Hey I think you guys (Arioch and ZZulu) are making this a black and white issue, like only CNS potentiation and size of muscle affect strength.
Eh? I am saying just the opposite, that it is impossible to say, and that there are far too many factors to have anything beyond simple working theories.
What about concentrations of various substances within the muscle?
Depends. Using limit strength as the example, there is not a lot that will affect this aside from certain issues which I will adress below. Hydration is a key factor, however.
As per the first, this is the principle that creatine supplementation works off of, making ATP more readily available in larger amounts to muscle cells.
ATP-CPK cycle takes about 6-10 seconds to effect a contractile change. Not too many lifts take that long to complete, however long it sometimes feels like. If one were doing more than one rep, this would certainly be an issue.
Who knows, maybe the concentrations or relative concentrations of substances such as calcium and potassium can affect strength. A severe deficiency would certainly cause severe weakness.
This is quite true, as well as numerous other minerals. Once again the importance of proper nutrition is displayed.
Isn't it possible that the 145 lb guy who benches 450 could have more of those per muscle cell in his pecs than the 215 lb guy that benches 350? This would amount to a higher strength vs. cross sectional area ratio.
Already been adressed. Differences in motoneuron function, motor unit ennervation, rate coding, synchronization, etc. are all part of the Neurophysiological structure that affects the ability of a muscle to generate force. And as was previously mentioned, it is hard to draw the line as to where neural ends and hypertrophyic response ends, as even fiber structure and size can effect the functioning of the motoneurons.