Safety in Mixed Martial Arts: a 7-Year Review of Cancelled MMA Bouts in Calgary, Alberta, During the Pre-bout Medical Examination Period
Curran-Sills Sports Medicine - Open
Safety in Mixed Martial Arts: a 7-Year Review of Cancelled MMA Bouts in Calgary, Alberta, During the Pre-bout Medical Examination Period
Gwynn Curran-Sills 0
0 Family Medicine and Primary Care Research Office, University of Calgary , G012 , Health Sciences Centre 3330 Hospital Drive NW , Calgary, Alberta T2N 4N1 , Canada
Background: Presently, there is no literature that examines the reasons for the cancellation of amateur or professional mixed martial arts (MMA) bouts. The purpose of this study was to review the circumstances that lead to the cancellation of MMA bouts by Calgary ringside physicians during the pre-bout examination period and to identify any emerging patterns that may guide the regulatoin of this sport. Methods: The case-series was constructed from the Calgary Combative Sports Commission pre-bout examination records and the medical records submitted by each athlete from January 2010 to December 2016. Results: Cancelled bouts in the pre-bout examination periods represented 5.4% of all MMA bouts in Calgary. A total of 25 reasons lead to bout cancellation and included the following: failure to obtain required neuroimaging (28.0%), neuroimaging abnormalities (24.0%), incomplete routine screening investigations (16.0%), exceeding maximum weight differential between the two athletes (16.0%), injury in the pre-competition period (8.0%), dehydration (4.0%), and ECG abnormalities (4.0%). The abnormalities on neuroimaging (n of 6) included the following: post traumatic gliosis on MRI (n = 1, 16.7%), flares diffusely and findings consistent with microhemorrhage on MRI (n = 1, 16.7%), chronic orbital fracture with fat pad extrusion on CT (n = 2, 33.3%), lacunar infarct on MRI (1), and unspecified MRI abnormality (n = 1, 16.7%). Twenty-two athletes had bouts cancelled and of these three athletes had their bouts stopped for two reasons. Conclusions: The following recommendations are presented and include: the creation of guidelines regarding pre- and post-bout neuroimaging, the implementation of industry-wide minimum medical screening standards, the adoption of a longitudinal approach to weight monitoring, the development of competent ringside physician groups, and active oversight by the Combative Sports Commission during the matchmaking process.
Mixed martial arts; Epidemiology; Injury; Head trauma
Cancelled bouts in the pre-bout examination periods
represented a small proportion (5.4%) of all MMA
bouts in Calgary.
Microstructural changes and bony abnormalities
accounted for the majority of neuroimaging findings
that lead to cancelled bouts.
The creation of industry-wide minimum medical
screening standards and the adoption of a longitudinal
approach to weight monitoring should be considered
by MMA regulatory bodies.
Mixed martial arts (MMA) is a relatively young sport for
which there is a limited but growing body of literature
that has focused on descriptive epidemiology of injuries
obtained in training [
], descriptive epidemiology and
risk factors associated with injuries sustained during
], risk factors associated with head
trauma during competition , the physiological and
performance characteristics of successful athletes [
and weight cutting practises employed by MMA athletes
]. Working within this framework of knowledge,
the American , Australian [
], British [
Canadian Medical Associations [
] have called for a
ban of the sport based upon assumptions that it is
unregulated, with minimal rules, and more violent and
injury prone than other sports. Despite the reservations of
these medical bodies, MMA continues to grow in
]. The call for a ban on the sport has
not deterred the burgeoning interest and increasing
athletic pursuit in the sport both on an amateur and
professional level [
]. Given this escalation in the popularity
of MMA, it is prudent for the medical community to
use an evidence-based approach to identify areas of risk
for MMA athletes. Once identified, the creation of
interventions to reduce these risks can be adopted by
sanctioning bodies to better protect these athletes.
For MMA in Canada, the regulatory body oversees
athlete health considerations in the peri-competition
period and regulation of professional and amateur
MMA bouts falls under the authority of combat sport
commissions across the country. Depending on the
jurisdiction, a commission’s authority will either be
associated with a municipality or a provincial government.
Regulation in the USA [
] and Australia [
] is similar;
however, for the UK, there is no formal regulatory body
]. Similar governmental regulation exists for
professional boxing and Muay Thai. However, amateur boxing
and Muay Thai are generally not regulated by
governmental bodies and instead are overseen by the associated
Boxing and Muay Thai Amateur Associations.
An athlete can participate in a MMA bout when he/
she obtains a licence from the appropriate commission.
This process involves specific bureaucratic and medical
requirements that vary between jurisdictions. At present,
there is no literature that examines the rationale for why
MMA bouts are cancelled during the pre-bout medical
examination period. The focus for this study is to review
the circumstances that lead to the cancellation of MMA
bouts by Calgary ringside physicians during the pre-bout
examination period and to identify any emerging
patterns that may guide the regulation of this sport.
