Yesterday we talked about anatomy. Today: physics! I know a lot less about physics than I do about anatomy, so maybe I’ll be brief? We can hope.
Force, as we all recall from physics, is mass multiplied by acceleration. When we do strength training, we are essentially doing a physics lab on ourselves. How cool is that? No dorky lab coat required, unless you want to wear one, in which case, do you!
In this instance, the mass part is the easy bit. It’s right there, on the dumbbell rack. Whichever one we choose, it will remain constant throughout our endeavor. (Unless we approach light speed. Then the workout will probably become irrelevant.) The other two parts of the equation will vary. When we lift the weight, we have to accelerate it from a standstill into motion. That initial acceleration against gravity results in a different amount of force than, say, at the top of the motion when we want to slow the movement down, stop it, and start the descent. As the acceleration of the motion changes, so does the amount of force we use.
The good news is that we don’t actually have to do the math on this. We have very smart bodies and brains that do the work for us. Motor units, the functional groups that do the work for us, consist of motor neurons and their muscle fibers. Those are plugged in to the central nervous system.
Bottom line: strength and strength training are a function of the central nervous system. It’s only a slight exaggeration to say that we get smarter when we lift weights.
Go play.