title: Validity of 10-HZ GPS and Timing Gates for Assessing Maximum Velocity in Professional Rugby Union Players.
abstract: OBJECTIVE
  The purpose of this study was to investigate the validity of timing gates and 10-Hz global positioning systems (GPS) units (Catapult Optimeye S5) against a criterion measure (50-Hz radar gun) for assessing maximum sprint velocity (Vmax).
  
  
  METHODS
  Nine male professional rugby union players performed 3 maximal 40-m sprints with 3 min rest between efforts with Vmaxassessed simultaneously via timing gates, 10-Hz GPSOpen(Openfield software), GPSSprint(Sprint software), and radar gun. Eight players wore 3 GPS units, while 1 wore a single unit during each sprint.
  
  
  RESULTS
  When compared with the radar gun, mean biases for GPSOpen, GPSSprint, and timing gates were trivial, small, and small, respectively. The typical error of the estimate (TEE) was small for timing gate and GPSOpenwhile moderate for GPSSprint. Correlations with radar gun were nearly perfect for all measures. Mean bias, TEE, and correlations between GPS units were trivial, small, and nearly perfect, respectively, while a small TEE existed when GPSOpenfieldwas compared with GPSSprint.
  
  
  CONCLUSIONS
  Based on these findings, both 10-Hz GPS and timing gates provide valid measures of 40-m Vmaxassessment compared with a radar gun. However, as error did exist between measures, the same testing protocol should be used when assessing 40-m Vmaxover time. Furthermore, in light of the above results, it is recommended that when assessing changes in GPS-derived Vmaxover time, practitioners should use the same unit for each player and perform the analysis with the same software, preferably Catapult Openfield.
authors.forename: Gregory
authors.initials: G
authors.lastname: Roe
authors.forename: Joshua
authors.initials: J
authors.lastname: Darrall-Jones
authors.forename: Christopher
authors.initials: C
authors.lastname: Black
authors.forename: William
authors.initials: W
authors.lastname: Shaw
authors.forename: Kevin
authors.initials: K
authors.lastname: Till
authors.forename: Ben
authors.initials: B
authors.lastname: Jones
mesh_terms: D054874:Athletic Performance; D005538:Football; D040362:Geographic Information Systems; D006801:Humans; D008297:Male; D012420:Running; D012984:Software; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: assessment; monitoring; speed