Isokinetic profile of wrist and forearm strength in elite female junior tennis players.

BACKGROUND: In tennis, injuries to the elbow and wrist occur secondary to the repetitive nature of play and are seen at increasingly young ages. Isokinetic testing can be used to determine muscular strength levels, but dominant/non-dominant and agonist/antagonist relations are needed for meaningful interpretation of the results. OBJECTIVES: To determine whether there are laterality differences in wrist extension/flexion (E/F) and forearm supination/pronation (S/P) strength in elite female tennis players. METHODS: 32 elite female tennis players (age 12 to 16 years) with no history of upper extremity injury underwent bilateral isokinetic testing using a Cybex 6000 dynamometer. Peak torque and single repetition work values for wrist E/F and forearm S/P were measured at speeds of 90 degrees/s and 210 degrees/s, with random determination of the starting extremity. Repeated measures analysis of variance was used to determine differences between extremities for peak torque and single repetition work values. RESULTS: Significantly greater (p<0.01) dominant arm wrist E/F and forearm pronation strength was measured at both testing speeds. Significantly less (p<0.01) dominant side forearm supination strength was measured at both testing speeds. CONCLUSIONS: Greater dominant arm wrist E/F and forearm pronation strength is common and normal in young elite level female tennis players. These strength relations indicate sport specific muscular adaptations in the dominant tennis playing extremity. The results of this study can guide clinicians who work with young athletes from this population. Restoring greater dominant side wrist and forearm strength is indicated after an injury to the dominant upper extremity in such players.

Velocity of a tennis serve and measurement of isokinetic muscular performance: brief review and comment.

Isokinetic strength testing provides objective and reliable muscular performance data on elite tennis players; however, such data are not highly correlated with performance on a multiple-joint kinetic chain activity such as the tennis serve. In this brief review, an overview of the muscular performance characteristics generated through isokinetic testing for elite tennis players is presented. Application of population specific isokinetic strength profiles in specific populations for rehabilitation and performance enhancement is recommended.

Assessment of shoulder strength in professional baseball pitchers.

STUDY DESIGN: A bilateral comparison of strength and range of motion testing in professional baseball pitchers. OBJECTIVE: We studied 39 professional male baseball pitchers to determine if the shoulder used for throwing was weaker or had less passive range of motion, compared to the nondominant arm. BACKGROUND: Shoulder muscle weakness has been proposed as a possible risk factor for developing injury. Therefore, objective quantification of the strength of glenohumeral and scapular rotator muscle groups should be studied in a population of professional baseball pitchers. METHODS AND MEASURES: Passive internal and external range of motion was bilaterally measured at 90 degrees of abduction. Muscle strength of the following muscles was measured bilaterally with a hand-held dynamometer: external and internal glenohumeral rotators, supraspinatus, middle trapezius, lower trapezius, and serratus anterior. RESULTS: Passive external rotation of the glenohumeral joint at 90 degrees of abduction on the pitching side was significantly greater than on the nonpitching side. Passive internal rotation range of motion on the nonpitching side was significantly greater than on the pitching side. The pitching arm's internal rotators, when tested in abduction, were significantly stronger than the nonpitching arm. The nonpitching arm's external rotators in the plane of the scapula, and in abduction, were significantly greater than those of the pitching arm. The pitching arm's middle and lower trapezius muscles were significantly stronger than those of the nonpitching arm. CONCLUSION: The range of motion and strength characteristics measured in this study can assist clinicians in evaluating athletes who use overhead throwing motions.

Quantification of anterior translation of the humeral head in the throwing shoulder. Manual assessment versus stress radiography.

Clinical evaluation of humeral head translation relies mainly on manual tests to measure laxity in the human shoulder. The purposes of this study were to determine whether side-to-side differences exist in anterior humeral head translation in professional baseball pitchers, to compare manual laxity testing with stress radiography for quantifying humeral head translation, and to test intrarater reliability of the manual humeral head translation and stress radiography tests. Twenty professional baseball pitchers underwent bilateral manual anterior humeral head translation and stress radiographic tests. Stress radiography was performed by imparting a 15-daN anterior load to the shoulder in 90 degrees of abduction with both neutral and 60 degrees of external rotation and recording the glenohumeral joint translation at rest and under stress in each position. Eight subjects were retested to assess the reliability of these methods. Results showed no significant difference between the dominant and nondominant extremity in the amount of anterior humeral head translation measured manually and with stress radiography, nor significant correlation between anterior humeral head translation measured manually and by stress radiography. Test-retest reliability was moderate-to-poor for the manual humeral head translation test and moderate for stress radiography.

