Archive for the ‘Safety Studies’ Category

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.

For those who study safety issues in combative and contact sports a useful article was published in the latest edition of Neurotrauma and Critical Care News discussing the state of science connecting CTE and other brain injury to contact sports.

The article, titled “Head Impacts in Contact Sports and Long-Term Brain Degeneration” offers an easy to read, plain English summary of what’s known and what still needs to be explored in the world of repetitive head trauma from sports and CTE.

In addressing CTE specifically the authors note as follows:

A 2016 National Institutes of Health (NIH) expert neuropathological panel established that the pattern of CTE is unlike any other form of brain degenerative disease with the collections of NFT or NT occurring in a unique and distinguishing pattern (3). It is believed that the more superficial and frontal areas of the brain are involved due to the direct contact with sports-related head impacts.

These pathophysiological features are associated with a characteristic behavioral syndrome for CTE, with symptoms in four categories: cognition, behavior, mood and occasionally motor. Behavioral changes include amplified aggression, increased impulsiveness, impaired judgment, and risk taking acts. Most often, a 6- to 12-year latency period following retirement from contact sports is then associated with failure in business, financial and marital relationships, homelessness, drug and/or alcohol abuse, depression, mild cognitive impairment and dementia, and many CTE sufferers commit suicide. Researchers have reported that CTE can be considered in two major clinical categories, with one group whose initial features develop at a younger age involving behavioral and/or mood disturbance and another group whose initial symptoms develop later in life and involve cognitive impairment. The language function is usually normal, but intelligence is often ultimately affected by the numerous effects described above (4).

While the risk of developing CTE has historically been discussed in the context of concussive injury and extensive neurotrauma exposure, emerging evidence indicates that a history of diagnosed or major concussions is not a requirement, but instead, repetitive subconcussive injury may play a prominent role in CTE development (5). This finding is based upon lack of documented concussive injury in numerous individuals diagnosed with CTE, although lack of self-reporting by athletes was common, and concussion without loss of consciousness was not recognized and treated as seriously as it is today. Evidence related to subconcussive injury and possible predilection to neurodegenerative disease includes the documented rates and severity of impacts in football linemen, a position in which retired athletes have been diagnosed with CTE (5). Additional evidence is the demonstration of neuroimaging and cognitive changes in those without a history of documented concussions as well as laboratory evidence indicating cellular and ultrastructural alterations without changes in levels of alertness or behavior. Despite the large number of people exposed to concussive and subconcussive injury through various sports and military service, CTE appears problematic for only a small subset of the population exposed to neurotrauma. Nonetheless, we currently do not know the incidence and prevalence of CTE since there has been no longitudinal study conducted to substantiate estimates of several prominent CTE research groups. The largest review to date, Maroon et. al., surveyed the clinical findings in all 153 CTE cases reported in the literature and found that 63 had a history of participation in football with majority of these having played at the professional level (6). The most common age at death of individuals with CTE was the range of 60 to 69, with 72.7 percent dying before the age of 70 (6).

Identification of other variables involved as risk factors for CTE remains in its early stage with speculation that genetics and lifestyle may be implicated. Just as in other forms of neurodegeneration such as Alzheimer’s disease, it has been postulated that the role of the ApoE ε4 (ApoE4) allele may be a susceptibility factor for the development of CTE; however, this has yet to be borne out.

Research continues to try to identify who is at greatest risk for getting concussions and ultimately, CTE. More studies are needed to follow former athletes over many years in order to know the true prevalence of CTE. A major focus of CTE research is investigating confirmation of the diagnosis of CTE in living individuals with several promising imaging technologies being evaluated, with F18DDNP PET imaging for tau and amyloid protein labeling being the most advanced (7).

Currently, there are no established treatments for CTE; therefore, reducing the risk for CTE development becomes the primary goal by limiting the exposure to concussive and subconcussive head impacts. There have been numerous positive changes in recent years involving contact sports, particularly football, resulting in greater safety for all participants. These include limiting contact in practice, eliminating head-to-head hits in practice drills, rule changes to penalize and prohibit egregious cranial hits, improvements in helmet design, new technology, such as helmet sensors and efforts to mitigate brain slosh, among others. It is hoped that in the near future CTE will be eliminated in contact sport athletes, but in the meantime, the possibility and implications of repetitive head trauma causing long-term effects, including brain degeneration, should be understood.

CTE is a part of combat sports.  In fact the disease, which used to be called dementia pugilistica (ie “punch drunk”) has its origins traced back to boxing.

