Controlling the velocity of linear passive manual movements in upper and lower limb joints: a pilot study in healthy subjects

The possibility to perform manual passive stretches of joint muscles through a range of velocities is very important in neurology and neuro-rehabilitation. While repetitive stretches at various velocities can be obtained using sinusoidal movements, the velocity of linear displacements is more difficult to control. The goal of this pilot work was to investigate, in healthy subjects, the reliability of a manual technique to perform passive linear movements at pre-set target velocities. The technique was based on the synchronisation of the movement with two repetitive auditory signals (the first for the start and the second for the end of the movement) played at different tone intervals by a metronome. Wrist, elbow, knee and ankle passive movements were recorded with a motion analyzer system in six healthy subjects. The investigated tone intervals ranged from 1.50 to 0.25s. The peak velocity depended on both the tone interval and the range of displacement according to a linear function, for all the tested joints. For a given range of movement, it was possible to modulate the velocity of passive displacement by changing the tone interval. Controlling the velocity of both sinusoidal and linear passive displacements without unwieldy equipment could be a major advantage in routine muscle tone examination.