1. Summary
2. Introduction
3. Overview of the nature of injuries in grappling sports 
4. Mechanism of Injury (MOI)
5. Risk Factors
6. Barriers & Facilitators of introducing injury prevention warm-up
7. Appraising evidence for warm-up intervention protocols
8. Conclusion 
9. Appendix
10. References

Summary

Grappling sports are becoming more popular, but with this injuries associated with grappling sports are on the rise. At present, no injury prevention warm-up (IPW) specifically addresses the requirements of grappling athletes. Using existing guidelines and frameworks from other sports and disciplines, this article proposes an IPW to meet the specific needs of the grappling athlete.

Introduction

Greco-Roman wrestling has been featured in the Olympic games since they started in 1896, with Catch wrestling being introduced in 1904 before being replaced by Freestyle wrestling in 1924. Regardless of the long history of the three sports, no injury-prevention warm-up has been published (1) despite poor warm-ups previously being cited as a common cause of injury in grappling sports (2). Additionally, there is currently no injury prevention warm-up (IPW) for other grappling sports such as Brazilian jiu-jitsu (BJJ) and Sambo. 

Overall injury rates for grappling sports can be up to 19.6 per 1000 hours of athlete exposure (AE) (3), with competition rates reaching 109 injuries/1000 AE (4). High injury recurrence rates have also been highlighted in grappling sports (5). Research has shown that the successful employment of warm-ups before sports can reduce athlete injury and recurrence rates (6, 7, 8). 

The Team-Sport Injury Prevention (TIP) cycle is a revised version of Flinch’s (2006) Translating Research into Injury Prevention Practice Framework (TRIPP). `TIP details the process of development of an evidence-based injury prevention programme. TIP identifies stages of designing an injury prevention programme as; (re)evaluate, identify, and intervene (9) (Figure 1). 

Figure 1. The Team-Sport Injury Prevention (TIP) cycle is a revised version of Flinch’s (2006) Translating Research into Injury Prevention Practice Framework (TRIPP) (9).

This review proposes an evidence-based injury prevention warm-up intervention to reduce injury incident rates in grappling sports. It will discuss the sites and types of injuries seen in wrestling, BJJ and Sambo, and the mechanism of injury (MOI) and barriers to delivery of an injury prevention warm-up. The approach to developing the IPW was to first assess the available research to establish the current injury situation in grappling sports, including the nature and frequency of injuries. Followed by the barriers and facilitators of introducing an injury prevention warm-up. Once the appraisal of the research literature was complete, an IPW was designed with the input of grappling researchers and practitioners.

Overview of the nature of injuries in grappling sports 

Incidence of injury

There are multiple injury surveillance data studies available for Freestyle wrestling. However, the injury incident rate (IR) does differ between samples, with overall IR being as low as 3.40 per 1000 hours of athlete exposure (AE) in British wrestlers (10) to 19.6 injuries/ 1000 AE seen in American collegiate male wrestlers (3). There is a paucity of published injury surveillance data for BJJ. However, two studies do report competition injury incident reporting rates ranging from 9.2 to 24.9 injuries/ 1000 AE (11. 12). This is much lower than rates seen in freestyle wrestling competitions, where rates range from 13.1 to 42.01/ 1000 AE (10, 13, 14, 15, 16).

Anatomical site of injuries and Type

Multiple Injury studies in BJJ have established that the Knee is the most commonly injured anatomical site, ranging between 20.8 to 81.1 % of all injuries occurring (5, 11, 12, 17, 18, 19, 20, 21). Two studies found hands and fingers to be the most frequent injuries in BJJ, followed by the Knee (22, 23, 24). In BJJ competitions the elbow was the most commonly injuries joint. However, the Knee had the highest incidence of medical diagnoses (11). None of the grapplers stated if injuries came from Gi-based BJJ or No-Gi BJJ. The head, neck and trunk were the leading injury sites present at American Emergency Departments for BJJ between 2008 to 2015 (25). BJJ Studies that reported injury type stated sprains as the leading diagnosis (21, 24, 26).

In several American collegiate wrestling injury surveillance studies, the Knee has been reported as the most frequent injury in competition and practice (16.7 % to 30.4 %) (3, 13, 14, 16, 27). However, this differs in American high school wrestlers, where the head/face (practices = 19.9 %, competitions = 21.4 %) and shoulder/clavicle (practices = 14.1 %, competitions = 21.0 %) were the most common injury sites (16). Data obtained from various demographics has established knee strains/sprains as the most frequent injury wrestlers (14, 28, 29).

