[MUSIC] So how does exercise impact how we recruit our, motor units? And it has a big effect. Strength training, lifting weights immediately starts to increase the likelihood that fast fatiguable motor units will be recruited. So, whereas if you haven't exercised in a while you lead a sedentary life maybe 60% of your fast fatiguable motor units will be recruited if, if asked to, to make a strong a muscle contraction as possible. But after a single bout of lifting weights you're going to get much closer to 100%. In addition, the ability of these fast fatiguables the, the firing pattern of them will change. So that for every, so that the likelihood that more force happens, is increased. And that is essentially through a firing pattern whereas instead of doing this, there's an action potential like that. There are these doublets. And two action potentials right next to each other. Instead of producing, if this produces increases in strength that go like this, this produces increases of strength that go like that. So the doublets produce more force for than single action potentials. Now all of these things are short term. They happen pretty immediately. They last for about three weeks. What happens in three weeks? Well, muscle mass. So, you sort of get this transition from neural mechanisms of strength to muscle mechanisms of strength. The muscle fiber itself can grow. And that increases the force that the muscle fiber produces. And so in about three weeks, it's the muscle fiber that is, has grown, and now these, these, the recruitment stays but, some of these other, short term adaptations pale in comparison to the increase in, in muscle size. So the muscle mass grows. And the contractility of the muscle also can change. So, short term, thereâs a lot of neural effects. And then more long term, get a lot of muscle effects. [MUSIC]