This project was a secondary analysis of data collected
for a retrospective cross-sectional study of Calgary
Combative Sports Commission (CCSC) records from
January 1, 2010 to December 31, 2016 in Calgary, Alberta,
Canada. The records included both professional and
amateur level athletes. Please see reference [
] for a
detailed description of the primary study and dataset. In
addition to the licencing requirements, the CCSC
conducted pre- and post-bout medicals for each athlete that
competed in the city of Calgary. Within Alberta, Canada,
combative sports are not regulated at a provincial level,
but instead at the municipal level. The pre- and
postbout medicals were performed by physicians with
nursing support. The cohort of athletes who had their
contests cancelled was constructed from the CCSC pre-bout
examination records and the medical records submitted
by each athlete. The pre-bout medical examination
occurred the day before the event in conjunction with the
CCSC weigh-in process. As part of the pre-bout medical
examination, athletes submitted and partook in the
following: clearance from their family physician to
compete; a review of their past medical and surgical history,
medications, and allergies; a complete physical
examination with system-focused review as necessary; screening
for infectious disease (Human Immunodeficiency Virus,
Hepatitis B and C within the last 6 months); screening
for pregnancy (less than 7 days prior the bout);
screening ECG within the last year; a fully dilated funduscopic
examination within the last year; and a screening
magnetic resonance imaging (MRI) of the head for any
athlete that previously competed in an unsanctioned bout.
Athletes who did not fulfil the pre-bout medical
requirements had their bouts cancelled and received a suspension
as determined by the examining physician. This
suspension information was recorded by the CCSC and
forwarded to the Association of Boxing Commissions (ABC)
to be disseminated to all the commissions that are part of
the ABC. This step is taken to prevent the athlete from
being able to compete in another sanctioned amateur or
professional bout in a different jurisdiction.
Descriptive statistics were generated and where
possible averages and standard deviations were calculated,
along with the range. These calculations and tables were
constructed using Microsoft Office Excel™ (Redmond,
Washington, USA). Regular ringside physician coverage
was defined as greater than 3 years of working with the
CCSC or a minimum of 12 events worth of experience.
An athlete’s bout experience was defined as the sum of
all previous sanctioned contests. The CCSC defined a
maximum weight differential between two athletes’ as
3.2 kg for Atomweight; 5.4 kg for Straw-, Fly-, Bantam-,
Feather-, and Lightweight; 6.8 kg for Welter- and
Middleweight; 9.1 kg for Light heavyweight; 13.6 kg for
Heavyweight; and 18.1 kg for Super Heavyweight [
this criterion was met, the bout was automatically
cancelled. A physician clinically determined if an athlete
was dehydrated (i.e., through mental status examination,
vital signs, and clinical gestalt); however, there was no
formal definition that was used by the ringside physicians
who covered these events and this determination was
subjective. There was no definition for an injury that resulted
in cancellation of a bout; this was at the discretion of the
ringside physician. The MMA promotional organization
bout cancellation percentage was defined as the (number
of cancelled bouts/number of hosted bouts) × 100.
From January 2010 to December 2016, 46 MMA events
were held in Calgary and this generated 390 bouts (see
] for a detailed description of that dataset).
Over this time frame, 21 bouts (5.4%) were cancelled
during the pre-bout examination period with 22 athletes
having reasons that contributed to the bout cancellation.
Table 1 outlines the event and athlete characteristics,
along with the reason for why each athlete was not
allowed to compete. Athletes involved in cancelled bouts
had an average age of 29.7 (± 5.9, 21–39) and 86.4% were
male. The average body mass was 81.3 kg (± 23.4, 52.1–
120.2) (contracted weights were used for three athletes),
with the average mass (where possible to calculate) as a
function of weight class being 59.4 kg (± 2.6, 57.6–61.2)
for bantamweight, 80.6 kg (± 6.2, 77.1–87.8) for
welterweight, 85.0 kg (± 1.4, 83.9–85.7) for middleweight,
92.5 kg (± 0.6, 92.1–93.0) for light heavyweight, and
114.4 kg (± 7.0, 103.4–120.2) for heavyweight. Of the 21
cancelled bouts, 71.4% were scheduled professional
contests. Athletes with cancelled bouts where
predominantly from Canada (72.7%), but also recorded country of
origin as the USA (18.2%), Brazil (4.5%), and Peru
(4.5%). The average athlete bout experience was 8.5
bouts (± 12.3, 0–44), with 18.2% of athletes having no
prior sanctioned MMA experience. Cancelled bouts
came from 11 events that were run by four different
MMA promotional organizations.
Of the 390 bouts held in Calgary, over the study period,
371 were run by organizations that had cancelled bouts in
the pre-bout examination period (Table 2) and the
remaining bouts were hosted by two promotional
organizations that had no cancelled bouts. The number of bouts
and the number of cancelled bouts as a function of MMA
promotional organization are represented in Table 2. Over
the study period, 5.4% of all bouts were cancelled. The
average MMA promotional organization bout cancellation
percentage was 13.2% (± 24.9, 0–63.6). However, the bout
cancellation percentage for all organizations were similar
exception for promotional organization D, which showed
a bout cancellation percentage of 63.6%.
