Development of measurement system for task oriented step tracking using laser range finder

Background: Avoiding a fall requires fast and appropriate step responses, stepping speed as a fall risk indicator has only been assessed in older adults. We have developed a new measurement system that applies a laser range finder to assess temporal and spatial parameters of stepping performance such as step speed, length, and accuracy. This measurement system has higher portability, lower cost, and can analyze a larger number of temporal and spatial parameters than existing measurement systems. The aim of this study was to quantify the system for measuring reaction time and stride duration by compared to that obtained using a force platform. Methods: Ten healthy young adults performed steps in response to visual cues. The measurement system applied a laser range finder to measure the position and velocity of the center of each leg and of both legs. We applied the developed measurement system to the rhythmic stepping exercise and measured reaction time and stride duration. In addition, the foot-off time and foot-contact time were quantified using the measurement system, and compared to the foot-off time and foot-contact time quantified using a force platform. Results: We confirmed that the measurement system can detect where a participant stood and measured reaction time and stride duration. Remarkable consistency was observed in the test-retest reliability of the foot-off time and foot-contact time quantified by the measurement system (p < 0.001). The foot-off time and foot-contact time quantified by the measurement system were highly correlated with the foot-off time and foot-contact time quantified by the force platform (reaction time: r = 0.997, stride duration: r = 0.879; p < 0.001). Conclusions: The new measurement system provided a valid measure of temporal step parameters in young healthy adults. The validity of the system to measure reaction time and stride duration was evaluated, and confirmed by applying to the rhythmic stepping exercise.