Specific Exercises for the Throwing Shoulder

Kevin E. Wilk

Michael M. Reinold

INTRODUCTION

Specific strengthening and flexibility exercises play a vital role in the ultimate function and injury prevention in the overhead throwing athlete. The most significant challenge facing the clinician (physical therapist, athletic trainer, strength and conditioning coach) is the achievement of a delicate balance between mobility and stability. The overhead throwing athlete must exhibit considerable glenohumeral joint mobility and laxity to allow the extreme motions necessary to throw effectively and without pain or injury.

The exercise program should include exercise drills to enhance flexibility, improve dynamic stabilization, increase muscular strength, enhance explosive power, and optimize muscular endurance. The clinician must carefully supervise so that the overhead athlete enhances flexibility, but not to the extent where excessive motion occurs; this may lead to glenohumeral joint instability. The strengthening exercises are designed to enhance muscular strength but not to create tightness and inflexibility. Other exercises such as plyometrics are designed to enrich explosive power and enhance the overhead thrower’s ball velocity. Thus, the exercise program is a delicate balance of all these elements, which should produce the ultimate goal of pain-free, injury-free unrestricted throwing. Furthermore, the program should enhance the athlete’s performance.

The repetitive microtraumatic stresses placed on the athlete’s shoulder joint complex during the throwing motion challenges the physiologic limits of the surrounding tissues. During the overhead throwing motion, the athlete places excessive stresses at end ranges with tremendous angular velocities (Fig. 7-1). Fleisig and colleagues (1) reported the angular velocity of the overhead throw to reach 7,265 degrees per seconds, which is the fastest human movement. Furthermore, these forces are generated when the shoulder joint is in excessive external rotation, often at 145 to 165 degrees of external rotation. This results in high forces generated at the joint and placed on the supporting structure (i.e., capsule or musculature) (2). Fleisig and colleagues (1) reported anterior forces up to 1 times body weight during external rotation (late cocking) and up to 1½ times body weight distracting the joint during the follow-through phase. Frequently, injury may occur as a result of muscle fatigue, muscle weakness and imbalances, alterations in throwing mechanics, and excessive capsular laxity. A well-designed and properly implemented program may prevent some of these injuries.

OVERVIEW

Most overhead athletes exhibit significant laxity of the glenohumeral joint. This allows them to accomplish the necessary motions required to perform their sport. However, this appears to be potentially problematic. Because of the excessive mobility, the surrounding stabilizing structures must play a significant role. We believe the surrounding musculature functions to dynamically stabilize the glenohumeral joint, provide movements, and dissipate the large forces generated during the throw. Thus, the exercise program must include exercise drills to enhance dynamic stabilization, improve acceleration power, and upgrade eccentric muscular efficiency. Furthermore, the exercise drills must not solely be confined to the glenohumeral joint, but must include the scapular region, core stability, and lower extremities. These components contribute to increased force generation as well as proper mechanics and efficiency.

This chapter discusses our approach to the rehabilitation and preventive program for the overhead throwing athlete. The rehabilitation principles and guidelines, and the specific programs for selected injuries are also reviewed.

FIGURE 7-1. Hyperangulation during the overhead throwing motion. During the late cocking phase of the overhead throw, as the thrower’s humerus excessively abducts horizontally, posterosuperior impingement of the shoulder joint may occur. To prevent this, the thrower must stay in the plane of the scapula. A: Normal angular relationship. B: Hyperangulation. (From Davidson PA, et al. Rotator cuff and posterior-superior glenoid injury associated with increased glenohumeral motion: a new site of impingement. J Shoulder Elbow Surg 1995:4:384-390, with permission.)

PHYSICAL CHARACTERISTICS OF THE OVERHEAD ATHLETE

The overhead throwing athlete exhibits several differences in physical characteristics than the nonoverhead athlete, specifically in shoulder range of motion, laxity, strength, and proprioception. These characteristics must be completely understood before an individualized rehabilitation program is developed. Briefly discussed are the typical characteristics of overhead athletes so that pathology may be appreciated on clinical examination and addressed through a structured rehabilitation program.

