Exploring the link between acute symptom changes and repetitive head impacts in boxing sparring

Objectives : The acute dose-response relationship between head impact exposure and the development of concussion remains elusive. Previous research has suggested that individual-specific approaches and the cumulative effects of head impacts should be investigated. This study aimed to monitor acute changes in concussion-related symptoms resulting from boxing sparring, and assess how they relate to head impact exposure. Design : Observational cohort study Methods : Seven competitive boxers participated in this exploratory study. Symptoms of concussion were captured via the SCAT5 symptom scale upon recruitment, immediately before, immediately after, and 48 hours after a sparring session. Head impact data were collected with instrumented mouthguards. Each session’s mean, median, highest-magnitude impact, cumulative sum, and time-weighted exposure for several injury severity metrics were qualitatively analyzed with respect to acute changes in symptom score. Results : Group-based analyses did not show any differences in symptom scores pre- and post-sparring; Three participants reported symptom changes in four instances (25% of all sessions). There was no strong association between session-specific exposure and change in symptoms, but time-weighted exposure metrics showed a better alignment than other metrics. Conclusions : Symptoms may have resulted from the combination of several factors, namely a high density of head impacts, several above-average-magnitude impacts, or pre-existing dispositions. Our results support the concept of individual-specific analyses, as this approach allowed us to identify patterns emerging from a few athletes that were not visible in cohort-averaged summaries. Understanding the relationships between head impact exposure, individual pre-disposition, and signs and symptoms of concussion is essential to designing risk reduction strategies.