Twenty-two athletes had bouts cancelled during the
pre-bout medical examination period, with three athletes
having two reasons for cancelling their bout. A total of
25 reasons lead to bout cancellations and included the
following: failure to obtain required neuroimaging (n = 7,
28.0%), neuroimaging abnormalities (n = 6, 24.0%),
incomplete routine screening investigations (n = 4, 16.0%),
exceeding the maximum weight differential between the
two athletes (n = 4, 16.0%), injury in the pre-competition
period (n = 2, 8.0%), dehydration (n = 1, 4.0%), and ECG
abnormalities (n = 1, 4.0%). The abnormalities on
neuroimaging (n of 6) included the following: post traumatic
gliosis on MRI (n = 1, 16.7%), flares diffusely and
findings consistent with microhemorrhage on MRI (n = 1,
16.7%), chronic orbital fracture with fat pad extrusion
on CT (n = 2, 33.3%), lacunar infarct on MRI (n = 1,
16.7%), and unspecified MRI abnormality (n = 1, 16.7%).
The number of ringside physicians at an event was at
least one, as mandated by the CCSC [
], but varied
from one to three physicians depending on size of the
event being run by the MMA promotional organizations.
Ten physicians were involved in the events in which a
contest was cancelled in the pre-bout medical
examination period. The clear majority of the events with
cancelled bouts (90.9%) were covered by six regular ringside
This is the first study to provide perspective on medical
and non-medical reasons for the cancellation of MMA
contests during the pre-bout examination period
conducted by an athletic commission. While the descriptive
epidemiology is relatively simple, and further
investigation of this area is required, it does highlight several
areas that require attention.
Abnormalities on Imaging of the Head
The frequency of neuroimaging or incidence of
abnormality on neuroimaging in this cohort of athletes that
competed in Calgary from January 2010 to December 2016 is
not possible to extrapolate. This occurred because the
NSF non-sanctioned fight, N/A not available, P professional record, A amateur record, ECG electrocardiogram
*The letter represents a distinct MMA promotional organization and the number denotes multiple events put on by this organization
^The X and Y represent physicians that do not and those that do provide regular coverage as a ring-side physician, respectively. The number represents a unique physician
&Did not weigh-in prior to bout being cancelled. The weight provided in the bracket represents the agreed contract weight for the bout
baseline number of athletes that required any
neuroimaging (as an example, imaging in the post bout period) could
not be determined from CCSC records over the entire
study period (records were only maintained for 1 year
period before destruction prior to 2014). What can be
inferred is that 780 athletes competed over the 7-year study
period, and 5 were identified with abnormal neuroimaging
that lead to an indefinite suspension in the pre-bout
period. Apart from the lacunar infarct finding (Athlete 22
in Table 1 was also a poorly controlled hypertensive
patient despite medication, along with electrocardiogram
abnormalities), each of the other neuroimaging
abnormalities is in keeping with a traumatic head mechanism of
]. More specifically, there is emerging evidence
from MMA and boxing literature suggesting that the
microstructural changes observed on these investigations
could be related to previously sustained training or
competition head trauma [
] and potentially correlate
with chronic traumatic encephaolopathy . This is
especially concerning as Hutchinson et al. reported a
knock out rate of 6.4 per 100 athlete-exposures for MMA
athletes, and those who were knocked out on average
sustain 2.6 head strikes after they have lost consciousness
prior to referee intervention [
The ABC Medical Committee provides minimal guidance
on the use of neuroimaging in the pre-bout examination
period and no guidance on the use of neuroimaging for
post-bout examination [
]. Presently, this is a nebulous
area for ringside physicians where there are many more
questions than definitive answers. Overarching themes
include the following: What is the frequency of screening
neuroimaging and does this depend of the athlete’s age? Is
neuroimaging warranted after an unsanctioned bout? What
are the needs for neuroimaging post traumatic brain injury?
What is the appropriate type of neuroimaging? While a
thorough review of the literature relating to neuroimaging
of head trauma from a combative sport perspective is
beyond the scope of this manuscript, the approach to these
scenarios would benefit from a consensus or guidelines
statement from the ABC Medical Committee or the
Association of Ringside Physicians (ARP).
Minimum Medical Screening Standards
The minimum medical screening standards (MMSS) are
vitally important as they set a benchmark for what is
deemed medically necessary to allow an athlete to
]. The CCSC has used screening medical
requirements that are in keeping with the
precedentsetting sanctioning bodies in the USA such as Nevada or
New Jersey State Commissions [
]. As such, the
CCSC has incorporated screening for infectious blood
borne pathogens, pregnancy, and cardiac,
ophthalmological, or neurological disease.