Range of Motion

One of the most characteristic differences between overhead athletes and nonoverhead athletes is shoulder range of motion. Most overhead athletes exhibit excessive external rotation and decreased internal rotation at 90 degrees of abduction in the throwing shoulder (3, 4, 5, 6). Brown and colleagues (4) reported that the mean range of motion in 41 professional baseball pitchers was 141 degrees ± 15 degrees of shoulder external rotation at 90 degrees of abduction and 83 degrees ± 14 degrees of internal rotation. External rotation was 9 degrees greater in the throwing shoulder than in the nonthrowing shoulder, and internal rotation was 15 degrees less than in the nonthrowing shoulder. Furthermore, external rotation of the throwing shoulder was 9 degrees greater in pitchers than in positional players. Similarly, Bigliani and colleagues (3) evaluated the range of motion characteristics in 148 professional baseball players. The authors reported a mean of 118 degrees of external rotation at 90 degrees of abduction (range 95 to 145 degrees) in the throwing shoulder of pitchers and a mean of 108 degrees external rotation in positional players. A statistically significant increase in external rotation and decrease in internal rotation was observed between the dominant and nondominant shoulder.

Wilk and colleagues (7) reported the shoulder range of motion characteristics in 372 professional baseball players. The authors reported a mean of 129 degrees ± 10 degrees of external rotation and 61 degrees ± 9 degrees of internal rotation in the throwing shoulder at 90 degrees of abduction. The authors noted that external rotation was 7 degrees greater and internal rotation was 7 degrees less in the dominant arm when compared with the nondominant arm. The concept of “total motion” was introduced in this article. Total motion is the motion value of external and internal rotation (at 90 degrees of abduction) added together. The authors noted that total motion is equal bilaterally in most throwers, usually within 7 degrees.

Reinold and colleagues (8) recently noted that range of motion is affected by overhead throwing. The authors evaluated shoulder range of motion in 31 professional baseball pitchers before and immediately after baseball pitching. External rotation before throwing (133 degrees ± 11
degrees) did not significantly change after throwing (131 degrees ± 10 degrees). However, there was a statistically significant decrease in internal rotation range of motion after pitching (73 degrees ± 16 degrees before; 65 degrees ± 11 degrees after) and a subsequent decrease of 9 degrees of total motion. The authors hypothesized that this decrease in internal rotation range of motion is due to the large eccentric forces observed in the external rotators during the follow-through phase of throwing. Furthermore, the overall decrease in total motion observed after throwing may make the athlete more susceptible to injury.

Laxity

The excessive motion observed in overhead athletes is commonly attributed to an increase in glenohumeral laxity. Numerous theories regarding this increased laxity have been reported. Some authors have reported that the excessive external rotation and limited internal rotation are due to anterior capsular laxity and posterior capsule tightness (9). Others have reported that the excessive laxity in throwers is the result of repetitive throwing and have referred to this as acquired laxity (J. R. Andrews, unpublished data, 1996), whereas others have documented that overhead throwers exhibit congenital laxity (3).

Bigliani and colleagues (3) subjectively examined laxity in 72 professional baseball pitchers and 76 positional players. The authors reported 61% of pitchers and 47% of positional players exhibited a positive sulcus sign, indicating inferior glenohumeral joint laxity. This laxity was present bilaterally, indicating a certain degree of congenital laxity.

Crockett and colleagues (10) examined the amount of humeral version in the dominant and nondominant shoulders of professional baseball players and nonthrowers. Results indicated a retroversion of the humeral head that was present in the dominant shoulder of throwers and not in the nondominant shoulder or shoulders of nonthrowers. Posterior capsular translation was consistently greater than anterior translation in all of the shoulders. Thus, the authors reported that the excessive external rotation and limited internal rotation may not be attributed to anterior capsular laxity and posterior capsular tightness, but rather to osseous adaptations to the throwing arm.

Borsa and colleagues (unpublished data, 2002) recently assessed the amount of anterior and posterior capsular laxity in professional baseball pitchers using an objective mechanical translation device (Telos device). The authors reported that posterior capsular laxity was significantly greater than anterior capsular laxity. This was true despite gross limitation of internal rotation. Furthermore, the investigators reported total translation (anterior and posterior) was equal bilaterally, thus the throwing shoulder was not more lax than the nonthrowing shoulder.

Thus, it appears that the unique range-of-motion characteristics in overhead athletes cannot be explained as a result of capsular laxity entirely. Rather, it appears that the increased external rotation and decreased internal rotation observed is due in part to a combination of osseous adaptations, soft tissue adaptations (e.g., posterior rotator cuff), congenital laxity, and superimposed acquired laxity as a result of adaptive changes from throwing.

