title: Variability of physical performance and player match loads in professional rugby union.
abstract: OBJECTIVE
  To examine the within- and between-player variability of physical performance and player match loads in professional rugby union.
  
  
  METHODS
  A single cohort, observational study.
  
  
  METHODS
  Physical match performance data were collected from 28 male, professional, English Championship players over 15 competitive matches. Using microsensors, the variables selected for analysis were total distance, low-speed running distance, high-speed running distance, very high-speed running distance, total impacts, repeated high-intensity efforts, body load (PlayerLoad™), and low velocity (<7.2kmh(-1)) body load. Ratings of perceived exertion represented match internal loads. Variability was quantified using the coefficient of variation, with the meaningful interpretation of change in physical performance and match loads calculated using magnitude-based inferences.
  
  
  RESULTS
  We found large between-match (within-player) variation for high-speed running distance (27.6%; ±90% confidence limits 6.9% [forwards], 20.1%; ±4.1% [backs]), very high-speed running distance (68%; ±19%, 34.1%; ±7.5%), total impacts (24.0%; ±5.9%, 36.4%; ±7.9%) and repeated high-intensity efforts (18.7%; ±4.4%, 39.5%; ±8.8%), with moderate variability for match ratings of perceived exertion (8.2%; ±1.8%, 10.8%; ±2.1%), body load (7.3%; ±1.7%, 10.0%; ±2.0%) and low velocity body load (8.9%; ±2.0%, 10.7%; ±2.1%). Threshold values for likely substantial between-match changes in high-intensity physical performance measures ranged from 21% to 76%, and were ∼10% for match ratings of perceived exertion, body load and low velocity body load.
  
  
  CONCLUSIONS
  Within- and between-player variability of high-intensity activity in professional rugby union is large, yet ratings of perceived exertion, body load and low velocity body load appear more stable by comparison and may be interpreted with greater accuracy.
authors.affiliation: Sport & Exercise Subject Group, School of Social Sciences, Business and Law, Teesside University, UK.
authors.forename: Shaun J
authors.initials: SJ
authors.lastname: McLaren
authors.affiliation: Sport & Exercise Subject Group, School of Social Sciences, Business and Law, Teesside University, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Weston
authors.affiliation: A S Strength and Conditioning Limited, UK; Nottingham Rugby, The Bay, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Smith
authors.affiliation: School of Applied Social Sciences, Durham University, UK.
authors.forename: Rob
authors.initials: R
authors.lastname: Cramb
authors.affiliation: Sport & Exercise Subject Group, School of Social Sciences, Business and Law, Teesside University, UK. Electronic address: m.portas@tees.ac.uk.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Portas
mesh_terms: D061725:Accelerometry / Q000379:methods*; D000328:Adult; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D005538:Football / Q000502:physiology*; D040362:Geographic Information Systems; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009048:Motor Skills / Q000502:physiology*; D055815:Young Adult
keywords: Between-match variation; External load; GPS; Internal load; RPE; Reliability