Validity and Interunit Reliability of 10 Hz and 15 Hz GPS Units for Assessing Athlete Movement Demands

Johnston R.J., Watsford M.L., Kelly S.J., Pine M.J., Spurrs R.W.

Purpose:
The purpose of this study was to assess the validity and inter-unit reliability of 10 Hz (Catapult) and 15 Hz (GPSports) Global Positioning System (GPS) units and to investigate the differences between these units as measures of team sport athlete movement demands.

Methods:

Eight trained male participants completed a team sport simulation circuit.
Movement demands examined included total distance covered (TD), average peak speed, distance covered, time spent, and number of efforts performed in low-speed running (0.00–13.99 km/h), high-speed running (14.00–19.99 km/h), and very high-speed running (>20.00 km/h).
Validity was assessed using a paired samples t-test and Pearson’s correlations.
Inter-unit reliability was established using percentage typical error of measurement (%TEM) and intraclass correlations.
Results:

The findings indicated that 10 Hz GPS units were valid (p < 0.05) and reliable (%TEM = 1.3%) measures of TD. In contrast, 15 Hz GPS units exhibited lower validity for TD and average peak speed. As the speed of movement increased, the level of error for both 10 Hz and 15 Hz GPS units increased (%TEM = 0.8–19.9). Comparisons between 10 Hz and 15 Hz GPS units should not be undertaken. In general, 10 Hz GPS units measured movement demands with greater validity and inter-unit reliability than 15 Hz units. However, both 10 Hz and 15 Hz units provided improved measures of movement demands compared to 1 Hz and 5 Hz GPS units. Conclusion: The study suggests that 10 Hz GPS units are more valid and reliable measures of movement demands compared to 15 Hz units. Additionally, both 10 Hz and 15 Hz units offer improved measures compared to lower frequency GPS units.