Muscle Strength

Several investigators have examined muscle strength parameters in the overhead throwing athlete with varying results and conclusions (4,11, 12, 13, 14, 15, 16, 17). Wilk and colleagues (16,17) have performed isokinetic testing on professional baseball players as part of their physical examinations during spring training. The investigators demonstrated that the external rotation strength of the pitcher’s throwing shoulder is significantly weaker (p < 0.05) than the nonthrowing shoulder, by 6%. Conversely, internal rotation strength of the throwing shoulder was significantly stronger (p < 0.05), by 3%, compared with the nonthrowing shoulder. In addition, adduction strength of the throwing shoulder is also significantly stronger than in the nonthrowing shoulder, by approximately 10%. The authors reported the optimal antagonist-agonist ration between external and internal rotation strength should be 66% to 76%. Table 7-1 illustrates the expected muscle strength values of professional baseball players.

Magnusson and colleagues (18) used a handheld dynamometer to study the isometric muscle strength of professional baseball pitchers and compared results with those of a control group of nonthrowers. The authors noted a significant decrease in supraspinatus strength of the dominant shoulder when compared with the nondominant shoulder. Additionally, pitchers exhibited strength deficits for shoulder abductors, external rotators, internal rotators, and supraspinatus (empty can maneuvers) when compared with nonthrowers.

Reinold and colleagues (19) evaluated external and internal rotation strength at 0 degrees and 90 degrees of abduction in 23 professional baseball pitchers using a handheld dynamometer. The mean peak force output for external rotation at 0 degrees of abduction was approximately 37 Nm bilaterally. Similarly, internal rotation at 0 degrees for the bilateral shoulders was approximately 44 Nm. The authors noted a statistically significant decrease of approximately 7 Nm of external and internal rotation strength when measured at 90 degrees of abduction. The 90-degree abducted position may be better suited to perform manual strength testing in professional baseball pitchers when determining subtle strength deficits or imbalances of the shoulder rotators.

The scapular muscles also play a vital role during overhead throwing (20). Wilk and colleagues (21) documented the isometric scapular strength values of professional baseball players. The results indicated that pitchers and catchers exhibited significantly greater strength of the scapular protractors
and elevators than positional players. Antagonist-agonist muscles values are also of importance in the scapular muscles. Table 7-2 illustrates the scapular muscle strength values of the overhead throwing athlete.

TABLE 7-1. ISOKINETIC SHOULDER STRENGTH CRITERIA FOR OVERHEAD ATHLETES

	Bilateral Comparisons (Dominant Arm/Nondominant Arm)
Velocity (deg/sec)	External Rotation (ER)	Internal Rotation (IR)	Abduction (Abd)	Adduction (Add)
180	98%-105%	110%-120%	98%-105%	110%-128%
300	85%-95%	105%-115%	96%-102%	111%-129%
	Unilateral Muscle Ratios
Velocity (deg/sec)	ER/IR	Abd/Add	ER/Abd
180	66%-76%	78%-84%	67%-75%
300	61%-71%	88%-94%	60%-70%
	Peak Torque to Body Weight Ratios
Velocity (deg/sec)	ER	IR	Abd	Add
180	18%-23%	28%-33%	26%-33%	32%-38%
300	12%-20%	25%-30%	20%-25%	28%-34%

Proprioception

The overhead thrower relies on enhanced proprioception to influence the neuromuscular system to dynamically stabilize the glenohumeral joint in the presence of capsular laxity and excessive range of motion. Blasier and colleagues (22) reported that persons with generalized joint laxity are significantly less sensitive to proprioceptive testing.

Allegrucci and colleagues (23) examined shoulder proprioception in 20 healthy overhead athletes. Testing of joint repositioning was performed on a motorized system with the subject attempting to actively reproduce a specific joint angle. The investigators noted that the dominant shoulder exhibited diminished proprioception compared with the nondominant shoulder. The investigators also noted improved proprioception toward end range of motion compared with early and mid range.

TABLE 7-2. SCAPULAR MUSCLE STRENGTH VALUES AND THEIR UNILATERAL RATIOS^a

	Scapular Muscle Values (ft-lb)								Unilateral Muscle Ratios (%)
	Protraction		Retraction		Elevation		Depression		Protraction/Retraction		Elevation/Depression
	D	ND	D	ND	D	ND	D	ND	D	ND	D	ND
Pitchers	71 ± 10	74 ± 13	62 ± 8	60 ± 7	83 ± 14	84 ± 5	22 ± 6	18 ± 5	87	81	27	21
Catchers	68 ± 10	73 ± 10	63 ± 5	59 ± 7	88 ± 15	85 ± 8	21 ± 4	16 ± 5	93	81	24	19
Positional players	58 ± 10	58 ± 11	57 ± 6	56 ± 6	65 ± 12	66 ± 11	19 ± 5	18 ± 5	98	94	29	27
^aD, dominant extremity; ND, nondominant extremity.

