The current study aims to characterize the cortical activity and proprioceptive acuity in baseball players with glenohumeral internal rotation deficit (GIRD). Additionally, the correlations between cortical activity, proprioceptive acuity, and pitching performance will be examined. The evaluation of proprioception will be conducted using the active joint reposition sense of the shoulder. Simultaneously, the investigators will record cortical activity by electroencephalography (EEG). To represent pitching performance, the investigators will collect ball velocity and pitching accuracy. This will help the investigators understand the process of proprioception in the central nervous system, as well as factors associated with pitching performance in baseball players with GIRD.
Study Type
OBSERVATIONAL
Enrollment
98
participants pitch fastball to the strike zone
Institute of Physical Therapy, National Taiwan University
Taipei, Taiwan, Taiwan
Active joint reposition test
Participants will mimic the pitching motion with reducing the influence from the lower limb by kneeling the knee and hip of the nondominant side 90° and their foot are flat on the ground. They will be blindfolded, with their non-throwing hand resting on the thigh. The reproducing arm-cocking and ball-release positions will be tested at random sequences for six trials, respectively. Results or feedback regarding the accuracy of individual trials will not be provided at any time. The acuity of active joint reposition will be calculated by 3-dimensional variable error scores for scapulothoracic (internal-external rotation, upward-downward rotation, posterior-anterior tilt) and glenohumeral (internal-external rotation, horizontal abduction-adduction, abduction-adduction) joint 55. Three-dimensional variable error scores (3DVE) reflect acuity (measured in degrees) in all planes of motion measured for individual joints.
Time frame: baseline
Pitching performance
Pitching performance will be collected by radar gun (JUGS company, Tualatin, OR, USA) and digital camera (JVC GC-PX100B, Yokohama, Japan) for ball velocity and pitching location, respectively. Participants will pitch on a mound 18.44 m away from the home plate. The target will be aligned with the theoretical line extending from the right edge of the home plate at a height of approximately 30 cm above the ground. After warming up at their own pace, each participant throws 30 game-like effort pitches in three 10-pitch sessions without specific instruction on focusing their attention. The fastest velocity of 10 pitches will be collected for analysis.
Time frame: baseline
Shoulder range of motion
The tester grasps the subject's forearm in a supine position to measure the shoulder horizontal adduction/abduction. The humerus will be moved until the movement ceases (firm end-feel), indicating the end of shoulder tissue flexibility. The recorder places the digital inclinometer parallel to the humerus. Each measurement will be performed 3 times, and the average data will be analyzed. GH internal/external (IR/ER) ranges will be measured accordingly following the method in a previous study. Participants lay down supine with 90° shoulder abduction and elbow flexion. Then GH IR/ER will be measured by the main assessor using a digital inclinometer by stabilizing the scapula by grasping the coracoid process and the spine of the scapula posteriorly, then moving the forearm to reach the end range. Each measurement will be performed 3 times, and the average data will be used for analysis.
Time frame: baseline
Humeral retrotorsion
Humeral retrotorsion will be measured with the T3300 ultrasound system (BenQ, Taipei, Taiwan). Participants lay supine with 90° shoulder abduction and elbow flexion. The main assessor places the transducer on the participant's anterior shoulder for a short-axis view of the lesser and greater tubercles. The two-person technique is adopted. The first assessor adjusts the probe perpendicular to the floor and rotates the participant's humerus with a line connecting the greater and lesser tubercles parallel to the horizontal plane. Then, the second assessor places a digital inclinometer on the ulnar side of the forearm to record the rotation angle, which is defined as the humeral retroversion.23 The ICC3,k of intra-rater reliability is 0.995. Each measurement will be performed 3 times, and averaged data will be used for analysis.
Time frame: baseline
Acromiohumeral distance
Acromiohumeral distance will be measured with the ultrasound transducer placed on the lateral aspect of the acromion in line with the longitudinal axis of the humerus to visualize the shortest distance between the humerus and the acromion.58 Three consecutive ultrasound images of the acromiohumeral distance are captured. The investigator captures 3 more consecutive ultrasound images at rest while the participant sit with the shoulder in the neutral position. The shortest distance will be measured with built-in calipers. The ICC3,k for intra-rater reliability is 0.963. Each measurement will be performed 3 times and averaged data will be used for analysis.
Time frame: baseline
Rotator cuff thickness
The probe will be positioned on the bicipital grove horizontally to measure subscapularis tendon thickness in a short axis of view. The participant's forearm is placed with the elbow flexed to 90° in slight internal rotation, with the palm facing upward and medially. This position allows the bicipital groove to be brought to an anterior position, allowing clear visualization of the tendon within the grove. .
Time frame: baseline
Posterior capsule thickness
For measurement of the posterior capsule thickness, the participants sit upright in a chair with both forearms resting on the thighs and upper arms by the participant's sides. The examiner positions a transducer on the posterior shoulder and visualizes the glenoid labrum, humeral head, rotator cuff, and posterior capsule. The posterior capsule is defined as the tissue immediately lateral to the tip of the labrum between the humeral head and rotator cuff. When the capsule is identified in the image, posterior capsule thickness will be measured with built-in calipers. The ICC3,k for intra-rater reliability is 0.951. Each measurement will be performed 3 times, and averaged data will be used for analysis.
Time frame: baseline
Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow score (KJOC)
The KJOC is the most common questionnaire for overhead athletes, and it was conducted in several studies.66 Recently, the Major League Baseball (MLB) organization adopted this evaluation tool as the standard for recovering injuries in MLB players.67 The questionnaire is commonly used to assess shoulder function and performance. It is valid, reliable in its pilot form, and responsive to the tested population of adult overhead athletes.66 KJOC questionnaire ranges from 0 to 100, and the lower score represents a limited function.
Time frame: baseline
Posterior capsule elasticity
To measure the posterior capsule elasticity, the participants sit upright in a chair with both forearms resting on the thighs and upper arms by the participant's sides. The examiner positions a transducer on the posterior shoulder and visualizes the glenoid labrum, humeral head, rotator cuff, and posterior capsule. The posterior capsule is defined as the tissue immediately lateral to the tip of the labrum between the humeral head and rotator cuff. When the capsule is identified in the image, posterior capsule elasticity will be recorded. Each measurement will be performed 3 times and averaged data will be used for analysis.
Time frame: baseline
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