The acute effect of whole body vibration on spasticity of the calf muscle in stroke patients

Stroke is one of the most common causes of complex disability. Stroke patients
have difficulty to walk because of their inability to make an effective
dorsiflexion in their ankle during the swing phase. This problem is partly due
to an inability to activate the ankle dorsiflexors and partly due to spasticity
in the calf muscles. Treatment of spasticity is an important prerequisite for
the restoration of normal gait in stroke patients who are suffering from
spastic drop foot. Nowadays, various treatments such as antispastic drugs,
electrical stimulation, ultrasonic therapy, and surgical procedures, have been
used to decrease spasticity. However most of the current treatment options have
certain limitations (e.g. short effects of the used physical therapy, and some
side effects of the medications).
It is suggested that spasticity results from an exaggerated monosynaptic
stretch reflex. Obviously any therapeutic intervention that would be able to
inhibit the stretch reflex will be effective on reduction of spasticity. Whole
Body Vibration (WBV) is a safe and efficient training method to improve muscle
function. The direct effects of WBV on spasticity have not been examined so
far. Ahlborg et al. (2006) reported that 8-week training of WBV could increase
muscle strength in adults with cerebral palsy without negative effects on
spasticity.

The purpose of this study is to investigate the acute effects of a single bout
of WBV on spasticity of calf muscle in stroke patients.

It is a cross-over study design. The study consists of two sessions, with a
one-week interval. During each session, the patient will stand on the device
(Power Plate, Power Plate international, USA) for 3 minutes. In one session
the device will be switched on (WBV- Condition; vibration frequency: 45 Hz, low
amplitude) and in the other session (Control-Condition) it will be switched
off. Before and immediately after standing on the device EMG and Range of
Motion (ROM) will be measured. The pre-post intervention data of the
WBV-Condition will be compared to the pre-post intervention data of the
Control-Condition.

Exposure to whole body vibration for three minutes in a standing position.

The whole body vibration training is not painfull or dangerous. During standing
on the vibration device two persons are standing beside the patient to minimize
risk of falling. The amplitude and frequency of whole body vibration are low
and, therefore, the measurements have a low physical strain.