Grüß Dich,

Der Sinn der Kontraktionsphase besteht darin, Schwung für die positive Phase "auszuschalten" und damit die ATP - Querbrückzyklen der Muskulatur besser kompensiert werden können. Desweiteren wird elastische Energie von außen ( Momentum) "gekillt". Dadurch erreichst Du eine höhere Rekrutierung von Muskelfasern > Mehr Schäden an Muskelfasern > Mehr Wachstumspotenzial. Im allgemeinen führt das zu einer höheren neuromuskulären Aktivität.

Kleiner Text dazu (Ist aber leider englisch):


A similar situation – on a much, much smaller scale – occurs as people fatigue during exercise, and you have some cross bridges which might not be able to detach due to ATP depletion – but of course all the rest of the muscle is attempting to lengthen, so there’s nothing else that can happen except damage to those cross-bridges. And the degree to which cross bridges can be formed depends of course upon the overlap of the myofibrils --- and the more overlap, the greater potential number of cross bridges that can be formed. And if you look at it that way it makes more sense to go into the fully contracted position during exercise. And if you’re going to do a static hold there’s really no other place that could be better than the Max Contraction position, because in that position you have the greatest potential for cross bridge attachments to be formed and, if you’re using a heavy enough weight, once you get to a point where you can’t hold it and that muscle has to lengthen, you’ve got more potential cross bridges that aren’t going to be able to let go and that are going to be damaged during that brief lengthening. And of course there’s other structures that are being subjected to some degree of damage as well – cell walls, etc., -- but overall being in that position of Max Contraction is what’s going to contribute to the micro-trauma and to the degree of growth stimulation.
Grüße Lefty