There are still grappling arts with no research data available, such as Catch Wrestling. Others, such as Sambo and Japanese jiu-jitsu, have limited research. Blach et al. (2022) (30) Joint study of spinal injuries in Sambo reported that 53 % of all reported spinal injuries occurred in the lumbar region. In traditional Jiu-jitsu, the knee (29.4 %) (31) is stated as the most frequent injury site, while minor contusions, sprains, and muscle injuries (54 %) were the leading injury type (32). 

Greco-Roman studies often show differences in the leading injury sites varying from the Neck, Ribs and Shoulder (33, 34, 35). In competition lactations to the face are the leading injury site and type (62%) (36). Mooren et al. (2023) (37) systematic review of Injuries during Judo Tournaments stated that the majority of studies reported the Head and Neck as the leading injury site. The leading time loss injury site was the knee, and the leading injury type was joint sprains followed by contusions and lacerations. Anterior cruciate ligament (ACL) ruptures have been reported as the primary injury type for time loss with 32 % of all ACLs taking 6-9 months for grapplers to return to play (38).

The review of the available research shows that the knee is the most commonly injured site in Freestyle wrestling (3, 13, 14, 16, 27), BJJ (5, 11, 12, 17, 18, 19, 20, 21) and traditional Jiu-jitsu (31)  and the leading time loss injury in Judo (37, 38). Ligament strains were reported as the leading injury type in Freestyle wrestling, BJJ (21, 24, 26) and Judo (37) and second in traditional Jiu-jitsu (32). In Greco-Roman Wrestling and Judo competitions, the grappling sports that do not allow leg attacks, the head, neck and trunk are the leading injury sites (33, 34, 35, 36, 37). 

Mechanism of Injury (MOI)

Freestyle wrestling research is unanimous in stating that takedowns were the leading MOI, resulting in 39 % to 54.3 % of all reported injuries (10, 13, 14, 16, 27, 39). The majority of these happened during practice sparring 37.5 % to 65.1 % (10, 13, 14, 27). This was also seen in BJJ, where studies reported that 74-77.6 % of injuries happened during training (17, 21). It was also established that submissions (29.7 %) were the leading MOI, followed by takedowns (26.4 %). An opponent attempting an armbar was the leading submission to cause injury, and the triangle submission was the leading cause of injury for grapplers attempting a submission on their opponent (17). The MOI has also been shown to differ between ages with one study reporting the leading MOI for adolescents as Tumbling/ Trauma and takedowns as the lead MOI for adults and masters (40). In BJJ competitions, the armbar was the most common MOI (28.8 %), followed by takedowns (13.9 %) (11). 

Sandeep and Haridas Kuloor’s (2017) (35) study of Greco-roman wrestlers states that most injuries accrued with contact with the opponent. However, it does not go any further as to what the contact was or why it occurred. A systematic review of competition injuries in Judo found that 50 to 85.2 % of injuries happened during Tachi-waza (Standing techniques) (37). The most frequent method of MOI in standing techniques is being thrown, followed by performing a throw then grip fighting (41, 42, 43). The available research shows that takedowns and throws are the leading aetiology in all styles of wrestling and Judo, with BJJ research fluctuating between takedowns and submissions.

Risk Factors

Compared to many sports physical risk factors in grappling is under-researched. However, some studies may help the design of the IPW. In youth freestyle wrestling a relationship has been found between reduced flexibility and an increased rate of skeletal and muscular-tendinous injuries (44). A link between bone injuries and isometric strength was also established (44). In Judo and BJJ interlimb asymmetries in strength, power and flexibility in the knee, shoulder and hip have been associated with injury risk (45, 46). In Judo breakfall techniques are heavily researched (47). Although no injury incident or prevalence studies exist, ample studies show that grapplers who show incorrect falling techniques demonstrate poor collision biomechanics associated with head and neck injuries (47). Practicing correct falling techniques has been shown to lower these dysfunctions (47).

Research has highlighted multiple factors that contribute to increased injury risk. Studies have shown that injury incident rates increase with age in BJJ, Freestyle wrestling and Judo (10, 17, 37, 48, 49). Multiple BJJ studies have shown females to be at greater risk of injury (5, 40). However, studies in Freestyle and Judo have presented mixed results for gender injury incident rates (37, 50). Grappling experience and training volume have also been established as risk factors (10, 26, 40, 48). However, studies have shown that grapplers with more experience train more times a week and for longer durations (49) meaning that the increased injury incident rates in experienced grapplers may come from increased training volume.

Although research into risk factors is lacking in grappling sports the available studies suggest that strength, power, and flexibility affect injury incident and prevalence rates. The decline in these physical attributes seen with age may be the reason that injury incident rates increase with age (51, 52). An exercise selection with evidence of increasing strength, power and flexibility will be included in the IPW.