Presently, there is no uniformity between commissions
across Canada, let alone from the international context,
when it comes to MMSS. Review of the MMSS across
the members on the ABC website will quickly highlight
the wide variations between commissions [
]. This can
range from conducting a pre-bout physical the day of
the event to a pre-bout physical plus screening for
infectious blood borne pathogens, pregnancy, and cardiac,
ophthalmological, or neurological disease and additional
requirements for older athletes. The ABC Medical
Committee has outlined MMSS [
] for combative sports
athletes. However, these are merely suggestions and do
not have to be incorporated into a commission’s
standard practice for that commission to maintain
membership in the ABC. In an effort to create uniformity, the
ABC and the ABC Medical Committee should institute
MMSS that must be followed by a commission if it is to
be entitled to membership in the ABC.
Weight Cutting and Dehydration
The policy around weight cutting is an active area of
review for regulatory bodies [
] with no uniformly
accepted approach. In this data set, only a single athlete
(Table 1, Athlete 5) was suspended from competition
secondary to dehydration in the pre-bout examination
period. Surprisingly, this indicates that 0.13% of MMA
athletes that reported to the CCSC weigh-in were
considered dehydrated. However, there was no formal
definition used to determine if athletes were dehydrated or a
means to estimate the level of dehydration. As such, it is
not possible to infer if this data set is representative of
the number of athletes that are dehydrated when they
present for weigh-in. There is no literature to support
this negligible number of athletes showing evidence of
dehydration, instead, there is mounting literature
identifying the trends of rapid weight cutting practice in
12, 13, 39
] and other combative sports [
literature supports that dehydration has become a
normal part of the weight-cutting culture in MMA [
A recent investigation by Matthews et al.  studied
MMA athletes’ weight-making practices and discovered
that at the official weigh-in, 57% of athletes were
dehydrated and the remaining 43% were severely dehydrated
according to their urinary hydration status. Jetton et al.
] identified that 39% of MMA athletes remained
significantly or seriously dehydration 2 h prior to
competition despite the official weigh-in process having
occurred 22 h prior. Dehydration in combative sports
has been linked to tangible health consequences. For
example, among other risks, it can leave athletes
susceptible to closed-head trauma [
] and transient cognitive
] when athletes are still dehydrated.
Over the last year and a half, a new approach has been
adopted by some American commissions that allows for
an early weigh-in process [
] to give athletes more
time to rehydrate before the commencement of the bout
in an effort to decrease the aforementioned dehydration
risks. Specifically, this new weigh-in procedure offers
athletes several more hours than the customary 24 h prior to
competition in which to rehydrate. The California State
Athlete Commission in May 2017 passed a 10-point
weight-cutting regulation  that endorsed the extended
rehydration period and proposed several
recommendations to curb extreme weight cutting. Alternatively, One
Championship has implemented a much more progressive
approach to prevent extreme weight cutting [
athlete’s competing weight class is assigned by One
Championship based upon their current walking weight and
daily training weights. Once the competition weight class
has been established, the athlete cannot alter their weight
class fewer than 8 weeks prior to the event and One
Championship can conduct random weight checks leading
up to the event. These two approaches highlight very
different interventions—one that tries to reverse the effects
of extreme weight cutting and the other that tries to
prevent extreme weight cutting from occurring. Intuitively,
the longitudinal approach offers a means to reframe the
weigh-in process and mitigate extreme weight-cutting
practices. However, the adoption of such a process will
need to overcome imbedded weight-cutting practices in
MMA culture and will require consistent support from
the sanctioning and promotional organizations in which
the athletes are competing. Beyond the initiation of any
new weigh-in practice, there should be further efforts to
scientifically validate the need for such measures and
subsequent investigation to show that the new practice is
creating a healthier or safer process of the athlete.
Support for Athletes to Withdraw from Competition
According to the data, two athletes (Table 1, Athletes 1
and 8) withdrew from competition of their own volition
secondary to injuries. In each of these incidences, the
athletes sought the withdrawal from competition after
conferring with the ringside physician. Partaking in
amateur or professional MMA bouts creates not only an
internal spirit of competition in the athlete but also
external expectations from their coaches, the
promotional organization, and the fans [
]. Having a medical
team that is not affiliated with any of these groups
provides credibility and support for the athlete’s health
concerns and creates a space where the athlete can make an
informed decision regarding competition [
Developing Competent Ringside Physicians
Establishing a competent group of ringside physicians
with a consistent approach to peri-competition medical
screening and suspensions is essential for athlete safety.