Wilk and colleagues (unpublished data, 2000) studied the proprioceptive capability of 120 professional baseball players using active reproduction of passive joint positioning. The researchers noted no significant difference bilaterally, although greater proprioception was achieved at end range of motion compared with mid range. In addition, Wilk and colleagues (unpublished data, 2000) compared the proprioceptive ability of 60 professional baseball players with that of 60 nonthrowing athletes. The authors noted no significant difference between groups. However, the overhead athletes exhibited a trend toward greater proprioception at end range when compared towards non-throwing athletes, although not statistically significant.

REHABILITATION PRINCIPLES AND GUIDELINES

The rehabilitation program for the thrower’s shoulder follows several principles and guidelines to maximize the athlete’s return to competition. The following section briefly explains several principles and guidelines followed by an
overview of the thrower’s rehabilitation program incorporating these principles.

Thrower’s Ten Program

Strengthening exercises of the entire upper extremity, including shoulder, scapula, elbow, and wrist exercises, are essential for the overhead thrower. We have developed the Thrower’s Ten Program (see Appendix 7-1 at end of book) based on numerous electromyographic (EMG) analysis studies to strengthen the muscles involved in the throwing motion (24, 25, 26, 27, 28, 29). The exercise program involves several exercises with emphasis on the scapulothoracic and rotator cuff muscles, particularly the external rotators (30). This program serves as a foundation to the strengthening program, around which skilled and advanced techniques may be superimposed.

Dynamic Stabilization

The excessive mobility and compromised static stability observed within the glenohumeral joint often result in numerous injuries to the capsulolabral and musculotendinous structures of the throwing shoulder. Efficient dynamic stabilization and neuromuscular control of the glenohumeral joint is necessary for overhead athletes to avoid injuries during competition (25). Dynamic stability refers to the ability of the shoulder to stabilize during the throwing motion to avoid injuries. This involves neuromuscular control and the efferent (motor) output to afferent (sensory) stimulation from the shoulder.

Dynamic stabilization exercises for the thrower’s shoulder begin with baseline proprioception and kinesthesia drills to maximize the athlete’s awareness of joint position and movement in space. Rhythmic stabilizations are incorporated to facilitate cocontraction of the rotator cuff and dynamic stability of the glenohumeral joint. These dynamic stabilization techniques may be applied as the athlete progresses to provide advance challenge to the neuromuscular control system.

Neuromuscular control of the shoulder involves stability of not only the glenohumeral joint but also the scapulothoracic joint. The scapula provides a stable base of support for muscular attachment and dynamically positions the glenohumeral joint during upper extremity movement. Scapular strength and stability are essential to proper function of the glenohumeral joint. Therefore, isotonic strengthening and dynamic stabilization of the scapular musculature should also be included into rehabilitation programs for the thrower’s shoulder to assure proximal stability.

Core Stabilization

Core stabilization drills are used to further enhance proximal stability with distal mobility of the upper extremity. Core stabilization is used based on the kinetic chain concept in which imbalance within any point of the kinetic chain may result in pathology throughout. Movement patterns, such as throwing, require a precise interaction of the entire body kinetic chain to perform efficiently. An imbalance of strength, flexibility, endurance, or stability may result in fatigue, abnormal arthrokinematics, and subsequent compensation.

Core stabilization is progressed using a multiphase approach, progressing from baseline core and trunk strengthening, to intermediate core strengthening with distal mobility, to advanced stabilization in sport-specific movement patterns.

Closed Kinetic Chain Exercises

The integration of closed kinetic chain (CKC) exercises, or axial compression exercises, is another important principle in the rehabilitation of the overhead athlete (31). CKC exercises are used to stress the joint in a weight-bearing position, resulting in joint approximation. The goal of this is to stimulate articular receptors and facilitate cocontraction of the shoulder force couples, thus incorporating a combination of eccentric and concentric contractions to provide joint stability.

CKC exercises are progressed to gradually increase the amount of challenge to the shoulder. Static stabilization exercises on a stable surface are progressed to dynamic stabilization exercises on an unstable surface. Single plane movements with a wide base of support are progressed to multiplane movements with a narrow base of support, and bilateral support is advanced to unilateral support. Furthermore, manual resistance, rhythmic stabilizations, and perturbation training may also be included to provide a constant increase in challenge to the neuromuscular control system.

