An Interval Throwing Program for Baseball Pitchers Based upon Workload Data.

Background: Interval throwing programs (ITP) have been used for decades to enable baseball pitchers to return to competition after injury or surgery by gradually applying load to the throwing arm. Past programs have been based on personal experience; however, advances in our understanding of the biomechanics and workloads of throwing allow for a more modern data-based program to be developed. Hypothesis/Purpose: To 1) develop a updated ITP for rehabilitation of modern baseball pitchers based upon biomechanical and throwing workload data, and 2) compare the updated program with a past program to determine differences in chronic workload and acute:chronic workload ratios (ACWR). Study Design: Cross-sectional study. Methods: Workloads (i.e. daily, acute, chronic, and ACWR) for the original ITP were built from the prescribed throwing schedule. Elbow varus torque per throw was calculated based upon a relationship between elbow varus torque and throwing distance. Throw counts, daily/chronic/acute workloads, and ACWR were calculated and plotted over time. A new ITP was built to model current pitcher's throwing schedules and gradually increased ACWR over time. Results: The original ITP had a throwing schedule of 136 days, final chronic workload 15.0, and the ACWR above or below the "safe" range (i.e. 0.7 - 1.3) for 18% of the program with a peak of 1.61. The updated ITP was built to consist of a 217-day schedule, final chronic workload of 10.8, and deviated from the safe range for 9% of the program, with a peak of 1.33. Conclusion: The newly created ITP is more familiar to modern baseball pitchers while exhibiting a more gradual buildup of chronic workload than traditional ITP programs. This ITP may be used to return baseball pitchers back to competition as safely and efficiently as possible, and potentially with less risk of setbacks or reinjury. The ITP may be used following common injuries or surgeries to the throwing shoulder and elbow, such as Tommy John surgery, while also serving as a basis for future development of shorter duration ITPs. Level of Evidence: 2c.

The Safety and Efficacy of Weighted Baseballs.

One of the most common methods of training to enhance pitching velocity is the use of weighted baseballs. As with anything else, the excitement and popularity often proceed our scientific understanding. While there is still a lot to learn, our understanding of the science and efficacy of weighted baseball training has grown in recent years. The purpose of this clinical viewpoint is to summarize our current scientific understanding.

Acute Effects of Weighted Baseball Throwing Programs on Shoulder Range of Motion.

BACKGROUND: Baseball pitching injuries are increasing at an alarming rate. While weighted ball throwing programs may be effective at increasing pitching velocity, previous research has identified a 24% injury rate and a 3.3° increase in shoulder external rotation (ER) range of motion (ROM) after performing a 6-week program. However, previous research has not investigated, separately, the immediate effects of throwing underloaded and overloaded balls on ROM. The purpose of this study was to examine the acute effects of throwing differently weighted baseballs on shoulder ROM. By analyzing these differences, it may be possible to determine the specific weight range that may lead to the greatest increase in ROM and potential injury risk. HYPOTHESIS: Throwing with weighted balls will result in an increase in shoulder ER ROM. STUDY DESIGN: Randomized controlled trial. LEVEL OF EVIDENCE: Level 2. METHODS: A total of 16 male high school baseball pitchers agreed to participate in this study. The participants were (mean ± SD) 17.1 ± 1.0 years of age, 1.81 ± 0.09 m tall, and had a mass of 79.2 ± 11.1 kg. Each participant was tested on 3 different days, 1 week apart, with 3 different conditions in random order: (1) underload throwing, using regulation 5-oz baseballs and 4- and 2-oz balls; (2) overload throwing, using 5-, 6-, and 9-oz balls; and (3) extreme overload throwing, using 5-, 16-, and 32-oz balls. Each testing session began by measuring passive shoulder ROM (external rotation and internal rotation) using standard goniometric measurements. Participants then performed 3 throws with each weighted ball from 3 different positions (kneeling, rocker, and run-and-gun) for a total of 27 throws each test session. ROM measurements were repeated at the end of each test session. The effect of each throwing condition on ROM was compared from pre- to posttraining using a paired t test (P ≤ 0.05). RESULTS: There was no significant difference in ER after throwing at underloaded weights. The overload condition showed a statistically significant increase of 3.3° in external rotation (P = 0.05). The extreme overload condition showed a statistically significant increase in ER of 8.4° (P < 0.001). There were no differences in internal rotation for any group. CONCLUSION: A significant increase in shoulder ER was observed immediately after throwing overload weighted balls. This effect increased as the weights of the balls increased. CLINICAL RELEVANCE: Throwing with overload weighted baseballs causes an immediate increase in shoulder ER ROM. It is unknown why these changes occur; however, the results may explain both the increase in velocity and injury rates previously observed from throwing weighted balls. The current study results may be used to develop more scientifically validated weighted ball programs. Heavier balls should be used with caution, and ROM should be monitored during implementation of these programs.

