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The Prevalence of Musculoskeletal Lesions in Badminton Players – a Study Regarding the Primary and Secondary Prevention Strategies

The practice of badminton predisposes to certain injuries, in addition to the many benefits it brings to the body. Our purpose was to identify those specific prevention means which can improve physical training and recovery sessions in order to obtain a more effective prevention of the specific injuries. A questionnaire designed in order to assess the particularities of warming, post-exercise recovery and prevalence of musculoskeletal injuries was applied to 35 players. From the musculoskeletal declared injuries, 77.35% were joint damages, 18.87% muscle damages and 3.78% bone lesions. The prevalence of traumatic injuries was not correlated with the particularities of age, sex, body mass index, the level of hydration, the presence of stretching as part of the physical training or warming duration. We concluded that the training must include some primary and secondary prevention methods and techniques and the main elements should be the stretching, proprioceptive coordination and plyometric exercises associated with an appropriate post-exercise recovery.


Introduction
Injuries of the locomotor apparatus in badminton are common especially in performance sport and affect both competitiveness and quality of life of badminton players. Although in Romania very few studies on this issue were made, at international level, particularly in countries where this sport is widespread practiced, surveys that reveal both the incidence and prevalence of this kind of injuries and their impact on athletes (physical inactivity days, sequelae, relapses etc.) were published.
A review of injury incidence at professional badminton players from Hong Kong, has shown that injuries in this sport have an incidence of 5.04 cases per 1,000 played hours; out of a total of 253 injuries, more than half (128) were relapses, and the most common injuries were localized on back, shoulders, hips and knees (Yung, Chan, Wong, Cheuk & Fond, 2007); another study conducted in Malaysia confirmed the predominance of traumatic lesions of the knee (Shariff, George & Ramlan, 2009).
A prospective study of one year, made on 100 players that were registered and treated at a hospital in Denmark, showed that they had 17% -minor lesions, 56% -moderate lesions and 27% -severe lesions (especially in players above 25 years) according to AIS (Abbreviated Injury Scale); 9% of sports injuries in that year were related to a previous injury; the study highlights that 12% of the injured players gave up badminton practice after injury, while 28% gave up sports activities and competitions for a period of at least 2 months (Hoy, Lindblad, Terkelsen & Helleland, 1994); according to a similar study, 58.5% of recorded injuries were represented by joint damage (especially of ligaments) and 19.8% of athletes had muscle injuries (mostly minor), occurred mainly in lower limbs and at players aged over 30 years (Kroner et al., 1994).

Material and methods
The hypothesis of this work is that highlighting the prevalence of the main types of musculoskeletal lesions in badminton associated with a proper application of primary and secondary prevention methods may be useful for achieving our goal -the improvement of training and/or recovery programs by adapting them to the particularities of this sport and to its specific pathology.
We developed a questionnaire in order to obtain information related to the injuries occurred in badminton players, as well as some information about specific training, the post-effort recovery thus to highlight the existence of predisposing factors of these injuries.
The questionnaire was conducted using http://docs.google.com and included 24 questions; 40 subjects were randomly selected from groups of amateur and performance players; the questionnaire was sent to these people by e-mail.
The first part of the questionnaire provided us with information of age, sex, anthropometric data: height, weight (with which was then the body mass index -BMI calculated for each participant), the period of time in which they played badminton (length of practice), the status of the player (amateur or professional), sports club affiliation, maximum performance, the number of workouts per week, their duration and warming particularities, hydration, which are the recovery methods used after exercise, if they had been diagnosed with any physical deficiencies (especially of the spine).
The second part of the questionnaire was completed only by those who had suffered musculoskeletal injuries and were requested, in this context, the following information for each injury: diagnosis, the followed treatment (medical, surgical, cast immobilisation or orthotics etc.), rehabilitation program (electrotherapy, hydrotherapy, physical therapy etc.), the imposed inactivity period (without training and/or competitions) and it if had been respected and, finally, if there had been taken some measures after rehabilitation in order to prevent relapses, as a secondary prevention strategy.
We particularly took into consideration the musculoskeletal injuries (of muscles, joints and bones) which occurred during training or competitions.
Out of the 40 badminton players who received the questionnaire, 35 have completed it, giving us a prior consent for use or publication of obtained data in our study.
For the statistical analysis Microsoft Excel Office 2010 software was used.

