The sports which will be particularly considered are tennis, badminton and squash although the information will be of relevance to other less popular racket sports. Generally, these sports would be described as ‘minimum hazard’ in terms of injury rate (Eastwood, 1964) in comparison with, for instance, American football, soccer, or even basketball. However, there are a range of injuries which do tend to be associated with particular demands of racket sports. Tennis, badminton, and squash all require frequent changes of direction in a confined space which involve abrupt deceleration and fast acceleration. Consequently, the ankle, knee and thigh are the sites of most lower extremity injuries among racket players. Other injuries arise from the fact that the upper extremity is used unilaterally, the shoulder and elbow being particularly vulnerable. The racket itself can be a lethal weapon, and the ball or shuttle is a particularly dangerous missile. Hence, head and eye injuries are not uncommon.
Because of this similarity of injuries across racket sports, the article is sectioned in terms of specific injuries rather than in terms of specific sports. The relative incidence of injuries within racket sports will be apparent from the particular emphases within sections. The practical causes of injuries are discussed, together with suggestions as to how their occurrence may be avoided or reduced.
HEAD AND EYE INJURIES
The most common head injury is facial laceration, usually caused by a widely swinging racket and, although it does occur in tennis and badminton doubles play, is, for obvious reasons, most prominent in squash. Jonah Barrington suffered cuts around the left eye on 17 occasions in eight years play, with his opponent’s follow-through causing most of the problems (Barrington, 1973).
Although facial lacerations can be traumatic, a more serious problem can arise from ocular injuries sustained in play. The partner’s racket in doubles play or the opponent’s racket in squash account for some eye injuries but the majority are attributable to the ball or the shuttle. In squash, North (1973) and Cobb (1977) found that approximately 30 per cent of eye injuries were caused by the racket and 70 per cent by the ball. In badminton, Chandran (1974) reported a ball-racket ratio of 6:1 in a total of 63 cases examined. Eye injuries in tennis are less frequently sustained with the overwhelming majority caused by the tennis ball in the doubles game (Burstein, 1963; Seelenfreund and Freilich, 1976).
Generally, spectacle wearers appear to be more at risk of serious injury. Ingram and Lewkonia (1973) examined squash players and found that 70 per cent of the most seriously injured were spectacle wearers. Seventeen per cent of North’s (1973) sample of squash players with ocular injuries had broken spectacles. Not wearing the corrective lenses during play is not the answer as near-sighted individuals are most at risk (Chandran, 1974). Those who need ocular correction should wear plastic or toughened glass safety lenses with a sturdy frame (Ingram and Lewkonia, 1973; Vinger and Tolpin, 1978); Ingram and Lewkonia (1973) and Koetting (1971) further suggested that contact lenses may reduce injury risk although Vinger and Tolpin (1978) took a contrary view. Blonstein (1975) was concerned enough about the injury risks that he tentatively suggested the use of protective headgear incorporating a visor in squash. Additional sound but ominous advice offered by North (1973) was that one-eyed individuals should be warned of the risks. Burstein (1963) argued that such individuals should be prevented from playing potentially hazardous sports. A similarly heavy handed approach has been adopted by at least one American university where athletes are required to wear safety lenses for high-risk sports (Rachun, 1969).
Examining the factors which are contributory to ocular injury in racket sports, it appears that inexperience is of major importance. In badminton, eye injuries usually result from the shuttle hitting a player following a smash hit, and Chandran (1972) noted that the most vulnerable players in this situation were between 11 and 20 years old. In tennis, the doubles player at the net is particularly vulnerable when inadequately instructed in the techniques of protecting himself from the rapidly played ball. In squash, it is likely that most of the eye injuries could be prevented by improved technique and a more rigorous enforcement of the rules.
