Tonic vibration reflex
Tonic vibration reflex is a sustained contraction of a muscle subjected to vibration. This reflex is caused by vibratory activation of muscle spindles - muscle receptors sensitive to stretch.
Tonic vibration reflex is evoked by placing a vibrator - which in this case is typically an electrical motor with an eccentric load on its shaft - on a muscle's tendon. 30-100 Hz vibration activates receptors of the skin, tendons and, most importantly, muscle spindles. Muscle spindle discharges are sent to the spinal cord through afferent nerve fibers, where they activate monosynaptic and polysynaptic reflex arcs, causing the muscle to contract.
The effects of sustained vibratory stimulation on muscle contraction, posture and kinesthetic perceptions are much more complex than merely contraction of the muscle being vibrated.
Russian scientists Victor Gurfinkel, Mikhail Lebedev, Andrew Polyakov and Yuri Levick used vibratory stimulation to study human posture control and spectral characteristics of electromyographic (EMG) activity.
References
- Gurfinkel, V.S., Lebedev, M.A., Levick, Yu. S. (1992) What about the so-called neck reflexes in humans? In: A. Bertoz, W. Graf, P. P. Vidal (Eds) The Head-Neck Sensory Motor System, New York, Oxford, Oxford University Press: 543-547.
- Gurfinkel, V.S., Lebedev, M.A., Levik, Yu. S. (1992) Switching effect in the system of equilibrium regulation in man. Neirofiziologiya (Kiev) 24: 462-470. Translation into English: Neurophysiology 24: 297-304.
- Lebedev, M.A., Polyakov, A.V. (1992) Analysis of surface EMG of human soleus muscle subjected to vibration. J. Electromyography and Kinesiology 2: 26-35.
- Gurfinkel, V.S., Levick, Yu. S. Lebedev, M.A. (1991) Body scheme concept and motor control. Body scheme in the postural automatisms regulation. In: Intellectual Processes and Their Modelling, Moscow, Nauka: 24-53.
- Lebedev, M.A., Polyakov, A.V. (1991) Analysis of the interference electromyogram of human soleus muscle after exposure to vibration. Neirofiziologiya (Kiev) 23: 57-65. Translation into English: Neurophysiology 23: 47-54.