As there continues to be wide variation in local practice
by commissions [
] when it comes to screening for
head-related trauma, MMSS, and weigh-in procedures,
ringside physician groups need to work collaboratively
to aid with mentoring any new physician that joins the
group. The creation of a competent group of ringside
physicians that understands not only the medical aspects
of care but also the regulatory, social, and economic
forces within MMA is necessary when balancing athlete
safety. To further develop ringside physician
competency, the ARP, along with the American Colleague of
Sports Medicine, provides the Certified Ringside
Physicians program [
]. In addition, the ARP offers
many online resources to assist physicians with
pericompetition medical screening and health challenges, as
well as continuing medical education [
Training and Bout Cancellation
Injury disclosure by an athlete (Table 1, Athletes 1 and 8)
that prevented them from competing in sanctioned contests
in Calgary from January 2010 to December 2016 accounted
for 8% of cancelled bouts or 36.6 injuries per 100,000
athlete-years (calculated as [2/(780 × 7)] × 100,000). It is
not possible to ascertain from the data if these injuries were
related to training or another mechanism of injury. Even if
it is assumed that these two injuries occurred during
training, this is a low occurrence of training-related injuries. A
single study from the MMA literature reported
trainingrelated injuries as 376.4 per 100 athletes (the time frame for
this study could not be determined) [
]. The literature on
training-related injuries in other combative sports shows
the following: for boxing, it is reported as 16.2 to 19.2 per
100 athlete-year [
]; for karate, its ranges from 20.2 per
100 athletes (the time frame for this study could not be
determined)  to 45.2 per 100 athlete-year [
taekwondo, it is reported as 7.1 to 92.8 per 100 athlete-year
]; for judo, it ranges from 8.2 to 29.6 per 100
]; and for wrestling 132.0 per athlete-years [
has been found. Additionally, there is a spectrum when it
comes to the proportion of injuries occurring in the training
phase of different combative sports: for boxing, it is 5.3 to
]; karate, it is 75.9% ; taekwondo, it is 36.0
to 81.5% [
]; judo, it is 11.6 to 70.0 [
wrestling, it is 63.0% [
]. It is not clear why there is such a large
discrepancy between the existing literature and the rate of
presumed training-related injuries in this study. However,
this may be explained by any of the following reasons: bouts
were cancelled due to athlete injury by the promoter before
the pre-bout examination period; athletes were not
volunteering the existence of injuries; the screening techniques
employed by ringside physicians did not detect the injuries;
or the injuries were considered minor by the ringside
physician and medical clearance was given. Ultimately,
additional study of the pre-competition period is necessary
to better quantify the existence and frequency of injury
during this phase of a MMA athlete’s career.
Matchmaking and Combative Sports Commission
Cancelled bouts in the pre-bout examination periods
represented 5.4% of all MMA bouts in Calgary over the
study period. When looked at from a MMA promotional
organization standpoint, the average bout cancellation
percentage is 13.2% (± 24.9, 0–63.6). However,
promotional organization D (Table 2) appears to be an outlier
at 63.6%, and if this is removed, the average bout
cancellation percentage drops to 3.1% (± 3.0, 0–6.7).
There is presently no combative sports literature that
reports on the occurrence of cancellations in the
prebout period for comparison.
What is highlighted by this finding is a consistent bout
cancellation percentage for all organizations but one.
This large discrepancy for promotional organization D
could be related to the following: the small number of
events and bouts held by the organization, limited
experience with the matchmaking process, or its ability to
attract seasoned amateur and professional athletes may
have been limited as it was a younger organization in
Calgary. However, promotional organizations B, C, E,
and F would also be considered young organizations in
Calgary and did not suffer from the same large bout
cancellation percentage. The CCSC is responsible for
licencing promotional organizations, along with the
athletes, and approving the matchmaking process. As such,
it behoves the commission to guide new or younger
promotional organizations through the matchmaking
process to ensure that athletes are safely chosen to
engage in competition prior to the pre-bout medical
examination. Alternatively, if there is an emerging
pattern of athlete safety concerns, as noted by cancelled
bouts, then the commission should consider not
granting a licence to such a promotional organization.
The matchmaking process is extremely dynamic, and as
such, there tends to be bouts that do not materialise for
a host of reasons. Most of these cancelled bouts will not
come to the attention of the CCSC as they will not make
it to the pre-bout period in which the commission is
involved. Quantifying this number of cancelled bouts in
the matchmaking process or the reasons for such is not
possible through the commission records but should be
considered for future study. There were no means to
ascertain if all of the contests cancelled by the CCSC in
the pre-bout examination period were captured in this
data set as the commission only maintained their
records for 1 year after the event prior to 2014.
The clear majority of contests that were cancelled
were done so for reasons that did not require
interpretation, i.e. failure to obtain required neuroimaging,
neuroimaging abnormalities, incomplete routine screening
investigations, exceeding the maximum weight
differential between the two athletes, and ECG abnormalities.
However, there was subjectivity when it came to
physician interpretation of the degree of pre-existing athlete
injury, the presence of dehydration, or the level of
dehydration that lead to the bout being cancelled. It was not
possible to quantify how clinical gestalt may have
affected the number of bouts that were cancelled or
allowed to continue when injury or dehydration was
present. Future work could consider implementing a
priori definitions for degree of injury or dehydration to
create more consistency when determining if a bout is
to be cancelled.
