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Updated: May 15, 2025

Measuring 3D In-vivo Shoulder Kinematics using Biplanar Videoradiography
Published on: March 12, 2021
Relationship Between Thoracic Spine Rotation Range, Trunk Contralateral Flexion Angle, and Maximum Elbow Valgus
1Department of Physical Therapy, Faculty of Health Science Technology, Bunkyo Gakuin University, Saitama, JPN.
Introduction:
Excessive trunk contralateral flexion increases elbow valgus torque during pitching. However, the cause of this excessive contralateral flexion is unclear. This study aimed to clarify the relationship between the lumbar rock rotation test (LLR-t), trunk contralateral flexion angle during shoulder joint in maximum external rotation, and maximum elbow valgus torque.
Methods:
This descriptive laboratory study included 21 healthy male baseball players with pitcher experience in the LLR-t. Angles were measured using an inclinometer. The maximum elbow valgus torque during pitching was measured using an inertial measuring unit (IMU), and the trunk contralateral flexion angle during shoulder joint in maximum external rotation (MER) was measured using ImageJ (National Institutes of Health, Bethesda, Maryland, United States) after video recording.
Results:
The throwing side LLR-t showed a significant negative correlation (r=-0.51, p=0.02) with the trunk contralateral flexion angle during MER and a significant negative correlation (r=-0.45, p=0.04) with the maximum elbow valgus torque during throwing. MER trunk contralateral flexion angle showed a significant positive correlation (r=0.47, p=0.03) with maximum elbow valgus torque during pitching.
Conclusions:
The LLR-t may be a useful method of measuring thoracic spine rotation range of motion in athletes with increased trunk contralateral flexion angle and high maximal elbow valgus torque during pitching.
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