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Whole Body Vibration:
Vibration therapy is becoming a more accepted form of therapeusis with musculo-skeletal disorders. On this page, we'll give you a brief introduction to WBV.
We find this modality a very useful addition the physical therapeutics used in the office to assist the clinician in treating musculo-skeletal issues like increasing strength, improving balance and flexibility. It is akin to the electrical stim setting known as "Russian Stim."
WBV is a neuromusuclar training methodology that utilizes vibration stimulus to incite an involuntary response in muscles. Mechanoreceptors, that include muscle spindles, and Golgi Tendon Organs-GTOs for short) are the sensory organs of the muscle which are sensitive to mechanical stimulation. Muscle spindles send information to higher cortical centers with information on the tention of the muscle, causing the muscle to contract when excited. Conversely, when the GTO (which is located inside muscle tendons) is excited, it causes the muscle to relax.
Thus, when stimulated by vibration, the muscle spindles, tendons and GTOs send impulses to the brain and cause the muscles to contract and relax at the rate of vibration; a phenomenon called Tonic Vibration Reflex (TVR). This response recruits nearly 100% of the muscle fibers in contraction and enhances neuromuscular efficiency. Skeletal muscles contract and release at the same frequency of the vibration. So, for example, if standing in a squat position on the vibration platform set at 30 Hz, muscles will contract and release 900 times in a 30 second session. These numbers would be impossible to stimulate during a normal exercise regime.
The mechanical rationale behind using WBV is simple, yet powerful.
Utilizing perhaps the most well known formula in all of physics, that of Issac Newton's Second Law of Motion:
Force = Mass X Acceleration. In traditional strength training, force production is primarily affected by Mass or increasing load by adding weight to an exercise. In WBV therapy, the acceleration variant is manipulated. The acceleration variable is increased as the result of the platform rapidly moving up and down at a specific frequency. Amplitude and frequency can be adjusted to a degree on this machine.
Optimal frequency has been confirmed in numerous papers to be in the 20 Hz - 50Hz range. The acceleration forces resulting from the vibration cause the muscles to contract. Due to this involuntary contraction of the muscles, many more muscle fibers are recruited than a voluntary movement (see Issurin & Tenebaum, 1999). EMG results further confirm this (see Bosco, et. al. 1999, and Delecluse et. al. 2003). The rapid contraction and relaxation of muscles in the 25 - 50 times per second range also works a a pump on both the circulatory and lymphatic systems, increasing blood flow and lymphatic drainage throughout the body (see Kershan - Schindle et. al 2001 and Lohman et. al. 2007).
Other research supporting WBV therapy:
1) Cheung WH, et. al., "High-frequency whole-body vibration improves balancing ability in elderly women," Archives of Phys Med and Rehab, 88(7), 852-857.
2) Savelberg HH, et. al., "Whole body vibration induced adaption in knee extensorsl consequences of initial strength, vibration frequency and joint angle," J Strength and Conditioning Research, 2007, 21(2). 3
3) Rittweger J, et. al., "Treatment of chronic Low Back pain with lumbar extension and whole-body vibration exercise," SPINE, Vol. 27, #17.
4) Luo J, et. al., "The use of vibration training to enhance muscle strength and power," Sports Med, 35(1).