Nervous system question.

[katiesaliba]

Would holding one's leg out (as a dancer would) develop leg strength by increasing the number of neuronal pathways? Considering the relatively small portion of the brain that concerns leg movement, it would cohere to some degree of logic. More neuronal pathways allows faster signal transmission and so the muscles would contract for longer periods of time, right? I know that this is probably beyond the scope of VCE biology, but I'm curious

[slothpomba]

More neuronal pathways does not mean faster transmission. It depends on the kind of neurons they are, the diameter they are and whether they're myelinated or not.

Neurons can be thought of as wires in a physics sense, a larger wire retains charge for longer (or think of a small pipe vs a large pipe with a hole in it and water running through). Larger neurons have their action potentials maintained for longer. Likewise, myelination (wrapping them or "hugging them with" myelin) greatly speeds them up/prevents degradation of the action potential. In general though, simply adding more neurons doesn't make that AP any "faster". More neural inputs can sum up (like 1+1+1+1), so, perhaps more neurons innervating a specific area would generate more EPSPs (excitatory post-synaptic potentials) making it much more probable (therefore easier for) the particular neuron to fire.

Keep in mind i'm far from an expert on muscles. That said, i believe neural adaptation does have some role to play in the earlier stages of learning any manual skill - Dancing, running, etc. Take the martial arts like Kendo (where you use swords), you need to be precise in your movements, you will actually probably have some degree of neural changes early on. Even in terms of starting a new running or weight lifting programme. This will quickly be eclipsed by strengthening and enlarging of the muscle though.

It's likely you've just developed your muscles more through sheer training. Try walking up like 50 stairs, you can really feel it in your legs. If you keep doing it for long enough, you'll eventually become better at it and you'll find you have stronger (and probably larger) leg muscles. Just a little interesting trivia too - If you look at very skilled kendo practitioners in Japan, they have tiny biceps (i guess the attractive muscles) and large forearms because swinging a sword in Kendo correctly is done with those muscles alone (kind of the reverse look most guys go to the gym for).