Doctors debate whether chokes in MMA are dangerous for brain function?

Wednesday, June 12, 2019

Earlier this year I highlighted debate among physicians addressing whether chokes in combat sports play any role in CTE.

More recently a study published in the Journal of Brain Injury suggests that MMA bouts (or training sessions) ending in a choking submission result in cognitive consequences similar to concussion. Like last year’s article, this recent suggestion has received some criticism from other doctors.

In the recent study, titled The King-Devick test in mixed martial arts: the immediate consequences of knock-outs, technical knock-outs, and chokes on brain functions, the authors looked at King-Devick times (an accepted concussion evaluation tool) in MMA trainees and competitors.  They looked at training/bouts that ended via head trauma events and those that ended via submission events.  The authors noted that both KO and non KO ‘events’ led to a slowing of King-Devick testing.  From this they concluded that “athletes who sustained non-head trauma “events” also demonstrated slowing on their K-D tests, suggesting these “events” may also cause some impairment in
brain function indicative of a concussion“.

The full abstract and conclusion read as follows:

The aim of this prospective cohort study was to determine the effect of an ‘event,’ defined as a knockout (KO), technical knock-out (TKO), choke, or submission, on King-Devick (K-D) test times in mixed martial arts (MMA) athletes. MMA athletes (28.3 ± 6.6 years, n = 92) underwent K-D testing prior to and following a workout or match. Comparison of baseline and post-workout/match K-D times to assess any significant change. K-D tests worsened (longer) in a majority of athletes following an ‘event’ (N = 21) (49.6 ± 7.8 s vs 46.6 ± 7.8 s, p = 0.0156, Wilcoxon signed-rank test). K-D tests improved (shorter) following a standard workout or match in which no ‘event’ occurred in a majority of cases (n = 69) (44.2 ± 7.2 s vs 49.2 ± 10.9 s, p = <0.0001, Wilcoxon signed-rank test). Longer duration (worsening) of postmatch K-D tests occurred in most athletes sustaining an ‘event’; K-D tests shortened (improved) in a majority of athletes not sustaining an ‘event’. Our study suggests MMA athletes suffering an ‘event’ may have sustained a brain injury similar to a concussion.

The vast majority of MMA athletes sustaining an “event” with witnessed head trauma (KO or TKO) had significant slowing of their K-D test. It is probable that slowing of the post-match or post-training K-D test in this population indicates that the athlete has sustained a concussive type brain injury. Furthermore, athletes who sustained non-head trauma “events” also demonstrated slowing on their K-D tests, suggesting these “events” may also cause some impairment in
brain function indicative of a concussion. Our findings suggest that any MMA athlete with a slowed post-match or posttraining K-D test requires further evaluation by a medical professional trained in concussion management.

This conclusion drew strong criticism from Samuel J. Stellpflug and Robert C. LeFevere of the Department of Emergency Medicine, Regions Hospital, Saint Paul, MN, USA. In reply to the above study the doctors summarized their criticism of the conclusions as follows:

In summary, this study doesn’t establish a link between transient choking and significant worsening in K-D times, nor between transient chokes and anoxic brain injury with cerebral changes comparable to concussion. The listed supporting references don’t support either of these claims. Additionally, the brief
hypoxia associated with transient chokes is analogous to brief vasovagal syncope, which does not cause lasting brain injury. Concussions involve a traumatic force causing injury that can have long-lasting effects. There is no established reason to believe, based on the different mechanisms, that brief hypoxia
causes the lasting damage that a concussion can cause. Lastly, there is a limitation in terming these MMA chokes as nontraumatic scenarios when the totality of the physical transgressions that lead to the choke is taken into account. Overall, this study does not provide any convincing data that chokes in combat sports cause injuries to the brain similar to concussion.

It would be of value to the combat sports community to have a study conducted involving grapplers who tap out due to chokes (who do not sustain any head impacts in the process as they would in an MMA competition) to see if the K-D scores are negatively impacted.  Such a study can help further this debate and add clarity to the competing points of view.


Author Erik Magraken is a British Columbia litigation lawyer, combat sports law consultant, founder of the Combat Law Sports Blog, and profoundly appreciated UGer.