or quadriceps muscles, they are meant to have specific functionality.

A term that we're going to use in muscle science all the time is structure equals function.

So the structure, the way that it is built equals the functionality.

So as a quick example, your hamstring muscles.

are primarily meant for explosive movements, to run, sprint, jump, stuff like that.

And so the way that they are built, the way that they contract and oriented and attached to the bone are different than, say, your spinal erectors, your low back muscles that are meant to just keep you up and vertical all day.

They're not really meant to be exploded or contract with a lot of force.

They want to be on and contracted mildly to keep you vertical and erect with that nice, great posture.

When we go to the cardiac side, then we start thinking, okay, what is the actual need and demand of the heart?