It has been reported that the angular velocity at the elbow during professional baseball pitching can reach up to 5,000 degrees per second(1). When throwing athletes ask the relatively small structures of the elbow to control and decelerate this much velocity over and over again, day in, day out, it is no wonder that their elbows can sustain extensive damage. These changes often lead to debilitating injuries from which recovery is very difficult.
Throwing athletes include those who perform the throwing motion as part of their sport: baseball players, particularly pitchers, tennis players when serving, and javelin throwers. To create efficient neuro-motor pathways for a skill such as the tennis serve requires repetition over a long period, possibly from the age of six upwards. It is from this early age (usually between six and 10 years old) that structural changes begin. So why don’t we give our young athletes the opportunity to look after themselves? I recommend that specific strengthening programmes be implemented from as young as 10 years old – or when the athlete is mature enough to learn and perform regular exercises diligently.
For the purpose of this article, I will divide the elbow into four categories – medial, anterior, lateral and posterior. Table 1 (below) summarises the structures in each category.
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To understand the loads imposed on the structures in these four components, it is best to separate the throw into four phases. We can then talk about which structures are stressed in each phase and the resulting injuries.
The aim of the first two phases – winding up and cocking – is to place the trunk, shoulder, elbow and hand in the correct position before the explosive acceleration phase. Although these phases don’t place a high load on any elbow structures, they are vitally important. The athlete must be able to prepare their body so that the legs and trunk can be incorporated effectively to generate power. If this isn’t done, the athlete will tend to ‘arm’ the ball (try to accelerate and gain power using only the upper limb). This places increased structural demands on the elbow.
Elbow angle and position in the cocking phase are critical to performance and injury risk. If the elbow angle is too great then the joint will sustain more valgus stress (lower half of the arm forced laterally) during the acceleration phase; too small an angle and the ulna nerve will be tractioned or stretched more. Elbow angle at late cocking phase should be approximately 75 degrees (slightly greater for javelin).
Adolescents and less skilled players are the most likely to have problems with these preparatory phases, because they are usually less technically sound, so the technical input of a coach, biomechanist and/or physiotherapist can be critical to enable the athlete to build a platform for a less stressful and more fluent, powerful throwing action.
In the late cocking phase and through the acceleration phase, massive valgus forces are imposed on the elbow. Herein lies the main mechanism of injury: valgus overload, when the valgus force exceeds the ability of the passive and active restraints. The ulna collateral ligament (UCL) – also known as the medial collateral ligament – bears the brunt of this force. When the UCL is overloaded it begins to attenuate (lengthen), or even to tear, which leads to instability of the medial elbow.
It is the role of the wrist flexors and pronators (flexor/pronator complex) – which both insert over the medial elbow – to contract eccentrically (contract and lengthen) and limit or control this valgus force. When the flexor/pronator complex is not effective, the UCL is more at risk to structural damage. It may be ineffective because of lack of strength, muscle endurance or poor neuro-motor control. Regardless, it all needs to be trained from a young age to prevent medial instability of the elbow. The flexor/pronator group is also at risk from overload, which manifests as flexor/pronator insertion tendinopathies.
Once instability is present, many structures are at risk. On the medial side, the ligament can deteriorate further and it alone can be a source of pain and limitation. With further overload, chronic degenerative tendinosis of the flexor/pronator complex insertion can develop. The medial epicondyle of the humerus will hypertrophy (produce bony enlargement) and the ulna nerve quite often can become irritated as it is tractioned (overstretched) through the ulna groove. This problem is compounded by medial epicondyle hypertrophy and the development of bony spurs in the area.
Injuries to the medial aspect of the elbow result from overstretching. This leads to compression-related injuries on the lateral aspect – but pain laterally will often appear only after pain has been present for a while medially and the athlete has continued to train and compete. Laterally the radial head will be impacted on the capitellum (lateral joint surface of humerus), which can cause radial head and capitellum hypertrophy, osteochondral lesions and loose body formation.
Later in the acceleration phase and into the final deceleration phase, the elbow is forcefully extended. Now the posterior structures are at risk as the articular cartilage of the olecranon fossa (joint surface of the bony posterior elbow) is sheared. The anterior structures which prevent over-extension – the biceps and brachialis muscles and the anterior capsule – are at risk of being acutely overstretched, producing anterior capsule sprains or biceps strain. Continual overload can cause chronic biceps tendinopathy.
Worse still, over-extension can lead to compression of the posterior structures with the consequent complications of osteophytes, loose bodies, scarring, hypertrophy, and/or an extension block. The wrist extensor musculotendinous complex is at risk of overload as it tries to control forceful wrist flexion.
If the beginning stages of the throwing action or serve are performed with good technique, it is more likely that during the acceleration phase, the whole body will contribute to dissipating the force via trunk flexion and rotation.
As you can see, any child performing high repetitions of the throwing action in training and competing as part of their sport, particularly with poor technique, is at risk of serious damage and long-term changes. These injuries are potentially career-threatening for young athletes. A strengthening programme will help to maintain the health and integrity of a young athlete’s elbow, or correct technique and enforce positive neuro-motor pathways once an athlete has presented with injury. I advocate a range of simple exercises that can be easily squeezed into a young athlete’s busy weekly routine of school, training and competing.
The exercises should be kept at a reasonably low intensity with high repetitions. They should be started in neutral positions and progress under supervision to more functional positions. The conditioning coach or sports physiotherapist should regularly review the athlete’s progress to check on technique and sanction appropriate progressions.
Any strengthening programme must work on both the elbow and the upper limb, as the results of two relevant studies confirm(2). A 1980 study revealed that tennis players with a history of tennis elbow had 63% greater chance of shoulder injury. And a 1988 study by the USTA revealed that 70% of 16-18 year-old ranked tennis players demonstrated significant shoulder muscle imbalances. Table 2 summarises the muscle groups that need to be involved in the programme.
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I understand that 10 years old sounds like a young age to start on a specific exercise programme. But it is very important to educate the parents and coaches of young athletes that if the child is going to get involved in serious training they need to integrate a careful, specific conditioning regime, too.
For example, the young athlete may spend one hour working on flexibility, stability and injury prevention three times a week. At no point should the exercises take the fun out of the sport.
If approached correctly, the programme will allow the athlete to enjoy competing and remain injury-free.