Study – MMA Fighter Brain Volume Not Decreased Based on Self Reported Sparring Frequency

Adding to this site’s combat sports safety study summaries, a recent study was published in the Journal of Sports Medicine reviewing MMA fighter brain volume measurements and their association with sparring frequency.

In the article, titled Sparring and the Brain: The Associations between Sparring and Regional Brain Volumes in Professional Mixed Martial Arts Fighters, the authors used data from the ongoing professional fighters brain health study. They reviewed data from 94 active pro MMA fighters. They reviewed the number of sparring practice rounds per week the athletes undertook and to see what difference this made on regional brain volumes which were measured via MRI imaging.

They found that among this group of still active fighters “More weekly rounds of sparring was not significantly associated with smaller volumes in any of the brain regions studied in active, professional MMA fighters“.

There is a lot of data that fighting and sparring in boxing is linked with decreases in brain volume. There is also data showing that cumulative number of bouts in MMAd and other combat sprots are linked to neurotrauma levels. The present study hoped to gain insight into sparring levels in MMA and brain volume decreases. The authors hypothesized that the more sparring, the more measurable brain volume decrease. To their surprise they found that this was not the case.

It is worth noting that the levels of sparring were self reported, not actually observed. The fighters simply self reported their “Sparring (# of rounds per week)” to researchers. The intensity of the sparring was also not dissected. As combat sports athletes can appreciate there can be profound differences in the intensity of sparring sessions.

In any event the findings are intriguing with the researchers calling for more research “including further investigations of sparring and the necessity of longitudinal research in both sparring and other forms of MMA and combat sports training“.

The full abstract reads as follows. The full paper can be purchased here.



Mixed martial arts (MMA) fighters, due to exposure to repetitive head impacts, are at risk for brain atrophy and neurodegenerative sequelae. Simultaneously, motor skills training and cognition-rich activities have been linked with larger regional brain volumes. The majority of an MMA fighter’s sporting activity occurs during practice (e.g., sparring) rather than formal competition. This study, therefore, aims to be the first to explore regional brain volumes associated with sparring in MMA fighters.


Ninety-four active, professional MMA fighters from the Professional Fighters Brain Health Study met inclusion criteria for this cross-sectional analysis. Adjusted multivariable regression analyses were utilized to examine the relationship between the number of sparring practice rounds per week during typical training and a select number of regional brain volumes (i.e., caudate, thalamus, putamen, hippocampus, amygdala).


A higher number of weekly sparring rounds during training was significantly associated with larger left (beta = 13.5 µL/round, 95% CI 2.26–24.8) and right (beta = 14.9 µL/round, 95% CI 3.64–26.2) caudate volumes. Sparring was not significantly associated with left or right thalamus, putamen, hippocampus, or amygdala volumes.


More weekly rounds of sparring was not significantly associated with smaller volumes in any of the brain regions studied in active, professional MMA fighters. Sparring’s significant association with larger caudate volume raises questions about whether fighters who spar more experience attenuated trauma-related decreases in caudate volume relative to fighters who spar less, whether fighters who spar more experience minimal or even positive changes to caudate volume, whether baseline differences in caudate size may have mediated results, or whether some other mechanism may be at play. Given limitations inherent to the cross-sectional study design, more research is needed to further explore the brain effects of sparring in MMA.


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