In this study, more than half (55.4%) of the Muay Thai fighters reported an injury in their most recent contest. Most of the reported injuries were soft-tissue injuries and lower on the injury severity scale. About 20% of the injuries involved a fracture or concussion. In most circumstances, the injuries were reported as not interfering with the completion of the fight, nor its outcome. Overall, the fighters reporting a higher frequency of injury were younger, female, had more ring experience, and were professional caliber fighters. Previous injury history was not associated with reported fight injuries in this sample.

The lower extremities (55/108, 51%) were the most commonly injured body region injured during fights, as detailed in the injury incident description. In contrast, concussion represented a small proportion of reported injuries. This finding may be due, in part, to the tactics involved in Muay Thai fighting where one can attack multiple targets, including the body and legs, with eight weapons (two hands, two elbows, two knees, and two legs). Given that scoring in Muay Thai awards strong kicks and knees, the whole body may be a primary target compared to boxing, which targets the head most frequently.

These findings are similar, in part, to the results of three previous studies published on Muay Thai (Gartland et al. 2005; Shirani et al. 2010; Gabbe et al. 2003) but differ with regards to the injury definition, severity level, exposure, and competition level (Table 5). Additionally, we were able to compare injured versus uninjured fighters for the first time.

Table 5 Summary of Muay Thai injury studies Full size table

Compared to previous research regarding Muay Thai injuries, the current study echoed common injury outcomes to the lower extremities from soft tissue contusions (Gartland et al. 2005), and to the head (Shirani et al. 2010). Injuries to the head were the second leading body region injured in the current study and one previous study (Gartland et al. 2005), but the primary outcome in two other studies (Gartland et al. 2005; Gabbe et al. 2003).

This finding lead to speculation that it might be an acceptable norm to incur minor bumps and bruises to the lower extremities which are not perceived to be injuries by the participants (Shirani et al. 2010). Wearing shin pads may conceal minor injuries rendering them undetectable by a referee or medic, leading to under-reporting, whereas noticeable contact to the head, as witnessed by the referee, may have led to increased reporting to the medics for precautionary measures. The current study’s finding of injury to the lower extremities among 55% amateur and 51% professional were comparable to the 64% amateur and 53% professional as well (Gartland et al. 2005). Further, the most common nature of injury in both studies was soft tissue injuries, predominantly contusions.

We did find found slightly more lacerations (20%), followed by fractures (13%) compared to previous research (Gartland et al. 2005) that reported fractures as the second leading nature of injury among professionals. The lacerations in the current study were generally (75%) the result of cuts from elbows to the head. Elbows are a dangerous technique rarely used in training exercises unless wearing heavy padding to reduce the potential danger of being cut. Because previous research (Gartland et al. 2005) included training exercises as an exposure and the absence of this technique in practice could explain the lower incidence of lacerations. Other research among a subset of Muay Thai fighters ranked lacerations were the most common outcome (93.3%) and more injuries were reported among the professionals (86%) compared to the amateurs (42%) (Gabbe et al. 2003). While the current study is not directly comparable, there were more professionals injured (65%) than amateurs (44%) and more head injuries among the professionals (33% vs. 25%). The professionals with head injuries in the current study did report lacerations (57%), injuries to the jaw (14%), concussions with pain (24%), and several eye injuries (5%). Those cut in all cases sought medical treatment, largely for sutures for the lacerations. The current work found that the majority of the facial lacerations to the professional fighters (84%) were from being elbowed, kneed (8%), or punched (8%) by the opponent. It is difficult to compare directly to previous research as it was not specified how, where or when these occurred, only commenting that it resulted from Muay Thai “participation.” (Gabbe et al. 2003) Further, the mechanism of injury was not presented, only the nature of the injury itself within a clinical setting.

We reported similar age ranges (18–47 years) with one study (14–51 years) (Gartland et al. 2005), having identical medians (26 years), but our sample was slightly older than those reported in two other studies (mean 17 and 20 years old) (Shirani et al. 2010; Gabbe et al. 2003).

Females comprised 17% in the current study, similar to 13 (Gartland et al. 2005; Shirani et al. 2010) and 20% (Gabbe et al. 2003). Differences were reported injuries among novice, amateur, and professionals but noted confusion about these definitions, possibly, since training exercises were included (Gartland et al. 2005). Not all participants were fighters, therefore some had difficulty self-identifying their rank or caliber. We looked exclusively at fight exposures, therefore professional or amateur were easier to categorize. Training reflects considerably less intense contact levels deliberately in effort to prevent injury (Table 5). This exposure level difference may account for relatively small percentages of time off from training (7%), defined as 7 days or more compared to 25.9% found in the current study (Gartland et al. 2005).