Results and Discussions
Through the first part of the mentioned questionnaire general information about the study group and data regarding the particularities of physical training program of each player were obtained (some of these results, are presented, as arithmetic means, in Table 1). Most athletes included in the study were from Timisoara (54.29%) and some from Bucharest (11.43%), Târgu-Mureș (8.57%), Iași (8.57%).
From the total of participants in this study, 23 (65.7%) are playing at amateur category and 12 (34.3%) play at performance level. The average number of weekly training sessions was 2.97±1.38, the training period -10.89±8.31 years; regarding the particularities of warming, we found out that the average duration was 9.20±2.47 minutes and stretching exercises were made by 91.43% of the participants.
16 (45.71%) respondents consume less than 1.5l water/day, and the rest hydrate themselves relatively fair.
Post-exercise recovery methods are reduced in the case of 19 cases (54.29%) only to hydration (2 athletes, representing 5.71% of the study group), or rest (3 competitors, 8.57% of total) or both (14 athletes representing 40% of the study group); at less than half of them (45.71% -16 people), associate other specific recovery methods to hydration and rest; only 2 people associated specific medication to recovery process, other 2 consume rebalancing fluids, and massage and/or saunas are used as means of recovery by other 5 athletes.
The second part of the questionnaire was completed, as previously mentioned, only by those who had musculoskeletal injuries during training or competitions (88.57%) ( Figure 1).   There were reported 7 grade III and 4 grade II ankle sprains and 9 third degree knee sprains (most with complete tears of the anterior cruciate ligament), 2 second degree (with damaging of anterior or posterior cruciate ligament) and a first grade knee sprain (with anterior cruciate ligament injury); there were reported 18 cases of meniscal injuries -mostly in internal meniscus (14, of which 9 at right knee and 5 at the left one).
By analysing the affected side, it can be easily observed that injury reports are in "favour" of the right side of the body with a ratio of about 2:1, which is the dominant part in most athletes ( Table 2).
On the second place as lesion type were the muscle injuries (5 fibrillar and fascicular ruptures and 5 cases of tendon injuries); muscle ruptures were localized in the adductor muscles (longus and magnus), soleus, gastrocnemius, and quadriceps femoris muscles.

Table 2. Joint injuries in study group
The tendon lesions were diagnosed as tendinosis, tendinitis or tenosynovitis at the right elbow extensors (3 cases), ulnar extensor carpi (1 case), quadriceps femoris (1 case) and a case of rupture of the Achilles tendon.
2 bone lesions were reported: 1 distal phalanx fracture of the right toe and 1 heel spur in the right foot).
After injuries, all players were recovered and confirmed that had adapted their training program (mainly referring to the process of local warming and decreasing the solicitation of previously affected area, by using special orthotics).
By calculating the Pearson coefficient between the presence of injuries and other types of information collected, we found no significant values for r; thus, we have not found significant correlation between the presence of the injury and the degree of hydration (r=0.093), practitioners' age (r=0.128), the number of recovery methods (r=0.156), the number of workouts per week (r=0.082), the number of muscle groups on which stretching have been applied (r=-0.132) or warming duration (r=-0.004). The number of injuries is not correlated either with the performance level, or body mass index.
The results of our study confirm that the injuries of badminton players from the study group were not favoured by age, degree of hydration, complexity of recovery, warming duration or the stretching complexity in training; although we would have expected a correlation with the presence of at least one of these factors, remains questionable the accuracy of information provided by the participants.
Considering that all information received from them were correct, we conclude that the injuries could be prevented probably in other way -increasing the quality of the following elements: hydration, stretching, recovery etc., in addition to the use of certain specific exercises for increasing the proprioceptive coordination and balance, and for the strength-speed development.
Although at performance level, the requests are higher in general, the players do not have considerably more injuries, may be because at that level, players does not make great mistakes in physical training, warming etc. We may add that the

