External rotation or lack thereof

When doing some backwards chaining drills and just overall throwing th ball hard I saw that on camera that once my arm gets into the high cock position it just stays like that as my shoulders rotate. My forearm lags behind 15 degrees max. What I see in elite pitchers is around 90. Any help would be appreciated and I can put up a video if someone needs to see what I am talking about.

The inertial mass of the baseball pushes the forearm back into “external rotation” (really external rotation and scapular tilt, but whatever). The faster the lead shoulder rotates and decouples from the rear shoulder (and the faster forward trunk tilt happens, amongst a few other kinematics) will primarily determine the amount of layback - as will dynamic and static flexibility in the shoulder.

I highly doubt you are getting 105 deg of ER (90 is arm in high cocked position by ASMI’s measurements) if you throw at all reasonably hard. More likely it’s happening way too fast for you to see. A video will help.

About the video being too low of a frame rate, I figured that was the problem. I’m just kind of caught up on how to properly use the upper body to whip the ball. More trial and error to go… and also what is your definition of reasonably hard throwing?

Wouldn’t separation also be a factor if coupled with the torso/shoulders? The shoulders would rotate at a higher velocity, thus laying the arm back at a greater angle.

How does the lead shoulder “decouple” from the rear shoulder? What does this mean?

“Decoupling” is just another - more accurate - word for separation. People get too caught up with the idea that the hips rotate ahead of the shoulders via promotion of the bottom-up teaching philosophies out there. I generally think that people need to learn to control the distal appendages of the body first and work down, similar to SETPRO/Woforth backchaining methodologies.

What “separation” often feels like is NOT the hips rotating ahead of the shoulders, but the greater amount of “scapular loading” occuring as the lead shoulder drives back and down and the throwing arm shoulder stays behind - rotation of the upper trunk is initiated by the glove arm shoulder as the hip pulls the trunk into rotation and forward flexion.

The best example of this is obvious Tim Lincecum in this famous pose:

Or Trevor Bauer:

“Reasonably hard” would be 75 MPH. Probably even lower than this.