Accuracy of local positioning systems to measure external load in sport settings: a brief review

The aim of this study was to review the validity of the commonly adopted local positioning systems (LPSs) in sports settings for measuring athletes’ external load (i.e. distances, speeds, accelerations, and decelerations), with a special focus on systems using radio-frequency identification (RFID) and ultra-wideband (UWB) technology. The reviewed articles showed that the validity of 6 LPSs including both RFID and UWB technologies was assessed by documenting acceptable validity for measuring distances (< 3.5% difference) when compared with reference systems across different activities and sports (indoor and outdoor). Inconsistent results have been presented for average speeds, with difference from reference systems of up to 35%. Additionally, high differences have been revealed for accelerations (up to 12%) and decelerations (up to 84%) during movements including changes of directions and for high-intensity speeds (up to 43% difference) during small-sided games. Finally, the reviewed studies suggest a higher validity in measuring instant speeds and accelerations in LPSs compared with other tracking systems (global positioning systems and video-based systems). In conclusion, this review paper implies acceptable validity of the investigated LPSs in measuring distances, while caution should be observed when measuring speeds, accelerations, and decelerations. Moreover, this review provides sports coaches, practitioners, and club directors with valuable information on purchasing and using LPSs in sports settings.