title: Within-Match PlayerLoad™ Patterns During a Simulated Soccer Match: Potential Implications for Unit Positioning and Fatigue Management.
abstract: OBJECTIVE
  To assess the acute alterations in triaxial accelerometry (PlayerLoad [PL(VM)]) and its individual axial planes (anteroposterior PlayerLoad [PL(AP)], mediolateral PlayerLoad [PL(ML)], and vertical PlayerLoad [PL(V)]) during a standardized 90-min soccer match-play simulation (SAFT90). Secondary aims of the study were to assess the test-retest reliability and anatomical location of the devices.
  
  
  METHODS
  Semiprofessional (n = 5) and university (n = 15) soccer players completed 3 trials (1 familiarization, 2 experimental) of SAFT90. PlayerLoad and its individual planes were measured continuously using micromechanical-electrical systems (MEMS) positioned at the scapulae (SCAP) and near the center of mass (COM).
  
  
  RESULTS
  There were no between-halves differences in PL(VM); however, within-half increases were recorded at the COM, but only during the 1st half at the SCAP. Greater contributions to PL(VM) were provided by PL(V) and PL(ML) when derived from the SCAP and COM, respectively. PL(VM) (COM 1451 ± 168, SCAP 1029 ± 113), PL(AP) (COM 503 ± 99, SCAP 345 ± 61), PL(ML) (COM 712 ± 124, SCAP 348 ± 61), and PL(V) (COM 797 ± 184, SCAP 688 ± 124) were significantly greater at the COM than at the SCAP. Moderate and high test-retest reliability was observed for PlayerLoad and its individual planes at both locations (ICC .80-.99).
  
  
  CONCLUSIONS
  PlayerLoad and its individual planes are reliable measures during SAFT90 and detected within-match changes in movement strategy when the unit was placed at the COM, which may have implications for fatigue management. Inferring alterations in lower-limb movement strategies from MEMS units positioned at the SCAP should be undertaken with caution.
authors.affiliation: Dept of Sport, Health and Exercise Science, University of Hull, Kingston Upon Hull, UK.
authors.forename: Steve
authors.initials: S
authors.lastname: Barrett
authors.forename: Adrian W
authors.initials: AW
authors.lastname: Midgley
authors.forename: Christopher
authors.initials: C
authors.lastname: Towlson
authors.forename: Andrew
authors.initials: A
authors.lastname: Garrett
authors.forename: Matt
authors.initials: M
authors.lastname: Portas
authors.forename: Ric
authors.initials: R
authors.lastname: Lovell
mesh_terms: D061725:Accelerometry / Q000379:methods*; D054874:Athletic Performance / Q000502:physiology*; D005221:Fatigue / Q000503:physiopathology*; D040362:Geographic Information Systems; D006801:Humans; D015203:Reproducibility of Results; D012420:Running / Q000502:physiology; D012916:Soccer / Q000502:physiology*