Asymmetry and evolution over a one-year period of the upward rotation of the scapula in youth baseball pitchers

Erik van der Graaff*, Bengt Kom, Femke van Dis, Xavier Gasparutto, Marco Hoozemans, Dirkjan Veeger

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


The pitching motion is an asymmetric action by which coordination of scapular rotation in the dominant arm might be affected in time and in comparison with the non-dominant arm. The study aimed to compare asymmetry and the evolution of scapular upward rotation over a one-year period. Data were collected twice, before and after a one-year period, from 92 participants (age = 15.1 SD 1.4 years, body height = 177.3 SD 10.9 cm, body weight 69.2 SD 14.5 kg). Scapular motion was tracked at different glenohumeral angles of elevation in the scapular plane: anatomical position (0°), 45°, 90° and 135°. Scapular upward rotation was calculated as the angle between the spinae scapula and the spine. Scapular upward rotation of the dominant arm was 5.1° (95% CI: 2.1°−8.1°) more compared to the non-dominant arm. Age group or glenohumeral angles of elevation did not affect this difference. Scapular upward rotation of the dominant arm decreased 1.9° (95% CI: −0.5° to 4.3°) after a one-year period, however, neither this observation, nor the interaction with age group or elevation angle was significant. These findings may indicate that pitchers could be at risk to develop shoulder injuries especially those that have been associated with scapular asymmetry.

Original languageEnglish
Pages (from-to)57-62
JournalInternational Biomechanics
Issue number1
Publication statusPublished - 2018


This work was supported by the STW under Grant [12893]. This STW-funded project, named project FASTBALL, is a cooperation between the Dutch baseball federation and the Vrije Universiteit Amsterdam, Delft University of Technology, the Bergman clinic, Motekforce Link and the fysiopractices Manual Fysion and Medicort.

FundersFunder number
Technische Universiteit Delft
Stichting voor de Technische Wetenschappen12893


    • baseball
    • overhead throwing
    • Pitching
    • scapular dyskinesis
    • scapular upward rotation


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