INTER- AND INTRA-RATER RELIABILITY OF PERFORMANCE MEASURES COLLECTED WITH A SINGLE-CAMERA MOTION ANALYSIS SYSTEM.

BACKGROUND: Previous reliability investigations of single-camera three dimensional (3D) motion analysis systems have reported mixed results.
PURPOSE: The purpose of the current study was to determine the intra- and inter-rater reliability of a single-camera 3D motion analysis system for subject standing height, vertical jump height, and broad jump length. STUDY
DESIGN: Experimental in vivo reliability study. PARTICIPANTS: Twelve subjects (age 20.6 ± 4.9 years) from a cohort that included high school to adult athletes who participated in sports at a recreational or competitive level entered and completed the study. Performance measurements were collected by a single-camera 3D motion analysis system and two human testers for standard clinical techniques. Inter- and intra-class correlation coefficients (ICC (2,k), ICC (2,1)) were determined. RESULT: Intra-tester and inter-tester reliability were excellent (ICC ≥ 0.935) for single-camera system measured variables. Single-camera system measurements were slightly more reliable than clinical measurements for intra-tester ratings (ICC difference 0.020) for the standing broad jump. Single-camera system measurements were slightly less reliable than clinical measures for both intra- and inter-specimen standing height (mean ICC difference 0.003 and 0.043, respectively) and vertical jump height (mean ICC difference 0.017 and 0.036, respectively).
CONCLUSIONS: The excellent reliability and previously demonstrated validity of the single-camera system along the anterior-posterior axis indicates that single-camera motion analysis may be a valid surrogate for clinically accepted manual measurements of performance in the horizontal plane. However, this single-camera 3D motion analysis system is likewise reliable, but inaccurate, for vertically oriented performance measurements. LEVEL OF EVIDENCE: 2b.