title: The Effect of Body Mass on the 30-15 Intermittent Fitness Test in Rugby Union Players.
abstract: OBJECTIVE
  To evaluate the difference in performance of the 30-15 Intermittent Fitness Test (30-15IFT) across 4 squads in a professional rugby union club in the UK and consider body mass in the interpretation of the end velocity of the 30-15IFT (VIFT).
  
  
  METHODS
  One hundred fourteen rugby union players completed the 30-15IFT midseason.
  
  
  RESULTS
  VIFT demonstrated small and possibly lower (ES = -0.33; 4/29/67) values in the under 16s compared with the under 21s, with further comparisons unclear. With body mass included as a covariate, all differences were moderate to large and very likely to almost certainly lower in the squads with lower body mass, with the exception of comparisons between senior and under-21 squads.
  
  
  CONCLUSIONS
  The data demonstrate that there appears to be a ceiling to the VIFT attained in rugby union players that does not increase from under-16 to senior level. However, the associated increases in body mass with increased playing level suggest that the ability to perform high-intensity running increases with age, although not translating into greater VIFT due to the detrimental effect of body mass on change of direction. Practitioners should be aware that VIFT is unlikely to improve, but it needs to be monitored during periods where increases in body mass are evident.
authors.affiliation: Research Inst of Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK.
authors.forename: Joshua
authors.initials: J
authors.lastname: Darrall-Jones
authors.forename: Gregory
authors.initials: G
authors.lastname: Roe
authors.forename: Shane
authors.initials: S
authors.lastname: Carney
authors.forename: Ryan
authors.initials: R
authors.lastname: Clayton
authors.forename: Padraic
authors.initials: P
authors.lastname: Phibbs
authors.forename: Dale
authors.initials: D
authors.lastname: Read
authors.forename: Jonathon
authors.initials: J
authors.lastname: Weakley
authors.forename: Kevin
authors.initials: K
authors.lastname: Till
authors.forename: Ben
authors.initials: B
authors.lastname: Jones
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D056352:Athletes; D054874:Athletic Performance; D001835:Body Weight; D005080:Exercise Test; D005538:Football / Q000502:physiology*; D006801:Humans; D008297:Male; D010809:Physical Fitness / Q000502:physiology*; D012420:Running / Q000502:physiology; D006113:United Kingdom; D055815:Young Adult