Armbars and Upper-body injury

One of the leading MOIs in BJJ is the armbar (11, 17). The armbar is a submission that involves grapplers hyperextending their opponent’s elbow joint by inflicting a posterior-to-anterior (P/A) force to the humerus and an anterior-to-posterior (A/P) force to the forearm (53, 54). Almeida et al. (2017) (54) study on the patterns and mechanisms of armbar injuries stated that force caused by the eccentric contraction of the forearm flexor muscles, leading to injury of the dynamic and static medial stabilisers of the elbow. The chances of dislocation and distal humerus shear fractures expand as the valgus moment increases when the elbow is at full extension (55, 56). Due to the level of force that can be produced, it is unlikely that the IPW will have any impact in reducing injuries from armbars; instead, sparring etiquette and the correct paring of sparring partners with similar weight and experience levels.

The head and neck are leading injury sites in Judo and Greco-Roman wrestling with the direct impact of the head on the mat being stated as a frequent MOI (47). Research in the elucidation of the causes of head injury in judo has shown that grapplers landing from unexpected throws (eyes closed) exhibited greater maximum angular acceleration of the head compared to expected throws (eyes open) (57). The delayed reaction to a push and delayed contraction of the neck muscles has also been linked to the increased risk of head injury (57). It was also seen that anterior cervical flexion strength had no impact on angular acceleration (57). Research on the Ukemi break-fall technique has shown that it can dramatically reduce peak resultant translational acceleration of the head that is associated with an acute subdural haematoma and coronal rotation that has been linked to diffuse axonal injury (58, 59, 60).

Research into neck strengthening exercises in the sport of Rugby Union and Mixed martial arts has shown a reduction in cervical muscle injuries and sports-based concussions (61, 62). Neck strength has been associated with Peak Angular Momentum of Neck Extension (PAMNE) (47). PAMNE is lower in experienced judoka when compared to novices when performing break-falls (63). As neck strength was not tested in the study it is unclear if PAMNE was lower due to better break-fall technique or from neck strength. It appears necessary to include both break-fall drills and neck strengthening exercises in the IPW. 

Leg attacks and Lower-body injury

Takedowns have been verified as the most utilised method for scoring points in competitions and are therefore practised regularly in grappling sparring and drilling (64, 65, 66). It has been established that many BJJ, freestyle, and catch wrestling takedowns, most noticeable leg attacks, involve knee torsion, lateral knee displacement and excessive force transmitted in the joint in the execution phase (67, 68, 69). Research in ACL and injuries states that the primary kinetic mechanisms are valgus forces, compressive anterior force of the quadriceps, and short axial compressive forces to the knee that cause anterior translation of the tibia (39). These variables contribute to the most frequent component of ACL strain, proximal tibia anterior shear (70, 71). The MCL is commonly injured through coronal plane impact merged with rotational forces (72, 73). The kinetic forces seen in pivoting movement, rapid deceleration, and forced hyperextension are chief mechanisms in combined knee ligament injuries (74).

These MOI align with the mechanisms of leg-based takedowns frequently performed in BJJ and Various types of wrestling. Additionally, it has been observed that freestyle wrestlers rely predominantly on leg attacks and not throws, as seen in Greco-Roman wrestling and Judo (64, 75). This is due to rulesets, as it is not permitted to grab the legs in Greco-roman wrestling and Judo. This has led to different defence strategies and postures between grappling styles that can attack the legs and those that cannot. Grappling styles that permit leg attacks, such as BJJ, freestyle and catch wrestling, demonstrate greater A/P excursion of the centre of pressure and greater knee flexion that results in significantly increased joint angles in the transverse and frontal planes at the knee and ankle due to the lowered stance needed to attack and defence the lower limbs (42, 76). This may contribute to the higher percentage of knee and lower limb injuries and higher injury prevalence rates seen in freestyle wrestling (34, 36, 77).

As suplexes are not permitted in BJJ (78), it can be presumed that the majority of takedowns are attacks to the legs and not throws, as seen in Greco-Roman wrestling and Judo (33, 37). This leads to the conclusion that grappling sports that allow leg attacks share similar MOI and can be separated from those that are not permitted to perform leg attacks. Unlike technique drilling for head injuries and coaching advisement for submission injuries there are many IPW that are designed to lower injuries to the knee joint. Research has shown that knee-focused IPW can successfully lower injuries in contact sports (79,80). Exercises from these IPW that are most relevant to grappling, can be included in the current IPW.

