Accuracy and Repeatability of the Polar ® RS800sd to evaluate stride rate and running speed

International audienceThe purpose of this study was to evaluate the accuracy and the reliability a new running computer system (RS800sd, Polar®, Kempele, Finland) which includes the measurement of running speed (RS) and stride rate (SR). Eight well-trained triathletes participated in this study. First, they completed an incremental continuous maximum test on a treadmill (from 12 km.h-1 9 to 18 km.h-1) at 0% grade. Secondly, the subjects took part in a second test to determine RS800sd intra-reproductibility to evaluate running speed. They ran twice during 5 minutes at a pace corresponding to their maximal lactate steady-state. During these two tests, RS and SR were recorded by the RS800sd system, by an optical sensor system (for RS) and a force-sensitive device (for SR). No difference was found between the RS800sd system and the reference systems both for RS (ICC=0.95) and SR (ICC=0.69). Moreover RS measures were statistically repeatable (r2=0.97, P