Track and field injuries: The throws

The throws provide contrasting spectacles in the respective events of shot, javelin, discus and hammer. In common, they demand finely tuned skills and great explosive power in execution. Throwers tend to be muscular and large, except in the javelin where body size is sacrificed for speed. The attempts to prohibit acquisition of mass by ingestion of anabolic steroids have gained universal support so that individuals can compete on fairer terms. The application of sensitive measures of drug detection (Beckett and Cowan, 1979) has, hopefully, begun to ehminate illegal steroid use. Strength and body size can also be increased by weight training which is an essential part of most throwers’ preparation and the occasion of many injuries. Safety procedures in handling and lifting weights should be rigidly adhered to and athletes should never work alone in the weight training room.

The throws are unique in the track and field calendar of events in that bystanders and spectators as well as competitors are exposed to risk. This applies especially to the discus, hammer and javelin where distances in the region of 70, 80 and 90m are reached respectively. Rules for competition dictate that practices are limited in location and that implements are carried and not thrown back in retrieval. All implements must fall within a restricted sector for a throw to be valid. This sector is roped off to avoid accidents in the shot and javelin. In the case of the discus and hammer, both of which involve turning before release, a cage or enclosure prevents the implement from flying off in the unwanted directions. The rules for competition strongly recommend the use of a cage of specified dimensions to promote spectator safety. Needless to say it must be well maintained by ground staff. Dissatisfaction is sometimes expressed with the C-shape of the hammer cage since it does not effectively account for different handed throwers or the turning of the hammer wire outside the head on release. A U-shaped cage increasing in height towards its front has been suggested (Johnson, 1979). A dramatic illustration of the inadequacy of the current cage was provided by a Russian competitor at the Montreal Olympic Games whose throw bounced off the track immediately in front of the assembled 5 000m runners.

Group practices also constitute a source of danger where safety considerations should be paramount. Youngsters can, for example, be taught javelin throwing in a cohort and must retrieve the implements as a group once the last individual has thrown. The teacher/coach must insist that the javelin is carried so that its metal head is not liable to cause injury. All bystanders should be aware of impending throws and keep clear of the landing areas. In discus throwing groups, left-handed individuals should be placed together at the left end of the line. If safety procedures are ingrained in the early years they will have become second nature by the time the athlete reaches senior competitive level.

A recurrent aetiological feature in throwing injuries is incorrect technique. For this reason the important performance principles will be covered for each of the throws. Additional detail is provided to present a flavour of the events.

SHOT PUTT

The shot putt is close to a pure power event and attracts individuals of great size and muscularity. A sphere 161b (7.25 kg) weight (4 kg for women) is impelled from a circle 7ft (2.13m) in diameter. A lighter shot is used in junior competition: at senior level no allowance is made for differences in bodyweight. Other things being equal, the greater the body size the greater the advantage in putting so that until weight categories are introduced for this event an element of unfairness will exist. A progressive increase in the size of putters in the major Games over the last two decades or so underlines this. An increase in weight via the muscular mass rather than body fat is preferred for greater power production.

Recognition of the importance of lean body mass has encouraged illegal ingestion of anabolic steroids to increase muscle size. The extent to which steroids have been used by putters of international standard must remain speculative. However, credence must be given to the admissions after retirement by numerous elite performers of extensive use of these drugs and acknowledgment of their adverse side-effects. Alterna- tively, body size may be legally increased by adoption of weight training regimes to boost muscle hypertrophy or by exorbitant energy intake levels. The high protein diets of many top throwers may have deleterious long-term effects as a result of the large cholesterol contents.

