An assessment of one-on-one inertial shoulder tackles in rugby league using instrumented mouthguards and qualitative video analysis.

In the recent past, head injuries in rugby union and league have been a cause for concern. Making use of instrumented mouthguards enables the recording of head acceleration events (HAE) experienced by athletes in real time. Increased magnitude and frequency of HAEs increases the risk of head injuries such as concussion. The aim of the study was to examine the effect different tackle types have on peak linear acceleration (PLA), peak angular acceleration (PAA) and peak angular velocity (PAV) during one-on-one inertial shoulder tackle HAE. The study involved the analysis of 80 tackles on male Leeds Rhinos players collected over 27 Super League matches. PLA, PAA and PAV of the head were recorded using the instrumented mouthguards with a 5 g or 500 rad/s2 triggering threshold, which is lower than the recommended threshold of 10 g. Qualitative video analysis was done to classify the tackles based on tackle height, tackler and ball carrier speed, tackler and ball carrier body position, tackle direction and whether the tackle was active or passive. Multiple linear regression was done to assess whether the different tackle types influenced PLA, PAA or PAV. Tackler speed and tackle height were determined to be significant predictors of PAV (p < 0.05). An increase in tackle height (B= 2.1, p < 0.05) and tackler speed (B= 1.08, p< 0.05) led to increased PAV. None of the other independent variables significantly predicted PLA, PAA or PAV. Majority of the impacts were below the recommended triggering threshold of 10 g. In conclusion, this study found that an increase in tackler speed and tackle height led to an increase in PAV. In addition to this, the study highlights the efficacy of using a combination of qualitative video analysis and instrumented mouthguards to quantify and categorise HAE in rugby league.