Squash players are particularly exposed to head and ocular injuries because two players are hitting the ball hard within a confined area and without a net to separate them. Hence, high degrees of skill, cooperation and sportsmanship are necessary in order to minimise injuries. Problems arise with the inexperienced or unwary player who takes his eye off the ball during rallies. Particularly when the ball is in the rear of the court and his opponent is behind him, this player is vulnerable when he finally does turn to see where the ball is. Inexperience is likely to be a factor in several other dangerous situations; when a player attempts a vicious reverse angle volley offthe serve of an opponent who is already moving to the centre of the court; when a player has an excessive follow-through of the racket after the shot ; when a player is ‘crowded’ by his opponent ; when a player ‘turns’ in the back corner and plays the ball; when a player obeys the natural tendency to play the ball at all times. Sound coaching can reduce these problems. A player should be encouraged to watch the ball until the opponent is playing the shot and he should be instructed in good stroke technique which will help prevent excessive racket swing and dangerous mis-hits. Additionally, he should learn to be cooperative on court, allowing his opponent ‘fair view and freedom of stroke’ and always refraining from playing a ball which might be considered dangerous to his opponent. In view of the safety problems created by left-handed players, coaches should advise players on the ways in which tactics must be adapted for the left-handed opponent. Officials should warn players about dangerous play and should not hesitate to employ the ultimate sanction of disqualification against the minority who create danger as an intimidatory tactic.
These suggestions can help reduce injury risk but a protective device for the eyes could provide complete safety. Difficulties may arise in persuading players to wear them.
SHOULDER AND BACK INJURIES
Injuries to the shoulder are fairly common in racket sports (Williams, 1978) because of the regular and excessive leverage forces to which the region is subjected. Players are prone to clinical conditions experienced by baseball players, only to a less extreme degree. In particular, the action of the tennis serve and the overhead smash in all racket sports can broadly be likened to the throwing action of the pitcher. Hence, during the backswing phase in the racket sports, the insertions of the anterior deltoid and pectoralis major muscles may be injured by severe tension (Novich and Taylor, 1972). In the impact and follow-through phases, the fully stretched scapular insertions of the posterior deltoid, rhomboid major and long head of the triceps may suffer trauma because of the overload. Anterior dislocations of the gleno-humeral joint as a result of the tennis serve have been documented (Novich and Taylor, 1972). An injury associated with constant motion of the shoulder as occurs in racket sports, is bicipital tenosynovitis (O’Donoghue, 1970). Priest and Nagel (1976) examined 84 world-class players and found that more than SO per cent had had shoulder symptoms at some stage. Anterior rotator cuff symptoms were most common, particularly among the males. The serve was associated most often with anterior cuff discomfort followed by the overhead smash and the backhand. They maintained that symptoms resulted from impingement of the cuff caused by abduction of the arm, but Bernhang (1976) felt that rotation of the shoulder, through approximately 200° in the case of the serve, coupled with maximal abduction, caused the symptoms. He further suggested that the reduced incidence of the injury among females is attributable to greater joint flexibility, allowing easier external and internal rotation.
It appears that the main cause of injury in this region is a faulty technique deriving from over-vigorous stroke playing. As in most sports skills, there exists a speed/accuracy trade-off and too much emphasis on speed, particularly when there is inadequate supporting musculature and flexibility, leaves the player vulnerable to injury. Preventive measures entail placing emphasis on accuracy of serving and stroke-making, initially at the expense of speed. The latter can be increased as a function of increased strength and flexibility.
Any sudden and severe change from spinal extension to flexion or vice versa can lead to back strain. The problem is exacerbated by simultaneous torsional movements of the upper body. For example, acute strain can be caused by an abrupt change of movement to make a recovery shot with consequent high torque overloading the attachments of the dorsal spinal ligaments (Sicular, 1971). Supple (1971) observed lumbar strain resulting from use of the complex American twist service in tennis. Back injuries are as likely to be linked with inadequate warm-up, lack of fitness, fatigue and climatic conditions as poor technique.
ELBOW AND WRIST INJURIES
The elbow is a frequent site of complaint in racket players. Priest et al (1977) found three main regions around the elbow at which symptoms occur in tennis players – the lateral epicondyle, the medial epicondyle, and the groove of the ulnar nerve. They found that medial symptoms were more common than lateral symptoms in top tennis players. The main cause of medial problems was the serve, with cubital tunnel pain being associated with the spin serve. Other than avoiding excessively strenuous serves and reducing the spin, it appears that there is little that the good tennis player can do to prevent medial symptoms. The problem is much less severe among club players.
