Biomechanical consideration following injury - a return to sport
Graham Jones explains the various stages of an injury healing process so that coaches may maximise the effects of the athlete's rehabilitation and help prevent a re-occurrence of the injury
Musculoskeletal injuries of the lower limb are an occurring feature in sports and can be divided into 2 groups: - (1) Acute, and (2) Overuse, but whichever type of injury it is, a carefully planned return to sport is essential to prevent further re-occurrence. to do this, we must first understand the mechanism of the injury and the various stages of the healing process. Soft tissue injuries are particularly common, especially in the lower limb, and when any stress (injury) occurs it results in damage to the cells. The first response to the stress of tissue damage is inflammation, and as it is one of the body's non-specific internal systems of defence it will respond similarly regardless of how the damage is caused (Sherwood, 1993). The functions of inflammation are to remove the irritant and to prepare for the repair of the tissues.
After a tendon becomes damaged, following the injury there is an inflammatory phase for up to 5 days depending on the extent of the tissue damage. During this time the site of the injury becomes infiltrated with both tendon and sheath cells, many of which are phagocytic (Wojciak & Crossan 1993). Without inflammation, there can be no healing and therefore, although vital, it is important during this phase to protect and control movement across the lesion, and prevent increased swelling over a wider area subsequently reducing the chances of secondary hypoxic injury (Knight, 1976). This is where the familiar rest ice compression and elevation (RICE) regimen is employed. Therefore, during this acute phase, applying ice reduces the metabolic requirements of the tissues and also reduces the vascularity to approximately 60% of its resting value (Metcalf, 1995).
However, as the lymphatic system is passive, and therefore dependent on external forces to promote movement of fluids, such as during a muscle contraction, moderate activity during this acute (cellular) phase promotes lymphatic drainage and hastens healing. This is why we now use the movement ice compression and elevation (MICE) regimen, (Knight, 1995). As the tissue enters its second stage, (fibroplastic) fibroplasts lay down collagen haphazardly increasing the tensile strength across the site of injury, restoring the structure but not the function. It is therefore essential at this time to use controlled exercise to create gentle tensioning across the wound to help tissue orientation in preparation for the final stage of remodelling (Hunter, 1994).
Although there is tensile strength there can be a lack of elasticity and adhesions can form restricting movement making the area vulnerable to further injury. Therefore, controlled exercise soon after an injury is essential to rehabilitation to speed up the healing process, (Rettig & Kraft, 1991). As static stretching overcomes the stretch reflex and decreases muscle spasm, it is therefore important to use progressive isometric stretches to increase elasticity and reduce further complications.
Once the wound has healed the rehabilitation process can enter the next phase (reconditioning). However, as collagen fibres can continue to contract for up to six months post-injury, continued stretching and adequate warm-up before exercise are essential. Pain can activate neural mechanisms within the body that inhibit strength, flexibility speed and power; it must be controlled before commencing this stage, (Knight, 1985). This is when ice can be very effective, as it diminishes pain and muscle spasm thus encouraging movement. After a near maximal muscle contraction-relaxation is often greater than it was before the contraction, and therefore by combining the effects of ice with static stretching we have the benefits of pain relief and increased relaxation. It is important to remember that there should be a gradual build-up to maximal contraction to avoid the risk of further muscle tear, and pain must be used as a guideline. Although ice is very effective it is important to use a barrier between the skin and the ice pack to prevent an ice burn and the athlete should only use it as directed by their Therapist.
In training, we often hear the expression 'no pain no gain'. However, this may be all well and good during general conditioning but has no place during rehabilitation following injury. It is therefore important to remember at this stage during the rehabilitation that all exercises should be pain-free, as pain during an activity is an indication that it is too vigorous and should, therefore, be toned down. On no account should the athlete attempt to deliberately overcome pain thus risking further trauma, slowing down their return to competitive sport. Once there is structural integrity and pain control over the site of injury with a good range of movement, indicating adequate healing has taken place we are ready to move into the final stages of rehabilitation.
As with all the various stages of recovery, it is important to gradually progress training to return to a pre-injury state whilst at the same time reducing the risks of the athlete developing a further injury. There is evidence from clinical experience and experiments that have been conducted on animals to show that previous injuries will predispose a muscle-tendon unit to a subsequent strain injury (Noonan, 1992). These experiments have shown that following an injury proper functional rehabilitation is the best way to avoid re-occurrence. According to Hess et al, (1989), there are two kinds of sports activities that lead to overuse injuries. These are endurance activities such as long-distance running and those associated with repetitive performances that require skill, technique, and power. If these are coupled with intrinsic factors (muscle weakness and imbalance) or extrinsic factors (training errors, improper footwear and equipment) the repetitive micro-trauma leads to an overuse injury (Renstrom, 1985). It is therefore important in the later stages to achieve flexibility, strength and coordination of the injured site before moving on to more specific skill patterns.
Practicing sport-specific skill patterns is the last part of the rehabilitation and is the only way to develop an integrated and coordinated movement (Wilkerson, 1992; Ryan et al. 1989)[10,12]. During this phase performing explosive type drills as fast as possible helps to develop muscular speed, and coordinated movement, however, it is important to pay careful attention to make sure that the activities are being performed correctly. As increasing proprioception is also a vital part of this final stage, it is often necessary to isolate a particular aspect of the skill pattern and work on this independently to increase this and improve the overall agility.
Therefore, by understanding the various stages of the healing process, it is possible to maximise the effects of the rehabilitation and help prevent a further re-occurrence. of the injury.
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About the Author
Graham Jones is a professional karate instructor (4th Dan). He attended Keele University, UK and graduated with a First-Class Honours Degree in Physiotherapy. Graham has conducted physiotherapy screening and treatment for sprints and many other sporting disciplines. He currently works as an Advanced Spinal Practitioner for Cheshire West National Health Service trust as well as running his private physiotherapy practice.