title: Methodological Considerations When Quantifying High-Intensity Efforts in Team Sport Using Global Positioning System Technology.
abstract: OBJECTIVE
  Sprints and accelerations are popular performance indicators in applied sport. The methods used to define these efforts using athlete-tracking technology could affect the number of efforts reported. This study aimed to determine the influence of different techniques and settings for detecting high-intensity efforts using global positioning system (GPS) data.
  
  
  METHODS
  Velocity and acceleration data from a professional soccer match were recorded via 10-Hz GPS. Velocity data were filtered using either a median or an exponential filter. Acceleration data were derived from velocity data over a 0.2-s time interval (with and without an exponential filter applied) and a 0.3-second time interval. High-speed-running (≥4.17 m/s2), sprint (≥7.00 m/s2), and acceleration (≥2.78 m/s2) efforts were then identified using minimum-effort durations (0.1-0.9 s) to assess differences in the total number of efforts reported.
  
  
  RESULTS
  Different velocity-filtering methods resulted in small to moderate differences (effect size [ES] 0.28-1.09) in the number of high-speed-running and sprint efforts detected when minimum duration was <0.5 s and small to very large differences (ES -5.69 to 0.26) in the number of accelerations when minimum duration was <0.7 s. There was an exponential decline in the number of all efforts as minimum duration increased, regardless of filtering method, with the largest declines in acceleration efforts.
  
  
  CONCLUSIONS
  Filtering techniques and minimum durations substantially affect the number of high-speed-running, sprint, and acceleration efforts detected with GPS. Changes to how high-intensity efforts are defined affect reported data. Therefore, consistency in data processing is advised.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Varley
authors.forename: Arne
authors.initials: A
authors.lastname: Jaspers
authors.forename: Werner F
authors.initials: WF
authors.lastname: Helsen
authors.forename: James J
authors.initials: JJ
authors.lastname: Malone
mesh_terms: D000054:Acceleration; D054874:Athletic Performance / Q000502:physiology*; D003163:Competitive Behavior / Q000502:physiology; D040362:Geographic Information Systems; D006801:Humans; D009068:Movement / Q000502:physiology; D012420:Running / Q000502:physiology*; D012916:Soccer / Q000502:physiology*; D012984:Software; D055815:Young Adult
keywords: GPS; acceleration; football; soccer; sprint