1. BMJ 1994; 308 : 1430 (Published 28 May 1994) <br />Education and debate<br />ABC of Sports Medicine: Overuse Injury In Sport<br />P N Sperryn<br />+ Author Affiliations<br />New Victoria Hospital, Kingston, Surrey and the Hillingdon Hospital, Uxbridge, Middlesex.<br />The demands of training make overuse injury endemic in modern sport. High volumes of hard work underpin strength and stamina, while skills are honed through endless repetitious practice of event techniques. <br />Causes of overuse injury<br />Load too great for conditions<br />Technique or posture poor<br />Equipment faulty or of poor quality<br />Posture or anatomy inappropriate<br />Sports training and competition have intensified with the the trend towards professionalism. For instance, many club level runners now cover some 50-110 kilometres a week, mostly on hard surfaces, instead of the previous generation's 30-40 kilometres. Field event athletes may train with weights of over 130 kg, and the scope for injury is obvious. Swimmers, often young adolescents, can train for several hours a day, and the physical, mechanical, and mental stresses are important factors in many youngsters' decisions to drop out of sports prematurely. <br />Overuse factors<br />Load<br />An appropriate training load is one that the athlete is ready to manage on a given day but no ready definition exists of ideal or safe training loads. The concept of gradual and continuous training increments is central to the serious athlete's career development as well as safety. In today's sport, the winner is no longer the best athlete, but the one who succeeds in reaching the start - a statement well illustrated by the familiar pattern of outstanding athletes overtraining at the peak of their careers and breaking down in the run up to major competitions. <br />Progressive resisted exercise - for training and rehabilitation<br />Intensity of exercise increases gradually<br />Loads increase slowly (rather than starting exercise too intensively and increasing loads too fast)<br />A training history is essential for the diagnosis and management of injury in athletes. Overuse injuries result from unaccustomed overload, such as going to training camps, working on new techniques, or being pushed by over ambitious coaches. More unexpectedly, simply returning to normal training after a rest long enough to “detrain” the tissues catches athletes unawares. The rule of “progressive resisted exercise” that governs medical rehabilitation also applies to training people with fit locomotor systems.<br />Technique<br />Technique is important to athletes. Axiomatically, the better the technique, the fewer the injuries (and the better the performance). Hence, if a doctor's role does not extend into coaching, he or she should at least recognise the need to refer an injured athlete to a competent event coach to clear up the current injury and to prevent its otherwise almost inevitable recurrence. <br />Preventing overuse injury<br />Recognise and correct poor technique or posture<br />Check fit and appropriateness of equipment<br />Warm up and stretch before and after sport<br />Gradually increase intensity and duration of practice<br />Posture<br />Posture is a key factor underlying injury related to movement, something long known in industrial medicine. There is often conflict between athletes' anatomy and the demands of their sports. In runners certain limb alignments and movement patterns predispose to injury. The importance of recognising such injuries is that their correction depends more on mechanical adjustment of running action than on medicine or physiotherapy. <br />Equipment<br />Equipment causes many overuse injuries, from arm strains due to faulty rackets to blisters from shoes, and equipment manufacturers are never far from the thoughts of sports physicians. <br />Combinations of factors<br />These factors - load, technique, posture, and equipment - may combine to cause pain and can be adjusted synergistically in treatment. For instance, knee pain in cyclists may be associated with cycling on a bicycle with a low saddle. Raising the saddle may relieve the symptoms by allowing the straighter leg action to balance better the strength of the quadriceps components and improve patellar tracking. Similar considerations apply to the backache that is common in cyclists, where judicious adjustments - up or down - of the saddle alter symptoms. <br />Types of overuse injury<br />Aids to diagnosing stress fracture<br />History of training<br />Pain on ultrasound therapy<br />Plain x ray film<br />Technetium bone scan<br />Computed tomogram<br />Tissues prone to overuse injury<br />Bones (stress fractures or metabolic overactivity)<br />Joints (soreness, tenderness, restricted movement, effusions)<br />Ligaments (overstrain)<br />Muscles (stiffness, (enthesiopathy rhabdomyolysis) at junctions with bones)<br />Tendons (overstrain, tenosynovitis)<br />Bone<br />Bone suffers from overt stress fractures. Stress fractures are recognised by their history of localised “crescendo” type pain related to exercise. Early plain films are normal, although painful response to localised therapeutic ultrasound is a diagnostic pointer. It is essential to treat a stress fracture by rest from the causal activity. This must be continued after the usual early pain relief, which may give a falsely good picture and encourage resumption of training.<br />More worrying for the clinician is the range of stress or overload lesions falling short of plain x ray film diagnosis. This may show a more diffuse metabolic overactivity on technetium scanning in line with more widespread bone overload. The tibia may show this diffuse pattern in some runners with shin soreness. This must be separated from long flexor strain or compartment syndromes. The practical implication is that the “tibial overload syndrome” needs a very protracted spell of rest from loading. As this probably means a year off running, the athlete is entitled to scanning “proof” of diagnosis before such a long rest sentence.