Accuracy of GPS Devices for Measuring High-intensity Running in Field-based Team Sports

We compared the accuracy of 2 GPS systems with different sampling rates for the determination of distances covered at high-speed and metabolic power derived from a combination of running speed and acceleration. 8 participants performed 56 bouts of shuttle intermittent running wearing 2 portable GPS devices (SPI-Pro, GPS-5 Hz and MinimaxX, GPS-10 Hz). The GPS systems were compared with a radar system as a criterion measure. The variables investigated were: total distance (TD), high-speed distance (HSR > 4.17 m.s(-1)), very high-speed distance (VHSR > 5.56 m.s(-1)), mean power (Pmean), high metabolic power (HMP > 20 W.kg(-1)) and very high metabolic power (VHMP > 25 W.kg(-1)). GPS-5 Hz had low error for TD (2.8 %) and Pmean (4.5 %), while the errors for the other variables ranged from moderate to high (7.5-23.2 %). GPS-10 Hz demonstrated a low error for TD (1.9 %), HSR (4.7 %), Pmean (2.4 %) and HMP (4.5 %), whereas the errors for VHSR (10.5 %) and VHMP (6.2 %) were moderate. In general, GPS accuracy increased with a higher sampling rate, but decreased with increasing speed of movement. Both systems could be used for calculating TD and Pmean, but they cannot be used interchangeably. Only GPS-10 Hz demonstrated a sufficient level of accuracy for quantifying distance covered at higher speeds or time spent at very high power.