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Session: MSK & Sweat sensing
Session starts: Friday 27 January, 11:30
Presentation starts: 12:00
Room: Room 530

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Lisa Noteboom (Faculty of Behavioral and Movement Sciences, Vrije Universiteit Amsterdam)
Marco Hoozemans (Faculty of Behavioral and Movement Sciences, Vrije Universiteit Amsterdam)
DirkJan Veeger (Department of Biomechanical Engineering, Delft University of Technology)
Frans Van der Helm (Department of Biomechanical Engineering, Delft University of Technology)

Abstract:
Introduction: While shoulder injuries as result of the bench press exercise are commonly reported [1], no biomechanical evidence regarding the technique with the lowest injury risk is currently available. Therefore, the aim of the present study was to compare musculoskeletal shoulder loads during several variations of the bench press. Methods: Ten experienced strength athletes performed 21 technical variations of the barbell bench press, including variations in grip width of 1,1.5 and 2 bi-acromial widths (BAW), shoulder abduction angles of 45, 70 and 90, and scapula poses including neutral, retracted, and released conditions. Motions and forces were recorded by an opto-electronic measurement system and an instrumented barbell. An OpenSim musculoskeletal shoulder model was employed to estimate net shoulder moments, muscle forces, and joint reaction forces for all technique variations. Within-subject ANOVAs with Bonferroni Post-hoc’s were performed to reveal the effects of the technique variations. Results: First results revealed that for all abduction angles, net shoulder moments were significantly larger with retracted shoulders, compared to neutral and released shoulders (p<0.05). For grip width, shoulder moments were significantly higher at 2 BAW compared to 1.5 BAW (at 70 and 90) and significantly higher for 1.5 BAW compared to 1.0 BAW (at 70). Moreover, shoulder moments were significantly larger for 90 compared to 45 abduction. No interactions were found. The highest mean shoulder moment (SD over subjects) of 37.317.3 Nm was found for a combination of retracted shoulders, 2 BAW and 70 abduction, whereas the lowest mean shoulder moment of 20.611.0 Nm was found for a combination of released shoulders, 1 BAW and 70 abduction. Results of muscle forces and joint reaction forces in the glenohumeral and acromioclavicular joints will be added before the conference. Discussion/Conclusion: The first results indicate that more load is placed at the shoulder during wide grips and retracted shoulders. Loads can be reduced by applying a technique with a small grip and released or neutral scapulae. However, other parameters including the muscle forces and joint reaction forces during the varying techniques need to be evaluated before final conclusions regarding the technique with the lowest injury risk can be drawn. References 1. Bengtsson, V., Berglund, L., & Aasa, U. (2018). Narrative review of injuries in powerlifting with special reference to their association to the squat, bench press and deadlift. BMJ open sport & exercise medicine, 4(1), e000382.