Reliability and concurrent criterion validity of a novel technique for analyzing hip kinematics during running

Excessive frontal plane hip kinematics during running has been associated with numerous running pathologies. Traditionally, assessment of hip kinematics during running required expensive and complex equipment and procedures making objective running assessment difficult for practicing clinicians. The aim of this study was to establish the reliability and validity of a novel technique designed for clinicians that allows for objective assessment of frontal plane hip kinematics during running. Hip angles and excursions were measured using videos and jpeg images of 10 subjects (five males and five females) running. A 2-D motion analysis system and computer algorithm served as reference measures. Six raters (three licensed physical therapists and three student physical therapists) took measures on two instances. Reliability was examined using intraclass correlation coefficients (ICC). Validity was investigated with ICCs, 95% limits of agreement (LA), and mean absolute differences (MAD) by comparing each rater's 2-trial average to the criterion reference values. The ICCs for interrater and intrarater reliability for angle and excursion measures ranged from 0.82 to 0.99. The validity ICCs of all measures ranged from 0.89 to 0.99 with acceptable LA. The MAD ranged from 0.5°-1.5°. These results indicate that this novel technique is reliable and valid for measuring hip kinematics compared to the reference measures making it suitable for broad-based clinical use.