title: Ground hardness and injury in community level Australian football.
abstract: OBJECTIVE
  To describe the risk and details of injuries associated with ground hardness in community level Australian football (AF).
  
  
  METHODS
  Prospective injury surveillance with periodic objective ground hardness measurement.
  
  
  METHODS
  112 ground hardness assessments were undertaken using a Clegg hammer at nine locations across 20 grounds, over the 2007 and 2008 AF seasons. Details of 352 injuries sustained by community level players on those grounds were prospectively collected as part of a large randomised controlled trial. The ground location of the injury was matched to the nearest corresponding ground hardness Clegg hammer readings, in gravities (g), which were classified from unacceptably low (<30 g) to unacceptably high hardness (>120 g).
  
  
  RESULTS
  Clegg hammer readings ranged from 25 to 301 g. Clegg hammer hardness categories from low/normal to high/normal were associated with the majority of injuries, with only 3.7% (13 injuries) on unacceptably high hardness and 0.3% (1 injury) on the unacceptably low hardness locations. Relative to the preferred range of hardness, the risk of sustaining an injury on low/normal hardness locations was 1.31 (95%CI: 1.06-1.62) times higher and 1.82 (95%CI: 1.17-2.85) times higher on locations with unacceptably high hardness. The more severe injuries occurred with low/normal ground hardness.
  
  
  CONCLUSIONS
  Despite the low number of injuries, the risk of sustaining an injury on low/normal and unacceptably hard grounds was significantly greater than on the preferred range of hardness. Notably, the severity of the injuries sustained on unacceptably hard grounds was lower than for other categories of hardness.
authors.affiliation: School of Human Movement and Sport Sciences, University of Ballarat, Australia. d.twomey@ballarat.edu.au
authors.forename: Dara M
authors.initials: DM
authors.lastname: Twomey
authors.forename: Caroline F
authors.initials: CF
authors.lastname: Finch
authors.forename: David G
authors.initials: DG
authors.lastname: Lloyd
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Elliott
authors.forename: Tim L A
authors.initials: TL
authors.lastname: Doyle
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000453:epidemiology*; D001315:Australia / Q000453:epidemiology; D005538:Football / Q000293:injuries*; D006244:Hardness; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D012720:Severity of Illness Index; D055815:Young Adult