Objectives Non-tackle American football is growing in popularity, and it has been proposed as a safer alternative for young athletes interested in American football. Little is known about the nature of head contact in the sport, which is necessary to inform the extent to which protective headgear is warranted. The objective of this study was to identify the location, types and frequency of head and body contacts in competitive 7v7 non-tackle American football.
Methods Video analysis was used to document the type, frequency and mechanism of contacts across a series of under 12, under 14 and high school non-tackle tournament games. A subset of impacts was quantitatively analysed via 3-D model-based image matching to calculate the preimpact and postimpact speed of players’ heads and the change in resultant translational and rotational velocities.
Results The incidence rate of head contact was found to be low (3.5 contacts per 1000 athlete-plays). Seventy-five per cent of head contacts were caused by a head-to-ground impact. No head-to-head contacts were identified. Most contacts occurred to the rear upper (occiput) or side upper (temporal/parietal) regions. Head-to-ground impact was associated with a maximum preimpact velocity of 5.9±2.2 m/s and a change in velocity of 3.0±1.1 m/s.
Conclusion Non-tackle football appears to represent a lower contact alternative to tackle football. The distribution of head impact locations, mechanisms and energies found in the present study is different than what has been previously reported for tackle football. The existing tackle football standards are not appropriate to be applied to the sport of non-tackle football, and sport-specific head protection and headgear certification standards must be determined.
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Contributors AE, GCG and RJ were responsible for study conception and design. RJ and EL were responsible for data collection and analysis. All authors were responsible for data interpretation, manuscript development, critical review and final approval.
Funding The study was funded by Xenith, a manufacturer of helmets, gear and apparel for American football and related sports.
Competing interests AE, GCG, RJ and EL are employed by Xenith. JZ is a paid scientific advisor for Xenith.
Patient and public involvement statement The study was designed after consulting with 7v7 coaches, players and parents about typical contact in the sport and their questions about player safety and appropriate protective equipment.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. Deidentified video analysis data by play (contact, contact type, location on field, play type, age group, location on head of impact, description of play) that underlie the results reported in this article are available upon reasonable request. Data will be available beginning 3 months after publication and ending 36 months following publication to researchers who provide a methodologically sound proposal for reuse in achieving the aims of this proposal. Proposals should be directed to firstname.lastname@example.org.
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