A relatively small number of amateur and professional
MMA bouts were cancelled during the pre-bout medical
examination period in Calgary, Alberta, from January
2010 to December 2016. The reasons for bout cancellation
included the following: failure to obtain required
neuroimaging, neuroimaging abnormalities, the athlete did not
complete the routine screening investigations, exceeding
the maximum weight differential between the two
athletes, injury in the pre-competition period, dehydration,
and ECG abnormalities. The following recommendations
are presented and include the creation of guidelines
regarding pre- and post-bout neuroimaging, the
implementation of industry-wide minimum medical screening
standards, the adoption of a longitudinal approach to
weight monitoring, the development of competent
ringside physician groups, and the active Combative Sports
Commission oversight during the matchmaking process.
ABC: Association of Boxing Commissions; ARP: Association of Ringside
Physicians; CCSC: Calgary Combative Sports Commission;
ECG: Electrocardiogram; MMA: Mixed martial arts; MMSS: Minimal medical
screening standards; MRI: Magnetic resonance imaging
The author wishes to thank Neil McDonald for his review of the manuscript
and provision of critical feedback.
Ethical Approval and Consent to Participate
This project received research ethics review and consent to include patient
information from the University of Calgary (REB13-0837).
Consent for Publication
Availability of Data and Materials
The dataset supporting the conclusions of this article is not publically available
at this time as ethics approval for public disclosure has not been secured.
Gwynn Curran-Sills has no competing interests to declare.
Springer Nature remains neutral with regard to jurisdictional claims in published
maps and institutional affiliations.
1. Rainey CE . Determining the prevalence and assessing the severity of injuries in mixed martial arts athletes . N Am J Sports Phys Ther . 2009 ; 4 ( 4 ): 190 - 9 .
2. Bledsoe GH , Hsu EB , Grabowski JG , Brill JD , Li G . Incidence of injury in professional mixed martial arts competitions . J Sports Sci Med . 2006 ; 5 (Cssi): 136 - 42 .
3. Scoggin JF 3rd, Brusovanik G , Pi M , Izuka B , Pang P , Tokumura S , et al. Assessment of injuries sustained in mixed martial arts competition . Am J Orthop . 2010 ; 39 ( 5 ): 247 - 51 .
4. Ngai KM , Levy F , Hsu EB . Injury trends in sanctioned mixed martial arts competition: a 5-year review from 2002 to 2007 . Br J Sports Med . 2008 ; 42 ( 8 ): 686 - 9 .
5. McClain R , Wassermen J , Mayfield C , Berry AC , Grenier G , Suminski RR . Injury profile of mixed martial arts competitors . Clin J Sport Med . 2014 ; 24 ( 6 ): 497 - 50 . 5
6. Lystad RP , Gregory K , Wilson J. The epidemiology of injuries in mixed martial arts: a systematic review and meta-analysis . Orthop J Sports Med . 2014 ; 22 ( 2 ): 1 . 6.
7. Buse GJ . No holds barred sport fighting: a 10-year review of mixed martial arts competition . Br J Sports Med . 2006 ; 40 ( 2 ): 169 - 72 .
8. Hutchison MG , Lawrence DW , Cusimano MD , Schweizer TA . Head trauma in mixed martial arts . Am J Sports Med . 2014 ; 42 ( 6 ): 1352 - 8 .
9. James L , Haff G , Kelly V , Beckman E. Towards a determination of the physiological characteristics distinguishing successful mixed martial arts athletes: a systematic review of combat sport literature . Sports Med . 2016 ; 46 ( 10 ): 1525 - 51 .
10. James LP , Beckman EM , Kelly VG , Haff GG . The neuromuscular qualities of higher and lower-level mixed martial arts competitors . International Journal of Sports Physiology and Performance . 2017 ; 12 ( 5 ): 612 - 20 .
11. James LP , Robertson S , Haff GG , Beckman EM , Kelly VG . Identifying the performance characteristics of a winning outcome in elite mixed martial arts competition . Journal of Science & Medicine in Sport . 2017 ; 20 ( 3 ): 296 - 301 .
12. Crighton B , Close GL , Morton JP . Alarming weight cutting behaviours in mixed martial arts: a cause for concern and a call for action . Br J Sports Med . 2016 ; 50 ( 8 ): 446 - 7 .
13. Matthews JJ , Nicholas C . Extreme rapid weight loss and rapid weight gain observed in UK mixed martial arts athletes preparing for competition . Int J Sport Nutr Exerc Metab . 2017 ; 27 ( 2 ): 122 - 9 .
14. Franchini E , Brito CJ , Artioli GG . Weight loss in combat sports: physiological, psychological and performance effects . J Int Soc Sports Nutr . 2012 ; 9 : 52 .
