Check out this artical; http://www.naturalstrength.com/resea...ArticleID=1155
So in reading all that what I got is that when one looks at individual motor units it is impossible to increase the force they out-put by increasing the force placed upon them. So what that means is that if I have 20lbs on the bar or 200lbs on the bar there is no difference in the stress a given motor unit which is active is feeling. There is a difference in the amount of stress a given muscle is feeling though as the muscle is made up of a ton of motor units. But the stress that the individual MU's feel is identical, the only difference is the number of MU's recruited to move the weight.
What this transfers out to, as far as I can tell, is that the higher the weight the more MU's are recruited. Now 'big, compound' movements [squat, DL, bench-press?, CJ and the like] are great because they stress a ton of different muscles, which inturn activates the max # of MU's. Since every MU is activated maximaly it is ideal to activate the largest number of them possible in accordance with your training goal.
This then makes me think that the reason CF is so great for stuff like fatloss and GPP is that the movements it stresses focus on full-body type stuff. CJ, Snatch, DL, Squat all activate almost the entire skeletal muscular system, thereby activating the most MU's possible. Since at base it is the activation of MU's that require energy. ie calories, doing stuff like this should burn more calories then just the repeated activation of some smaller number of MU's, as in running and what not.
I guess what all this boils down to is that the 'big, compound' movements are best suited for the achievment of either of two fitness/health goals; strenght or weightloss. Strenght is basic to see I think, actually activating more MU's teaches your CNS how to activate more at one time therefore increasing ones strenght. This then accounts for the strenght gains people see from CNS adaptation rather then muscle gain. Fatloss or conditioning is a little harder. What that comes from is that since you are activating more MU's you are requiring more energy, since each MU activates maximally the only way to burn more energy is to activate more MU's or achieve more MU activations over time.
So does that rambling, bumbling account seem to make sense to everyone/anyone? What do you guys think?