Biceps Tendon Changes and Pitching Mechanics in Youth Softball Pitchers

Abstract

With the lack of pitch count regulation, youth softball pitchers are experiencing unremitting high stresses on the anterior shoulder. The purpose of this study was to examine the association of acute changes in the long head of the biceps tendon with pitching kinematics and kinetics in youth softball pitchers following an acute bout of pitching. Twenty-three softball pitchers (12.17±1.50 yrs.; 160.32±9.41 cm; 60.40±15.97 kg) participated. To investigate the association between biceps tendon changes and kinematic and kinetic changes from pre- to post-simulated game, each biceps tendon measure was split into those whose biceps tendon thickness, width, and/or area increased pre- to post-simulated game, and those whose did not. There were significant differences in biceps tendon longitudinal thickness (Z=− 2.739, p=0.006) and pitch speed; as well as a difference between groups in biceps tendon transverse thickness and the amount of change in trunk rotation at the start of the pitching motion (p=0.017) and the amount of change in trunk flexion at ball release (p=0.030). This study illustrates the association of trunk and lower extremity kinematics and shoulder kinetics with morphologic changes in the biceps tendon with an acute bout of windmill softball pitching.

Biomechanics Related to Increased Softball Pitcher Shoulder Stress: Implications for Injury Prevention

“…While previous research has noted that the biceps tendon endures great stress during the windmill pitch, 4,23,33 increased throwing shoulder distraction force linked with increased elbow extension moment might further point to the biceps tendon as a location of injury and anterior shoulder pain among softball pitchers. The biarticular and mechanical nature of the biceps tendon and its influence at the shoulder and elbow joint can make it particularly susceptible to injury.…”

“…In light of the sequential nature of the arm during the pitching motion, more research is needed to understand how these interactions might influence forces at the shoulder joint and potentially help to minimize risk of injury at the shoulder joint. While previous research has noted that the biceps tendon endures great stress during the windmill pitch, 4,23,33 increased throwing shoulder distraction force linked with increased elbow extension moment might further point to the biceps tendon as a location of injury and anterior shoulder pain among softball pitchers. The biarticular and mechanical nature of the biceps tendon and its influence at the shoulder and elbow joint can make it particularly susceptible to injury.…”

“…5,33 In lieu of the high demand placed on the biceps brachii 5,33 and the high rates of shoulder injury among pitchers, 16,19,29,38 research analyzing the kinematics and kinetics that lead to increased throwing shoulder distraction force is warranted. Previous researchers have sought to understand the biomechanics involved with windmill softball pitching, 5,13,[22][23][24]27,28,40,41 including 1 study that examined the relationship between throwing shoulder distraction force and kinematics and kinetics in an elite pitching population. 41 However, because of the varied mechanics according to pitcher expertise and age, 10,21,24 more research is needed to examine softball pitching biomechanics within more homogeneous pitching populations to better apply findings.…”

“…5 Therefore, researchers have delved into the role of the biceps brachii and considered the large role that it plays during the windmill pitch to be a potential mechanism of injury. 4,23 Specifically, the biarticular nature of the biceps brachii may predispose it to active insufficiency in that it cannot adequately lend itself to control both joint actions. It is possible that the demand of the biceps brachii to properly flex the elbow for accurate BR is too great, and as a result, the long head of the biceps tendon near the shoulder cannot properly manage shoulder distraction force, although this is currently unknown.…”

Supraspinatus Tendon Changes and Glenohumeral Range of Motion in College Baseball Players

“…Therefore, excessive IR deficit may aggravate internal impingement, consequently increasing mechanical load and the risk of throwing-related rotator cuff injuries. In human studies, increased mechanical load acutely induced an increase in tendon thickness 43 44 45 46 . Therefore, our result suggested that excessive posterior capsule tightness increased mechanical load with internal impingement, and accumulation of this increased load induced SST abnormalities.…”