Combat Sports as a Model for Measuring the Effects of Repeated Head Impacts on Autonomic Brain Function: A Brief Report of Pilot Data

Automated pupil light reflex (PLR) is a valid indicator of dysfunctional autonomic brain function following traumatic brain injury. PLR’s use in identifying disturbed autonomic brain function following repeated head impacts without outwardly visible symptoms has not yet been examined. As a combat sport featuring repeated ‘sub-concussive’ head impacts, mixed martial arts (MMA) sparring may provide a model to understand such changes. The aim of this pilot study was to explore which, if any, PLR variables are affected by MMA sparring. A cohort of n = 7 MMA athletes (age = 24 3 years; mass = 76.5 9 kg; stature = 176.4 8.5 cm) took part in their regular sparring sessions (eight rounds 3 min: 1 min recovery). PLR of both eyes was measured immediately preand post-sparring using a Neuroptic NPi-200. Bayesian paired samples t-tests (BF10 3) revealed decreased maximum pupil size (BF10 = 3), decreased minimum pupil size (BF10 = 4) and reduced PLR latency (BF10 = 3) post-sparring. Anisocoria was present prior to sparring and increased postsparring, with both eyes having different minimum and maximum pupil sizes (BF10 = 3–4) and constriction velocities post-sparring (BF10 = 3). These pilot data suggest repeated head impacts may cause disturbances to autonomic brain function in the absence of outwardly visible symptoms. These results provide direction for cohort-controlled studies to formally investigate the potential changes observed.

MMA Sparring and Autonomic Brain Function: Pilot Data on Repeated Head Impacts.

The pilot study aimed to explore the effect of MMA sparring on PLR variables, which are indicators of dysfunctional autonomic brain function following traumatic brain injury. The study found that PLR variables were altered after sparring, with decreased maximum pupil size and minimum pupil size, and reduced PLR latency. Anisocoria was also present prior to sparring and increased after sparring. These results suggest that repeated head impacts may cause disturbances to autonomic brain function in the absence of outwardly visible symptoms, and provide direction for future cohort-controlled studies to formally investigate the potential changes observed.

This research is important as it sheds light on the potential long-term effects of repeated head impacts on athletes participating in combat sports such as mixed martial arts (MMA) sparring, even in the absence of outwardly visible symptoms. It highlights the importance of understanding the impact of sub-concussive head impacts on brain function, which can have significant implications for athlete health and performance.

Key Takeaways:

1. Repeated head impacts experienced during combat sports may cause disturbances to autonomic brain function in the absence of outwardly visible symptoms.

2. The study found changes in pupil constriction, reduced PLR latency, and increased anisocoria following MMA sparring.

3. These findings provide direction for future cohort-controlled studies to investigate the potential changes observed.