In squash, medial symptoms are relatively infrequent but would be associated with ‘wristy’ forehand shots played from postures of marked anatomical weakness. As well as problems with the medial epicondyle, this kind of action may lead to strains of the forearm flexors and sprain of the wrist in extreme cases. In squash, the remedy lies in playing with a cocked wrist for the whole of the stroke. Similarly, if this technical principle is not observed on the backhand stroke, acute strain and tenosynovitis of the forearm extensors may result.
Lateral epicondylitis, or classic ‘tennis elbow’ is by far the best documented injury. The syndrome was first described in the 1870s, and since then many explanations have been offered for its occurrence. Nirschl (1974a) commented that ‘the concepts of massive overload, multiple repetition, quality of tissue, age, potential hormonal imbalance (in women) and available strength, endurance, flexibility, as well as mechanical joint design, all play their respective roles’. Interacting with these factors are the equipment used and the skill level of the player.
Equipment related factors have often been associated with the occurrence of elbow injuries. Plagenhoef (1970) implicated head-heavy rackets whereas others stress the damaging effects of an abrupt change of racket type, especially from light to heavy (e.g. Slapak, 1964). Williams and Sperryn (1976) suggested that a change from wood to steel without an accompanying change in technique is causative. Clearly, this factor needs further investigation in the light of Priest’s (1976) finding with a large sample of tennis players that the occurrence of symptoms was highest in those using wood rather than steel or aluminium rackets. To add to the aetiological confusion, Steiner (1976) argued that the type of racket is not a significant factor in elbow injuries. He also suggested that the size of the racket handle is of minor importance. However, several experts hold a contrary opinion. Williams and Sperryn (1976) suggested that whereas the tennis grip size is near-optimal the badminton grip size may be incorrect. Nirschl’s (1977) investigations have led him to suggest a reliable method of determining the correct racket handle size of the tennis racket – the circumference equalling the distance from the proximal palmar crease along the radial border of the ring finger to the tip of the ring finger. The same formula cannot be applied to badminton and squash because of the important differential influence of impact forces, forearm strength, racket weight, and so on, across the three games. Research is needed to identify optimal grip sizes in badminton and squash. In the absence of specific information, it is best to adopt as large a grip as is comfortable.
Excessive string tension has also been mentioned as a causative factor in elbow injury in that the ball impact vibrations transferred to the arm are increased (e.g. Nirschl, 1977). Generally, relatively light and non-rigid rackets with moderate string tension should be preferred. Gut is preferable to synthetic stringing (Novich and Taylor, 1972). Plagenhoef (1970) recommended a gut tension in the tennis racket of approximately 561b (25.4kg), whereas Nirschl (1974b) advised conventional stringing with sixteen gauge gut at 521b (23.6kg). This discrepancy can be explained in terms of the greater gut tension requirement of the advanced player.
Most information on causative factors in elbow injury relates to inadequate techniques and the specific physical demands of racket games. During games, extensor overload is caused by the powerful repetitive hyperextension movements of the arm linked with vigorous rotary movements of the forearm. Although tennis elbow can be caused by pronation or supination of the forearm in racket games, it tends to be associated* with pronation. More specifically, Nirschl (1975) maintained that extensor overload can occur in all positions from full pronation of the forearm to neutral. The reason presented was that tennis professionals are less prone to tennis elbow than amateurs in that they tend to avoid pronation strokes and use the extremity less for power and range of motion.
Somewhat surprisingly, Priest et al (1977) found that among amateurs, tennis elbow was more common in higher ranking players. However, epicondylitis can be caused by both poor technique, more common among low-ranked amateurs, and by cumulative effects of powerful hitting associated with the higher ranking amateurs and the professionals. Slapak (1964) argued that the club player’s elbow symptoms are linked with mishitting, whereas the good player may succumb to the combined effects of fatigue and overuse.