Current recommendations to reduce injury

Grindstaff & Potach (2006) (81) reviewed wrestling injuries and suggested exercises to be incorporated into a strength and conditioning (S&C) programme. This resource is useful for S&C coaches and provides a framework for a gym-based injury prevention programme. However, many of the exercise suggestions involved gym equipment that would not be possible to use for a team warm-up. However, some bodyweight exercises, such as wheelbarrow holds and bear crawls, may be adapted to fill a warm-up format. Von Gerhardt et al. (2023) (82) designed an injury-prevention warm-up for Judo called the Injury Prevention and Performance Optimization Netherlands (IPPON). It is the only published injury prevention warm-up tailored for a grappling sport. However, it focused purely on the injuries and MOIs seen in Judo. However, the IPPON intervention did not significantly reduce the overall and severe injury prevalence.

Injury prevention warm-ups have successfully reduced injury rates and precursors to injury in sports such as Football, Basketball and rugby (83, 84, 85, 86). Following a similar systematic evidence-based approach as these programs have previously, an effective injury prevention warm-up protocol for grappling arts may be designed. 

Barriers & Facilitators of introducing injury prevention warm-up

Barriers to Injury Prevention

There are some frequently reported barriers to compliance with injury prevention programmes in sport. The Minnig et al. (2022) (87) review of the barriers to the adoption of evidence-based injury prevention programmes states perceived time, financial cost, coaches lacking confidence in their ability to implement it, and the inclusion of exercises that were difficult or confusing to follow. Studies that were not included in the review stated similar barriers such as not knowing what to do, not having been previously injured, not having the correct equipment and a lack of knowledge from coaches on how to implement the programme (88, 89, 90).

Facilitators of Injury Prevention

Research on the barriers and facilitators of injury prevention programmes has stated coach education is a major contributor to improving compliance (89, 90, 91).  The British Wrestling Association (BWA) has agreed to act as a facilitator for the injury prevention programme. This encompasses embedding IPW into the British wrestling coaching course, as seen in FIFA coaching licence courses and the FIFA 11+ IPW. The BWA will also make the IPP warm-up available as an online continuous professional development course (CPD) for international grappling coaches. 

To overcome other barriers such as lack of time (87, 90), costs (92), scheduling (93), and equipment (89) the IPW is designed to last 15 to 20 mins and will take place at the start of scheduled training sessions or completions. The IPW will not need any equipment and can be implemented by coaches to minimise the cost of hiring S&C coaches or physiotherapists. It has been stated that athletes and coaches perceive performance increases as a higher motivation than injury prevention (94). Research has shown that associating injury prevention programmes with increased performance benefits increases compliance rates (95, 96, 97). Due to this, the IPW will be designed in the Raise, Activate/ Mobilise and Potentiate (RAMP) (98) structure will be used as it was designed to optimise performance preparation (98). The IPW also includes Plyometric and  Post-activation Potentiation Enhancement (PAPE) techniques that have been shown to increase athletic performance (96, 97, 99).

Appraising evidence for warm-up intervention protocols 

Duration and protocol 

A frequently reported barrier to injury prevention programmes is perceived time and scheduling (87, 90, 93), so keeping the IPW protocol compact is a requirement that may help with compliance from coaches and grapplers. A 2016 systematic review on the effect of team warm-ups by Silva et al. (2018) (100) found that a warm-up protocol of 15 minutes was the optimal period to increase explosive performance. In terms of reducing injury kinematic and kinetic dysfunctions associated with injury risk factors and reduced injury incidence, several IPWs lasting between 15 to 20 minutes have been shown to be effective (101, 102, 103, 104, 105, 106). Studies have shown a compliance rate of a minimum of 2 times a week is needed for IPW of this duration to be successful (101, 106, 107, 108).

The RAMP warm-up protocol has been successfully used in combat and contact sports such as Rugby league and boxing (99, 109). The rationale for the activities included in the IPW is formatted in the structure of the RAMP protocol.

Raise

The raise section aims to elevate body temperature, heart rate, respiration rate, blood flow, and joint fluid viscosity via low-intensity activities (98). Reviews have shown that effective warm-up protocols increase the intensity until a heart rate similar to that of a competitive environment is reached (100). Research has recorded an average heart rate of 180 to 182 bpm in grappling matches and can reach a maximum of 190 – 200 (110, 111). Exercises such as high knees, heels to glutes, and head rolls have increased dynamic mobility of the spine and peripheral joints (84). Meanwhile, rolling has been shown to increase proprioception and postural control (112, 113). Additionally, Grapplers need the ability to produce a rate of force development (RFD) and acceleration for movements such as takedowns (69). Shuffle sprints will help with the RFD (114) and aid in increasing HR.

