Non-throwing Arm Research Articles

Elbow isokinetic strength characteristics among collegiate baseball players

ObjectivesTo compare the bilateral strength characteristics of the wrist flexors, extensors, pronators, and supinators among baseball players. DesignCross-sectional. SettingLaboratory. Participants30 collegiate baseball players with no recent history of upper extremity injury. Main outcome measuresBilateral pronation, supination, wrist flexion, and wrist extension peak torque (PT) and peak torque to body weight (PT/BW) strength were measured at speeds of 90 and 180°/second. ResultsPaired t-tests showed that the throwing arm of baseball players produced significantly less PT/BW strength for supination at 90°/second compared to the non-throwing arm (P = .001). The throwing arm produced significantly more PT/BW strength for pronation (P = .001) at 180°/second compared to the non-throwing arm. Furthermore, the throwing arm had more PT and PT/BW strength for wrist extension (P < .005) at 180°/second. Conversely, the throwing arm had less PT and PT/BW strength for supination (P < .004) and wrist flexion (P < .004) at 180°/second compared to the non-throwing arm. ConclusionsSignificant bilateral strength differences exist in pronation, supination, wrist flexion, and wrist extension among collegiate baseball players.With the steady increase in ulnar collateral ligament injuries of the elbow among baseball players and the proven resistance to valgus force provided by the flexor-pronator mass of the elbow, the results of this study may prove beneficial in the prevention, evaluation, and rehabilitation of such dysfunctions.

Mechanical work, efficiency and energy redistribution mechanisms in baseball pitching

Though baseball pitching is assumed to achieve proper technique in which a great deal of energy is imparted from the trunk to the throwing arm, through a kinetic chain of the entire body, few studies have answered the question of how segmental energy is generated/transferred by muscles and intersegmental joint forces. The purpose of this study was to calculate the mechanical energy produced by the individual joint moments or joint forces in throwing, and further breaking down the joint moments into their muscular and non-muscular interactive moments, assessing their contribution to the generation of mechanical energy. The pitching motion of eight collegiate baseball pitchers was measured using a three-dimensional motion capture system. A model including multiple segments and joints of the throwing arm, non-throwing arm and trunk was developed to establish the relationships between causal muscle work and distributed segmental energy. Using the model, the mechanical energy of each segment was decomposed int...

Playing level achieved, throwing history, and humeral torsion in Masters baseball players

Humeral torsion is thought to be beneficial for throwing. To examine this hypothesis, the throwing and non-throwing arms of 84 Masters baseball players over 35 years of age were measured for humeral torsion, and the highest playing level they achieved and their playing history were recorded. Regression analyses were used to obtain predictors of the highest playing level achieved, throwing arm humeral torsion, and side-to-side difference in humeral torsion. Equations accounting for 36%, 46%, and 12% of the variance respectively were produced. Achieving representative level playing status was associated with the number of seasons played under 16 years of age and having greater throwing arm humeral retrotorsion. Throwing arm humeral retrotorsion was associated with non-throwing arm humeral retrotorsion and an increased number of seasons played before the age of 16 years. A model in which repeated throwing develops an adaptive unilateral bone torsion along with growth in baseball expertise is proposed. Thus dominant arm humeral retrotorsion is a predictor of highest baseball playing level achieved, which in turn is influenced by genetic endowment (as seen in the torsion of the non-throwing arm) and amount of throwing activity, particularly prior to the age of 16.

Humeral Head Retroversion in Competitive Baseball Players and Its Relationship to Glenohumeral Rotation Range of Motion