The technical problems particularly associated with the backhand stroke are exacerbated by the common strategy of playing the ball or shuttle early. This demands precise timing but without the advantage of time for elaborate preparation of the stroke. Mistiming may well involve extensor overload, particularly if the missile is hit off-centre and the torque is increased beyond a manageable level. A tighter grip would be needed to counteract the inability to find the sweet spot and the resultant increased vibrational shocks transmitted to the arm may be a cause of tennis elbow (Hatze, 1976). There is also indirect evidence that moderate players are likely to suffer local fatigue because of unnecessarily sustained grip pressure, a situation which would leave them more vulnerable to the development of elbow symptoms. Bernhang et al (1974) found that better tennis players have a short-duration maximum grip pressure which is also coordinated more closely with ball impact. It seems that tennis and squash players particularly should be more discriminating in the application of maximum grip pressure, and that learners should use only moderate grip tightness to diminish the effects of torque recoil forces being transmitted to the elbow.
Poor backhand stroke production in tennis and squash is characterised by the predominant use of the forearm extensors as the power source for the stroke rather than correct weight transference and shoulder muscle power. Nirschl (1975) noted that the faulty backhand in tennis is often accompanied by an exaggerated backhand grip with the thumb placed behind the handle for additional power. Such a combination of factors means that the player tends to pronate the forearm and punch at the ball with the extending elbow and wrist. Bernhang et al (1974) referred to this as the ‘leading-elbow’ stroke which they noticed in players afflicted with tennis elbow.
An additional outcome in squash is for the players to employ a very wristy backhand to achieve the necessary power. If the ball is missed, or even mistimed, the extensor overload resulting from a wristy stroke will be high. Similarly, high overload exists where a back-swing is negligible or absent as a means of disguising a stroke, as for example when a squash player at the front of the court whose arm is fully extended and pronated to play a short shot, suddenly plays a lob to the back with a flick of the wrist . The wrist is necessarily used in badminton but the consequences are less severe because of the relatively light racket and missile.
Preventive measures must come through sound coaching; specifically they will involve learning to extend the power source to the shoulders and incorporating transference of weight to the leading foot on impact. Moreover, the swing should begin early so that these aims can be accomplished more easily. It is clear that the forces acting on the extensors can be greatly reduced with the two-handed tennis backhand, and the fact that this stroke is employed successfully by world class players suggests that its widespread introduction should be encouraged.
THIGH, KNEE AND LOWER LEG INJURIES
Strains of the adductor group of muscles on the inner side of the thighs and the iliopsoas muscles are frequent in racket sports. Particularly in badminton and squash, deep lunging movements are required which involve severe eccentric contraction of adductors and maybe over-active contraction of the iliopsoas. For right-handed squash players, the adductors of the right leg are affected as it is this leg which tends to lead in the deep lunges to the front of the court . The deep lunge is a valuable aspect of play in that it can often save time in reaching the ball and recovering to the middle of the court. As it must remain part of the racket player’s repertoire, systematic flexibility exercises and a thorough pre-match warm-up are recommended as a means of reducing the risk of adductor strain.
Knee and lower leg injuries
As in other sports which demand twisting, turning and sudden changes of speed and direction, knee injuries are quite common in racket sports. Sprains of the medial or lateral menisci and ruptures of the cruciate ligaments have been observed in tennis players (Supple, 1971). Williams (1978) noted 15 cases of racket players with chondromalacia of the patella among a sample of 100 sportsmen with this injury. It can be caused by repeated abrupt checking of the extended knee and reversal of direction or as a consequence of synovitis of the joint (O’Donoghue, 1970). An awareness of optimum footwear traction, together with relevant strength and flexibility training will help minimise the occurrence of trauma associated with the inherent stresses of racket games. Some authorities recommend knee strapping where strain is a possibility (e.g. Reahl, 1967).
One of the most common lower leg injuries among racket games players is calf muscle strain. Sometimes referred to as ‘tennis leg’, it usually involves a rupture of the medial gastrocnemius belly (Arner and Lind-holm, 1958). It occurs when the foot is in maximal plantar flexion and is exposed to violent dorsiflexion while the knee joint is extended. The fact that the injury commonly occurs in middle-aged sportsmen suggests that diminishing strength and flexibility are contributory factors. Froimson (1969) faulted the flat-heeled tennis shoes which allow exaggerated dorsiflexion, thereby tightening the heelcord and encouraging gastrocnemius rupture.
