Do hard playing fields increase the risk of injury in community level Australian football?

Introduction: Certain ground conditions, including hardness, have been associated with an increased injury risk. Many sporting grounds have been deemed unplayable based on hardness measures and subsequently closed. However, most research linking injury to ground conditions has been based on subjective observations or focussed at high performance venues. The aim of this study was to identify the relationship between ground hardness and injury incidence in community level Australian football. Methodology: Measurements of ground hardness, using the Clegg hammer, were recorded on eight community level football grounds between 4 and 8 times during the 2007 season. Injury data was collected by trained data collectors over the season. The 1st Clegg hammer drop was used as the hardness measure, and injuries were ranked as ‘likely’, ‘possibly’, and ‘unlikely’ to be related to grounds by three independent assessors. Results: 130 injuries were recorded at the grounds tested. The Clegg hammer measures ranged from 55 to 134 gravities (g), with four injuries sustained at readings over 120 × g. Of the 130 injuries, 12 were classified as ‘likely’ to be related to ground conditions, 29 ‘possibly’ related, 75 ‘unlikely’ and 14 unknown due to incomplete details. None of the ‘likely’ injuries were sustained on readings over 120 × g. No significant relationships were found between ground hardness and any injury profiles (0.02 < r < 0.14, p < 0.01). Conclusions: Presently, sporting grounds are being closed with hardness readings exceeding 120 × g. The results of this study provide some evidence to challenge this, however, due to low injury rates further research with a larger cohort is necessary