Only if a more extreme run such as a marathon - but you should be keeping your protein levels high anyway, depending on your goals.
For sprinting, deffo, because that's pretty much the same thing as weights but jogging or running, 'power walking' and all that tends to burn carbs then fat. Relatively little muscle tissue is destroyed once you've conditioned your legs to it.
If you're still at the stage where a run leaves you with DOMS (hurts next day) then sure, protein is your friend but stocking back up on carbs helps too.
My main point is that long distance running, as opposed to sprinting, is NOT a good way to develop great legs or your physique in general. Half an hour on a squat rack will do you more good.
So the next question is why are you doing long runs? If that's your actual interest and you're wondering if protein will prevent you becoming the scrawny chicken-legged type like your fellow runners, sorry bub but that aint gonna work.
Anyway, I'm getting too complicated..
Yes there are benefits to protein after a long run.
Because you haven't eaten for a long time
No it won't make your legs all muscular.
B.