The application of isokinetics in testing and rehabilitation of the shoulder complex.

OBJECTIVE: We review the application of isokinetic testing and training for the shoulder complex, the interpretation of isokinetic testing data, and the application of normative data in the rehabilitation and performance enhancement of the athlete. DATA SOURCES: We searched MEDLINE for the years 1989- 1999 using the key words "isokinetics," "shoulder," and "upper extremity." DATA SYNTHESIS: Isokinetic testing and training is an integral part of the comprehensive evaluation and treatment of the shoulder complex. This mode of exercise allows for objective, isolated joint testing and training. CONCLUSIONS/RECOMMENDATIONS: Isokinetic training and testing is an important part of the comprehensive evaluation and rehabilitation of the patient with a shoulder injury. Research has demonstrated its efficacy in training and in providing clinically relevant information regarding muscular performance. When integrated with a complete history, subjective examination, and physical and functional evaluation, isokinetic exercise can be a valuable tool for the clinician in the assessment, rehabilitation, and performance enhancement of the athlete.

Glenohumeral joint range of motion and rotator cuff strength following arthroscopic anterior stabilization with thermal capsulorraphy.

STUDY DESIGN: Single-session, posttest only, descriptive analysis of range of motion (ROM) and strength. OBJECTIVES: To measure ROM and strength approximately 12 weeks following arthroscopic anterior stabilization of the glenohumeral joint with thermal capsulorraphy. BACKGROUND: Treatment of the patient with anterior, unidirectional glenohumeral joint instability often includes surgical stabilization. Current methods focus on arthroscopic stabilization and early ROM and strengthening to restore normal function to the upper extremity. METHODS AND MEASURES: Twenty patients diagnosed with unidirectional shoulder instability (mean age 24.5 years, SD = 8.48) underwent a postoperative rehabilitation program following unilateral arthroscopic shoulder stabilization with thermal capsulorraphy. Objective testing including ROM and isokinetic internal rotation (IR) and external rotation (ER) strength at 90, 210, and 300 degrees/s was performed 12 weeks postoperatively. RESULTS: Ten patients had a complete return of shoulder flexion ROM at 12 weeks. There were deficits compared to the noninjured extremity in postoperative glenohumeral joint mean abduction (9.8 +/- 12.7 degrees), IR (8.4 +/- 15.0 degrees), and ER (13.1 +/- 14.4 degrees). Isokinetic testing showed a complete return of ER strength on the postoperative extremity compared to the uninjured extremity for 12 patients with a 4% (+/- 21.1%) mean deficit measured in IR strength at the slowest testing velocity. No significant difference was found between extremities in the external/internal rotation ratios. CONCLUSION: Postoperative rehabilitation emphasizing progressive ROM and rotator cuff and scapular strengthening has produced favorable results in patients 12 weeks postoperatively with respect to glenohumeral joint ROM and IR and ER strength. Further research and follow-up is required to obtain long-term outcomes with respect to patient satisfaction and stability of the glenohumeral joint following this arthroscopic procedure.

Testing isokinetic muscular fatigue of shoulder internal and external rotation in elite junior tennis players.

