Effects Of Standing Frames On Muscle Length

Effects of standing frames on muscle length, joint range of movement, muscle tone and spasticity

Prolonged muscle stretch (PMS) has been proposed as an effective technique to reduce muscle spasticity of CNS origin in adults (Odeen and Knutsson, 1981). The spastic muscle is stretched to the end of its pain free range and the stretch is maintained until the therapist ‘feels’ the reduction in tone in the stretched muscle. Reducing tone and spasticity through PMS also helps maintain muscle length and joint range of movement, both central aspects in the physiotherapy management of long term conditions such as CP.

Numerous investigators (Burke et al., 1971; Odeen, 1981; Tremblay et al., 1990; Richards et al., 1991; Kunkel, 1993) have studied the effects of prolonged muscle stretch (PMS) on spastic patients with cerebral palsy (CP) by means of long-term application of plaster ankle casts. Such interventions have been shown to increase the passive range of motion (ROM) of the ankle joint, to reduce muscle tone and to change variables during gait. Odeen and Knutsson (1981) found that when a paraplegia patient received a prolonged plantarflexor muscle stretch on a tilt-table for 30 minutes, the resistance of passive ankle dorsiflexion decreased significantly. In another study, Odeen (1981) reported that mechanical stretching of the hip adductor in CP subjects led to increased passive and active ROM of hip abduction and less myoelectric activity in the hip adductor during active hip abduction. Tremblay et al. (1990) found that when children with CP received PMS of plantarflexor on a modified tilt table for 30 minutes, the passive ROM of ankle dorsiflexion increased. The neuromuscular responses (torque and EMG) to passive movement of the ankle joint were also significantly reduced. Burke et al. (1971) studied the effects of static stretch on the plantarflexor in the prone position. Increasing passive dorsiflexion of the ankle resulted in progressive diminution of the H-reflex. These studies provide limited evidence that PMS can reduce spasticity and improve contraction of the antagonist muscle, but they do not describe the changes in reflexes. They also do not describe for how long the spastic muscle should be stretched to achieve the required reduction in tone.

Tsai et al. (2001) conducted a study on adult hemiplegic stroke patients in which they aimed specifically to look at the effective duration of PMS applied to spastic muscle. Seventeen patients with spastic hemiplegia were selected to receive treatment. Subjects underwent PMS of the triceps surae (TS) by standing with the feet dorsiflexed on a tilt-table for 30 minutes. Four outcome measures were used (modified Ashworth scale of the TS, the passive range of motion (ROM) of ankle dorsiflexion, the H/M ratio of the TS, and the F/M ratio of the tibialis anterior (TA)). The results indicated that the passive ROM of ankle dorsiflexion increased significantly (p < 0.05) compared to that before PMS treatment. Additionally, PMS reduced motor neuron excitability of the TS and significantly increased that of the TA (p < 0.05). These results suggest that 30 minutes of PMS is effective in reducing motor neuron excitability of the TS in spastic hemiplegia in adults.




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