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 [DEC Max ], average deceleration [DEC Ave ], time to stop, and distance to stop). Methods : Thirty-two male elite youth academy soccer players (age 18.1 [1.6] y, body mass 76.6 [7.9] kg) completed the acceleration–deceleration ability test with 16 completing a second test to assess test–retest reliability. Maximal horizontal deceleration ability was measured concurrently using GPS Raw (10-Hz data), GPS Export (STATSports software), and a radar device. Bland–Altman method and equivalence testing assessed concurrent agreement and intraclass correlations with coefficient of variation (%) was used to assess test–retest reliability. Results: Equivalence testing showed mean difference between the radar device and GPS-derived values of DEC Ave and DEC Max were within equivalence bounds. GPS Raw and GPS Export derived values of DEC Max showed good overall (intraclass correlations = .84–.86, coefficient of variation % = 4.50–5.48) test–retest reliability. Conclusion : Practitioners can consider using deceleration variables (DEC Ave and DEC Max ) obtained from GPS as a cost-effective, valid, and reliable alternative to radar technology to assess maximal horizontal deceleration ability in team-sport players.