VALIDITY AND RELIABILITY OF VIDEO-BASED ANALYSIS OF UPPER TRUNK ROTATION DURING RUNNING

Background: Two-dimensional (2D) video analysis is a practical tool for assessing biomechanical factors that may contribute to running-related injury. Asymmetrical or altered coordination of transverse plane trunk movement has been associated with low back pain, increased vertical and horizontal ground reaction forces, and altered hip abduction torque and strength. However, the reliability and validity of 2D transverse plane upper trunk rotation (UTR) has not been assessed. Study Design: Validity and reliability study Purpose: To determine the validity and reliability of 2D video-based, transverse plane UTR measurement during running. Methods: Sixteen runners ran at self-selected speed on a treadmill while three-dimensional (3D) and 2D motion capture occurred synchronously. Two raters measured peak UTR for five consecutive strides on two occasions. Interrater and intrarater reliability and the minimum detectable change was calculated for right and left peak 2D UTR measurement. Concurrent validity and agreement between 2D and 3D measures were determined by calculating Pearson Product Correlation Coefficients (r) and Bland-Altman plots, respectively. Results: Using a single UTR measure per runner, intrarater and interrater reliability (ICC2,1) was excellent (intrarater ICC2,1 range: 0.989-0.999; interrater ICC2,1 range: 0.990-0.995) and the minimum detectable change was 0.39-1.4 degrees. Measurements in 2D and 3D were significantly correlated for peak UTR (all r >= 0.986; all p-values < 0.001) and showed good agreement in Bland-Altman plots. Conclusion: Two-dimensional video-based measurement of transverse plane peak UTR is valid and reliable.