Importance of GNSS data quality assessment with novel control criteria in professional soccer match-play.

This study assessed the quality of Global Navigation Satellite System (GNSS) signal during professional football match play in different stadia with the application of a novel Data Quality Control Criteria (DQCC). DQCC was applied to GPS-files from match play, derived using 10 Hz GNSS devices for 27 professional soccer players across a season to assess external load measures accounting for poor positioning quality (%) and horizontal dilution of precision. Performances were categorised on playing position (Wide or Central) to assess proximity to stand cover on GNSS signal quality. An average reduction in total distance (11.2%), high-speed running distance (6.4%), sprint distance (7.0%), accelerations (10.3%) and decelerations (10.0%) (all P < 0.01) was observed upon DQCC application. In worst cases, 90% of an external variable was affected by poor-quality signal. Signal quality was worse for wide-positioned players than centrally positioned (positioning quality 2.6% lower (P < 0.01)), resulting in larger reductions of external variables upon DQCC application. Large stands in football stadia affect the data quality of GNSS and is exacerbated for players positioned closer to stand cover. Viewing only data with acceptable Position Quality and HDOP meaningfully reduce measured external loads, which has implications for the application of match data. [ABSTRACT FROM AUTHOR]