MMA is not immune from CTE.  It is a real risk. Several athletes likely have the disease with fighters such as Gary Goodridge being diagnosed with CTE and being vocal about its realities.  Despite the high likelihood that many MMA athletes have CTE it is a diagnosis that cannot be made definitively until death as study of brain tissue is required.

Now, the Boston Globe Reports, MMA has its first proven case of CTE.

Former Bellator fighter, Jordan Parsons, who was recently killed in a pedestrian/vehicle collision, has been diagnosed with CTE post-mortem.

The Globe reports as follows:

Now, six months after he was struck and killed as a pedestrian by an alleged drunken driver, Parsons is the first fighter in the multibillion-dollar MMA industry to be publicly identified as having been diagnosed with the degenerative brain disease known as chronic traumatic encephalopathy (CTE)

The diagnosis was disclosed to the Globe by Dr. Bennet Omalu, a forensic pathologist who first discovered CTE in a professional football player (in 2003) and a professional wrestler (2007).

Omalu provides the following grounded and sober comments “As a scientist, a physician, and a person of faith, I beg everybody involved with these sports to come together and identify the problems and find solutions’’

Combat Sports athletes should participate only with informed consent of the sport’s real dangers.  Comments calling MMA “the safest sport in the world” do no favors.  Informed consent only comes from an acknowledgement and understanding of the science of CTE and its links to acute and repetitive head trauma.

Regulators also must grapple with this reality both in making informed choices as to when an athlete has been exposed to too much mileage and when considering safety issues such as the fact that gloves, while making for more exciting fights, do much to increase the likelihood of brain trauma.

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 Sport Nutrition and Exercise Metabolism  finding all MMA athlete participants being dehydrated when weighing in for competition with the magnitude of rapid weight loss and strategies being “comparable to those which have previously resulted in fatalities“.

In the study, titled Extreme Rapid Weight Loss and Rapid Weight Gain Observed in UK Mixed Martial Arts Athletes Preparing for Competition, the authors measured dietary intake, urinary hydration status, and body mass of several MMA athletes in the week prior to competition.  Despite the small sample size the authors observed troubling findings that “”At the official weigh-in 57% of athletes were dehydrated… and the remaining 43% were severely dehydrated

The authors call for “Rule changes which make RWL impractical should be implemented with immediate effect to ensure the health, safety and wellbeing of competitors.”  Given the ever growing Rapid Weight Loss Injury/Fatality List in MMA this is a sensible call to action.

Below is the study’s full abstract:

There is a lack of research documenting the weight-making practices of mixed-martial-arts (MMA) competitors. The purpose of the investigation was to quantify the magnitude and identify the methods of rapid weight loss (RWL) and rapid weight gain (RWG) in MMA athletes preparing for competition. Seven athletes (mean ± SD, age 24.6 ± 3.5 yrs, body mass 69.9 ± 5.7 kg, competitive experience 3.1 ± 2.2 yrs) participated in a repeated-measures design. Measures of dietary intake, urinary hydration status, and body mass were recorded in the week preceding competition. Body mass decreased significantly (p<0.0005) from baseline by 5.6 ± 1.4 kg (8 ± 1.8%). During the RWG period (32 ± 1 hours) body mass increased significantly (p<0.001) by 7.4 ± 2.8 kg (11.7 ± 4.7%), exceeding RWL. Mean energy and carbohydrate intake were 3176 ± 482 kcal·day−1and 471 ± 124 g·day−1, respectively. At the official weigh-in 57% of athletes were dehydrated (1033 ± 19 mOsmol·kg−1) and the remaining 43% were severely dehydrated (1267 ± 47 mOsmol·kg−1). Athletes reported using harmful dehydration-based RWL strategies, including sauna (43%) and training in plastic suits (43%). Results demonstrated RWG greater than RWL, this is a novel finding and may be attributable to the 32 hour duration from weigh-in till competition. The observed magnitude of RWL and strategies used are comparable to those which have previously resulted in fatalities. Rule changes which make RWL impractical should be implemented with immediate effect to ensure the health, safety and wellbeing of competitors.

Adding to this site’s archives of safety studies in combat sports, a recent article was published in the Journal of Neurology and Neurorehabilitation Research further noting the connection between neurological system impairment and the frequency and severity of subconcussive head impacts.