Prospective case series. To determine if an osseous component in the form of increased humeral head retroversion may contribute to observed differences in the amount of rotation between the throwing and nonthrowing shoulders of competitive baseball players. Differences in side-to-side shoulder rotation range of motion (ROM) are seen in throwing athletes. In the past, these differences have been attributed to adaptive changes to the surrounding soft tissue structures, including attenuation of the anteroinferior capsule and ligaments, and tightening of the posterior capsule. Recent studies, however, suggest that a possible osseous adaptation in the form of increased humeral head retroversion may be the cause of this side-to-side ROM difference. bilateral computed tomography (CT) scans to determine the angle of humeral head version. Maximal shoulder internal and external rotation ROM at 90 degrees abduction were measured both passively and actively for both shoulders. Players had statistically significant (P<.001) side-to-side difference in humeral head version, with an average of 10.60 greater retroversion in their throwing arm compared to their nonthrowing arm. A significant side-to-side difference was not observed in the control group (average difference, 2.30; P = .197). Greater humeral head retroversion was associated with greater external rotation ROM and lesser internal rotation ROM in the throwing arm of the throwers. Our results indicated that highly competitive baseball players do have greater humeral head retroversion in their dominant arm, which can partially explain the observed differences in side-to-side shoulder rotation ROM.

Kinematic Comparison of Youth Pitching Using Lighter Baseballs

0933 Many youth sport programs, such as football and basketball, have reduced the weight and size of the ball to accommodate youth athletes. However, baseball continues to use the same 5-ounce, 9 inch size baseball for Little Leaguers and Big Leaguers alike. PURPOSE: To investigate the effect of a lighter baseball on kinematic values of youth league baseball pitchers (age range: 9–12 yr, height: 1.54 ± 0.09 m, mass: 44.36 ± 9.42 kg). METHODS: Thirty-four youth baseball pitchers were tested in an indoor biomechanics laboratory. Each subject completed ten pitches using the 5-ounce and ten pitches using the 4-ounce baseball. Reflective markers were attached bilaterally to the distal end of the mid-toe, lateral malleolus, lateral femoral epicondyle, greater trochanter, lateral tip of the acromion, and lateral humeral epicondyle. Reflective markers were also attached to the ulnar and radial styloid processes along with the distal end of the third metacarpal of the throwing arm and to the ulnar styloid process of the non-throwing arm. The pitching motions of each subject were quantified with a three-dimensional automatic digitizing system using six electronically synchro-nized cameras that transmitted pixel images of the reflective markers directly into a video processor. Sixteen kinematic (11 position and 5 velocity) parameters were calculated and compared while throwing the different weight baseballs using two separate, two-way mixed factorial repeated measures ANOVA (velocity by weight of ball and position by weight of ball). RESULTS: There were no significant differences shown in the 11 position parameters, yet 3 of the 5 velocity parameters did show significant differences. An increase in maximum elbow extension velocity, maximum internal rotation velocity, and ball velocity were reported for the lighter, 4-ounce baseball compared to the 5-ounce baseball. CONCLUSIONS: Greater angular velocities at the shoulder and elbow, along with greater ball velocity using the 4-ounce baseball suggest that the quality of the game may be improved while reducing the weight of the baseball for young athletes. Since there were no differences shown in the position parameters, the increase in angular velocities and ball velocity is achieved without loss of proper pitching mechanics.

Kinematic Comparison of Youth Pitching Using Lighter Baseballs

0933 Many youth sport programs, such as football and basketball, have reduced the weight and size of the ball to accommodate youth athletes. However, baseball continues to use the same 5-ounce, 9 inch size baseball for Little Leaguers and Big Leaguers alike. PURPOSE: To investigate the effect of a lighter baseball on kinematic values of youth league baseball pitchers (age range: 9–12 yr, height: 1.54 ± 0.09 m, mass: 44.36 ± 9.42 kg). METHODS: Thirty-four youth baseball pitchers were tested in an indoor biomechanics laboratory. Each subject completed ten pitches using the 5-ounce and ten pitches using the 4-ounce baseball. Reflective markers were attached bilaterally to the distal end of the mid-toe, lateral malleolus, lateral femoral epicondyle, greater trochanter, lateral tip of the acromion, and lateral humeral epicondyle. Reflective markers were also attached to the ulnar and radial styloid processes along with the distal end of the third metacarpal of the throwing arm and to the ulnar styloid process of the non-throwing arm. The pitching motions of each subject were quantified with a three-dimensional automatic digitizing system using six electronically synchro-nized cameras that transmitted pixel images of the reflective markers directly into a video processor. Sixteen kinematic (11 position and 5 velocity) parameters were calculated and compared while throwing the different weight baseballs using two separate, two-way mixed factorial repeated measures ANOVA (velocity by weight of ball and position by weight of ball). RESULTS: There were no significant differences shown in the 11 position parameters, yet 3 of the 5 velocity parameters did show significant differences. An increase in maximum elbow extension velocity, maximum internal rotation velocity, and ball velocity were reported for the lighter, 4-ounce baseball compared to the 5-ounce baseball. CONCLUSIONS: Greater angular velocities at the shoulder and elbow, along with greater ball velocity using the 4-ounce baseball suggest that the quality of the game may be improved while reducing the weight of the baseball for young athletes. Since there were no differences shown in the position parameters, the increase in angular velocities and ball velocity is achieved without loss of proper pitching mechanics.

