Concurrent validity and intrasession reliability of the IDEEA accelerometry system for the quantification of spatiotemporal gait parameters.

The aim of this pilot study was to evaluate concurrent validity and intrasession reliability of the IDEEA (Minisun, Fresno, CA) accelerometry system (and associated software) with force plate measurements for spatiotemporal gait variables recorded during normal walking. Ten healthy individuals were asked to walk at a self-selected comfortable speed, over five multicomponent force plates embedded into the walkway floor. For each trial, spatiotemporal gait parameters (single support time, cadence, speed, step and stride length) obtained by the force plates were compared to those recorded by IDEEA. Concurrent (criterion-related) validity between the two systems was analysed with intraclass correlation (ICC) (2,1). Intrasession reliability was quantified by using coefficient of variations (CV) and ICC. For the ensemble of the parameters, ICC (2,1) ranged between 0.998 (cadence) and 0.784 (step length right) (p<0.001-0.01). However, speed, step length and stride length were significantly lower for IDEEA (~7%; p<0.001) compared to force plate data. Intrasession reliability of IDEEA was excellent, with CV lower than 5.7 and ICC higher than 0.961. The present accelerometry system demonstrated strong concurrent validity for the assessment of spatiotemporal gait parameters. However, spatial variables (stride and step length) and walking speed were significantly underestimated compared with analyses using force plates.