Effect of a 6-Week Weighted Baseball Throwing Program on Pitch Velocity, Pitching Arm Biomechanics, Passive Range of Motion, and Injury Rates.

BACKGROUND: Emphasis on enhancing baseball pitch velocity has become popular, especially through weighted-ball throwing. However, little is known about the physical effects or safety of these programs. The purpose of this study was to examine the effects of training with weighted baseballs on pitch velocity, passive range of motion (PROM), muscle strength, elbow torque, and injury rates. HYPOTHESIS: A 6-week weighted ball training program would result in a change in pitching biomechanical and physical characteristics. STUDY DESIGN: Randomized controlled trial. LEVEL OF EVIDENCE: Level 1. METHODS: During the baseball offseason, 38 healthy baseball pitchers were randomized into a control group and an experimental group. Pitch velocity, shoulder and elbow PROM, shoulder strength, elbow varus torque, and shoulder internal rotation velocity were measured in both groups. The experimental group then performed a 6-week weighted ball throwing program 3 times per week using balls ranging from 2 to 32 ounces while the control group only used a 5-ounce regulation baseball. Both groups performed a strength training program. Measurements were then repeated after the 6-week period. Injuries were tracked over the 6-week training program and the subsequent baseball season. The effect of training with a weighted ball program was assessed using 2-way repeated-measures analysis of variance at an a priori significance level of P < 0.05. RESULTS: Mean age, height, mass, and pretesting throwing velocity were 15.3 ± 1.2 years (range, 13-18 years), 1.73 ± 0.28 m, 68.3 ± 11 kg, and 30.3 ± 0.7 m/s, respectively. Pitch velocity showed a statistically significant increase (3.3%) in the experimental group ( P < 0.001). There was a statistically significant increase of 4.3° of shoulder external rotation in the experimental group. The overall injury rate was 24% in the experimental group. Four participants in the experimental group suffered elbow injuries, 2 during the training program and 2 in the season after training. No pitchers in the control group were injured at any time during the study. CONCLUSION: Performing a 6-week weighted ball throwing program increased pitch velocity. However, the program resulted in increased shoulder external rotation PROM and increased injury rate. CLINICAL RELEVANCE: Although weighted-ball training may increase pitch velocity, caution is warranted because of the notable increase in injuries and physical changes observed in this cohort.

Deficits in Glenohumeral Passive Range of Motion Increase Risk of Shoulder Injury in Professional Baseball Pitchers: A Prospective Study.

