Objective To develop an observational tool to reliably code the situational characteristics and mechanism of contact for fights ending in knockout (KO) or technical KO (TKO).

Design Digital video images and fight card information were collected retrospectively for UFC events during 2006–2009.

Subjects Two coders independently viewed and completed to the Mixed Martial Arts (MMA) ‘Knockout’ Tool for 60 events (30=KO's 30=TKO's) chosen randomly from the pool of identified events during 2006–2009.

Outcome Measures The MMA ‘Knockout’ Tool was developed by consensus and consists of 17 factors, including the Situational Context (eg, Round, octagon location, technical position), Pre-KO/TKO Strike Profile (eg, striking implement, strike location), Assessment of Fighters (eg, visual obstruction, clinical signs of concussion), and KO strike profile (eg, striking implement, strike location, head motion, additional head impacts). Intercoder agreements for each factor of interest were calculated using weighted κ coefficient.

Results Coders achieved substantial agreement for the majority of the factors with κ coefficients ranging from 0.46 to 1.00. An overall reliability value was calculated based on all factors of the MMA ‘Knockout’ Tool, with an average κ coefficient of 0.81.

Conclusion The MMA ‘Knockout’ Tool is reliable for coding the situational characteristics and mechanism of contact(s) for fights ending in a TKO or KO.

Acknowledgements The Canadian Institutes of Health Research (CIHR) Strategic Team in Applied Injury Research funded this research

Competing interests None.