HAMSTRING REHABILITATION

The goals of the exercise rehabilitation programme are the same for this injury as most other soft tissue injuries, to maintain cardio- vascular fitness and return the injured tissue to its full strength and extensibility.

Rehabilitation of hamstring strength At the end of the rehabilitation programme the injured hamstring has to be able to generate a high velocity eccentric contraction of sufficient force to overcome the concentric contraction of the quadriceps during the swing phase of running (or the follow through of a kick). In order to achieve this a progressive strength- ening programme is undertaken with the progression of loading on the muscle gauged by the muscles response to that loading.

Put

simply, if an exercise hurts beyond the strain expected of an exer- cise it is too hard and the load must be decreased.

Figure 4a

The progressive strengthening programme follows the principles outlined within the specific programme tailored for the injured footballer’s hamstring in diagram 1. Examples of specific exercises are given in figures 1-3. The principle behind the exer- cise progression is to begin with the least stressful mode of exercise; isometric mid- range, and progress the forces applied until the tissue is able to accept sport-specific stresses. A progression protocol for running in patients with hamstring strains has been described elsewhere, but follows the same principles (4).

Figure 4b Figure 4a+b: Starting positions for stretching

Initially the stretching exercises in the period prior to wound con- traction (day 14) take the form of ‘range of movement’ exercises short of per- ceived resistance. Once wound contrac- tion has begun after day 14 post-injury, tensile loading to elongate the tissue to maintain tissue length can begin. Static stretches are applied to the tissue, using the exercises shown in figures 4a and b. For biceps femoris the limb is taken into a position of hip flexion, abduction and internal rotation, knee extension and internal rotation. Initially, the stretch is held at the point of resistance for greater than 15 seconds.

In figure 3a an EMG biofeedback unit is used to provide feedback of hamstring activity during the closed kinetic chain activity. Coactivation of the hamstring dur- ing functional activities is essential to maintain stability at the knee. It is there- fore important during rehabilitation of the hamstrings following injury, that its role during this function is also rehabilitated. A closed kinetic chain exercise progression for the lower limb has been previously described (SportEX Medicine Iss 7).

Figures 3b and 3c show the force progression in a kicking drill. Here the patient attempts to kick the ball, initially at a slow velocity. At the point of contact the hamstrings are contracted to limit/decel- erate contact force. This is initially carried out in mid range (figure 3b) progressing from low to high velocities and then at slow pro- gressing to fast velocities in the outer range (figure 3c).

Rehabilitation of hamstring extensibility At the end of the rehabilitation programme the hamstring muscle must have sufficient extensibility to allow necessary excursion for normal function at both the knee and the hip simultaneously. In the early stages of tissue healing stretching beyond the limit of the tissues is of little benefit, in fact it may prove deleterious, pulling apart the delicate collagen matrix as it is laid down. Excessive stretch pre-14 days causes disruption of cell membranes and cell death. It is only 14 days or so after the injury that stretching

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When range of movement is bilaterally equal, and strength equates to level 9 in figure 1 (that is the hamstring is able to eccentrically over come slow concen- tric contraction of the quadriceps). Ballistic stretching can be begin and would initially be carried out in the same position, oscillating the limb at the end of range. At all times normal lumbar lordosis is maintained and the

lumbar spine is not allowed to flex or the pelvis tilt posteriorly.

All stretching is applied in combinations of hip flexion, adduction, internal rotation, knee extension and tibial internal rotation in order to fully lengthen the muscle. The sequence in which these movements are applied is determined during assessment (3). In either of these positions the sequence of additional direction of movement can vary but the principle remains the same.

References 1. Joint Football Association and Professional Footballers Association Research Project. An audit of injuries in professional football. The Football Association 2001. 2. Joint Chartered Society of Physiotherapy (CSP) and Association of Chartered Physiotherapists in Sports Medicine (ACPSM) Clinical Guidelines. Guidelines for the management of soft tissue injury with Protection, Rest, Ice, Compression and Elevation. CSP/ACPSM 1999 3. Hunter, G. Specific soft tissue mobilisation in the management of soft tis- sue dysfunction. Manual Therapy 1998;3(1):2-11 4. Herrington, L. Patients with hamstring muscle strains returning to sport in less than fourteen days, a report of the treatment used. Physical Therapy in Sport 2000;1(4):137-138

beyond the tissue limits (that is to a point where a stretch on the tissues is perceived) becomes a useful adjunct to treatment.

At this point most fibroblasts (the cells which produce the colla- gen) change to myofibroblasts. These are rich in actin and myosin (the structural proteins of muscle) and are very similar in structure to smooth muscle, having contractile properties. The myofibroblasts cause the collagen scar formed to shrink due to their contraction which pulls the collagen fibres closer together. Obviously excessive shrinkage of the scar is undesirable with its potential for reducing range of movement and so a stretching programme is required to increase (or maintain) the range of movement.