BACKGROUND: Shoulder injuries from repetitive baseball pitching continue to be a serious, common problem. PURPOSE: To determine whether passive range of motion of the glenohumeral joint was predictive of shoulder injury or shoulder surgery in professional baseball pitchers. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Passive range of motion of the glenohumeral joint was assessed with a bubble goniometer during spring training for all major and minor league pitchers of a single professional baseball organization over a period of 8 successive seasons (2005-2012). Investigators performed a total of 505 examinations on 296 professional pitchers. Glenohumeral external and internal rotation was assessed with the pitcher supine and the arm abducted to 90° in the scapular plane with the scapula stabilized anteriorly at the coracoid process. Total rotation was defined as the sum of internal and external glenohumeral rotation. Passive shoulder flexion was measured with the pitcher supine and the lateral border of the scapula manually stabilized. After examination, shoulder injuries and injury durations were recorded by each pitcher's respective baseball organization and reported to the league as an injury transaction as each player was placed on the disabled list. RESULTS: Highly significant side-to-side differences were noted within subjects for each range of motion measurement. There were 75 shoulder injuries and 20 surgeries recorded among 51 pitchers, resulting in 5570 total days on the disabled list. Glenohumeral internal rotation deficit, total rotation deficit, and flexion deficit were not significantly related to shoulder injury or surgery. Pitchers with insufficient external rotation (<5° greater external rotation in the throwing shoulder) were 2.2 times more likely to be placed on the disabled list for a shoulder injury (P = .014; 95% CI, 1.2-4.1) and were 4.0 times more likely to require shoulder surgery (P = .009; 95% CI, 1.5-12.6). CONCLUSION: Insufficient shoulder external rotation on the throwing side increased the likelihood of shoulder injury and shoulder surgery. Sports medicine clinicians should be aware of these findings and develop a preventive plan that addresses this study's findings to reduce pitchers' risk of shoulder injury and surgery.

Deficits in glenohumeral passive range of motion increase risk of elbow injury in professional baseball pitchers: a prospective study.

BACKGROUND: Injuries to the elbow joint in baseball pitchers appear common. There appears to be a correlation between shoulder range of motion and elbow injuries. PURPOSE: To prospectively determine whether decreased ROM of the throwing shoulder is correlated with the onset of elbow injuries in professional baseball pitchers. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: For 8 consecutive years (2005-2012), passive range of motion of both the throwing and nonthrowing shoulders of all major and minor league pitchers within a single professional baseball organization were measured by using a bubble goniometer during spring training. In total, 505 examinations were conducted on 296 pitchers. Glenohumeral external rotation and internal rotation were assessed in the supine position with the arm at 90° of abduction and in the plane of the scapula. The scapula was stabilized per methods previously established. Total rotation was defined as the sum of external rotation and internal rotation. Passive shoulder flexion was assessed with the subject supine and the scapula stabilized per methods previously established. Elbow injuries and days missed because of elbow injuries were assessed and recorded by the medical staff of the team. Throwing and nonthrowing shoulder measurements were compared by using Student t tests; 1-tailed Fisher exact tests were performed to identify significant associations between shoulder motion and elbow injury. Nominal logistic regression was performed to determine the odds of elbow injury. RESULTS: Significant differences were noted during side-to-side comparisons within subjects. There were 49 elbow injuries and 8 surgeries in 38 players, accounting for a total of 2551 days missed. Neither glenohumeral internal rotation deficit nor external rotation insufficiency was correlated with elbow injuries. Pitchers with deficits of >5° in total rotation in their throwing shoulders had a 2.6 times greater risk for injury. Pitchers with deficit of ≥5° in flexion of the throwing shoulder had a 2.8 times greater risk for injury. CONCLUSION: Bilateral differences in shoulder total rotation and flexion had a significant effect on the risk for elbow injuries in pitchers. Clinicians need to be aware of these findings and plan preventive programs that address these issues in hopes of reducing elbow injuries.

Nonoperative and postoperative rehabilitation for injuries of the throwing shoulder.

The repetitive overhead motion involved in throwing is responsible for unique and sport-specific patterns of injury to the shoulder joint. Specific strengthening and flexibility plays a vital role in the ultimate function and injury prevention in the overhead-throwing athlete. The clinician must achieve a delicate balance between mobility and stability, which often presents as a significant challenge. Most shoulder injuries in the overhead thrower can be successfully treated nonoperatively to allow the athlete to return to competition. A well-structured, in-season strengthening program that is designed to maintain the athlete's strength, power, and endurance while not inhibiting with the athlete's ability to compete on a regular basis is critical.

The recognition and treatment of superior labral (slap) lesions in the overhead athlete.

