I hear the phrase in the thread title a lot, especially associated with doing deadlifts too much. I also hear it in relation to warming up; do box jumps before your workout to really fire up the CNS, etc.
I understand what the CNS is but I guess I don't really understand why deadlifting too much would 'exhaust' it more than say squatting, what exhausting it specifically means, and why box jumps 'fire' it up.
Figure I should know everything about something before I suggest the same things to a friend and not be able to answer them if they ask 'why'?
Also another question completely off topic from the title but one I don't feel merits its own thread:
My friend likes to drag me along to a 15 minute ab class every once in a while. I figured it can't hurt. I jokingly called it a 15 minute hip flexor class because that's what feels sore and that's what I feel working when I do the class. The instructor told me it's because my abs are too weak and my hip flexors are compensating. Does this sound right? The class is mostly just doing a bunch of movements (flutter kicks, holds, scissors, up / downs, etc) with the legs while holding them 6 inches off the ground.
Thanks for any help!