The rules for the event dictate that the putt is made from the shoulder close to the chin and that the arm shall not be dropped below this position or be brought behind the line of the shoulder. Besides body size, the major determinants of performance are the acceleration of the shot before release and the angle of release, which optimally is about 40°. Acceleration of the shot is enhanced by moving it as far as possible across the circle. Consequently three main techniques have developed from the basic side-on stance of Fonville and Fuchs in the 1940s. Firstly, the step-back involves a quick glide across the circle with the legs crossing scissor-like while in the air. The O’Brien method, named after the Olympic champion of 1956 and 1960, is favoured by most top throwers and coaches . Finally, the Baryshnikov spiral involves turning as in a discus throw and requires even more adroit balance as control of the body after release of the shot tends to be difficult. All methods ultimately arrive at a fundamental throwing posture with the chin, knee and supporting big toe in virtual vertical alignment prior to further rapid and upward acceleration of the shot. Putting correctly from this basic position from a standing throw is essential before the refinements of the glide can be coached or if later injuries from poor technique are to be avoided.

The power for putting is generated by forced extension of the knee and hip, augmented by back extension and supplemented by successive shoulder, arm, wrist and finger involvement in the final pushing action. Coordination of muscle action in these segments must be finely timed for efficient performance and so each is liable to injury.

Lower limbs

Muscle tears in the lower limbs are rare but may occur from loss of balance in the glide or attempts to avoid fouling the stopboard after release. Wet concrete circles and poorly gripping footwear are often implicated. In cold conditions competitors may retain track-suit bottoms during putts and keep warm in the intervals between to avoid muscle pulls. The rotational movement in the glide across the circle may endanger the meniscus of the knee.

Back injuries

Back injuries may originate from using heavy loads in weight training and are aggravated in throwing prac- tices. Improper timing of the sudden violent contraction of the back muscles can lead to tears from their attachment or through the muscle belly. Reflex spasms of uninjured muscles provide some protection. Sprains of the ligaments may occur with the more serious back muscle injuries (Littin, 1971). Rupture of the back extensors and avulsion fractures of the cervical and thoracic spines have also been reported (Groh, 1972).

Shoulder and upper arm

The shoulder is a common site of injury, probably as a result of its intrinsic instability. Development of the muscles around the joint provide a measure of security. Injury, due to imperfect timing, can occur in any of the rotator cuff muscles which fasten the humeral head in the glenoid cavity. These may be damaged at their origin, mid-portion or attachment at the greater tuberosity of the humerus with possible avulsion fracture here. The most common tendon injury is that of the long head of the biceps.

Muscle tears at the elbow include those from origins at the humeral epicondyles. Immediate pain is felt at the side of the joint. Avulsion fracture of the olecranon has also been found (Groh, 1972). The predisposing technique faults may be poor synchronisation of the arm and trunk muscles, taking the throwing elbow through too low or ahead of the shot, or overcompensation from dropping the shoulder on the non-throwing side.

Lower arm

Sprains of the ligaments of the wrist are almost widespread in shot putters which is evident in the frequent use of supports for this joint in practices. The wrist bears the weight of the shot and, additionally, is put through an extreme degree of forcible flexion. Pain is immediate and usually accompanied by mild swelling; the injury is therefore easily recognisable. Tenderness may be located either at the distal end of the radius or at the ligamentous insertion in the metacarpals.

The fingers contribute in gripping the shot throughout and in the final propulsive effort. The extensor tendons of the terminal phalanges are especially liable to damage. Injury to the tendon of the long extensor of the thumb is also possible if the thumb is not correctly positioned on the side of the shot.

JAVELIN

The javelin is thrown from behind a scratch line after utilising an approach run to gain momentum. This linear acceleration in the run-up is supplemented by transitional steps and arm movement, all in the line of intended throw. The complex interplay of segmental action is founded on a basic throwing posture with the body forming a bow-like shape. This is attained by withdrawing the spear over two strides behind the body in transition from the run-up, coming down heel first after a high knee-lift two strides later ahead of bodyweight. A wide throwing base is achieved in reaching out with the lead leg for the other to drive the hip forward on the throwing side. The throwing action is completed by taking the shoulder through quickly, the elbow high and over the shoulder and the lower arm through late in a flail-like action, the spear being released over or in front of the non-throwing foot . The optimum angle of release varies with the type of implement used.