UNLABELLED: The overhead athlete presents with a unique profile that may predispose them to specific pathology. Injury to the superior aspect of the glenoid labrum (SLAP lesions) poses a significant challenge to the rehabilitation specialist due to the complex nature and wide variety of etiological factors associated with these lesions. A thorough clinical evaluation and proper identification of the extent of labral injury is important in order to determine the most appropriate non-operative and/or surgical management. Postoperative rehabilitation is based on the specific surgical procedure that has been performed, as well as the extent, location, and mechanism of labral pathology and associated lesions. Emphasis is placed on protecting the healing labrum while gradually restoring range of motion, strength, and dynamic stability of the glenohumeral joint. The purpose of this paper is to provide an overview of the anatomy and pathomechanics of SLAP lesions and review specific clinical examination techniques used to identify these lesions in the overhead athlete. Furthermore, a review of the current surgical management and postoperative rehabilitation guidelines is provided. LEVEL OF EVIDENCE: 5.

The modified sleeper stretch and modified cross-body stretch to increase shoulder internal rotation range of motion in the overhead throwing athlete.

SYNOPSIS: Stretching techniques that focus on increasing posterior shoulder soft tissue flexibility are commonly incorporated into prevention and treatment programs for the overhead athlete. The cross-body and sleeper stretch exercises have been described as stretching techniques to improve posterior shoulder soft tissue flexibility and to increase glenohumeral joint internal rotation and horizontal adduction range of motion in the overhead athlete. But, based on the inability to stabilize the scapula and control glenohumeral joint rotation with the cross-body stretch and the potential for subacromial impingement with the sleeper stretch, the authors recommend modifications to both of these commonly performed stretches. This clinical commentary reviews the literature on posterior shoulder stretches, describes modifications to both of these commonly performed stretches, and outlines a strategy to maintain or improve posterior shoulder soft tissue flexibility and glenohumeral joint internal rotation range of motion in the overhead athlete. LEVEL OF EVIDENCE: Therapy, level 5.

Nonoperative and postoperative rehabilitation for glenohumeral instability.

The glenohumeral joint is an inherently unstable joint that relies on the interaction of the dynamic and static stabilizers to maintain stability. Disruption of this interplay or poor development of any of these factors may result in instability, pain, and a loss of function. Rehabilitation will vary based on the type of instability present and the key principles described. Whether a course of nonoperative rehabilitation is followed or the patient presents postoperatively, a comprehensive program designed to establish full ROM and balance capsular mobility, in addition to maximizing muscular strength, endurance, proprioception, dynamic stability, and neuromuscular control is essential. A functional approach to rehabilitation using movement patterns and sport-specific positions along with an interval sport program will allow a gradual return to athletics. The focus of the program should minimize the risk of recurrence and ensure that the patient can safely return to functional activities.

Rehabilitation of the Overhead Athlete's Elbow.

The activities required during overhead sports, particularly during baseball pitching, produce large forces at the elbow joint. Injuries to the elbow joint frequently occur in the overhead athlete because of the large amount of forces observed during the act of throwing, playing tennis, or playing golf. Injuries may result because of repetitive overuse, leading to tissue failure. Rehabilitation following injury or surgery to the throwing elbow is vital to fully restore normal function and return the athlete to competition as quickly and safely as possible. Rehabilitation of the elbow, whether following injury or postsurgical, must follow a progressive and sequential order, building on the previous phase, to ensure that healing tissues are not compromised. Emphasis is placed on restoring full motion, muscular strength, and neuromuscular control while gradually applying loads to healing tissue. In addition, when one is creating a rehabilitation plan for athletes, it is imperative to treat the entire upper extremity, core, and legs to create and dissipate the forces generated at each joint.

Passive range of motion characteristics in the overhead baseball pitcher and their implications for rehabilitation.