In the article, titled “PROTECT THE PLAYER, PROTECT THE GAME: SUBCONCUSSION AND CHRONIC TRAUMATIC ENCEPHALOPATHY”  the authors note the following findings consistent with other research indicating that mileage matters when it comes to sports related brain trauma:

Our recent clinical studies suggest that some of neurological system may be impaired and reflective of frequency and magnitude of subconcussive head impact sustained. For example, 10 bouts of soccer headers with an average magnitude of 14.5 g led to a transient dysfunction in vestibular processing, causing significantly larger postural sway while static and walking (Hwang, 2016). Similarly, soccer headings acutely blunted the ocular-motor system, particularly near point of convergence, and the impairment persisted even after 24 hours of resting (Kawata, 2016), pointing to the possibility that vulnerability and slow recovery nature of the ocularmotor system. A follow-up prospective longitudinal study in collegiate football players confirmed our finding that the degree of impairment in the ocular-motor function was dependent on the frequency and magnitude of subconcussive head impact sustained (Kawata, 2016). Taken together, although a direct causality between subconcussive head impact exposure and development of CTE remains elusive, it is imperative to employ prospective cohort approaches, rather than case-reports, as to delineate chronic effects of head impact and different factors (e.g. age, gender, genetics) contributing to the disease.

Mild traumatic brain injury is sometimes referred to as an ‘invisible injury’ as there is often no objective evidence to help diagnose the damage done. Instead a diagnosis is made based on a host of subjective complaints.  Repetitive concussive and sub-concussive blows are linked to CTE.  This disease also cannot be diagnosed with certainty in living individuals and objective criteria demonstrating risk of this disease are lacking.

An interesting study was published in JAMA Neurology this month, however, showing promise that certain biomarkers may be “an objective tool to assess the degree of central nervous system injury in individuals with PCS (post concussion syndrome)” and further that this tool may even be used to screen athletes that are at high risk of developing CTE.

In the study, titled “Neurochemical Aftermath of Repetitive Mild Traumatic Brain Injury” the authors reviewed 16 athletes with a history of Post Concussion Syndrome (approximately half of which recovered within a year and the others having persistent symptoms beyond a year) along with a control group.  Neurofilament light proteins were significantly increased in players with PCS for more than 1 year and players with PCS had significantly lower cerebrospinal fluid amyloid-β levels compared with control individuals.

The authors concluded that these biomarkers could potentially be used to help screen athletes showing signs of too much damage which could, in turn, help athletes make a more informed retirement decision from combative and other contact sports.

Here is the study’s full abstract:

Importance  Evidence is accumulating that repeated mild traumatic brain injury (mTBI) incidents can lead to persistent, long-term debilitating symptoms and in some cases a progressive neurodegenerative condition referred to as chronic traumatic encephalopathy. However, to our knowledge, there are no objective tools to examine to which degree persistent symptoms after mTBI are caused by neuronal injury.

Objective  To determine whether persistent symptoms after mTBI are associated with brain injury as evaluated by cerebrospinal fluid biochemical markers for axonal damage and other aspects of central nervous system injury.

Design, Settings, and Participants  A multicenter cross-sectional study involving professional Swedish ice hockey players who have had repeated mTBI, had postconcussion symptoms for more than 3 months, and fulfilled the criteria for postconcussion syndrome (PCS) according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) matched with neurologically healthy control individuals. The participants were enrolled between January 2014 and February 2016. The players were also assessed with Rivermead Post Concussion Symptoms Questionnaire and magnetic resonance imaging.

Main Outcomes and Measures  Neurofilament light protein, total tau, glial fibrillary acidic protein, amyloid β, phosphorylated tau, and neurogranin concentrations in cerebrospinal fluid.

Results  A total of 31 participants (16 men with PCS; median age, 31 years; range, 22-53 years; and 15 control individuals [11 men and 4 women]; median age, 25 years; range, 21-35 years) were assessed. Of 16 players with PCS, 9 had PCS symptoms for more than 1 year, while the remaining 7 returned to play within a year. Neurofilament light proteins were significantly increased in players with PCS for more than 1 year (median, 410 pg/mL; range, 230-1440 pg/mL) compared with players whose PCS resolved within 1 year (median, 210 pg/mL; range, 140-460 pg/mL) as well as control individuals (median 238 pg/mL, range 128-526 pg/mL; P = .04 and P = .02, respectively). Furthermore, neurofilament light protein concentrations correlated with Rivermead Post Concussion Symptoms Questionnaire scores and lifetime concussion events (ρ = 0.58, P = .02 and ρ = 0.52, P = .04, respectively). Overall, players with PCS had significantly lower cerebrospinal fluid amyloid-β levels compared with control individuals (median, 1094 pg/mL; range, 845-1305 pg/mL; P = .05).

Conclusions and Relevance  Increased cerebrospinal fluid neurofilament light proteins and reduced amyloid β were observed in patients with PCS, suggestive of axonal white matter injury and amyloid deposition. Measurement of these biomarkers may be an objective tool to assess the degree of central nervous system injury in individuals with PCS and to distinguish individuals who are at risk of developing chronic traumatic encephalopathy.