On-field Head Acceleration Exposure Measurement Using Instrumented Mouthguards: Missing Data Imputation for Complete...

Accurate quantification of head acceleration event (HAE) exposure is critical for investigating brain injury risk in contact sports athletes. However, missing HAEs may be unavoidable in real-world data collection. This study introduces missing data imputation methods to estimate complete video- and sensor-based HAE exposure.

We captured and verified university men's ice hockey HAEs using video and instrumented mouthguards (iMGs) in one varsity season (n_athletes = 27, n_games = 31). A statistical mapping technique was first introduced to impute missing video-based HAEs during away games with limited camera angles. We then applied multiple imputation to impute missing iMG-based HAEs using captured data, including the complete video-based HAE exposure. This enabled estimation of complete exposure data at a per-athlete level over all games of the season.

Among 591 athlete-games, 45% did not have any recorded iMG data. We find that data imputation increased the median values of per-athlete-season video- and iMG-based HAE counts by 10% and 69%, respectively. Consequently, common head kinematics- and brain deformation-based cumulative exposure metrics also increased substantially (median per-athlete-season cumulative peak linear acceleration by 95%, peak angular acceleration by 109%, and corpus callosum strain by 69%).

This study highlights the potential underestimation of exposure metrics due to missing HAEs and fills a critical gap in sports HAE exposure research. Future studies should incorporate missing data imputation methods for more accurate estimation of HAE exposure in investigating acute and long-term brain trauma risks.