BACKGROUND: Repetitive overhead throwing motion causes motion adaptations at the glenohumeral joint that cause injury, decrease performance, and affect throwing mechanics. It is essential to define the typical range of motion (ROM) exhibited at the glenohumeral joint in the overhead thrower. QUESTIONS/PURPOSES: We (1) assessed the glenohumeral joint passive range of motion (PROM) characteristics in professional baseball pitchers; and (2) applied these findings clinically in a treatment program to restore normal PROM and assist in injury prevention. METHODS: From 2005 to 2010, we evaluated 369 professional baseball pitchers to assess ROM parameters, including bilateral passive shoulder external rotation (ER) at 45° of abduction, external and internal rotation (IR) at 90° abduction while in the scapular plane, and supine horizontal adduction. RESULTS: The mean ER was greater for the throwing and nonthrowing shoulders at 45° of abduction, 102° and 98°, respectively. The throwing shoulder ER at 90° of abduction was 132° compared with 127° on the nonthrowing shoulder. Also, the pitcher's dominant IR PROM was 52° compared with 63° on the nondominant side. We found no statistically significant differences in total rotational motion between the sides. CONCLUSIONS: Although we found side-to-side differences for rotational ROM and horizontal adduction, the total rotational ROM was similar. CLINICAL RELEVANCE: The clinician can use these PROM values, assessment techniques, and treatment guidelines to accurately examine and develop a treatment program for the overhead-throwing athlete.

Recent advances in the rehabilitation of anterior cruciate ligament injuries.

Rehabilitation following anterior cruciate ligament surgery continues to change, with the current emphasis being on immediate weight bearing and range of motion, and progressive muscular strengthening, proprioception, dynamic stability, and neuromuscular control drills. The rehabilitation program should be based on scientific and clinical research and focus on specific drills and exercises designed to return the patient to the desired functional goals. The goal is to return the patient's knee to homeostasis and the patient to his or her sport or activity as safely as possible. Unique rehabilitation techniques and special considerations for the female athlete will also be discussed. The purpose of this article is to provide the reader with a thorough scientific basis for anterior cruciate ligament rehabilitation based on graft selection, patient population, and concomitant injuries.

Correlation of glenohumeral internal rotation deficit and total rotational motion to shoulder injuries in professional baseball pitchers.

BACKGROUND: Glenohumeral internal rotation deficit (GIRD) indicates a 20° or greater loss of internal rotation of the throwing shoulder compared with the nondominant shoulder. PURPOSE: To determine whether GIRD and a deficit in total rotational motion (external rotation + internal rotation) compared with the nonthrowing shoulder correlate with shoulder injuries in professional baseball pitchers. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Over 3 competitive seasons (2005 to 2007), passive range of motion measurements were evaluated on the dominant and nondominant shoulders for 170 pitcher-seasons. This included 122 professional pitchers during the 3 seasons of data collection, in which some pitchers were measured during multiple seasons. Ranges of motion were measured with a bubble goniometer during the preseason, by the same examiner each year. External and internal rotation of the glenohumeral joint was assessed with the participant supine and the arm abducted 90° in the plane of the scapula, with the scapula stabilized anteriorly at the coracoid process. The reproducibility of the test methods had an intraclass correlation coefficient of .81. Days in which the player was unable to participate because of injury or surgery were recorded during the season by the medical staff of the team and defined as an injury. RESULTS: Pitchers with GIRD (n = 40) were nearly twice as likely to be injured as those without but without statistical significance (P = .17). Pitchers with total rotational motion deficit greater than 5° had a higher rate of injury. Minor league pitchers were more likely than major league pitchers to be injured. However, when players were injured, major league pitchers missed a significantly greater number of games than minor league pitchers. CONCLUSION: Compared with pitchers without GIRD, pitchers with GIRD appear to be at a higher risk for injury and shoulder surgery.

Rehabilitation following Microfracture of the Knee.

Postoperative rehabilitation programs following articular cartilage repair procedures will vary greatly among patients and need to be individualized based on the nature of the lesion, the unique characteristics of the patient, and the type and detail of each surgical procedure. These programs are based on knowledge of the basic science, anatomy, and biomechanics of articular cartilage as well as the biological course of healing following surgery. The goal is to restore full function in each patient as quickly as possible by facilitating a healing response without overloading the healing articular cartilage. The purpose of this article is to overview the principles of rehabilitation following microfracture procedures of the knee.

Glenohumeral internal rotation measurements differ depending on stabilization techniques.

