Archive for the ‘Safety Studies’ Category

In my ongoing efforts to highlight relevant safety studies addressing combat sports,  a recent study was published in the Journal of Neurology documenting decreased brain volume with associated cognitive dysfunction in professional fighters.

The recent study, titled Longitudinal MRI and Cognitive Change in Professional Fighters, is part of the Professional Fighter Brain Health study which is perhaps the biggest ongoing study to date of fighter brain health.   It is funded in part by a host of combat sports stakeholders including the UFC, Haymon Boxing, the UCLA Dream Fund, Bellator and Top Rank.

The authors reviewed MRI brain imaging of 76 professional fighters with a mean number of professional fights of 14.46.  These fighters were followed, on average, between 2-5 years.  The fighters also underwent cognitive testing.

The data revealed decreased brain volume coupled with cognitive dysfunction related to these findings.  The full abstract reads as follows:

Objective: To assess the relationship between change in MRI measured regional brain volumes and cognitive performance in professional fighters.

Background: Previous cross sectional research has demonstrated a relationship between lower brain volumes in specific regions and poorer performance on certain tests of cognitive function in a cohort of professional fighters. Little is known as to whether longitudinal decline in brain volumes are associated with cognitive performance.

Design/Methods: 76 subjects participating in the Professional Fighters Brain Health Study and who have been followed over at least 2 years were included in this study. Subjects underwent MRI brain imaging, along with computerized cognitive testing (CNS Vital Signs), at baseline and on an annual basis for a minimum of 2 subsequent visits.

Rate of decline in volumes was assessed both as a continuous and categorical variable. Analyses were performed to assess the relationship between decline in regional volume and decline in each of the cognitive spheres tested (processing speed, reaction time, psychomotor speed and memory), adjusting for age, race and years of education.

Results: The mean age of the cohort was 29.54 years, with mean number of professional fights 14.46, and years of education 13.06. Duration of follow up ranged from 2–5 years. Decline in the anterior corpus collusum, left cerebellum, left hippocampus, and right thalamus were significantly associated with decline in processing speed; whereas decline in right and left thalamus and left and right cerebellum was associated with decline in memory. Comparing the decliner v. non-decliner groups, subjects in the decliner group for left hippocampus and posterior corpus collusum showed a significant association with decline in performance in processing speed.

Conclusions: MRI brain volumetric measures may warrant further study as a tool to follow accumulating brain injury over time.


Although not combat sports related, an important study was published last month in journal Neuroimage: Clinical revealing the rapid toll on brain structure that a short span of repeated subconcussive hits can bring.

In the recent study titled “The Effect of Repetitive Subconcussive Collisions on Brain Integrity in Collegiate Football Players over a Single Football Season” the 20 NCAA football players had their brains imaged via multiple MRI sequences both before and after a single college football season.  All of the participants were asymptomatic for signs of concussion at the start of the season with the authors noting “none of the athletes were recovering from, or were diagnosed with, a concussion during the period of study, or in the nine months prior to the pre-season evaluation.

The study revealed statistically “significant” changes on imaging at the conclusion of the season.  Of note, none of the players were diagnosed with a concussion during the season making the volume of subconcussive hits the most likely cause for the noted changes.

The authors concluded as follows:

In a study of clinically asymptomatic collegiate football athletes, statistically-significant MRI changes were observed that are likely a consequence of participation for one season at the NCAA Football Bowl Subdivision level. Specifically, these changes (at Post, relative to Pre) were found in measures derived from multiple MRI modalities: CBF, rs-fMRI, and SWI. Critically, these changes were greater in athletes who were more likely to have an impact history including larger average numbers of high-G impacts (≥ 80G). A linkage between high intensity impacts and neuroimaging-observed changes adds to the growing literature in support of the hypothesis that collision-sport athletes may be at increased risk of long-lasting changes to brain functional and structural integrity. Future work in larger cohorts and involving a broader array of integrated biomarkers will enable more precise identification of athletes who are at risk, and will facilitate development of intervention strategies to permit collision-sport participation with reduced risk.

While it goes without saying that combative sports have inherent dangers, this is yet another study stressing the need for combat sports participants to take measures to reduce exposure to sub concussive blows in training.

New York State Athletic Commission chief medical officer and practicing neurologist Dr. Sethi published an article in the latest edition of the South African Journal of Sports Medicine addressing best practices for medical stoppages of boxing bouts with the sensible conclusion that it is better to err on the side of safety.