Activate

The activate section focuses on identifying the key muscles needed for grappling and then using a selection of dynamic movements to activate them (115). The physical demands of grappling involve all major muscle groups (116, 117). This section of the IPW will start with walking lunges with trunk rotation. EMG research has demonstrated that forward lunges increased activation in the Vastus Mediali and gluteus Medius and have been used in peer-reviewed injury prevention and performance warm-ups (118, 119, 120). The lunges will be followed by bear crawls, which have been used in wrestling and functional training settings to activate the wrists, pelvis and lower limbs (121, 122). Sports-specific movements have been shown to be effective in previous injury prevention programmes (123). The wheelbarrow position mimics wrestling positions that require the grappler to support their body weight with their upper extremities (81). Research using EMG has shown that press-up variations such as the wheelbarrow exercise activated the lower trapezius and the serratus anterior (124). Press-ups have been demonstrated to increase upper body and core activation (125, 126, 127) and have been used effectively in injury prevention warm-ups (128). Hindu press-ups involve a significant degree of trunk and hip flexion that mimics the 110 degrees of trunk/hip flexion seen in the biomechanical analysis of a sprawl (129).

Much like the Hindu press-up, Hindu squats are commonly used in various wrestling styles. The squat has been successfully used to lower injury prevention and increase performance in the FIFA 11 + protocol (8, 130). The Hindu squat also allows grapplers to move into greater degrees of knee flexion needed to perform movements such as the double leg takedown (147 degrees) (129). Research has shown that many head, neck and trunk injuries in BJJ are a result of landing (25). It has been recommended that increased training in landing techniques will aid in preventing landing and fall injuries as previously demonstrated in Judo (25, 47, 63). Short-term breakfall practice has been shown to improve electromyography (EMG) activity in Stenocleidomastoid, External Oblique and Rectus Abdominis muscles (131).

Mobilise

The lack of mobility has been acknowledged as an injury precursor in grappling sports (17). Additionally, it has been shown that grappling requires athletes to exert force in large degrees of an athlete’s range of movement (ROM). This can be seen in suplexes in Greco-Roman wrestling (132), throws in Judo (47), bridges in Swiss wrestling (133) and shooting for takedowns in BJJ and freestyle wrestling (69, 129). Biomechanical analysis of Greco-roman wrestling has shown that many trajectories from throws, takedowns and presses follow Circular and Helicoidal paths, resulting in hip and spinal rotation (67). Therefore, the IPW adopts the scorpion exercise to increase ROM in these areas. Neck mobilisations are also required as research has shown that neck strengthening reduces cervical injuries in combat sports (62) as well as sports-related concussions (61).

Potentiate

The potentiate stage aims to increase activity to maximal intensity in preparation for competition (98). This often includes techniques such as PAPE (99). This technique is primarily used to improve sports performance and the focus of the IPW is to reduce athlete injury. However, it has been shown that coaches and athletes perceive performance as a higher priority than injury prevention (94). Flinch’s  (2006) (134)  proposal of the Translating Research into Injury Prevention Practice Framework (TRIPP) states that only research adopted by sports participants, their coaches, and sporting bodies can prevent injuries. By including performance aspects in the IPW, compliance levels are anticipated to increase. The potentiate section of the IPW starts with plyometric exercises. Plyometric training in adolescents has also been evidenced to increase neural drive to the agonist’s muscles, reactive strength stretches, shorting cycle efficiency, fascicle length, and Vastus Lateralis pennation angle and aid in the development of muscle activation strategies (135, 136, 137). PAPE exercises such as plyometric press-ups have shown increases (4.9 %) in peak power output (138).

This section also includes partner contact drills. Wrestling and contact drills have also been recommended as injury prevention strategies for contact injuries in Rugby League and Union (139, 140). The IPW concludes with a partner reaction drill designed by the British wrestling team’s coaching staff. This involves grapplers performing takedown defensive and attacking movements as they react to their partner’s cues. Visual processing, visual fields, and visual reaction times are essential to the performance of numerous sports and play a role in athletic injuries (141, 142). The partnered drills also allow grapplers to raise their heart rate after an anticipated drop in the mobilise section.

Conclusion

This is the first evidence-based IPW for grappling sports and may act as a resource for coaches of all grappling arts. It provides athletes and coaches with a warm-up that can be performed before grappling practice and competition. The IPW will be embedded into the British Wrestling Association’s (BWA) coaching courses and as a continuous professional development course (CPD) option for international grappling coaches. Further studies can be undertaken to verify the IPW effectiveness in reducing biomechanical injury risk factors, injury incident rates and performance benefits.

Appendix

Table 1. IPW with rationale and coaching points

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