Effects of Non-throwing Arm on Trunk and Throwing Arm Movements in Baseball Pitching

The purpose of this study was to investigate the effects of non-throwing arm on trunk and throwing arm movements in baseball pitching. Ten right-handed collegiate baseball players were asked to throw baseballs under two conditions, the normal and the restricted conditions. Under the restricted condition, non-throwing arm was fixed to the trunk by a rubber band. Their motions were analyzed by three-dimensional high-speed motion analysis and compared between two conditions. Under the restricted condition, upper torso rotated more counterclockwise and trunk twist angle decreased, at the instant of stride foot contact on the ground. It might be because the moment of inertia of upper torso and upper extremities along the trunk axis was smaller without non-throwing arm movement. Additionally, the maximum angular velocities of shoulder internal rotation and elbow extension as well as pitched ball velocity were lower under the restricted condition. When trunk twist, which stretches trunk rotator musculature, is small, the energy exerted by the musculature and transferred to throwing arm would decrease. Therefore, non-throwing arm in baseball pitching motion is considered to contribute to enhance pitched ball velocity by controlling the moment of inertia of upper torso and upper extremities along the trunk axis.

Shoulder joint movement of the non-throwing arm during baseball pitch—comparison between skilled and unskilled pitchers

The shoulder of a non-throwing arm during a baseball pitch must be in a constant position while the shoulder of the throwing arm moves in a nearly circular path around it. However, it has not been investigated whether a skilled pitch requires less shoulder-joint movement. It was hypothesized that pitchers with less shoulder movement of the non-throwing arm can be considered to have higher skill and to attain higher initial ball velocity. Nine baseball pitchers were used as subjects. The coach classified them into a skilled and an unskilled group. The pitching motions were recorded using two high-speed cameras. The time series of three-dimensional landmark coordinates of the shoulder joint of the non-throwing arm during the baseball pitch were calculated using the direct linear transformation method. The shoulder-joint movement (SJM) index, which expresses the movement (displacement) of the shoulder joint of the non-throwing arm quantitatively, was proposed to compare the SJM at different skill levels and investigate the relationship between SJM and initial ball velocity. The SJM of the skilled pitchers was smaller than that of the unskilled pitchers, and the smaller value of the SJM led to faster initial ball velocity. The data suggest that the less SJM of the non-throwing arm is required to attain a skilled pitch and higher initial ball velocity.

Long term changes of the throwing arm of former elite javelin throwers.

The aim of this study was to determine long term changes in shoulder and elbow joints of former elite javelin throwers. Twenty-one elite javelin throwers were examined at an average of 19 years after the end of their high performance phase. Mean age at examination was 50 years. Functional assessment of both shoulders was determined by the Constant-score. The shoulder of the throwing arm was examined by magnetic resonance imaging. Both elbow joints were examined clinically and radiographically. Five athletes complained about transient shoulder pain in their throwing arm affecting activities of daily living, fourteen athletes had a deficit of internal rotation of at least ten degrees. Constant-scores of throwing arms were six points lower than those of non-throwing arms (P < 0.05). Complete ruptures and partial tears of the rotator cuff were frequent. Three athletes complained about transient elbow pain in their throwing arm affecting activities of daily living; ten athletes had a deficit of extension of more than five degrees. All dominant elbows had advanced arthrotic alterations (osteophytes, sclerosis) compared to the non-dominant side. Athletes who trained with weights of more than 3 kg had a significantly higher risk of degenerative changes than athletes who did not (P < 0.01). We therefore recommend to avoid throwing training with weights of more than 3 kg.

