Concurrent agreement and test-retest reliability of a global positioning system device for measuring maximal horizontal deceleration ability in elite youth academy soccer players

Purpose: Investigate the concurrent agreement and test-retest reliability of 10 Hz global positioning system (GPS) device against a criterion measure (47 Hz radar device) to assess maximal horizontal deceleration ability (maximum deceleration [DECMax], average deceleration [DECAve], time to stop [TTS], and distance to stop [DTS]). Methods: Thirty-two male elite youth academy soccer players (18.1 ± 1.6 yrs; 76.6 ± 7.9 kg) completed the acceleration-deceleration ability test with sixteen completing a second test to assess test-retest reliability. Maximal horizontal deceleration ability was measured concurrently using GPSRaw (10 Hz data), GPSExport (STATSports software), and a radar device. Bland-Altman method and Pearson correlations assessed concurrent agreement and intra-class correlations (ICC) with coefficient of variation (CV%) was used to assess test-retest reliability. Results: Large to very large correlations (r = 0.51 to 0.78) were observed between radar and GPSRaw and GPSExport derived values of DECMax and DECAve. GPSRaw and GPSExport derived values of DECMax showed good overall (ICC = 0.84 to 0.86, CV% = 4.50 to 5.48) test-retest reliability. Conclusion: Practitioners can consider using GPS as a cost-effective, valid, and reliable alternative to radar technology to assess maximal horizontal deceleration ability in team sports players.