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 (PRE), immediately after (POST), and 48h (48H) 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/POST-sparring (median change in total symptom severity score [deltaTSSS]: -1, p=0.85, p=0.07). Symptom number and TSSS were significantly lower at 48H compared to PRE (median deltaTSSS: -1, p=0.02, r=0.55). Four of 16 sessions (25%) from three participants showed a deltaTSSS >5. 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 Symptom number and severity PRE/POST sparring changes were rare and subtle, and the link to head impact exposure is unclear. Our exploratory analyses support the concept of individual-specific approaches, as this 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. Practical implications • The SCAT symptom scale can be easily implemented to assess pre/post-sparring changes in symptoms. • Symptoms can peak a few hours after sparring; repeated assessments at 5 h and 48 h allow the capture of the delayed effects of head impact exposure. • Head impact exposure should be interpreted alongside symptom reports, and compared to an athlete's past exposure to identify whether a session's load was unusually high.
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