STUDY DESIGN: Single group, post-test only descriptive analysis of isokinetically measured shoulder internal and external rotation muscular fatigue. OBJECTIVES: To determine whether differences in isokinetically measured muscular fatigue exist between shoulder external (ER) and internal rotation (IR) and between the dominant (DOM) and nondominant (NDOM) extremity in elite junior tennis players. BACKGROUND: The importance of the rotator cuff in stabilizing the humeral head during repetitive athletic overhead motions has been identified in biomechanical investigations. The application of exercise to improve muscular function of the shoulder and prevent injury is a common practice in physical therapy, but shoulder fatigue in tennis players has received little attention in the literature. METHODS AND MEASURES: Seventy-two elite junior tennis players (ages 12 to 18) underwent bilateral isokinetic testing with 90 degrees of glenohumeral joint abduction. A muscular fatigue protocol consisting of 20 maximal-effort concentric contractions of ER and IR was used to measure muscular fatigue at 300 degrees/s. A relative fatigue ratio was calculated by dividing the work in the last 10 repetitions by the work in the first 10 repetitions. Higher fatigue ratios indicate improved muscular fatigue resistance. A 2x2 ANOVA was used to assess differences in fatigue in DOM versus NDOM arm, and in IR versus ER. RESULTS: Relative muscular fatigue ratios for ER and IR were 69.1+/-15.3% and 82.93+/-14.81% for the DOM extremity, respectively. In the NDOM extremity, ER and IR fatigue ratios were 71.13+/-15.07% and 83.9+/-16.5%, respectively. These results indicate significant differences between the fatigue ratios for ER and IR. No significant difference between extremities in either ER or IR relative fatigue ratios was found. CONCLUSIONS: These data have implications for rehabilitation and conditioning of the rotator cuff musculature.

Medial elbow joint laxity in professional baseball pitchers. A bilateral comparison using stress radiography.

Injuries to the ulnar collateral ligament frequently occur in throwing athletes because of large, repetitive valgus stresses to the elbow during the cocking and acceleration phases of throwing. Identification of injury to this ligament is important in evaluating the throwing elbow. The purpose of this study was to determine whether differences in medial elbow laxity exist between the dominant and nondominant extremities in uninjured baseball pitchers. Forty uninjured professional baseball pitchers were tested bilaterally with a Telos GA-IIE stress radiography device. Joint space width between the trochlea of the humerus and the coronoid process of the ulna was measured on anteroposterior radiographs obtained with no stress applied and with a 15-daN valgus stress. Results showed significant differences between the medial joint space opening of the dominant and nondominant elbows with no stress applied. With stress, the dominant elbow opened 1.20 +/- 0.97 mm, while the nondominant elbow opened 0.88 +/- 0.55 mm. A significantly greater difference in medial joint space opening between the stressed and unstressed elbows was measured in the dominant elbow compared with the nondominant elbow (0.32 +/- 0.42 mm). This study identifies increased medial elbow laxity in the dominant arm in uninjured pitchers.

Concentric isokinetic shoulder internal and external rotation strength in professional baseball pitchers.

Objective measurement of shoulder internal and external rotation strength is an important part in the comprehensive evaluation and rehabilitation of athletes who perform predominantly unilateral upper extremity movement patterns. Apparatus- and population-specific descriptive data are needed to enhance the interpretation of results from isokinetic dynamometers. The primary purpose of this study was to measure isokinetically glenohumeral joint internal and external rotator peak torque and work in professional baseball pitchers and determine whether significant differences exist between the dominant (throwing) extremity and nondominant extremity. One hundred twenty-five healthy professional baseball pitchers were tested bilaterally on a Cybex 300 series isokinetic dynamometer at 210 and 300 degrees/sec for concentric internal and external rotation of the glenohumeral joint with the arm in 90 degrees of abduction. A standardized protocol and testing guidelines were strictly followed. A dependent t test was used to test for differences between extremities for peak torque and single repetition work isokinetic parameters. No significant difference between the dominant and nondominant shoulder was found for external rotation peak torque or single repetition work at either testing speed. Significantly greater (p < .001) dominant arm shoulder internal rotation was measured for both peak torque and single repetition work at 210 and 300 degrees/sec compared with the nondominant extremity. The results of this study are important for the application and interpretation of isokinetic data on unilaterally dominant upper extremity athletes. The use of a population-specific, descriptive isokinetic data profile is important in both rehabilitation and prevention of shoulder injuries.

Glenohumeral joint internal and external rotation range of motion in elite junior tennis players.

