Preventing Shoulder Injuries in Baseball Pitchers
Overhead throwing is an extremely complex movement that places significant stress on the shoulder joint of a pitcher. The shoulder is a hypermobile joint that is susceptible to injury from the repetitive high stress of pitching. Upper extremity injuries comprise more than half of all baseball injuries, the majority of which are shoulder injuries and affect pitchers more than position players. Physical therapy can effectively treat baseball-related shoulder injuries and help pitchers prevent injury through a throwing mechanics assessment and pre-season conditioning program. A successful rehabilitation program is multi-phased, gradually re-introducing the functional demands of the pitcher’s position for a safe return to sport.
Anatomy of the Shoulder
Overhead throwing is an extremely complex movement, starting from the foot and ankle generating force from the ground and transferring that force throughout the body to the shoulder and arm until the ball is released from the pitcher’s hand. Baseball pitchers are particularly susceptible to shoulder injuries due to the repetitive and extremely high stress of overhead throwing on the shoulder. The shoulder is a highly mobile joint with a wide range of motion, which allows for powerful overhead throwing; however, the price for such mobility is less stability in the shoulder. The stabilizing forces of the shoulder are incredibly complex and can be vulnerable to injury.
The shoulder is made up of a ball and socket joint comprised of the humerus (upper arm bone), shoulder blade, and collarbone. The head of the humerus fits into a rounded socket in the shoulder blade (the glenoid) that is surrounded by strong fibrous tissue, the labrum. The labrum deepens the shoulder socket and stabilizes the shoulder joint while serving as an attachment point for many of the ligaments and tendons of the shoulder.
Three important ligament and tendon groups in the shoulder include 1) the rotator cuff which is made up of four muscles that come together as tendons to form a cuff of tissue around the head of the humerus, 2) the biceps muscle and tendon that attach at the shoulder blade, and 3) the shoulder capsule which is a strong connective tissue and ligament system that keeps the head of the humerus centered in the glenoid socket.
Mechanics of Throwing in Baseball Pitchers
There are six phases of the throwing motion: windup, stride, early and late arm cocking, acceleration, deceleration, and follow-through. A deficiency at any point in the throwing cycle can contribute to increased stress on the thrower’s shoulder.
Phase 1: Windup: The windup phase begins with the pitcher’s first movement from that static position of facing the batter with both feet on the mound and ends with the lead leg reaching maximum knee height. The risk of injury is low, but it is essential that the pitcher reach a balance point position in which the pitcher’s shoulders are aligned between home plate and second base with a stable center of gravity stabilized by the ankle, leg, gluteal, and lumbopelvic muscles.
Phase 2: Stride: The stride phase begins with the throwing shoulder horizontally abducting to 90 degrees and ends with the front foot striking the ground. From the ground up, the athlete engages the ankles, legs, pelvis, core, thoracic spine, and shoulder. It is key to have good lumbar stability and thoracic mobility.
Phase 3: Cocking Phase: The cocking phase begins with the front foot striking the ground and ends with a maximum shoulder external rotation at 150 to 180 degrees. During the early cocking phase, potential energy is accumulated and is transferred to the throwing arm during the late cocking phase to prepare for acceleration and ball release.
Early Cocking: During the early cocking phase, the quadriceps of the lead leg contract to stabilize the body while the pelvis rotates toward home plate. Trunk rotation and extension lag behind pelvic rotation, which transfers energy from the pelvis to the upper torso, requiring core activation to stabilize the trunk.
Late Cocking: During the late cocking phase, potential energy from the trunk is transferred to the throwing arm as it externally rotates and horizontally adducts. The arm is preparing for forward acceleration and ball release. The phase ends when the throwing arm is maximally rotated to 150 to 180 degrees and horizontally adducted to 20 degrees.
Phase 4: Acceleration Phase: During this phase, the potential energy accumulated by the throwing arm is utilized to accelerate the ball to its maximal velocity. The trunk flexes forward to a neutral position as the throwing arm rotates internally and the elbow extends.
Phase 5: Deceleration Phase: This phase takes place between the time of the ball release as the humeral head of the humerus maximally rotates and the elbow is extended. Scapular and upper back muscles, such as the teres minor, infraspinatus, and posterior deltoid, are responsible for slowing the shoulder down and dissipating the compressive forces across the shoulder joint.
Phase 6: Follow-Through Phase: Once the ball is released, follow-through begins and the ligaments and rotator cuff tendons at the back of the shoulder must absorb significant stresses to decelerate the arm and control the humeral head.