Plyometric Exercises

Plyometric exercises provide a quick, powerful movement involving a prestretch of the muscle, thereby activating the stretch shortening cycle of the muscle (32, 33, 34). Plyometrics replicates several functional movement patterns, such as throwing, that involve stretch-shortening cycles of the muscle tissue. The goal is to train the upper extremity to efficiently develop and withstand force.

Stretch-shortening muscle contractions use a prestretching of the muscle spindles and Golgi tendon organs to produce a recoil action of the elastic tissues, which results in improved muscle performance by the combined effects of the stored elastic energy and the myotactic reflex activation of the muscle.

There are three phases of stretch-shortening exercises. The first phase, the eccentric stretch phase, increases the activity of the muscle spindle. The second phase, the amortization phase, is the time between the eccentric and concentric contractions. This phase relies on the rate of stretch rather than the length of stretch. Excessive amortization time may result in the dissipation of energy as heat and a deactivation of the stretch reflex. The last phase, the concentric response phase, is the summation of the previous phases producing a facilitated shortening contraction.

TABLE 7-3. INTERVAL THROWING PROGRAM FOR BASEBALL PLAYERS: PHASE I

45 ft Phase
Step 1:	A.	Warm-up throwing
	B.	45 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	45 ft (25 throws)
Step 2:	A.	Warm-up throwing
	B.	45 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	45 ft (25 throws)
	F.	Rest 5-10 min
	G.	Warm-up throwing
	H.	45 ft (25 throws)
60 ft Phase
Step 3:	A.	Warm-up throwing
	B.	60 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	60 ft (25 throws)
Step 4:	A.	Warm-up throwing
	B.	60 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	60 ft (25 throws)
	F.	Rest 5-10 min
	G.	Warm-up throwing
	H.	60 ft (25 throws)
90 ft Phase
Step 5:	A.	Warm-up throwing
	B.	90 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	90 ft (25 throws)
Step 6:	A.	Warm-up throwing
	B.	90 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	90 ft (25 throws)
	F.	Rest 5-10 min
	G.	Warm-up throwing
	H.	90 ft (25 throws)
120 ft Phase
Step 7:	A.	Warm-up throwing
	B.	120 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	120 ft (25 throws)
Step 8:	A.	Warm-up throwing
	B.	120 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	120 ft (25 throws)
	F.	Rest 5-10 min
	G.	Warm-up throwing
	H.	120 ft (25 throws)
150 ft Phase
Step 9:	A.	Warm-up throwing
	B.	150 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	150 ft (25 throws)
Step 10:	A.	Warm-up throwing
	B.	150 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	150 ft (25 throws)
	F.	Rest 5-10 min
	G.	Warm-up throwing
	H.	150 ft (25 throws)
180 ft Phase
Step 11:	A.	Warm-up throwing
	B.	180 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	180 ft (25 throws)
Step 12:	A.	Warm-up throwing
	B.	180 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	180 ft (25 throws)
	F.	Rest 5-10 min
	G.	Warm-up throwing
	H.	180 ft (25 throws)
Step 13:	A.	Warm-up throwing
	B.	180 ft (25 throws)
	C.	Rest 5-10 min
	D.	Warm-up throwing
	E.	180 ft (25 throws)
	F.	Rest 5-10 min
	G.	Warm-up throwing
	H.	180 ft (20 throws)
	I.	Rest 5-10 min
	J.	Warm-up throwing
	K.	15 Throws progressing from 120 ft → 90 ft
Step 14:	Return to respective position or progress to step 14.
All throws should be on an arc with a crow-hop
Warm-up throws consist of 10-20 throws at approximately 30 ft
Throwing program should be performed every other day, 3 times per week unless otherwise specified by a physician or rehabilitation specialist.
Perform each step ____ times before progressing to next step.
Flat Ground Throwing for Baseball Pitchers
Step 14:
A. Warm-up throwing
B. Throw 60 ft (10-15 throws)
C. Throw 90 ft (10 throws)
D. Throw 120 ft (10 throws)
E. Throw 60 ft (flat ground) using pitching mechanics (20-30 throws)
Step 15:
A. Warm-up throwing
B. Throw 60 ft (10-15 throws)
C. Throw 90 ft (10 throws)
D. Throw 120 ft (10 throws)
E. Throw 60 ft (flat ground) using pitching mechanics (20-30 throws)
F. Throw 60-90 ft (10-15 throws)
G. Throw 60 ft (flat ground) using pitching mechanics (20 throws)
Progress to Phase II—Throwing Off the Mound
45 ft = 13.7 m; 60 ft = 18.3 m; 90 ft = 27.4 m; 120 ft = 36.6 m; 150 ft = 45.7 m; 180 ft = 54.8 m.