BACKGROUND: The loss of glenohumeral internal rotation range of motion in overhead athletes has been well documented in the literature. Several different methods of assessing this measurement have been described, making comparison between the results of studies difficult. HYPOTHESIS: Significant differences in the amount of internal rotation range of motion exist when using different methods of stabilization. STUDY DESIGN: Descriptive laboratory study. METHODS: THREE TECHNIQUES WERE USED BILATERALLY IN RANDOM FASHION TO MEASURE GLENOHUMERAL INTERNAL ROTATION RANGE OF MOTION: stabilization of the humeral head, stabilization of the scapula, and visual inspection without stabilization. An initial study on 20 asymptomatic participants was performed to determine the intrarater and interrater reliability for each measurement technique. Once complete, measurements were performed on 39 asymptomatic professional baseball players to determine if a difference existed in measurement techniques and if there was a significant side-to-side difference. A 2-way repeated-measures analysis of variance was used. RESULTS: While interrater reliability was fair between all 3 methods, scapular stabilization provided the best intrarater reliability. A statistically significant difference was observed between all 3 methods (P < .001). Internal rotation was significantly less in the dominant shoulder than in the nondominant shoulder (P < .001). CONCLUSION: Differences in internal rotation range of motion measurements exist when using different methods. The scapula stabilization method displayed the highest intrarater reproducibility and should be considered when evaluating internal rotation passive range of motion of the glenohumeral joint. CLINICAL RELEVANCE: A standardized method of measuring internal rotation range of motion is required to accurately compare physical examinations of patients. The authors recommend the use of the scapula stabilization method to assess internal rotation range of motion by allowing normal glenohumeral arthrokinematics while stabilizing the scapulothoracic articulation.

The effect of neuromuscular electrical stimulation of the infraspinatus on shoulder external rotation force production after rotator cuff repair surgery.

BACKGROUND: Muscle weakness, particularly of shoulder external rotation, is common after rotator cuff repair surgery. Neuromuscular electrical stimulation has been shown to be an effective adjunct in the enhancement of muscle recruitment. HYPOTHESIS: Shoulder external rotation peak force can be enhanced by neuromuscular electrical stimulation after rotator cuff repair surgery. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty-nine patients (20 men, 19 women) who had undergone rotator cuff repair surgery were tested a mean of 10.5 days after surgery. Testing consisted of placing patients supine with the shoulder in 45 degrees of abduction, neutral rotation, and 15 degrees of horizontal adduction. Neuromuscular electrical stimulation was applied to the infraspinatus muscle belly and inferior to the spine of the scapula. Placement was confirmed by palpating the muscle during a resisted isometric contraction of the external rotators. Patients performed 3 isometric shoulder external rotation contractions with and without neuromuscular electrical stimulation, each with a 5-second hold against a handheld dynamometer. Neuromuscular electrical stimulation was applied at maximal intensity within comfort at 50 pulses per second, symmetrical waveform, and a 1-second ramp time. The 3 trials under each condition were recorded, and an average was taken. The order of testing was randomized for each patient tested. A paired samples t test was used to determine significant differences between conditions (P < .05). Each group was also divided based on age, rotator cuff tear size, number of days postoperative, and neuromuscular electrical stimulation intensity. Analysis of variance models were used to determine the influence of these variables on external rotation force production (P < .05). RESULTS: Peak force production was significantly greater (P < .001) when tested with neuromuscular electrical stimulation (3.75 kg) as opposed to without neuromuscular electrical stimulation (3.08 kg) for all groups tested. There was no significant difference based on the size of the tear, age of the patient, number of days after surgery, or level of neuromuscular electrical stimulation intensity. CONCLUSION: Peak shoulder external rotation force was significantly increased by 22% when tested with neuromuscular electrical stimulation after rotator cuff repair surgery. Neuromuscular electrical stimulation significantly increased force production regardless of the age of the patient, size of the tear, intensity of the current, or the number of days postoperative. CLINICAL RELEVANCE: Neuromuscular electrical stimulation may be used concomitantly with exercises to enhance the amount of force production and potentially minimize the inhibition of the rotator cuff after repair surgery.

