title: Accuracy and reliability of SPI ProX global positioning system devices for measuring movement demands of team sports.
abstract: OBJECTIVE
  The aim of this study was to determine the accuracy and reliability of SPI ProX global positioning system (GPS) devices for measuring movement at various speeds and movement patterns as evident in team sport demands.
  
  
  METHODS
  Eleven amateur soccer players performed a 40 m straight sprint test (with 10-20-30 m split times), a zigzag test, 30 m walking, jogging and moderate intensity runs.
  
  
  RESULTS
  Results indicated that the SPI ProX GPS measurements showed acceptable accuracy for all movement patterns for distance (coefficient of variation [CV]=0.14% to 3.73%; 95% ratio limits of agreement [95% ratio LOA]=0.97 x / ÷ 1.09 to 1.00 x / ÷ 1.05) and speed (CV=4.22% to 9.52%; 95%LOA=-0.17 ± 1.70 km h-1 to 2.30 ± 1.17 km h-1) compared with the measured distance and speed determined from timing gates, respectively. Furthermore, acceptable reliability of SPI ProX GPS measures for distance (CV=0.34% to 3.81%; 95%LOA=-0.09 ± 0.23 m to -0.34 ± 2.31 m) and speed (CV=3.19% to 6.95%; 95%LOA=-0.05 ± 3.90 km h-1 to 0.42 ± 3.68 km h-1) were also evident.
  
  
  CONCLUSIONS
  Whilst SPI ProX GPS devices were within acceptable ranges of reliability, they remained significantly different to criterion measures of team sport movement demands.
authors.affiliation: Pamukkale University, Faculty of Sport Sciences and Technology, Denizli, Turkey - ykoklu@pau.edu.tr.
authors.forename: Y
authors.initials: Y
authors.lastname: Köklü
authors.forename: Y
authors.initials: Y
authors.lastname: Arslan
authors.forename: U
authors.initials: U
authors.lastname: Alemdaroğlu
authors.forename: R
authors.initials: R
authors.lastname: Duffield
mesh_terms: D054874:Athletic Performance / Q000502:physiology*; D005500:Follow-Up Studies; D040362:Geographic Information Systems / Q000592:standards*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D015203:Reproducibility of Results; D012916:Soccer / Q000502:physiology*; D013647:Task Performance and Analysis; D055815:Young Adult