Reply to Fanton et al.: Comment on “Frequency and Magnitude of Game-Related Head Impacts in Male Contact Sports Athletes: A Systematic Review and Meta-analysis”

Background Sensor devices have enabled estimations of head impact kinematics across contact sports. Objectives To quantitatively report the magnitude (linear and rotational acceleration) and frequency of game-related head impacts recorded in male contact sports athletes. Methods A systematic review was conducted in June 2017. Inclusion criteria were English-language in vivo studies published after 1990 with a study population of male athletes aged ≥ 16 years, in any sport, where athletes were instrumented with an accelerometer device for measuring head impacts. Study populations were not limited to players with a clinical diagnosis of concussion. Results Twenty-one studies met the inclusion criteria with 12 conducted on American Football athletes. Six of these studies were included for meta-analysis. At a threshold of 10 g , amateur rugby players sustained the most impacts per player per game (mean = 77, SD = 42), followed by amateur Australian Football (mean = 29, SD = 37) and collegiate lacrosse athletes (mean = 11.5, SD = 3.6). At thresholds of greater than 14.4 g , high school American Football athletes sustained between 19 (SD = 19.1) and 24.4 (SD = 22.4) impacts per player per game. Statistically significant heterogeneity was observed among the included studies, and meta-analysis of impact magnitude was limited. Conclusions The frequency of “head acceleration events” was quantified and demonstrated substantial variation in methodology and reporting of results. Future research with standardised reporting of head impacts and inclusion of non-helmeted sports is warranted to enable more robust comparisons across sports. Prospero ID CRD42017070065.