According to Hay (1973) the speed of release is by far the most important single factor in determining the distance thrown. Since acceleration of the implement is enhanced with increasing range of movement during the throw, mobility at the shoulder, back and hip is all important. Specific exercises to increase the extent of movement are desirable. A solid support in the heel plant during the penultimate foot placement helps set up a stable throwing base. The heel spikes in the javelin boot assist this purpose though repetitive practising of the final strides on hard surfaces can cause contusions in the soft tissue of the heel.

Coaching the correct throwing technique at an early stage is essential if injuries in the propulsive arm are to be avoided. This starts with the proper grip on the missile binding and the provision of a good launching platform from an elevated palm. The throw itself is grossly similar to baseball pitching or bowling in cricket and the correct motor pattern can be introduced by throwing a cricket ball. Other useful drills might include throwing for accuracy at 15 to 20m against an incline or throwing from a kneeling position. Greater strength is promoted if the coach provides some resistance on the tail of the missile in a standing throw preventing its release or by strategic use of medicine ball throws. Strength, power and speed of limb movement are more important than body size in this event, as many top throwers are only moderate in build.

Probably the most frequent fault in novices is the tendency to throw round arm rather than with a high lead of the elbow over the shoulder. As a result the medial collateral ligament of the elbow joint can be strained. A side arm throw with the arm abducted parallel to the ground and the elbow in 90° flexion swinging through at the level of the shoulder similarly exposes the medial ligament to considerable strain. Damage appears to be cumulative rather than from a single incident. Recurrent minor strains of the ligament are characterised by pain on the medial aspect of the joint before extension of the elbow begins when the medial ligament is transmitting most force. The pain interferes with performance to varying degrees, rapidly resolves with rest but returns on further practices. The intensity of training must be reduced and the underlying fault corrected.

Another fault of novice throwers is a tendency to let the wrist only get out to the side beyond the line of the elbow joint when throwing. At the end of the throwing action the forearm is pronated sharply to prevent the whip of the javelin. According to Littin (1971) this aggravates the strain on the medial collateral ligament of the elbow. The combination of forceful elbow extension with forearm pronation may cause a pivoting of the ulna in the trochlea, forcing the olecranon medially with increased pressure on the medial side because of the long arm of the ulnar shaft. Littin referred to reports of transient paralysis of the ulnar nerve in some javelin throwers and fractures of the olecranon. Repeated stress of this type can lead to the formation of bony spurs on the medial side of the elbow. Careful attention to the positioning of the wrist under the cord grip once the javelin is withdrawn, and a correct pull through the long axis of the missile is essential for prevention.

Elbow pain is experienced by almost every competitor at some time varying from slight discomfort to symptoms severe enough to stop participation. Even accomplished javelin throwers may hyperextend the elbow at the end of the throw, impinging and injuring the tip of the olecranon process against the floor of the olecranon fossa. The symptoms result from a single errant throw and are completely disabling (Miller, 1960).

Groh (1972) reported that rupture of the pronator teres is often found in specialists in this event. This injury is probably a result of imperfect alignment of .the javelin before the throw commences. In the final phase of elbow extension and pronation the flexor muscles and pronator teres act as a brake to achieve a trip-up effect (Waris, 1946). Other common findings include rupture of the tendon of the long head of the biceps and of the tendon of the long extensor of the thumb (Groh, 1972). This last injury probably results from a faulty grip on the binding.

DISCUS

Discus throwing originated in the Greek Games thirty centuries or so ago and was included in the first of the ancient Olympic Games. It was among the events in the programme of the first revised Olympic Games in Athens in 1896 and is today moderately well supported by both sexes at all competitive levels. The discus is platter-shaped, weight 2kg for senior men’s and 1kg for senior women’s competitions with lower weights for juniors and youths. It is thrown from a circle 98.5 inches (2.5m) in diameter normally of concrete whose final surface is lightly stippled to give a firm footing without retarding the thrower’s movements.

