Originally Posted by TomT
Not that similar to my arm arrangement at contact (which is upper arm within ~ 10 degrees of alignment with the shoulders, and lower arm within ~ 15 degrees of alignment with the upper arm -- a much smaller angle than the ~ 90 degree elbow flexion you were experimenting with, as you note below).
When I look at your first video
At 14 sec, around impact, which is hard to see, I would say that the angle between your forearm and your upper arm is much larger than 15°, guessing roughly 40°. Also, your upper arm may have a more forward angle to it relative to the line between the shoulders.
Keep in mind also that the camera is showing you a 2D projection of the 3D space so things can be deceptive, especially shortened, etc.. What camera and frame rate were you using and can you set a faster shutter?
It looks as if you stretch the internal shoulder rotator muscles very cleanly with external shoulder rotation. Sec 7-12.
Anyhow, some serving technique observations for you to research.