Does Variability within a Sports Field Influence Ground-Derived Injuries?.

A two year pilot study was conducted on two ‘Tifway 419’ hybrid bermudagrass [Cynodon dactylon L. (Pers.) x C. transvaalensis Burtt-Davy] recreational fields at the University of Georgia (UGA) to evaluate the influence of within-field variations on ground-derived injuries. Participants were club athletes from the UGA men’s and women’s rugby and ultimate frisbee teams, as well as the women’s lacrosse team. Injury locations were self-reported using a geo-referenced alphanumeric grid (3 m² cells). Geo-referenced soil moisture (volumetric water content), turfgrass quality (normalized difference vegetation index), surface hardness, and turfgrass shear strength data were obtained either weekly or bi-weekly. Data were averaged by month and hot spot maps were generated to identify significant within-field variations. Injury locations from a given month were compared to hot spot maps from that month. Twenty three ground-derived injuries were reported. The most injuries occurred within a hot or cold spot of turfgrass quality (79%), followed by soil moisture (76%), and then surface hardness and turfgrass shear strength (57%). The observed proportions of injuries that occurred in a hot or cold spot of turfgrass quality and soil moisture was significantly different (P<0.01) than their expected proportions (i.e. the overall proportion of the field that was a hot or cold spot; 35% and 43%, respectively). Interestingly, the majority of injury locations for all measured surface properties (except turfgrass shear strength) appeared to occur along edges of hot or cold spots. Results from this study suggest that within-field variations should be accounted for in future ground-derived athlete injury studies.