Changes in shoulder and elbow passive range of motion after pitching in professional baseball players.

BACKGROUND: The overhead throwing athlete has unique range of motion characteristics of the shoulder and elbow. Numerous theories exist to explain these characteristics; however, the precise cause is not known. Although it is accepted that range of motion is altered, the acute effect of baseball pitching on shoulder and elbow range of motion has not been established. HYPOTHESIS: There will be a reduction in passive range of motion immediately after baseball pitching. STUDY DESIGN: Controlled laboratory study. METHODS: Sixty-seven asymptomatic male professional baseball pitchers participated in the study. Passive range of motion measurements were recorded using a customized bubble goniometer for shoulder external rotation, shoulder internal rotation, total shoulder rotational motion, elbow flexion, and elbow extension on the dominant and nondominant arms. Testing was performed on the first day of spring training. Measurements were taken before, immediately after, and 24 hours after pitching. RESULTS: A significant decrease in shoulder internal rotation (-9.5 degrees), total motion (-10.7 degrees), and elbow extension (-3.2 degrees) occurred immediately after baseball pitching in the dominant shoulder (P<.001). These changes continued to exist 24 hours after pitching. No differences were noted on the nondominant side. CONCLUSION: Passive range of motion is significantly decreased immediately after baseball pitching. This decrease in range of motion continues to be present 24 hours after throwing. High levels of eccentric muscle activity have previously been observed in the shoulder external rotators and elbow flexors during pitching. These eccentric muscle contractions may contribute to acute musculotendinous adaptations and altered range of motion. The results of this study may suggest a newly defined mechanism to range of motion adaptations in the overhead throwing athlete resulting from acute musculoskeletal adaptations, in addition to potential osseous and capsular adaptations.

Electromyographic analysis of the supraspinatus and deltoid muscles during 3 common rehabilitation exercises.

CONTEXT: Investigators have observed electromyographic (EMG) activity of the supraspinatus muscle and reported conflicting results. OBJECTIVE: To quantify EMG activity of the supraspinatus, middle deltoid, and posterior deltoid muscles during exercises commonly used in rehabilitation. DESIGN: One-factor, repeated-measures design. SETTING: Controlled laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-two asymptomatic subjects (15 men, 7 women) with no history of shoulder injury participated. MAIN OUTCOMES MEASURE(S): The dominant shoulder was tested. Fine-wire EMG electrodes were inserted into the supraspinatus, middle deltoid, and posterior deltoid muscles. The EMG data were collected at 960 Hz for analysis during maximal voluntary isometric contraction (MVIC) and 5 repetitions of 3 exercises: standing elevation in the scapular plane ("full can"), standing elevation in the scapular plane with glenohumeral internal rotation ("empty can"), and prone horizontal abduction at 100 degrees with glenohumeral external rotation ("prone full can"). We calculated 1-way repeated-measures analysis of variance (P < .05) and post hoc 2-tailed, paired t tests to detect significant differences in muscle activity among exercises. RESULTS: No statistical difference existed among the exercises for the supraspinatus. The middle deltoid showed significantly greater activity during the empty-can exercise (77 +/- 44% MVIC) and prone full-can exercise (63 +/- 31% MVIC) than during the full-can exercise (52 +/- 27% MVIC) (P = .001 and .017, respectively). The posterior deltoid showed significantly greater activity during the prone full-can exercise (87 +/- 53% MVIC) than during the full-can (P = .001) and the empty-can (P = .005) exercises and significantly greater activity during the empty-can exercise (54 +/- 24% MVIC) than during the full-can exercise (38 +/- 32% MVIC) (P = .012). CONCLUSIONS: While all 3 exercises produced similar amounts of supraspinatus activity, the full-can exercise produced significantly less activity of the deltoid muscles and may be the optimal position to recruit the supraspinatus muscle for rehabilitation and testing. The empty-can exercise may be a good exercise to recruit the middle deltoid muscle, and the prone full-can exercise may be a good exercise to recruit the posterior deltoid muscle.