title: Running-Intensity Fluctuations in Elite Rugby Sevens Performance.
abstract: OBJECTIVE
  To investigate temporal variation in running intensity across and within halves and evaluate the agreement between match-analysis indices used to identify fluctuations in running intensity in rugby sevens.
  
  
  METHODS
  Data from a 15-Hz global positioning system (GPS) were collected from 12 elite rugby sevens players during the IRB World Sevens Series (N = 21 full games). Kinematic (eg, relative distance [RD]) and energetic (eg, metabolic power [MP]) match-analysis indices were determined from velocity-time curves and used to investigate between-halves variations. Mean MP and RD were used to identify peak 2-minute periods of play. Adjacent 2-minute periods (prepeak and postpeak) were compared with peak periods to identify changes in intensity. MP and RD were expressed relative to maximal oxygen uptake (VO2max) and speed at VO2max, respectively, and compared in their ability to describe the intensity of peak periods and their temporal occurrence.
  
  
  RESULTS
  Small to moderate reductions were present for kinematic (RD; 8.9%) and energetic (MP; 6%) indices between halves. Peak periods (RD = 130 m/min, MP =13 W/kg) were higher (P < .001) than the match average (RD = 94 m/min, MP = 9.5 W/kg) and the prepeak and postpeak periods (P < .001). RD underestimated the intensity of peak periods compared with MP (bias 16%, limits of agreement [LoA] ± 6%). Peak periods identified by RD and MP were temporally dissociated (bias 21 s, LoA ± 212 s).
  
  
  CONCLUSIONS
  The findings suggest that running intensity varies between and within halves; however, the index used will influence both the magnitude and the temporal identification of peak periods.
authors.affiliation: Exercise and Sport Science, University of New England, Armidale, Australia.
authors.forename: Nicola
authors.initials: N
authors.lastname: Furlan
authors.forename: Mark
authors.initials: M
authors.lastname: Waldron
authors.forename: Kathleen
authors.initials: K
authors.lastname: Shorter
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Gabbett
authors.forename: John
authors.initials: J
authors.lastname: Mitchell
authors.forename: Edward
authors.initials: E
authors.lastname: Fitzgerald
authors.forename: Mark A
authors.initials: MA
authors.lastname: Osborne
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Gray
mesh_terms: D000054:Acceleration; D000328:Adult; D056352:Athletes / Q000523:psychology; D054874:Athletic Performance / Q000523:psychology; D001696:Biomechanical Phenomena; D003163:Competitive Behavior; D004734:Energy Metabolism; D005538:Football / Q000523:psychology; D040362:Geographic Information Systems; D006801:Humans; D008297:Male; D009043:Motor Activity; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance; D012420:Running; D013647:Task Performance and Analysis; D013997:Time Factors; D055815:Young Adult