Reliability of Two-Dimensional Video-Based Analysis in Adolescent Runners

BACKGROUND: Running analysis is an essential component of evaluation of both injured runners and uninjured runners seeking advice on injury prevention. Reliability of two-dimensional (2D) video analysis has been reported in the adult running population. However, these findings may not apply to youth runners given their unique state during growth and development. The reliability of quantitative and qualitative video-based running gait analysis in the adolescent population is unknown. PURPOSE: The purpose of this study was 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 videos were recorded of 10 healthy runners between 14-18 years old running on a treadmill at self-selected speed with markers attached to the thoracic spine, pelvis, and lower extremities. Kinematic variables in the sagittal and frontal planes were measured using Dartfish Motion Analysis Software™ (Fribourg, Switzerland) by three raters. 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 primary sports 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. CONCLUSION: The results of this study demonstrate that a 2D video-based running analysis can be reliably performed in an adolescent population on all kinematic variables except for step width and foot progression. Inexperienced raters can be properly trained in the video analysis of running kinematics using Dartfish Software in order to consistently assess the same runner.