In the article, titled “Good versus bad medical stoppages in boxing: Stopping a fight in time” Dr. Sethi reaches the following conclusion after addressing what he believes to be considerations ringside physicians should keep in mind when stopping a bout –

It is recommended that the above proposed best practice guidelines be debated vigorously by ringside physicians and the wider scientific community and that evidence-based guidelines on medical stoppages be developed by the medical community in conjunction with the professional boxing governing bodies. Boxing can be made safer but it shall be foolhardy to forget that frequently there is a very fine line between a good medical stoppage (i.e. medical stoppage done at the right time during the bout and for the right indication) versus a bad medical stoppage (i.e. medical stoppage done either too late, too prematurely, or for the wrong indication). It is far better to stop a fight early rather than too late. A ringside physician should never forget that in boxing one punch can change everything.

The full article can be found here – Dr. Sethi Artilce re Medical Stoppages of Boxing Bouts

An interesting article was published in the latest edition of the International Journal of Pathology and Clinical Research diagnosing what is believed to be the first known case of an individual having Chronic Traumatic Encephalopathy who did not have a history of concussions.

In the article, titled “Chronic Traumatic Encephalopathy-like Neuropathological Findings Without a History of Trauma” a 45 year old man who was found dead in his sleep had his brain examined post mortem and CTE like changes were revealed.  This was noteworthy to researchers as the patient had no known history of head trauma.  The authors note as follows

To our knowledge, this is the first description of a patient with neuropathological features of CTE-MND in the absence of a history traumatic brain injury. Interestingly, despite cortical tau pathology, our patient never exhibited cognitive impairment, which speculatively could be explained by the relative sparing of the nucleus basalis of Meynert. This highlights the uncertainty surrounding the pathogenesis and pathophysiology of CTE and underscores the need for further detailed studies to elucidate the causative role of trauma. Nevertheless, our case report has several important limitations. For example, the lack of a trauma history comes only from the recollection of the patient’s wife and early life subconcussive blows cannot be entirely excluded. There are also inherent limitations to drawing conclusions from the results of a single patient.

To date, repetitive traumatic brain injury has been shown to be associated with no neuropathological changes, with CTE alone, with -CTE and another neurodegenerative disease, or with non-CTE neurodegeneration. Since CTE is a postmortem diagnosis, the majority of samples have come from brains of symptomatic individuals referred by family; these individuals are more likely to demonstrate some type of neuropathology thus introducing a selection bias. Our case adds to this complexity given the observation that CTE-like changes can occur in the absence of any known head injury; casting doubt that trauma is always the inciting etiological factor. Future studies should assess whether CTE-like pathology is prevalent in non-concussed patient populations.

The full article can be found here.


Adding to this site’s archived combat sports safety studies a recent study was published at the University of Cambridge discussing the efficacy of MRI and Neuropsychological testing to detect early signs of brain damage in amateur boxers.

In the study, titled “Advanced magnetic resonance imaging and neuropsychological assessment for detecting brain injury in a prospective cohort of university amateur boxers” the authors queried whether early brain injury could be detected using this combination of diagnostic tools.

40 amateur boxers were recruited although only 10 stayed in the study to its conclusion contributing the needed longitudinal assessment protocol.

The authors concluded that this combination of testing “could not detect any evidence of brain injury” in the participants.

Below is the study’s full abstract –

Background/aim:Background/aim: The safety of amateur and professional boxing is a contentious issue. We hypothesised that advanced magnetic resonance imaging and neuropsychological testing could provide evidence of acute and early brain injury in amateur boxers. Methods:Methods: We recruited 30 participants from a university amateur boxing club in a prospective cohort study. Magnetic resonance imaging (MRI) and neuropsychological testing was performed at three time points: prior to starting training; within 48 hours following a first major competition to detect acute brain injury; and one year follow-up. A single MRI acquisition was made from control participants. Imaging analysis included cortical thickness measurements with Advanced Normalization Tools (ANTS) and FreeSurfer, voxel based morphometry (VBM), and Tract Based Spatial Statistics (TBSS). A computerized battery of neuropsychological tests was performed assessing attention, learning, memory and impulsivity. Results:Results: During the study period, one boxer developed seizures controlled with medication while another developed a chronic subdural hematoma requiring neurosurgical drainage. A total of 10 boxers contributed data at to the longitudinal assessment protocol. Reasons for withdrawal were: logistics (10), stopping boxing (7), withdrawal of consent (2), and development of a chronic subdural hematoma (1). No significant changes were detected using VBM, TBSS, cortical thickness measured with FreeSurfer or ANTS, either cross-sectionally at baseline, or longitudinally. Neuropsychological assessment of boxers found attention/concentration improved over time while planning and problem solving ability latency decreased after a bout but recovered after one year. Conclusion:Conclusion: While this neuroimaging and neuropsychological assessment protocol could not detect any evidence of brain injury, one boxer developed seizures and another developed a chronic sub-dural haematoma.

The California State Athletic Commission has taken a step which has received little publicity but is deserving of attention by the combative sports community.  They have produced a series of videos focusing on fighter health and safety issues, namely acute traumatic brain injury, cumulative concussions and dangers of dehydration.  With CTE being a potential reality in any contact sport these are important topics to understand.