15. Reale R , Slater G , Burke LM . Acute-weight-loss strategies for combat sports and applications to Olympic success . Int J Sports Physiol Perform . 2017 ; 12 ( 2 ): 142 - 51 .
16. American Medical Association. H- 470 . 965 ultimate and extreme fighting . Available from: https://searchpf.ama-assn.org/SearchML/searchDetails. action?uri=% 2FAMADoc%2FHOD.xml-0-4281.xml. Accessed 5 Mar 2017 .
17. Australian Medical Association. Mixed martial arts must be banned . Available at: http://www.amawa.com. au/mixed-martial-arts- mustbe- bannedama-wa/. Accessed 5 Mar 2017 .
18. White C . Mixed martial arts and boxing should be banned, says BMA . BMJ . 2007 ; 335 : 469 .
19. Canadian Medical Association. Mixed martial arts (MMA) ban . Available at: https://www.cma.ca/Assets/assets-library/document/en/about-us/Bulletinjune11_EN.pdf#search=mma. Accessed 5 Mar 2017 .
20. Philipott K. The Business of MMA [Internet] . MMAPayout [published November 29 2010 ]. Available from: http://mmapayout.com/ 2010 /11/theufc-fan -base/?utm_source=feedburner&utm_medium=feed&utm_ campaign= Feed%3A+Payout+%28Payout%29&utm_content=Google +Reader. Accessed 5 Mar 2017 .
21. Kim S , Greenwell TC , Andrew DPS , Lee J , Mahony DF . An analysis of spectator motives in an individual combat sport: a study of mixed martial arts fans . Sport Mark Q . 2008 ; 17 : 109 - 19 .
22. Ko Y , Kim Y , Valacich J . Martial arts participation: consumer motivation . Int J Sport Mark Spo . 2010 ; 11 : 105 - 23 .
23. Warner M. Head trauma in mixed martial arts: letter to the editor . Am J Sports Med . 2014 ; 42 ( 7 ): NP43 - 4 .
24. Association of Boxing Commissions. Medical Requirements by Commission [Updated March 6 , 2017 ]. Available at: http://www.abcboxing.com/medicalrequirements-by-commission/. Accessed on 5 Sept 2017 .
25. Government of Western Australia. Combat Sports Commission. Available from: https://www.dsr.wa.gov.au/support-and -advice/combat-sportscommission . Accessed 5 Mar 2017 .
26. Curran-Sills G , Abedin T . Risk factors associated with injury and head trauma in sanctioned amateur and professional mixed marital arts bouts in Calgary, Alberta . Under review.
27. Calgary Combative Sports Commission. Mixed Martial Arts Calgary Unified Rules [published January 3 , 3016]. Available at: http://www.calgary.ca/CSPS/ ABS/Documents/Calgary%20Combative %20Sports%20Commission/ Calgary%20Unified%20Rules%20DRAFT%20VERSION%202-7-2.pdf. Accessed on 5 Sept 2017 . Bigler ED. Traumatic brain injury, neuroimaging, and neurodegeneration . Front Hum Neurosci . 2013 ; 7 : 395 .
28. Krishna R , Grinn M , Giordano N , et al. Diagnostic confirmation of mild traumatic brain injury by diffusion tensor imaging: a case report . J Med Case Rep . 2012 ; 6 : 66 .
29. Turner RC , Lucke-Wold BP , Robson MJ , et al. Repetitive traumatic brain injury and development of chronic traumatic encephalopathy: a potential role for biomarkers in diagnosis, prognosis, and treatment? Front Neurol . 2012 ; 3 : 186 .
30. Shin W , Mahmoud SY , Sakaie K , et al. Diffusion measures indicate fight exposure-related damage to cerebral white matter in boxers and mixed martial arts fighters . Am J Neuroradiol . 2014 ; 35 ( 2 ): 285 - 90 .
31. Bernick C , Banks SJ , Shin W , et al. Repeated head trauma is associated with smaller thalamic volumes and slower processing speed: the Professional Fighters' Brain Health Study . Br J Sports Med . 2015 ; 49 ( 15 ): 1007 - 11 .
32. AC MK , Cantu RC , Nowinski CJ , et al. Chronic traumatic encephalopathy in athletes: progressive tauopathy following repetitive head injury . J Neuropathol Exp Neurol . 2009 ; 68 ( 7 ): 709 - 35 .
33. Stern RA , Riley DO , Daneshvar DH , et al. Long-term consequences of repetitive brain trauma: chronic traumatic encephalopathy . PM R . 2011 ; 3 ( 10 ): S460 - 7 .
34. The Association of Boxing Commission - Medical Committee . ABC medical committee recommendations/guidelines for the improvement of the safety of combat sports participants . Trenton: The Association; 2011 . p. 2 - 4 .