FOOT AND ANKLE INJURIES
Foot injuries can be minimised by a reliance upon durable and well-fitting footwear. Too often, especially with new or ill-fitting footwear, players develop calluses and friction blisters on the tops of the toes or the balls of the feet. Bruising of the heel or ‘black-heel’ (Benjamin, 1973) can result from a combination of poor footwear and hard playing surfaces. Cushion-soled socks or more than one pair of socks is recommended and special care should be taken in the selection of footwear. There should be a fixed cushioned sole with arch support and there should be room for only minimal lateral and horizontal movement of the foot. If too much movement is possible, then the usually excellent traction of modern footwear can cause the foot to be forced into the front of the shoes when the player suddenly stops. This condition, sometimes described as ‘tennis toe’ involves haemorrhage beneath the toenails (Gibbs, 1973). The fact that ingrown toenails can also occur in such circumstances suggests that proper care of the feet is also essential.
Ankle injuries, mainly strains and sprains, are fairly common in racket sports and this too may be in some measure due to the design of modern footwear, e.g. too much traction, too low cut. The player is often required to change direction laterally which can place overload on the lateral ligaments of the ankle. Some sports shoes, either through wear or design fault, exhibit a rounded continuity between the sole and the upper at the lateral aspect which increases the likelihood of lateral rotation of the foot . Vulnerability would be present, for instance, when a player moving to the right suddenly uses his right foot to check his stride and moves to the left. The foot is forcibly inverted and the momentum of the weight passes over the outside of the joint. The ankle is at its most vulnerable when the foot is simultaneously plantar flexed.
McCluskey et al (1976) described how lateral ligament sprains can result from a bowstringing of the tight Achilles tendon when the foot is in extreme dorsiflex-ion. They recommended heelcord stretching exercises as a preventive measure. Heelcord tightening accompanied by a violent movement of the toes causes rupture of the Achilles tendon. Berson et al (1978) found that this injury constituted approximately 18 per cent of lower extremity injuries in squash players, whose average age was 39.5 years. In view of the fact that exaggerated dorsiflexion is implicated in ankle sprains, and ruptures of the Achilles tendon and gastrocnemius, it seems that there is a need for a specially designed shoe with an elevated heel, which would be particularly desirable for middle-aged racket players.
In cases where there is a known weakness of the ankle, strapping is sometimes recommended. However, controversy exists as to the ultimate benefits of strapping. Reahl (1967) suggested that in sports where the ankle is vulnerable, strapping should be mandatory. Wiecher (1967) and Williams and Sperryn (1976) were less convinced, arguing that there will be an increasing dependence effect with relevant muscles tending to atrophy. Wiecher further stated that strain may be transferred to the knee because of the constraining effects of the strapping. However, Garrick and Requa (1973) found a decreased frequency of ankle sprains over two seasons in basketballers using ankle strapping and no consequent increase in knee strains.
Only those injuries which are most commonly associated with racket sports have been dealt with. Of course, racket players occasionally sustain contusions, dislocations, fractures, and so on, but the incidence of such injuries does not warrant their inclusion here.
The risk of incurring many of the injuries described can be reduced or eliminated by a sensible appreciation of safety on court. In tennis, badminton, and particularly squash, there must be an awareness of the need for cooperation between players in a competitive environment. Equipment must be well-maintained and appropriate for the particular conditions, e.g. shoes with soles suited to the playing surface, a racket grip with a non-slip quality, and so on. A strict enforcement of the rules should complement these measures.
Other injuries are caused by technical deficiencies, inadequate flexibility and muscular development, fatigue, and extreme overuse. The remedies are self- explanatory, but usually difficult to initiate systematically. Expert advice is necessary for the avoidance or removal of technical faults and for the planning of relevant strength and flexibility training programmes. Players should resist the temptation to continue playing when extremely fatigued, as the muscles are more vulnerable to overload stresses per se and the player is more likely to error and technical deficiency.
Overuse injuries usually involve a progressive deterioration and players should seek medical advice, or at the least, restrict activity, at the first signs of discomfort.
It is likely that the incidence of many common racket sport injuries will be reduced in the future as a function of improved facilities, equipment, coaching, off-court training, player awareness, and, not least, by the increased sophistication and availability of sports medicine facilities.
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