Validity and reliability of a radio positioning system for tracking athletes in indoor and outdoor team sports

Radio-frequency local positioning systems (LPS) have the potential to provide accurate location information about sport players for performance analysis, making available for study the emergent nature of interpersonal coordination and collective decision-making behaviour among players in both indoor and outdoor sports. However, no available publications have validated the performance of LPS for indoor sports. The objective of this study was to validate the performance of an LPS in an indoor venue and to compare it to performance observed in an outdoor venue using static and dynamic measurements. Our results showed that the absolute positioning errors obtained from the static measurements of the LPS were comparable for both indoor and outdoor venues, with mean errors of 12.1 cm outdoors and 11.9 cm indoors. From the dynamic measurements, we analysed the relative position error and the distance estimation performance of the system. The 90th-percentile relative position errors were 28 cm for the indoor venue versus 18 cm for the outdoor venue. On average, the LPS overestimated the distance travelled, and the performance was similar for both indoor and outdoor venues. On a linear course, the mean errors of the distance estimates were 2.2% of the total distance indoors and 1.3% outdoors, and on a nonlinear course, they were 2.7% indoors and 3.2% outdoors.