Glenohumeral joint: internal and external rotation range of motion in javelin throwers.

OBJECTIVE: To assess differences in glenohumeral joint rotatory range of movement in javelin throwers between the throwing and non-throwing arm. METHOD: A universal 360 degrees goniometer was used to assess...

Changes in peak torque arm-shoulder strength of high school baseball pitchers during the season.

Pre- and postseason measurements of peak torque arm strength were made at 180 deg./sec. and 300 deg./sec. on both throwing and nonthrowing arms of five male high school varsity baseball pitchers. The major findings were significant losses in adduction strength in both throwing and nonthrowing shoulders at 180 deg./ sec. and internal rotation strength for both sides at both speeds. The primary implication from these preliminary findings is that significant losses of arm-shoulder strength may be associated with injuries to the pitching arm.

Isokinetic Testing of the Shoulder Abductors and Adductors: Windowed vs Nonwindowed Data Collection

Presented at the Sports Physical Therapy Section Team Concept Meeting, December 1991, New Orleans, LA The manner of acquiring strength-testing data may influence the results of an investigation. The purpose of this study was to determine if a significant difference exists between windowed and unwindowed data collection during isokinetic testing of the shoulder abductors/adductors. Fifty healthy professional baseball pitchers participated in this study. Testing was performed on a Biodex isokinetic dynamometer at 180 and 300 degrees /sec for both the throwing and nonthrowing shoulders. Testing procedures regarding testing protocol, repetitions, positioning, and stabilization followed established guidelines for each subject. Statistical analysis was performed using a paired t-test with a p < 0.01 level of significance. Statistically significant differences were demonstrated between windowed and unwindowed mean peak torque data for both shoulders at both test speeds. The results indicated an average nonthrowing arm difference of 20.2 ft/lbs at 180 degrees /sec and 51.7 ft/lbs at 300 degrees / sec for the abductors. In each instance, the unwindowed mean peak torque values were higher than the windowed values, and significant end range torque spikes were elicited during unwindowed data collection. The nonthrowing adductors exhibited an average of 39.3 and 48.3 ft/lb differences at 180 and 300 degrees /sec, respectively. The throwing shoulder demonstrated average abductor differences of 25.6 ft/lbs at 180 degrees /sec and 47.7 ft/lbs at 300 degrees /sec. The average throwing adductor difference was 24.4 ft/lbs and 54.6 ft/lbs, respectively, at both test speeds. This investigation offers clinical relevance for those using isokinetic testing of the shoulder abductors/adductors in demonstrating the significant differences between windowed and unwindowed data, identifying torque spike data misinterpretation, and describing a clinical means of controlling aberrant torque production during testing. J Orthop Sports Phys Ther 1992;15(2):107-112.

Shoulder Antagonistic Strength Ratios: A Comparison between College-Level Baseball Pitchers and Nonpitchers

The purpose of this study was to investigate the shoulder strength ratios obtained from college-level baseball pitchers and age- and sex-matched nonpitchers. Shoulder flexion/extension and externallinternal rotation strength ratios were assessed in 10 pitchers and 9 nonpitchers. Speeds selected for testing were 180 and 300 degrees /sec on the Cybex /I.@R esults indicated that both pitchers and nonpitchers generated greater peak torque values for the extensors and internal rotators than for the flexors and external rotators of the shoulder. A comparison of shoulder strength ratios between a pitcher's throwing arm and his nonthrowing arm was statistically significant (p < 0.05) for shoulder external/internal rotation at the speeds of 180 and 300 "/set. A comparison of shoulder strength ratios between pitchers and nonpitchers on the nondominant arm was not statistically significant for any of the speeds or directions tested. A comparison of the shoulder strength ratios between pitchers and nonpitchers on the dominant arm was statistically significant (p < 0.05) for all directions and speeds tested. The relationship between shoulder muscle imbalance and injury was discussed. J Orthop Sports Phys Ther 1987;8(9):451-461.