In modern discus throwing the athlete starts at the rear of the circle facing opposite to the eventual direction of throw. The discus is held against the palm and wrist with the fingers evenly spaced, the pads of their ends curled over the lip of the discus. The grip should be relatively relaxed so that the implement is not tightly held or the wrist cocked to avoid chronic tendinitis: supination is not required to prevent the discus from falling once it is kept in motion. This applies while preliminary relaxed swings are taken with the discus at arm’s length before it is finally withdrawn as far as possible with the trunk twisted to the side. In the last preliminary swing the throwing shoulder is twisted right back while the arm is also extended behind the line of the shoulder as far as possible with the discus held at shoulder height. Flexibility in the trunk and shoulder is necessary to allow this. Bodyweight in this coiled position is supported on an extended right leg. An orthodox thrower then flexes the supporting knee, shifts bodyweight onto a flexed left leg and begins to move to the left across the circle in a semi-running stride. As the thrower spins in rotation in getting across the circle, the discus is held back in the outstretched arm so its angular velocity can be maximised. Proportionally long arms provide the athlete with a mechanical advantage which is apparent in the builds of top throwers (Tanner, 1964). The rotation culminates in a strong throwing position from which the discus is slung.

The run across the circle combines a thrust from the left leg with a lift from the right thigh, the thrower arriving at about the centre of the circle. By the time the right foot lands, the hips lead the shoulders which the discus in turn trails. The left leg scissors rapidly past the right landing heel first at the front of the circle. This allows the thrower to drive the right side of the body powerfully against a left side in a long throwing action with the chest at right angles to the direction of the throw. The thrower reaches out in delivering the missile opposite the right shoulder in a final squeezing action of wrist and fingers assisted by the lift from vigorous extension of the legs. The discus parts off the index finger which spins it clockwise, this gyroscopic effect increasing the distance of the throw by keeping the missile flat in flight. The throw is best if delivered into the prevailing wind while optimal angle of release varies with wind conditions between 30 to 40°. On release the feet normally reverse to retain balance within the circle.

To avoid injuries arising from poor technique it is important that the correct actions be coached from the beginning. Repetitive practices of winding up for a standing throw are usually effective in establishing the basic action. In the standing throw the athlete faces the direction of flight with the feet balanced slightly wider than hip width apart. Bowling the discus helps novices get the correct release off the index finger. They may also learn by tossing it vertically in an underarm action, catching it and repeating. Use of a rubber discus can help keep strain from repetitive spinning off the fingers. Rupture of the extensor tendons of terminal phalanges is common in this event (Groh, 1972). A discus strapped onto the hand can help in learning to execute the turn. The strap prevents release and allows concentration on balance and footwork without the need for retrieval. Efficient rotation is important so that the torque on the menisci of the knee is minimised.

Holding the discus correctly in an extended arm serves to avoid the wrist injuries associated with putting and those associated with elbow hyperextension in javelin throwers. Conditioning exercises for the major muscle groups of the body are recommended for this event. Strength and power of the thigh, back and shoulder musculature should be developed, since these groups are integrally involved in the coordination of a good throw. As with the shot putt, the rotator cuff muscles are liable to injury in sudden forceful contractions. Since top throwers rely heavily on weight training for strength development, it is again emphasised that such regimes should be conducted with care to avoid injury.

HAMMER

The hammer is technically the most complex of the throws and is the only one restricted to male competitors. The basic skills take years to perfect so that top hammer throwers tend to be older than their counterparts in other throwing events. In general they are also stockier in build than discus or shot putt specialists, a feature that facilitates balance in turning prior to release.

The hammer is thrown from a circle 7ft (2.13m) in diameter. The implement consists of a 161b (7.25kg) ball at the end of a 4ft (1.22m) spring steel wire. The handle is connected to the head by a swivel and to the grip by means of a loop. The orthodox thrower holds the hammer by placing the left hand inside the right with the handle resting on the middle joint of the fingers. When high release speeds are reached blisters and skin abrasions result unless a glove is worn on the inside hand. A leather glove on this hand is permitted while most throwers additionally bind the middle portions of the fingers with adhesive tape.