Internal meniscus injury 9 5
External meniscus injury 2 2 BMI is not important as a predisposing factor in our study because 82.86% participants have a normal BMI (only 6 participants are overweight and none obese) Racquet sports require an increased endurance of the joints, muscular and cardiovascular systems. Knees and ankles are the most solicited joints in accelerated movements and quick changes of direction; this aspect is supported by a large number of injuries reported in these joints; also, the repeated ample movements of the upper limb during services are challenging these limbs, and especially the shoulders; repeated overhead actions can produce bursitis, rotator cuff tears or impingement syndrome. Lower back pain can occur also due to overextension of the spine.
The hip adductor muscles, wrist muscles may be also affected by the repetitive or sudden contractions during the game. In badminton, a special coordination and balance, excellent stability of the legs for the rapid changes of direction are also necessary; a good range of motion, strength and speed are required when the players hit the ball and, also, a good stability in order to transfer the power is essential (British Medical Association, 2011).
During warming, the body temperature should increase slightly, with a small load of the cardiovascular system and should include all muscle groups used in the game. Physical training should be centred on developing strength, power and cardiovascular fitness; thus, interval training for cardio-vascular system combined with plyometric exercises for developing power will be indicated Stretching has two important roles for badminton players: in preventing injuries and in increasing performance (Norris, 2013), even, if, after some authors (Hausswirth & Mujika, 2010), stretching does not improve maximal strength, rate of force development, vertical jumps (indicators of explosiveness) or time to exhaustion; in racquets sports, the hips, upper body (especially the shoulders) and back are under a considerable strain; also, the wrists, elbows and ankles must be flexible in order to perform effectively on court (Norris, 2013).
Flexibility can be developed especially through stretching; it will reduce stiffness and thus, the risk of injury; types of stretching which are recommended in badminton are passive and active (isometric, ballistic sport) ones; stretching is particularly important for both warming and for the end of the training; stretching alone is not generally effective as a recovery method and has sometimes contraindications; quoting Hausswirth et al. (2010), stretching should be avoided immediately after muscle strengthening sessions or specific physical activities that induce muscle soreness.
An important stretching exercise for badminton players is "sleeper stretch" which involves the stretching of the posterior scapular-humeral joint capsule which is particularly important in preventing posterior shoulder tightness and glenohumeral internal rotation deficit (Mine, Nakayama, Milanese & Grimmer, 2016) or impingement syndrome (Manske, Grant-Niermann & Brennen, 2013).
Increasing strength of the muscles that are frequently solicited or injured in badminton should also be an important part of the physical preparation; an effective exercise is called "lawnmower", which is dedicated to the rotator cuff muscles in the upper and middle back; it helps developing the coordination between the upper and lower parts of the back and increases the control over the shoulders.
The ability to generate power is critical in performance and success in badminton. A plyometric program improves the coordination, efficiency, speed and power in preparation for sport participation (Houglum, 2010); in badminton, plyometric training have an important role in improving lower body strength and stability. It is demonstrated that lower extremity plyometric exercises reduce injuries in team sports, while combined with other neuromuscular training (i.e. strength training, balance training and stretching); on the other hand, plyometric exercises involve an increased risk of injury due to the large force generated during training and requires a good strength, flexibility and proprioception (De Bremaeker, 2013).
To minimize the risk of injury, warm-up training is recommended to prepare the athlete in terms of coordination and muscle pre-stress for the challenges ahead. Plyometric exercises include jumps and sideways hopes in all forms and can be done based on the needs of each athlete, being individualized also on age, body weight, competitive level, surface, footwear, proper technique, progression and goals; also, a rest of between one and two minutes is suggested and reactive jumps on the court floor are recommended (Fröhlich, Felder & Reuter, 2014) and, in addition, we must take into consideration the precautions and contraindications for plyometric training both in rehabilitation and training (Houglum, 2010).
The importance of hydration in sport and mental performance and also in rehabilitation processes is well known. Even if the low hydration level of our study group is not correlated with the prevalence of injuries, it is recognized that the performance quality and the safety of the players depend largely on an adequate hydro-electrolytic balance; that includes, beside a proper hydration, also the electrolyte replacement during recovery (Hausswirth et al., 2010) This last one aspect is present only for a few players from our study group.
We consider that the mentioned changes should be included, where appropriate, in physical training programs of the players in order to improve their performance level; it will also be useful to monitor the recurrence rate of injuries among them.

Conclusions
Soft tissue injuries of the lower limbs (especially, ligaments and muscles) are the most common injured tissues in badminton players, data which is confirmed also by the available data in scientific literature; the lesions are more common in older age groups, but have not confirmed any link between injuries and gender. Sprains remain the most common injury of young players, while muscle injuries (including tendon lesions) dominate in senior players.
Although they are rare in badminton compared to other competitive sports, the serious injuries can appear also, requiring specialist treatment and a longer rehabilitation period. Individualized training programs are a necessity in this sport, given the high rate of recurrence of lesions; they must include primary and secondary prevention methods, where the main elements should be stretching, proprioceptive coordination and plyometric exercises, and also post-exercise recovery methods suitable for the athletes' needs.
Although at the athletes followed in this study significant correlations between the occurrence of injuries and age, number of workouts, warming duration, realization of stretching were not found, we conclude that prevention of injury could depend on increasing the recovery and warming quality, the use of certain specific exercises for proprioceptive coordination, balance and for development of strength in speed regime.