Australian Football League Injury Characteristics Differ Between Matches and Training: A Longitudinal Analysis of Changes in the Setting, Site, and Time Span From 1997 to 2016.

Background: Injury surveillance has been used to quantify the scope of the injury burden in Australian football. However, deeper statistical analyses are required to identify major factors that contribute to the injury risk and to understand how these injury patterns change over time. Purpose: To compare Australian Football League (AFL) injury incidence, severity, prevalence, and recurrence by setting, site, and time span from 1997 to 2016. Study Design: Descriptive epidemiology study. Methods: A total of 15,911 injuries and medical illnesses recorded by team medical staff at each club were obtained from the AFL's injury surveillance system and analyzed using linear mixed models with 3 fixed effects (setting, time span, site) and 1 random effect (club). All types of injuries and medical illnesses were included for analysis, provided that they caused the player to miss at least 1 match during the regular season or finals. Five-season time spans (1997-2001, 2002-2006, 2007-2011, and 2012-2016) were used for comparisons. Incidence rates were expressed at the player level. Recurrences were recoded to quantify recurrent injuries across multiple seasons. Results: Compared with training injuries, match injuries had a 2.8 times higher incidence per season per club per player (matches: 0.070 +/- 0.093; training: 0.025 +/- 0.043; P < .001). Match injuries resulted in 1.9 times more missed matches per club per season (matches: 17.2 +/- 17.0; training: 9.1 +/- 10.5; P < .001). and were more likely to be recurrences (matches: 11.6% +/- 20.0%; training: 8.6% +/- 21.8%; P < .001). From the 1997-2001 to 2007-2011 time spans, overall injury severity increased from a mean of 3.2 to 3.7 missed matches (P <= .01). For the most recent 2012-2016 time span, injuries resulted in 3.6 missed matches, on average. Hip/groin/thigh injuries had the highest incidence (0.125 +/- 0.120) and prevalence (19.2 +/- 16.4) rates, and recurrences (29.3% +/- 27.9%) were 15% more likely at this site than any other injury site. Conclusion: The risks of match injuries are significantly higher than those of training injuries in the AFL. Compared with the 1997-2001 time span, injuries became more severe during the 2007-2011 time span.