Common Shoulder Injuries in Baseball Pitchers
Upper extremity injuries comprise more than half of all baseball injuries, the majority of which are shoulder injuries and affect pitchers more than position players. Injuries sustained by pitchers tend to be more severe compared to those of position players and require surgery more often. A study of 629 collegiate pitchers showed that 51.8% of pitchers report sustaining a pitching-related upper extremity injury and 17.8% reported having surgery because of their injuries. Shoulder muscle and tendon injuries made up 52.8% of injuries, while glenoid labrum injuries made up 25.3%. Once surgery is performed, a prolonged loss of time playing is expected because many baseball-related injuries requiring surgery have a recovery period of months.
Common baseball-related shoulder injuries include:
SLAP Tears: A SLAP tear is a shoulder labral tear in which the top part of the labrum is injured, occurring at the biceps tendon attachment point on the labrum. It typically occurs during the late cocking phase of the throw and can cause deep pain within the shoulder and a catching or locking sensation.
Biceps Tendinitis: Biceps tendinitis develops from repetitive throwing that inflames and irritates the upper biceps tendon, causing pain in the front of the shoulder and weakness. If left untreated, it can lead to a tear of the biceps tendon.
Rotator Cuff Tendinitis and Tears: The rotator cuff is frequently irritated in pitchers and can cause pain that radiates from the front of the shoulder to the side of the arm when throwing. Rotator cuff tears begin with inflammation of the tendons and progress to fraying and then a full or partial tear. Once one or more of the rotator cuff tendons are torn, the tendon no longer fully attaches to the head of the humerus, causing instability in the shoulder.
Shoulder Internal Impingement: During the cocking phase of the throw, the rotator cuff tendons at the back of the shoulder can be pinched between the humeral head and the glenoid which is internal impingement and can result in tearing of the rotator cuff tendons and damage to the labrum. Internal impingement risk is heightened when the structures of the front of the shoulder joint are loose or there is muscle tightness in the back of the shoulder.
Shoulder Instability: Shoulder instability occurs when the head of the humerus slips out of the shoulder socket, causing the shoulder to dislocate. Chronic shoulder instability occurs when the shoulder is loose and the head of the humerus moves out of place repeatedly. This can develop over years from repetitive throwing that stretches ligaments and creates increased laxity.
GIRD: GIRD, or Glenohumeral Internal Rotation Deficit, occurs due to the extreme external rotation that is required to throw at high speeds, which causes the ligaments at the front of the shoulder to stretch and loosen. This then causes the soft tissues in the back of the shoulder to tighten, leading to a loss of internal rotation and contributing to a greater risk of labral and rotator cuff tears.
Scapular Rotation Dysfunction: The scapula connects only to the clavicle and relies on muscles of the upper back to position it to support healthy shoulder movement. During throwing, repetitive use of scapular muscles creates changes in muscles that affect the position of the scapula and increase the risk of a shoulder injury. Scapular rotation dysfunction is characterized by drooping of the affected shoulder. The most common symptom is pain in the front of the shoulder near the collarbone.
Physical Therapy for Baseball Pitchers
Physical therapy can effectively treat baseball-related shoulder injuries and help pitchers prevent injury through a throwing mechanics assessment and pre-season conditioning program. A successful rehabilitation program is multi-phased, gradually re-introducing the functional demands of the pitcher’s position for a safe return to sport.
Rehabilitation focuses on intramuscular balance, strength, endurance, neuromuscular control, and dynamic stability and on strengthening all elements of the kinetic chain when throwing, from the lower body and core to the shoulder, arm, and upper back. The therapist specifically targets rotator cuff strength and endurance as well as correcting range of motion deficits, optimizing the scapulothoracic joint stabilization and shoulder flexibility, and progressively reintroducing functional sport-specific stresses.
Physical therapy uses manual therapy and targeted strengthening exercises to improve the range of motion of the shoulder and strengthen the muscles that support the shoulder. Physical therapists address tight muscles in the upper back as well as strengthen the structures in the front of the shoulder to relieve stress on the labrum and rotator cuff. The therapist also conducts a throwing mechanic assessment and instructs the athlete on correct body positioning to reduce excessive stress on the injured shoulder’s structures. The therapist provides patient education regarding age-appropriate pitch count and needed rest periods in order to avoid future overuse injuries in the shoulder.
Should surgery be necessary, post-surgical rehabilitation is essential to regain function in the shoulder. Initially, the therapist helps the athlete manage pain, regain range of motion, and prevent stiffness in the shoulder. As the athlete heals, the therapist progresses the athlete through a strengthening exercise program of the shoulder, upper back, and core and functional training for a safe return to sport.
Give us a call at Mangiarelli Rehabilitation to start your program to improve throwing mechanics and treat and prevent baseball-related shoulder injuries this year!