Objective measurement of range of motion of the glenohumeral joint is important for the rehabilitation and prevention of shoulder injury. The primary purpose of this study was to determine whether significant differences exist between the dominant (tennis playing) and nondominant extremity in active internal and external rotation range of motion in elite junior tennis players 11-17 years of age. Two hundred three elite junior tennis players (113 males, 90 females) were bilaterally measured for internal and external rotation at 90 degrees of abduction in a supine position with a specific methodology attempting to isolate glenohumeral motion, while minimizing or negating scapulothoracic motion. A standard universal goniometer was utilized to measure active range of motion (AROM). Dependent t tests were used to compare differences between extremities. No significant difference was found for males or females between the dominant and nondominant arm in external rotation. Analysis of internal rotation (AROM) differences showed significantly less (p < .001) internal rotation (AROM) on the dominant arm for both males and females. Significantly less (p < .001) dominant arm total rotational range of motion was also found in both males and females. The loss of dominant arm internal rotation (AROM) has clinical application for both the development of rehabilitation and preventative flexibility/range of motion programs.

Rehabilitation of shoulder and elbow injuries in tennis players.

Optimization of treatment of the tennis player with an upper extremity overuse injury requires a thorough understanding and analysis of the biomechanical and physiologic stresses inherent in the game of tennis. Anatomic adaptations found in the upper extremity of elite tennis players provide the framework for evaluation and treatment of overuse injury through both an anatomically based total-arm strength program and efforts to normalize joint arthrokinematics. Integration of these key factors allows the clinician to rehabilitate the patient and design preventive conditioning programs in a scientifically based, sport-specific manner.

Test-retest reliability of the biodex isokinetic dynamometer.

The purpose of this study was to determine the test-retest reliability of the Biodex (Biodex, Corp., Shirley, NY) isokinetic concentric mode for a healthy active population for knee extension/flexion utilizing the parameters peak torque and work. Nineteen healthy active male and female subjects ages 20-35 with no history of knee injury were tested bilaterally for concentric knee extension and flexion at 60, 180, 240, and 300 degrees /sec., utilizing standard Biodex protocol. Seven days following the pre-test, a post-test was administered using identical protocol. Data collection of pre- and posttesting was done via a Compaq Desk Pro personal computer and Biodex software programming. The parameters of peak torque and single repetition work were analyzed for knee extension/flexion. Statistical analysis of data showed the intraclass correlation coefficient (ICC) of knee extension peak torque at 60 degrees /sec to be r = 0.95; at 180 degrees /sec, r = 0.96; at 240 degrees /sec, r = 0.95; and at 300 degrees /sec, r = 0.97. Knee extension work ICC values were at 60 degrees /sec, r = 0.96; at 180 degrees /sec, r = 0.97; at 240 degrees /sec, r = 0.96 and r = 0.95 at 300 degrees /sec. All ICCs are significant at the 0.05 level. Therefore, the isokinetic concentric mode of the Biodex dynamometer was reliable for test-retest measures of peak torque, and single repetition work. J Orthop Sports Phys Ther 1990;11(7):298-300.

Rehabilitation of overuse injuries of the shoulder.

The most common overuse injuries in sports medicine are rotator cuff tendinitis and shoulder impingement. Anatomic and biomechanical analysis of the shoulder complex demonstrates the likelihood of overuse injury to this region. Total rehabilitation includes relief of inflammation, restoration of normal joint arthrokinematics, and rotator cuff strengthening. The reduction of force overload to the shoulder in sport-specific activities and total arm strengthening are also emphasized in a comprehensive rehabilitation program.

Concentric versus eccentric isokinetic strengthening of the rotator cuff. Objective data versus functional test.

Twenty-two male and female college varsity tennis players trained for 6 weeks, one group using eccentric isokinetic internal and external shoulder rotation, and the second group using concentric isokinetic internal and external shoulder rotation. Subjects pretested and posttested both concentrically and eccentrically, so that training overflow and specificity could be examined. Three maximally hit tennis serves made before and after training, which were analyzed by high speed cinematography to obtain ball velocity, served as a functional performance measurement. Statistical analysis of peak torque (newton meters) and peak torque to body weight ratio have revealed significant concentric strength gains (P less than 0.005) in the concentric as well as the eccentric training groups. Eccentric strength gains were demonstrated by the concentric training group at selected speeds (P less than 0.05 and P less than 0.005) but were not generated in the eccentric group at the P less than 0.05 significance level. Functional test analysis shows an increase in maximal serve velocity at a significance level of P less than 0.005 in the concentric training group, with no significant (P greater than 0.01) increases in the eccentric group.