If you are a combat sports fighter, trainer, manager or other stakeholder these videos are well worth your time to get up to speed on these important topics.  With fighter safety being the primary reason for an Athletic Commission’s existence  Andy Foster and the CSAC deserve a public thank you for a job well done in producing these insightful videos.

Adding to this site’s archived combat sports safety studies a recent study was published in the British Journal of Sports Medicine addressing head injury rates in high level karate competitions.

In the study, titled “Low Risk of Concussions in Top Level Karate Competitions” the authors reviewed injuries that took place in 4 consecutive karate world championships.  They found there was only “1 concussion in every 1156 fights, or 0.43/1000 athlete-exposures“.

The full article can be purchased here.  The abstract reads as follows:

Background Although it is well known that injuries occur in combat sports, the true incidence of concussions is not clearly defined in the literature for karate competition

Aim To determine the incidence of concussions in top-level (World Karate Federation World Championships) karate competition.

Methods Injuries that took place in 4 consecutive World Karate Championships (from 2008 to 2014) were prospectively registered. A total of 4625 fights (2916 in the male category and 1709 in the female category) were scrutinised, and concussions were identified and analysed separately for frequency (rate per fight) and injury risk.

Results A total of 4 concussions were diagnosed by the attending physicians after carrying out athlete examinations. Globally, there was 1 concussion in every 1156 fights, or 0.43/1000 athlete-exposures (AE). In male athletes, the rate of concussion was 1/5832 min of fighting, and in female athletes, it was 1/6836 min. OR for concussion in women is 0.57 (95% CI 0.06 to 5.47; z=0.489; p=0.6249) and risk ratio for concussions in men is RR 1.478 (95% CI 0.271 to 8.072), p=0.528, representing a higher risk of definite concussions in men than in women, but not statistically significant. There is not a significantly higher risk of concussions in team competition (no weight limit) when compared with individual competition (held with strict weight limits for each category).

Conclusion The risk of concussions in top-level karate competition is low, with a tendency for an increased risk for men and for competition without weight limits, but not statistically significant with respect to women or individual competition.

An article was published in the latest edition of the South African Journal of Sports Medicine levying criticism at professional boxing’s lack of standardized protocols for athletes to return to training/competition after suffering concussive injury.

The article, authored by Dr. Sethi from the Department of Neurology, New York Presbyterian Hospital is titled “Post-concussion return to boxing protocol” and can be found here.

Dr. Sethi fairly points out that

Immediately following a concussion, an athlete is usually advised physical and cognitive rest until post-concussion symptoms abate. The athlete then enters a stepwise return-to-play protocol. Premature return to play risks a second concussion, second impact syndrome, exacerbation and persistence of post-concussive symptoms. Various sports governing organisations such as the National Football League have developed postconcussion return to play protocols”

After noting professional boxing lacks a standardized protocol for return to sport following concussion Dr. Sethi proposes the following criteria to be adopted:

The following post-concussion return to boxing protocol is proposed based on evidence from other sports and clinical acumen:

Once the boxer is symptom free for at least 24 hours and a release has been signed by the treating physician, he/she can begin a graded return to boxing as detailed below.

Day 1: Light aerobic activity (walking or stationary bike for 10 minutes, no resistance training)

Day 2: Sport-specific activity (jumping rope, shadow boxing)

Day 3: Non-contact training drills (Skill drills-pad work, speed bag, heavy bag)

Day 4: Full-contact practice (sparring with head gear)

Day 5: Return to boxing (return to competitive boxing occurs when the period of mandatory medical suspension has expired)

Each of the above steps should take 24 hours so that a boxer would take approximately one week to progress through the full post-concussion protocol once they are asymptomatic at rest. If any post- concussion symptoms occur while in the stepwise return to boxing programme, then the boxer should be instructed to return to the previous asymptomatic level and try to progress again after a further 24-hour period of rest has passed.

CTE Brain Image.PNG(Image via this PBS article)

A worthwhile study was recently published in the Journal of Vascular and Interventional Neurology discussing what is known and not known about CTE in athletes competing in contact sports.

In the study, titled “Chronic Traumatic Encephalopathy in Athletes Involved with High-Impact Sports” the authors reviewed major clinical studies identifying CTE cases in athletes looking for conclusions and shortcomings in the data.

Among the conclusions drawn are that, of known athletes with CTE, professional boxers demonstrated the most debilitating symptoms.  Also of note the authors suggest that strengthening neck muscles (a topic previously canvassed here) can help minimize the risks of CTE for contact sports athletes.

The study is worth reading in full and can be accessed here.

