RESUMO
PURPOSE: Three-dimensional motion analysis is the "gold standard" for evaluating kinematic variables during treadmill running. However, its use is limited by temporal and financial restraints. Therefore, the purpose of this study was to assess the concurrent validity and reliability of 2D video analysis for frontal plane kinematic variables during treadmill running. METHODS: Twenty-four healthy male and female collegiate cross-country runners completed a running protocol at a self-selected speed. Frontal plane kinematic data were collected using 3D and 2D motion analysis systems. Variables of interest included contralateral pelvic drop (CPD), peak hip adduction angle (HADD), and peak knee abduction angle (KABD). Pearson Product Correlation Coefficients were used to determine the relationship between the 3D and 2D systems for each variable. Intra-Class Correlation Coefficients (ICC) were used to assess intra-rater reliability of the user of the 2D software. RESULTS: The 2D testing method demonstrated excellent intra-rater reliability for peak HADD (ICCs: 0.951-0.963), peak CPD (0.958-0.966), and peak KABD (ICCs: 0.955-0.976). Moderate correlations between 2D and 3D measures of HADD on the left (0.539; p=0.007) and the right (0.623; p=0.001) and peak KABD on the left (0.541; p=.006) lower extremity were found. No statistically significant correlation of CPD was found between the 2D and 3D systems. The 2D measure of CPD had a strong correlation to the 2D assessment of HADD on both the left (0.801; p=0.0001) and the right (0.746; p=0.0001) extremity. CONCLUSION: These findings and the ease of data capture using 2D software provide support for the utility of 2D video analysis in the evaluation of frontal plane variables, specifically HADD. LEVEL OF EVIDENCE: 2B.
