Reliability of 2-Dimensional Video Analysis in Adolescent Runners.

Background: The literature on the reliability of qualitative and quantitative measures for running video analysis in the adolescent population is limited. Reliability of 2-dimensional (2D) video analysis has been reported in adult runners, but these findings may not apply to youth runners. Purpose: We sought to determine the intra-rater and inter-rater reliability of sagittal and frontal plane kinematics using 2D video analysis in healthy adolescent runners.
Methods: High-definition (1080p) videos were recorded of 10 healthy runners between 14 and 18 years old running on a treadmill at self-selected speed with markers attached to the cervical spine, pelvis, and lower extremities. Kinematic variables in the sagittal and frontal planes were measured using Dartfish Motion Analysis Software by 3 raters (2 sports medicine physical therapists and a research assistant). Intra- and inter-rater reliability were calculated using intraclass correlation coefficients (ICCs).
Results: Of the 10 runners, 4 (40%) were male and the mean age was 16 ± 1.5 years. The intra-rater ICC for all kinematic variables ranged from 0.574 to 0.999 for the experienced physical therapist, and 0.367 to 0.973 for the inexperienced research assistant. The inter-rater ICC for all raters ranged from -0.01 to 0.941. Eleven kinematic variables showed substantial agreement and 4 showed almost perfect agreement. Step width and foot progression showed fair and poor agreement, respectively. Conclusions: Running analysis using 2D video can be performed reliably in adolescents on all kinematic variables except for step width and foot progression. Inexperienced raters can be properly trained in the video analysis of running kinematics to consistently assess the same runner.