The Rotator Cuff: What is it and what does it do?

In baseball, we often here about the rotator cuff. We hear about big leaguers missing time due to a rotator cuff injury or we hear our coaches saying we need to strengthen pitchers rotator cuffs.  But what is the rotator cuff and why is it so important? Unfortunately most coaches can’t even point to the rotator cuff muscles let alone explain to you what purpose they serve.
The rotator cuff is comprised of four muscles including the supraspinatus, infraspinatus, subscapularis, and teres minor. rotatorsThese muscles begin on the scapula (shoulder blade) and end on the proximal aspect of the humerus. They are responsible for several movements including internally and externally rotating the shoulder as well as moving the arm away from the body (abduction).However, the most important function of the rotator cuff is for the muscles to work together to provide stability to the shoulder.
We often think of the shoulder as a “ball in socket” type joint. However, it is more accurate to think of it as a golf ball sitting on a tee. The golf ball represents the head of the humerus, which is the long bone in the upper arm. The rotator cuff works in synergy to provide stability to that joint. The rotator cuff also works to help decelerate the arm once we have released the ball.
If we are throwing properly, the power comes from our legs and core which is then transferred to the arm. All of that power must be harnessed and controlled at the point of the scapula via the rotator cuff before being transferred to the arm and eventually hand/ball. Our scapular stability becomes the limiting factor for how hard we can throw accurately. We all have two speeds we can throw: hard as we possibly can with no idea where it is going and hard as we can while being able to hit a target. Properly training the rotator cuff can help bring these two speeds closer together.
We all know players who throw hard but walk as many people as they strike out. Higher levels of competition will eventually weed these guys out. Most Division 1 college baseball programs want their pitchers at a 3:1 strikeout-to-walk ratio or higher. Keep in mind that means three strikeouts for every walk against Division 1 hitters. At the high school level, they are looking for something closer to 5 or 6:1. With poor scapular stability, it will be nearly impossible to achieve these metrics.
Our orthopedic assessments will evaluate your rotator cuff function as a scapular stabilizer and give you the tools you need to keep it healthy, build arm endurance for the later innings, and improve your accuracy from both the mound and in the field.
About Tim Lynn, DPT

Tim Lynn is a Wadsworth, Ohio native that attended Canton Central Catholic High School where he was a 4 year member of the varsity baseball team. Following his time at Central, he accepted a baseball scholarship to pitch at the University of Dayton. He performed both starting and relieving roles for the Flyers during his freshman season. He underwent Tommy John surgery in the fall of his sophomore year but was able to return to the mound nine months later. He was able to lead the Flyers pitching staff in ERA his senior year.

While rehabbing from Tommy John surgery, Tim became very interested in the biomechanics of the throwing motion and how these types of injuries can be prevented. This lead him to pursue a degree in Pre-Physical Therapy. Upon finishing his undergraduate degree, Tim stayed at the University of Dayton to earn his Doctorate of Physical Therapy Degree. The focus of his studies involved biomechanics of the throwing athlete and injury prevention combined with sports performance. He had the opportunity to participate in research projects with NBA franchises and collegiate athletes from a variety of sports, further deepening his background.
Tim currently serves as the clinic director for two Orthopedic Physical Therapy clinics in Stark County. He practices orthopedics as well as sports medicine. He specializes in manual therapy, dry needling, and full-body assessments of the throwing athlete. To set up an orthopedic evaluation, please click here or email

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