How far from the gold standard? Comparing the accuracy of a Local Position Measurement (LPM) system and a 15 Hz GPS to a laser for measuring acceleration and running speed during team sports.

Karin Fischer-Sonderegger,Martin Rumo,Wolfgang Taube,Markus Tschopp,Cristina Cortis

doi:10.1371/journal.pone.0250549

Karin Fischer-Sonderegger, Martin Rumo + Show 3 more

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https://doi.org/10.1371/journal.pone.0250549

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Abstract

This study compared the validity and inter- and intra-unit reliability of local (LPM) and global (GPS) position measurement systems for measuring acceleration during team sports. Devices were attached to a remote-controlled car and validated against a laser. Mean percentage biases (MPBs) of maximal acceleration (amax) and maximal running speed (vmax) were used to measure validity. Mean between-device and mean within-device standard deviations of the percentage biases (bd-SDs and wd-SDs) of amax and vmax were used to measure inter- and intra-unit reliability, respectively. Both systems tended to underestimate amax similarly (GPS: -61.8 to 3.5%; LPM: -53.9 to 9.6%). The MPBs of amax were lower in trials with unidirectional linear movements (GPS: -18.8 to 3.5%; LPM: -11.2 to 9.6%) than in trials with changes of direction (CODs; GPS: -61.8 to -21.1%; LPM: -53.9 to -35.3%). The MPBs of vmax (GPS: -3.3 to -1.0%; LPM: -12.4 to 1.5%) were lower than those of amax. The bd-SDs and the wd-SDs of amax were similar for both systems (bd-SDs: GPS: 2.8 to 12.0%; LPM 3.7 to 15.3%; wd-SDs: GPS: 3.7 to 28.4%; LPM: 5.3 to 27.2%), whereas GPS showed better bd-SDs of vmax than LPM. The accuracy depended strongly on the type of action measured, with CODs displaying particularly poor validity, indicating a challenge for quantifying training loads in team sports.

Highlights

Team sports are characterized by frequent changes of direction (CODs) and many accelerations and decelerations [1, 2]
The Mean percentage biases (MPBs) of amax were lower in trials with unidirectional linear movements (GPS: – 18.8 to 3.5%; Local Position Measurement (LPM): −11.2 to 9.6%) than in trials with changes of direction (CODs; GPS: – 61.8 to −21.1%; LPM: −53.9 to –35.3%)
The exceptions were high acceleration from standstill (HA) and abrupt deceleration (A-D), which were slightly overestimated by GPS (MPB: 3.5% and 1.1%, respectively) and high acceleration from a flying start (HA-flyingS), which was overestimated by LPM (MPB: 9.6%)

Summary

Introduction

Team sports are characterized by frequent changes of direction (CODs) and many accelerations and decelerations [1, 2]. In order to assess short, intense actions that are typical of team sports, position measurement systems that can accurately measure acceleration are needed [1]. Both global (GPS) and local (LPM) position measurement systems have been used to this end [6,7,8]. GPS uses satellites to determine the positions of players; it is not locally bound and can be used flexibly across different sites (e.g., home and away games, training and match fields). We hypothesized that the LPM measurement accuracy would be higher than GPS, when measuring athletes’ movement patterns in team sports

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