The influence of tester experience on the reliability of 3D kinematic information during running.

The efficacy of 3D motion capture in both sports and clinical research settings is largely dependent on the reliability of the obtained measurements. This study aimed to determine whether there are 3D kinematic differences both between and within researchers with three different levels of familiarity in 3D marker placement. Fifteen male participants ran across a 22 m laboratory at 4.0 m.s(-1). Three researchers (experienced, intermediate and novice) positioned lower extremity markers on two occasions. Differences in 3D joint kinetics/kinematics both between and within researchers were examined using mixed ANOVA's. The within researcher reliability of the kinetic/kinematic waveforms were further analysed using intraclass correlations. The results show that significant differences in discrete parameters were observed in the transverse plane between researchers and also in the coronal and transverse planes within researcher for the novice practitioner. Furthermore, the results also showed that the experienced researcher was associated with the highest levels of reliability in marker placement. This suggests that it may be prudent for 3D analyses, in particular those with a clinical component to be conducted using experienced practitioners and for analyses to state the experience level of the researchers conducting the anatomical marker placement.