<br />Joints<br />Joints may become sore after exertion such as running on hard pitches in stiff boots. Clinically there may be joint tenderness and restricted movement. More serious lesions, such as infection or the adolescent hip disorders, must be excluded but a clear history of inappropriate overload is a basis for the diagnosis of overuse strain, though the pathological nature of the strain may be uncertain. Occasionally an effusion is seen after acute overtraining - for example, in the knee. This usually settles rapidly with rest. There is no indication for corticosteroid injection in these cases. <br />Ligaments<br />Ligaments are very often overstrained. Strains of the collateral ligaments of the knee and ankle provide much of the routine clinical load of “sports medicine.” Such injuries may reflect faulty technique or posture that needs to be corrected for full recovery. For example, persistent running on the same side of a strongly cambered road may lead to chronic ankle ligament pain - on the “downside” lateral and “upside” medial collaterals. Appropriate advice often makes formal medical treatment unnecessary.<br />Enthesiopathy<br />Enthesiopathy describes strains of muscle, tendon, or ligament attachments to the periosteum. These may include wrist extensor strains in racket sports, tibialis anterior strain in young footballers, elbow epicondylitis in racket sports and golf, and some cases of runners' shin pain. Treatment is by correcting any sporting causes, rest, and physiotherapy, and these strains often respond well to local corticosteroid injection. <br />Muscle<br />Muscle overuse starts with everybody's “stiffness” after unaccustomed exercise. More tennis elbows probably result from industrial work, gardening, or carpentry than from sport. Rhabdomyolysis may occur after severe exertion and, rarely, leads to serious illness including renal failure. It is also seen in marathon runners, some of whom have remarkable tolerance for, and recovery from, this form of severe tissue damage. Initial rest and lower exercise levels are the essential treatment for muscle soreness after exertion. The athlete should be advised on more gradual increments in future training. Despite extensive folklore, there is no established therapeutic benefit from heat, cold, or massage, and non- steroidal anti-inflammatory drugs have been shown to help only through their analgesic effects. Warming up and stretching before exercise help to raise muscle temperature and improve coordination. Stretching immediately after exertion is important in minimising subsequent stiffness.<br />Tendons<br />Tendons are often and painfully overstrained in sport. The typical acutely painful swelling of tenosynovitis follows acute overtraining and requires rest or immobilisation. The major tendons, the Achilles and patellar, have no formal synovial sheaths. They may become inflamed through simple overuse or because of friction - for example, from footwear rubbing on the Achilles. Chronic overuse injuries may be associated with focal necrotic lesions; chronic peritendinous fibrosis; and partial, sub-total, or complete ruptures. The importance of identifying any sporting cause is great as early diagnosis may prevent protracted disability. <br />Principles of management of overuse injuries<br />Treatment of overuse injury<br />Rest affected part, but exercise remainder of the body<br />Non-steroidal anti-inflammatory drugs<br />Physiotherapy<br />Local corticosteroid injection (except intra-articularly)<br />Corrected or improved exercise technique<br />Firstly, correct the causes and apply compensatory “underloading.” Rest need not necessarily be absolute. To athletes training intensively reduction from running, say, 150 kilometres a week on road to 50 kilometres on grass may relieve symptoms while allowing continued exercise. In other cases a lesion may be rested while a planned exercise programme can increase the load on all the other limbs. Athletes emerging from rehabilitation programmes often return quickly to, or exceed, their previous peak because they have switched from stereotyped and narrow overtraining regimens to more generally beneficial conditioning work, which provides a stronger basis for their special event endeavours.<br />Local physiotherapy methods are traditionally applied. Non-steroidal anti- inflammatory drugs may help in early and acute lesions - that is, when there is inflammation - rather than in long established chronic fibrosis. Local soft tissue corticosteroid injections are best reserved for injuries that have failed to respond adequately to the conservative methods of exercise correction, technique improvement, non-steroidal anti- inflammatory drugs, and physiotherapy. Intra-articular injection should never be undertaken lightly. Carefully supervised rehabilitation is essential after injection, as good initial response may be negated by precipitate overtraining while tissue is still healing. Accurate diagnosis and localisation are essential, and athletes should be told that, because corticosteroids weaken collagen, caution should apply especially towards premature resumption of heavy loading of the tendon at the lesion. For the same reason, direct injection into any tendon must be avoided. <br />The crux of the management of overuse injury is accurate recognition and correction of its sporting factors. Otherwise, resumption of the same training habits and sports techniques readily leads to demoralising recurrences. Time spent correcting faulty habits is well rewarded. <br />