Information on the mechanism of injury, protective equipment worn and a brief narrative was collected in the present study. Of the 44 injured amateur fighters, 25 incurred injuries to the lower extremities (7 not wearing shin pads; 18 padding worn). The brief narrative description revealed that the majority of these (16 out of 25) were a consequence of being struck by the opponent, who presumably would also be wearing shin pads, as fighters wear the same level of protection in sanctioned fights. Damage inflicted to the lower extremity was reported by fighters while wearing protection, against a similarly padded opponent. This increased level of detail was absent from previous research (Shirani et al. 2010).

That study (Shirani et al. 2010) concluded that younger, less experienced, and heavier fighters were at increased risk for injury. This result is quite different than reported in the current study, which was that younger, more experienced and lighter fighters were at increased risk. One possible reason might be that the previous work (Shirani et al. 2010) did not include professional fighters, and among those amateurs, a lower reported a mean of 3.4 fights was quite different compared to the 16 fights mean, with nearly 50% being professional fighters in this study. A bias was also noted in the previous study in the heavier weight classes due to extremely small sample size (n = 4) with a considerably high number of injuries reported (Shirani et al. 2010).

Another possible explanation for why less experienced fighters were at increased risk in the previous study compared to the current work might be due to the level of intensity (Shirani et al. 2010). Younger, experienced professionals are more adept and often driven by fight incentives such as purse or prize money and titles. Professional fighters are considerably more skillful. Coupled with a winning drive, this may lead to more furious efforts when compared to the relative neophytes in the previous study’s sample, who are still learning and honing techniques, both offensively and defensively (Shirani et al. 2010).

One previous study reported an injury rate based on competition minutes recorded at the events, and identified an average rate of 9.1 injuries/100 min of competition (Shirani et al. 2010). In the current study, considering the 44 injured amateurs and bout time fought per fight (3 rounds × 2 min) results in roughly 264 min of competition time. This number would be an overestimate since fights stopped during the round were rounded up, not every bout went the distance, and, although rare, some less experienced amateurs may fight 1.5 min rounds. These numbers result in 16.6 injuries/100 min competition time, slightly higher than and perhaps how the injuries were reported (referee, medic, some self vs. self-report) lead to more over reporting in this current work’s sample.

There were some limitations with our study. Self-selection survey bias exists as fighters who were injured may be more likely to complete a survey targeting injury outcomes, so while only collecting the primary injury and not multiple injuries, we may be overestimating the incidence, particularly compared to other combat sports such as MMA (Bledsoe 2009) (28.6/100) or boxing (Zetaruk et al. 2005) (25/100). Additionally, we employed a non-probability sample, or convenience sample, therefore introducing sample bias and therefore the results are not representative. However, as the population of Muay Thai fighters is less quantifiable, extrapolating back to that target population was not a primary objective but rather to investigate the relationships between several key variables among those sampled.

We defined an acute injury as “painful” physical harm sustained during an actual fight and asked respondents to consider fight-specific injuries (in the ring), rather than those sustained during training prior to the fight. If multiple injuries were sustained, the primary injury of interest was the injury the fighter felt was the most severe. This study did not capture all of the injuries during the fight but focused on a single injury that was self-reported to be the most severe. Additionally, as the case definition concentrated on the pain aspect of the injury, it does not factor in that the mechanism of injury could have started prior to the fight without the emergence of pain. As pain threshold is an entirely subjective phenomenon, some individuals may tolerate higher levels of pain compared to others, therefore resulting in differences in reporting injury according to the current study’s case definition. For example, the identical injury occurring for two different fighters may result in only one reporting the injury based on the definition focusing on reported pain. Additionally, fighters may have not experienced pain with concussion, therefore may not have disclosed an injury which conceivably could lead to underreporting of concussions within this study.

The retrospective nature of the study design introduces the possibility of recall bias. By design, the current study restricted the recall period to a maximum of 6 months, since Gabbe’s publication (Zazryn et al. 2006) found that injury rates over a 1-year time period had perfect recall whether an injury had occurred, with decreasing percentages of participants recalling the exact number, body region or diagnosis. Therefore, it stands to reason that the current study’s injury rate is likely to be accurate, perhaps with decreasing accuracy in the reported total number of injuries, location, and diagnosis obtained from self-reporting. There were two different recall periods, as within the targeted sample, fighters were approached within a week of fighting, compared to the convenience sample that allowed for injury recall up to 6 months. Training injuries were not included in this survey, another limitation, though previous fights with an injury sustained were documented by asking fighters, “How many fights have you had in the past 6 months where you sustained at least 1 injury?”

Despite these limitations, the current study also has several advantages. Our injury criteria were concrete and encompassed a wide range of injuries seen within the combat sports, particularly within Muay Thai. Although not validated, the survey piloted a means of electronic delivery for web-based surveying, which could easily be replicated on a grander scale among more participants. This study was structured as a pilot which could provide areas of focus for further studies. A larger, prospective study with a validated survey and examination of injury rates and patterns with elements related to experience, protection, preexisting injury, length of time in the sport (stratifying for amateur and professional fight exposures), and training activities may then be explored in more detail to help design effective prevention strategies to reduce injury rates and aid Muay Thai grow into a safe and effective sport and recreational activity.