The comparison of Holux and Qstarz GPS receivers in free living conditions: Dynamic accuracy in different active transport modes

Background: Physical activity (PA) is one of the major factors influencing human health. An important group of determinants are elements forming the built environment. For a proper understanding of relationships between the built environment and PA, we need to measure PA in space. Objective: This study aims to verify the accuracy of the Holux RCV-3000 GPS logger, which has not yet been validated in relation with PA. Methods: Two GPS receivers (Holux RCV-3000 and already validated Qstarz BT-Q1000XT) were tested during walking, running and cycling. A total of 1,908 GPS points were recorded by each device. For each trip, we calculated the percentage of points that fell within 1, 2.5, 5, and 10 m buffers, as well as the mean and median error. Results: Our results showed that 53.1% of all Holux and 45.1% of Qstarz GPS points fell within 2.5 m of the expected location, 90% (Holux) and 80% (Qstarz) fell within 10 m and the median error was 2.33 m and 3.15 m, respectively. Conclusions: The dynamic spatial accuracy of the tested Holux RCV-3000 was better than more expensive Qstarz device and can be considered as a valid instrument for assessing the spatial location of PA in future work.