Originally Posted by dominikk1985
at the very end when the chest is nearly facing the net. biomechanically the best time is when the trunk rotation has reached maximum speed and starts to decelerate.
look at this javelin thrower:
while his body rotates the arm barely moves and while the arm moves the chest barely moves (stopped). high level is to rotate early and separate the arm action from the rotation a lot.
the rotation adds some MPH but the actual shoulder velocites are quite low (under 10 mph). that means the main effect of rotation is not pulling the arm around (although that also plays a role) but to create potential energy and pre stretch the muscles above for their contraction.
Ok thanks that makes sense. But so when the chest is nearly facing the net, you are saying the arm is not to be whipped around passively at this point, but to be actively accelerated using the shoulder muscles, right? Also where exactly on the swing path is the RACQUET when this happens? About half way through the swing path, no?