Glenohumeral Internal Rotation Deficit on Pitching Biomechanics and Muscle Activity

Abstract

To characterize the scapular pitching biomechanics in symptomatic GIRD pitchers (SG) compared to asymptomatic GIRD (ASG) and healthy pitchers. The scapular kinematics and associated muscle activities during pitching were recorded in 33 high school pitchers. Compared to healthy, GIRD pitchers had less scapular posterior tilt in each pitching event (average difference, AD = 14.4°, p < 0.01) and ASG demonstrated less scapular upward rotation at ball release (AD = 12.8°, p < 0.01) and greater muscle activity in the triceps brachii in the early-cocking phase (AD = 9.9%, p = 0.015) and in the serratus anterior in the late-cocking phase (AD = 30.8%, p < 0.01). Additionally, SG had less muscular activity on triceps brachii in the acceleration phase and serratus anterior in the cocking phase (AD = 37.8%, p = 0.016; AD = 15.5%, p < 0.01, respectively) compared to ASG. GIRD pitchers exhibited less scapular posterior tilt during pitching, which may cause impingement. Since tightness of the anterior shoulder is a common cause of inadequacy of posterior tilt during arm elevation, stretching exercise of the anterior shoulder is recommended. Given the inadequate recruitment during pitching in the GIRD pitchers, symptoms may develop following potential impingement.

Correlation of Glenohumeral Internal Rotation Deficit with Shoulder Pain in Elite Table Tennis Players

“…The key to treating GIRD is to stretch the posterior capsule and muscles, 27,28 and effective stretch methods are “sleeper stretch” and “cross-arm stretch.” 29 According to Burkhart et al, 10 90% of throwers with GIRD will reduce GIRD to an acceptable level with the use of “sleeper stretch.” Furthermore, athletes with GIRD may benefit from hold-relax proprioceptive neuromuscular facilitation 30 . It is suggested that physical therapists and team doctors use the mentioned treatment to improve the IR ROM of table tennis players and to help them achieve better athletic performance.…”

“…The key to treating GIRD is to stretch the posterior capsule and muscles, 27,28 and effective stretch methods are "sleeper stretch" and "cross-arm stretch." 29 According to Burkhart et al, 10 90% of throwers with GIRD will reduce GIRD to an acceptable level with the use of "sleeper stretch."…”

Pitching Biomechanics and Shoulder Function in Baseball Pitchers with Scapular Dyskinesis

“…Maximum voluntary isometric contraction (MVIC) was collected for normalization of the EMG data 11 29 . The methods were described in a previous study 21 . After the collection of the MVIC, the participants warmed up by throwing and catching a ball with a catcher at a self-selected pace.…”

“…A secondary analysis of our previously published study was conducted [21]. In the original study, 38 male high school baseball pitchers aged 15 to 18 years were recruited from 4 high schools in the pre-season.…”