Quote (bnrhodes2 @ Mar 1 2016 01:44am)
I didn't know about the EMG, but I never delved deeply in to the subject. The hand dynamometer was more as a gauge for training response than for an actual CNS test I suppose. The purpose was for the actual planning of the training than for the root physiological reason of the fatigue - there is undeniable fatigue and it can be observed, but CNS fatigue or overload may be the incorrect term that is used by laymen. I can't say that it is possible to easily ascertain the actual scientific cause of the fatigue without testing in a lab, so a practical approach in the field is beneficial for real world use in training manipulation.
I don't have the answers obviously, nor do I necessarily have the correct explanations as to why it happens, but I do know that nervous system response and fatigue does play a role in training and have been around enough elite athletes to have seen and heard discussion of such. I would be interested in seeing this stuff tested and observed in populations that have highly acute senses of the states of their bodies. I have seen so many instances of up and down days when it comes to response to stimulus, that I can't decide what else to attribute it too.
I can only relate with my own experience since I don't have the lab to test these things, and I know that with science, anecdotal and untested information isn't good enough for an explanation. I just see what is going on in the field. I know the throwing events in track and field as that is where my experience has been for over a decade - in that time I have trained with and observed world champions, olympic medalists, and world record holders. At that level of performance, their strength and power has reached a point that training in that aspect generally at a point of diminishing return and they stay around that level. Their main improvements and focus then come from the neural connection with technical changes, rhythm, and response to stimulus (such as ground contact time for force application, application of force to the implement, velocity in varying parts of the technique, etc). That is generally how they talk about their training - how it feels, how they can respond to movement, how they can cause movement, etc. So when there are days or weeks where that response is down, they refer to it as nervous system fatigue. That may be the incorrect way to label it, but when people talk about CNS fatigue, I think that is what they are referring too. When someone is highly in tune with their body, they can tell the difference between being tired, having soreness/doms, and actually feeling like your body won't respond to stimulus the same way. I just don't know what else I would call the later of those things.
When I talk about CnS fatigue I'm not counting motor learning as part of that. Motor patterning is a completely different story as well but the brain and spinal cords ability to innervate muscle sufficiently does not diminish over days of training. Metabolic fatigue is certainly possible ( lack of substrate ) and like I said chronic structural wear but the neuromuscular system doesn't fatigue in the long term as far as we currently know