It’s no secret that Driveline Baseball is a pioneering force when it comes to high-speed video and its application to training pitchers and analyzing pitching mechanics here in the Pacific Northwest, but an underappreciated consequence of analyzing our pitchers using the Edgertronic, that can shoot up to 17,000 fps, are the training-related modifications to their workout programs.
External Rotation – Two Factors That Matter
Pitchers who have more Maximum External Rotation (MER) during the end of the arm cocking phase and the beginning of the ball acceleration phase of the pitching delivery will tend to have more laxity in static external rotation and a tighter posterior capsule when stretching the shoulder into internal rotation (IR). This isn’t anything new, of course – for years, trainers have been telling their baseball athletes to stretch their shoulder into IR using the sleeper stretch or a variant of that stretch.
However, the absolute value of MER is only one factor that we pick out using high-speed video (tough to tell on standard video due to motion blur). The other factor is the rate of external rotation during the pitching delivery. If a pitcher has a more internally rotated humerus at stride foot contact (SFC) compared to a pitcher with a less internally rotated humerus, all things being equal (primarily shoulder and hip rotation angular velocities), the pitcher with the more internally rotated humerus at SFC will experience a higher rate of the forearm entering maximum external rotation (rMER). Pitchers with this mechanical marker are often described in research papers as having more stress on the bones (Werner et al) and ligaments (Fleisig et al) of the pitching arm. This mechanical “flaw” is generally described as the Inverted W or Inverted L by various gurus out there. While the discussion of the Inverted W / Inverted L is a series of blog posts I have planned in the future, let’s stay focused on how this would affect a client of ours. While we might suggest mechanical changes that lower the amount of rMER without compromising the amount of MER the pitcher gets to (since higher rates of MER are positively correlated with ball velocity – Fleisig et al), we can address the muscular issues this flaw may cause in the trainer’s room.
Corrective Exercise for the Pitcher with High rMER
The sleeper stretch above is a great posterior capsule stretch that we might use for pitchers with higher-than-normal rMER, but isometrically working the external rotators at the specific degree of IR can be very helpful. Isometric strength training is fairly controversial in the exercise science community, but most will agree that isometric training works within a small range of motion where the training is being used (some say as high as 15-30 degrees). Consider this: When the pitcher releases the baseball, the humerus is very close to its maximum internal rotation angular velocity – after which it rapidly decelerates, putting a lot of stress on the decelerators of the shoulder. By putting an athlete in a position where he releases the baseball (another marker you can generally only see with high-speed video) and having him isometrically work his external rotators (not internal – he’s already getting a lot of work by throwing baseballs), he can strengthen the muscles responsible for safe deceleration where it’s most important!
How to do this: Imagine the sleeper stretch above. Have an assistant place their hand on the distal wrist of the pitcher and position the forearm and hand where the pitcher approximately releases the baseball in relation to his shoulder. Instead of pushing down to stretch out the posterior capsule into IR, have the athlete press against you into ER for 5-15 seconds for multiple reps. Give him a rest and repeat this every so often. Try it on his glove arm – I bet you see a major difference in perceived strength!
Appropriate Exercises to Pair
Pair passive ER strengthening techniques like backwards medicine ball throws with this for maximum benefit:
As well as shoulder perturbations and/or manual therapy as necessary. High-speed video can help in multiple ways – while it’s incredibly useful for mechanical analysis and review, don’t forget it has a huge place in the weight room and trainer’s office for strength and durability.