Biomechanical Profiles of Diagnosed Concussions in Rugby Union: A Case Study Using Instrumented Mouthguards.

BACKGROUND

This case study presents biomechanical profiles of three confirmed concussions in professional Under 21 (U21) academy rugby union players, recorded using instrumented mouthguards (iMGs).

METHODS

Across 34 matches (254 player matches) and 241 playing hours, 4414 head acceleration events (HAEs) were captured, with three concussions clinically diagnosed. Metrics analysed included Peak linear acceleration (PLA), Peak angular acceleration (PAA), Peak angular velocity (PAV), and angular measures: change in Peak angular velocity (ΔPAV) and Rotational Velocity Change Index (RVCI).

RESULTS

Peak linear acceleration ranged from 27.6 to 48.4 g, PAA from 3234 to 4089 rad/s2, and ΔPAV from 17.7 to 28.5 rad/s. Player #3, who lost consciousness following a high-speed head-on-head collision, recorded the highest ΔPAV (28.5 rad/s) and RVCI (27.3). Player #2, diagnosed post-match, showed the highest cumulative angular load (ΔPAV: 144.3 rad/s; PAA: 17,340 rad/s2) despite no clear concussive impact, suggesting cumulative sub-concussive exposure.

CONCLUSION

These findings demonstrate that concussions can result from both single high magnitude impacts and cumulative impacts. The variability in biomechanical signatures reinforces the need for multi-metric monitoring approaches rather than reliance on isolated thresholds. This study is the first in rugby to report confirmed concussions using iMGs with both peak and cumulative kinematic data. The results support the integration of angular metrics and cumulative load monitoring to understand concussion risk and management in collision sports.