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Old 05-20-2007, 08:26 AM   #9
Paul Kayley
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Join Date: May 2007
Posts: 40

Firstly, great response Neal. You've got me scratching my head, which is what these forums are all about to me.

"The anaeribic sysytem has little impact on maximal aerobic capacity and lactate threshold? I couldn't disagree more. Working in the anaerobic system, specifically the glycolic pathway, imporoves both VO2max and lactate threshold."
Thats not exactly what I was meaning. Yes, I agree that training the type IIa fibres to become more aerobic, and potentially even training type IIb fibres to become more like the IIa fibres, will of course raise the LT and muscle specific oxygen uptake capacity (QO2). I am trying to understand what exactly are the mechanisms responsible in increasing strength which can be carried over into endurance performance?

"Assuming that VO2max is a performance limiter."
From my research it would appear that in sports like swimming, biking, and running - provided an athlete is blessed with, or has trained a high muscle specific oxygen uptake capacity, then the limiter to maximal aerobic performance appears to be central VO2max, particularly cardiac output.

If I get what you're saying here, your assertion is that strength training decreases the amount of intensity that is required to activate higher threshold motor units, and thus cause the higher threshold motor units to perform aerobic work thus changing their fiber characteristics. But, that is the opposite of what happens.
I am asking if it might be that with improved neural abilities (improved wiring conductivity if you want) will one be able to recruit a greater range and number of fibres for the same level of perceived exertion, compared with pre-strength training? And/or as you suggest, is it that in response to high resistance work that the ST contingent become more able to generate force somehow, therefore reducing the need for the higher fibres which 'feel' more difficult to recruit?

I would like to better understand what is physiologically responsible for the increases made in strength following training.... From what I can gather... first there are neural improvements - improved motor unit recruitment (although I cant find a definition of what precisely this means!), intramuscular coordination (defined as "the extent to which individual fibres in a muscle are voluntarily activated"-Zatsiorsky - does this mean that there is such a thing as a 'partial activation' of a muscle fibre... I thought they were 'all or nothing'!), intermuscular coordination (smoothness of action with no antagonistic opposition?), rate coding (speed of MU firing and repetition), MU synchronization (coordinated MU firing); then fibre hypertrophy (sarcoplasmic and/or myofibrillar depending upon type of strength training emphasis). I would like a better definition of what is really happening?

For example, if I get stronger, say, improve my squat from 100lbs. to 400lbs., doing a squat at 100lbs. when my max is 100lbs. will require immediate recruitment of my type IIB, whereas doing 100lbs when my max is 400lbs may only require my ST fibers unless I try and move the weight at maximal velocity.

So, on the contrary, increasing strength increases the level of intensity that is required for higher threshold motor units to get activated.

I think what I'd like to know is why is it that following training to a new max of 400Lbs, the 100Lbs which previously was a maximal effort now feels easy? The untrained 100LBs effort will have involved all available fibres, and now it only requires the lower threshold fibres, mainly the ST and maybe some FTa? If this is the case, then strength training is somehow increasing the force generation abilities of the ST fibres, which is a very positive argument in its favour for endurance athletes.

Could this the case???
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