The throw starts with the athlete at the rear of the circle, his back towards the direction of release with the hammer resting on the ground behind his right foot. A series of preliminary swings are taken before the thrower enters his first turn. At least three turns are taken by seasoned throwers to maximise the acceleration of the hammer head before it is released into a 45° sector (reduced to 40° by recommendation of the IAAF Technical Sub-committee, 1979). The athlete, in turning quickly, is forced to sit back against the hammer as the centrifugal forces exerted on him increase with successive turns. The speed of turning increases progressively while the counter-balancing movements of the body become more pronounced. The athlete is coached to keep the arms fully extended, sit back and keep the weight over the left foot to retain balance and continuous acceleration. In the turns the athlete spins around the left foot while each time the right comes down in a pawing-like action. Good footwear is needed for protecting the soles of the feet as the spin is made on the left heel with the turn taken up in rolling fashion at the small toe: the right foot turns on the ball of the foot. The right foot retains contact with the ground for as long as possible allowing the shoulders to lead the hips and causing a transverse abdominal stretch which can then be exploited. Errors in timing at this phase may injure the transverse abdominal muscle. The hammer is delivered at the high point of the final turn at about shoulder level. The usual angle of release is about 40 to 45° to the horizontal.

The novice progresses from simple swings to learning to turn. Giddiness is overcome by focusing on one point during each rotation. A shortened wire is often used in the early stages to facilitate learning. The delicate interplay of footwork must be coordinated with the powerful leg, back and shoulder muscle action to perfect the turn. The rotational and linear forces must be integrated in explosively executing the throw. If release is marginally retarded the shoulder joint is particularly vulnerable as the hammer attempts to rip away from its tether. According to Groh (1972) pec-toralis major, trapezius and the rhomboids are common locations of injury. Back extensor muscles, cervical and thoracic vertebral spines are also susceptible. Many hammer throwers’ injuries originate in the strenuous strength training programmes these specialists employ. As weight training is usually conducted close to maximal efforts, special attention to safety is needed. Practice sessions tend to be lengthy during which errors in technique creep in from fatigue especially under turning or overturning. To pre-empt any accident arising from such episodes training should be conducted according to the safety recommendations of the rules book.

All throwing events demand highly specialised techniques as well as fast explosive actions. The most effective injury-preventive mechanism is correct skill acquisition achievable over painstaking practices. Use of portable video-tape machinery in training sessions for immediate feedback of performance is a valuable coaching aid to eliminating faults. Timing and coordination of the various body segments are essential if each is to make maximal contribution towards the total effort. Strength training of involved muscle groups is recommended in conjunction with establishment of the correct motor patterns. Specific flexibility and balance are other requisites for effective injury prevention.

A thorough warm-up prior to competition is advised. This need not include all-out throws since experience suggests that maximal efforts are best left until the competition. As this may be prolonged it is important to keep warm and supple in the intermissions between trials. In all the events a good grip on the implement should be secured, especially in wet conditions. Use of resin on the hands is permitted to effect this while a towel for drying the implement is an important item to complete the athlete’s kit.

REFERENCES

Beckett, A. H. and Cowan, D. A. (1979). Misuse of drugs in sport. British Journal of Sports Medicine, 12, 185-194. Groh, H. (1972). Sport injuries and damage to the locomotor system. In O. Grupe, D. Kurz and J. M.

Teipel (eds). The scientific way of sport. Springer

Verlag, New York. Hay, J. G. (1973). The biomechanics of sports techniques.

Prentice-Hall, Englewood Cliffs. Johnson, C. T. (1979). Hammer safety. Athletics Coach, 13, 18-25. Littin, L. O. (1971). Acute and subacute injury: weights.

In L. A. Larson (ed). Encyclopedia of sports sciences and medicine. Macmillan, New York. Miller, J. E. (1960). Javelin thrower’s elbow. Journal of Bone and Joint Surgery, 42, 788-792. Miller, S. J. (1971). Acute and subacute injury. In L. A.

Larson (ed). Encyclopedia of sports sciences and medicine. Macmillan, New York. Tanner, J. M. (1964). The physique of the Olympic athlete. George Allen and Unwin, London. Waris, W. (1946). Elbow injuries of javelin throwers.

Acta Chirurgica Scandinavica, 93, 563-575.

Sorry, comments are closed for this post.

Share On Facebook
Share On Twitter
Share On Google Plus
Share On Pinterest