Objective: To quantify the relationship between therapist-applied velocity of passive movement during a manual muscle test of muscle tone and the level of muscle tone represented by the relaxation index of the pendulum test.
Design: Comparison of therapist-applied passive limb movement velocity during a manual muscle test with the same subject's level of muscle tone measured by the pendulum test. Three different therapists tested each subject. The relation between the velocity scores and pendulum test scores both intratherapist and intertherapist were assessed statistically by means of analysis of variance and correlation coefficients.
Setting: A university-affiliated tertiary care outpatient and inpatient spinal cord injury rehabilitation center.
Participants: Twenty-two volunteer subjects with spinal cord injuries.
Main outcome measures: Passive knee angular displacement data were collected during both manual knee muscle testing and pendulum tests by using an electrogoniometer.
Results: The therapists produced significantly different movement velocities during the manual muscle tests (p < .05). A significant correlation (p < .001) was found between pendulum test scores and passive velocities, indicating that in higher levels of muscle tone, the greater stretch reflex present provided greater resistance against the therapist force and subsequently decreased the velocity of the passive stretching.
Conclusions: Measurement of average velocity during passive stretching by itself can be used to evaluate muscle tone.