In addressing the increased symptoms in boxers vs football players and discussing possible strategies to reduce risk the authors note as follows:

Clinical and pathological features of CTE can manifest differently between sports, as rTBI exposure and mechanisms of impact can vary considerably. In fact, an analysis of previously reported CTE cases by Montenigro et al. [29] showed a vast difference in clinical presentation. 83% (5/6) of professional boxers, who had more debilitating motor impairments, compared to 18.8% (3/16) of professional football players. In addition, severe dentate neurofibrillary tangles were present in 17% (2/12) and 80% (4/5) of professional football players and boxers, respectively, indicating a more pernicious progression in boxers [29]. The difference in symptoms and neuropathology may be explained through the frequency of linear and rotational impact forces that occur in both sports.

Rotational forces causing angular accelerations are frequent in boxing. Boxers face their greatest danger when their opponent lands a hook punch, where impact near the lateral side of the head cause rapid outward rotation of the skull and twisting forces the brain [29]. Lateral bending of the neck can also occur, but linear forces from a punch are often below the mTBI threshold [58]. The rotational movement of the brain causes shearing forces that can lead to axonal damage [59]. Shearing forces are most prominent near areas such as the midbrain section, where glial and axonal injury could result in severely debilitating consequences [29,58].

As opposed to punches, helmet-to-helmet or helmet-to-ground contact forces cause the majority of mTBI injuries in professional football players. Viano et al. [58] have shown that in professional football concussions, inertial forces can be up to 30% greater than inertial forces in professional boxers who endure a hook punch. The greater inertial forces correlate with a higher linear acceleration endured by football players, suggesting that linear forces are prominent in causing concussive and subconcussive impacts in professional football players. In support of this mechanism, brain modeling shows that rotational accelerations from uppercuts or hook punches are much greater than rotational accelerations in professional football helmet-to-helmet impacts [58]. The linear to rotational force ratio difference between boxers and football players could explain the differences in clinical presentation between the two sports.

In professional football, helmet-to-helmet collisions can cause the head to move in the anterior or posterior direction. The incidence rates of mTBI have been shown to vary depending on position, with running backs and wide receivers suffering from mTBI more than linemen [60]. Neck musculature acts to stabilize the position of the head, and a more developed musculature is directly correlated to lowered mTBI risk [61]. Linemen have been found to have stronger necks and larger girth compared to running backs, which could act to slow linear accelerations of the head and reduce risk of mTBI [62]. The differences in neck strength between positions may explain the varying incidence rates of mTBI. Additionally, it should be noted that different player positions may be more prone to certain types of impacts—linemen may experience more frequent subconcussive helmet-to-helmet impact, while wide receivers could endure more threatening forces while being tackled. The pathological repercussions of variations in impact type and frequency between boxing and football have yet to be elucidated in full detail, but they may partially explain the difference in clinical presentation between different types of athletes.


Adding to this site’s archived combat sports safety studies and weight cut reform articles, a study was recently published in the International Journal of Sports Physiology and Performance addressing the impact of rapid weight loss / gain and the outcome of boxing bouts.

In the study, titled “Weight Re-Gain is Not Linked to Success in a Real Life Multi-Day Boxing Tournament” the authors compared the weigh-in weight of 100 boxers competing in the Australian National Championships and then re-checked their weight one hour prior to competition.  The amount of body mass increase was then contrasted with performance and the results showed that athletes who gained size over their opponents through rapid weight cut / rehydration practices did not enjoy competitive advantage.

The full abstract reads as follows:

Combat sport athletes acutely reduce body mass (BM) prior to weigh-in in an attempt to gain a size/strength advantage over smaller opponents. Few studies have investigated these practices among boxers and none have explored the impact of this practice on competitive success.

One hundred (30♀/70♂) elite boxers participating in the Australian National Championships were weighed at the official weigh-in and an hour before each competition bout. Re-gain in BM after weigh-in was compared between finalists and non-finalists, winners and losers of each fight, males and females and weight divisions. Boxers were surveyed on their pre and post weigh-in nutrition practices.

The lightest male weight category displayed significantly greater relative BM re-gain than all other divisions, with no difference between other divisions. BM pre-bout was higher than official weigh-in for males (2.12±1.62% (p < 0.001; ES=0.13)) and females (1.49±1.65% (p < 0.001; ES=0.11)). No differences in BM re-gain were found between finalists and non-finalists, winners and losers of individual bouts, or between preliminary or final bouts. BM re-gain was significantly greater (0.37% BM, p < 0.001; ES=0.25) prior to an afternoon bout compared to a morning bout.

Boxers engage in acute BM loss practices before the official competition weigh-in but this does not appear to affect competition outcomes, at least when weight re-gain between weigh-in and fighting is used as a proxy for the magnitude of acute loss. While boxers recognise the importance of recovering after weigh-in, current practice is not aligned with best practice guidance.