35. Nevada State Athletic Commission. Regulations for Mixed Martial Arts . Available at: http://boxing.nv.gov/uploadedFiles/boxingnvgov/content/ home/features/2016-09-09 -ADOPTEDREGULATIONS-R062-16A.pdf. Accessed 5 Sept 2017 .
36. New Jersey State Athletic Commission. Mixed Martial Arts Unified Rules of conduct [published September 9 , 2016 ]. Available at: http://www.nj.gov/lps/ sacb/docs/martial.html. Accessed 5 Sept 2017 .
37. Association of Boxing Commissions. Unified Rules of Mixed Martial Arts [published July 30 , 2009 ]. Available at: http://www.abcboxing. com/ committee-report-on-unified-rules-for-mma/ . Accessed 5 Sept 2017 .
38. Raimondi M. CSAC passes ground-breaking package of weight-cutting regulations . MMAFighting [published May 16 , 2017 ]. Available at: https:// www.mmafighting.com/ 2017 /5/16/15648532/csac-passes -ground-breakingpackage-of-weight-cutting-regulations . Accessed 5 Sept 2017 .
39. Jetton AM , Lawrence MM , Meucci M , et al. Dehydration and acute weight gain in mixed martial arts fighters before competition . J Strength Cond Res . 2013 ; 27 ( 5 ): 1322 - 6 .
40. Dickson JM , Weavers HM , Mitchell N , et al. The effects of dehydration on brain volume-preliminary results . Int J Sports Med . 2005 ; 26 ( 6 ): 481 - 5 .
41. Weber AF , Mihalik JP , Register-Mihalik JK , et al. Dehydration and performance on clinical concussion measures in collegiate wrestlers . J Athl Train . 2013 ; 48 ( 2 ): 153 - 60 .
42. Raimondi M. Different weigh-in procedures for UCF 199 explained . MMAFighting [published June 2 , 2016 ]. Available from: http://www. mmafighting.com/ 2016 /6/2/11827266/different-weigh -in-procedure-for-ufc199-explained . Accessed 5 Sept 2017 .
43. Martin D. Nevada commission approves early weigh-ins for upcoming UCF events . Fox Sports [published June 21 , 2016 ]. Available from: http://www. foxsports.com/ufc/story/ufc-200 - nevada -commission-approves-early-weighins-upcoming- events-062116. Accessed 5 Sept 2017 .
44. One Championship . General Regulations and Policies [publication date not disclosed] . Available at: General Regulations & Policies Related To Athletes' Weight https://onefc.com/martial_arts/. Accessed 5 Sept 2017 .
45. Dijkstra HP , Pollock N , Chakraverty R , Alonso JM . Managing the health of the elite athlete: a new integrated performance health management and coaching model . r J Sports Med . 2014 ; 48 ( 7 ): 523 - 31 .
46. Greenfield BH , West CR . Ethical issues in sports medicine: a review and justification for ethical decision making and reasoning . Sports Health . 2012 ; 4 ( 6 ): 475 - 9 .
47. Sabato TM , Walch TJ , Caine DJ . The elite young athlete: strategies to ensure physical and emotional health . Open Access J Sports Med . 2016 ; 7 : 99 - 113 .
48. American College of Sports Medicine. ARP/ACSM Certified Ringside Physician [published 2015 ]. Available at: https://certification.acsm. org/acsmarp-certified-ringside-physician . Accessed 5 Sept 2017 .
49. Association of Ringside Physicians. ARP/ACSM Certified Ringside Physician [published 2017 ]. Available at: http://www.ringsidearp. org/Certification. Accessed 5 Sept 2017 .
50. Junge A , Engebretsen L , Mountjoy ML , et al. Sports injuries during the summer Olympic games 2008 . Am J Sports Med . 2009 ; 37 ( 11 ): 2165 - 72 .
51. Zazryn T , Cameron P , McCrory P . A prospective cohort study of injury in amateur and professional boxing . Br J Sports Med . 2006 ; 40 ( 8 ): 670 - 4 .
52. Ziaee V , Shobbar M , Lotfian S , Ahmadinejad M. Sport injuries of karate during training: an epidemiologic study in Iran . https://doi.org/10.5812/ asjsm.26832. Epub 2015 Jun 20
53. Destombe C , Lejeune L , Guillodo Y , et al. Incidence and nature of karate injuries . Joint Bone Spine . 2006 ; 73 ( 2 ): 182 - 8 .
54. Lystad RP , Graham PL , Poulos RG . Epidemiology of training injuries in amateur taekwondo athletes: a retrospective cohort study . Biol Sport . 2015 ; 32 ( 3 ): 213 - 8 .
55. Kujala UM , Antti-Poika I , Tuominen R . Acute injuries in soccer, ice hockey, volleyball, basketball, judo, and karate/analysis of national registry data . BMJ . 1995 ; 311 : 1465 .
56. Pasque CB , Hewett TE . A prospective study of high school wrestling injuries . Am J Sports Med . 2000 ; 28 ( 4 ): 509 - 15 .