Originally Posted by toly
I analyzed Federer inside out hard FH on the APAS System http://www.youtube.com/watch?v=pPLmCqGIotM
There are data about his arm speed and acceleration around the wrist during forward swing.
The picture demonstrates that Federer is able to increase acceleration/force of the arm from frame #1 to #9. The magnitude of the force declined after frame #9. Around impact, frame #24, acceleration decreased more than 70%.
So, he is not able to accelerate the arm significantly near impact. But, this is very hard FH and without doubt he is trying to produce maximum acceleration/force.
Question: What is wrong with Federer?
There is figure from http://sanderroosendaal.wordpress.co...raction-speed/
Figure 1. Muscle force versus muscle contraction speed
Figure 1 shows the muscle force versus muscle contraction speed. It’s a very important graph because it marks where classical mechanics stops and exercise physiology starts. Note that the graph is idealized, with no absolute values on the axis. Each athlete will have a slightly different graph, which will probably also change as a result of training.
This fundamental property of muscle has numerous biomechanical consequences, including limiting racquet speed and force around impact.
So, there's nothing wrong with Federer. It's just a biomechanical law that he must unquestioningly obey!