Whole Body Vibration Training Simplified: Explanation for the Public, Coaches, and Clinicians

What is Whole Body Vibration (WBV)?
Whole Body Vibration is the method of exercise, or act of doing a task, on a vibrating platform which causes the entire body to vibrate. These machine are considered high frequency as they function within, and above, 3 to 30Hz. Frequency means the amount the plate moves within a given time. In addition, the amount of vibration is also affected by not only the speed at which the platform moves, but also how much. This is called amplitude, and it is often measured in vertical distance change. Most of the machines can move between 1-4 mm in vertical displacement. The higher end machines also allow users to customize these settings.

History
In the early days, local body vibration (LBV) was used in commercial gyms when "spot training" was still thought to be possible. People would wrap a strap around their stomachs and butt, and then turn machines on that would vibrate those areas only. The fad quickly died for numerous reasons, mainly being that this is not how weight loss or muscle building works.

Whole Body Vibration came on the scene in the 1980's in European countries with gurus claiming it increased strength and performance when exercises were performed on them. The United States then began following, with many companies claiming those same benefits. Research was mixed, however they did find some effective uses for the technology. There is evidence that it prevents severe decline of bone density in sedentary patients in hospital beds. If there is no stimulus to the bones, the body will stop laying down more bone for growth. For the science folks, the mechanism is the principle of Wolff's Law. That research was then, and is still conducted today, in regards for space travel. With no gravity in space, astronauts often face muscle atrophy and bone density decline which can lead to overall decline in health and functional activities. Vibrations as a stimulus to bones may be the answer to the problem.

Today, WBV platforms are in numerous gyms, clinics, and sports perfmance centers. I researched this topic in 2011, and only found literature for bone density, but now that there is a lot more research out there, let's talk about why they're in facilities, if they work, and if so, how they work (or not).

What's the Mechanism
So this can get a bit sciencey, but that's important in understanding all the junk that's out there. Hopefully by the end of this, you can get why these machines are good at something, and then apply that knowledge to anything related to vibrations and fitness. After years of research, the highly agreed upon theory is that the vibrations cause change due to muscle spindles (below).

Muscle spindles are in muscle fibers and act reflexively to contract your muscle if it feels stretch in the muscle. For example, it can be a protective device when you swing your arm so hard that your elbow may hyperextend.  The muscle spindle of the biceps activate to contract the bicep to avoid the hyperextension.

The vibrations from WBV are said to activate these muscle spindles since the amplitudes of the platform change the length of muscles quickly, resulting in micro-contractions. So it seems the mechanism is due to a nueral mechanism rather than size increase of muscle. Keep this in mind as we move on to the next section, and it should be a lot easier to think logically about the research.

What the Evidence Says it Does
- Increases muscle activation of the quadricep muscles and plantarflexors (calves). EMG studies showed higher muscle activation after WBV training in a static positon was performed. Even standing on it in a static position recruited more activation of the muscles of the lower extremity than on a stable surface. Activation from standing on it ranged between 12-87% of MVIC (their maximum isometric contraction strength).
- Increases early rate of torque development for functional activities such as gait and running post ACL reconstruction (ACLR). Rate of torque development is important in activating proper timing and strength in leg muscles during gait. Particularly, if the quads do not extend the knee or eccentrically load at the right time, individuals will have impaired walking. Normally, peak RTD occurs at 300 milliseconds, but for walking, the peak needs to occur much faster. After ACL reconstruction, peak RTD is even further delayed. Studies showed doing isometric squats (with hand assistance) at 90 degrees on the platform increased RTD at 100 milliseconds after WBV. This means it can assist clinicians who have a hard time having patients activate their quads for gait and closed-chain exercises after ACLR. This point may not be useful for the healthy general public, as it pertains to those who have a hard time activating their quads.
- Decreases bone density reduction in sedentary acute care patients. This was already mentioned above, but has little to do with the neural aspect of muscles, but rather the bone. The bone gets a stimulus from the vibration and therefore feels the need to stay strong. Bone density will still decrease in sedentary individuals, but at a slower rate. Weightbearing and resistance training is important in maintaining and improving bone density.
- Increases balance (measured by Berg Balance Test). There could be the neural mechanism explained earlier accounting for this, however it is most likely due to an individual standing on an unstable surface, which is a form of balance training. In more specific research, it did not improve balance for stroke patients since some stroke patients may not yet have enough strength to even stand on two feet with equal weight distributuion.
- Increases functional mobility in non-cardiopulmonary patients (measured by 6-minute walk test). After 8 to 12 weeks of WBV training, individuals who went through this training were able to walk further in 6 minutes than those who did not perform exercises on it. For stroke patients, the effectiveness is inconclusive with some benefiting, and some not. It does not work for cardiopulmonary patients because the limiting factor is not the musculoskeletal system, but rather the cardiopulmonary system.
- Prevents muscle and blood vessel loss when paired with resistive training. Decreases in cross-sectional muscle area and capillaries in sedentary individuals occurs from disuse. WBV prevented a greater decline in both when compared to those who did not receive WBV. This was must likely due to the resistive training than the WBV. Additionally, the stimulus increased blood volume within capillaries which increased peripheral blood pressure. This pressure tells the body it needs that tissue, and therefore the decline in your small blood vessels is reduced. This is good because it allows for more potential for oxygen exchange.
- Increases repair and growth of small blood vessels. Angiogensis is the repair and growth of new blood vessels. This was by far my most exciting finding from the research. As mentioned in the above point, it increases the amount of blood in a local area's small blood vessels. This creates pressure and shearing forces on the blood vessels. It signals the body to strengthen these vessels, and also to create more. Additionally, looking at blood serum, it showed pro-angiogenetic growth factors in the blood after WBV, which suggests WBV also has a hormonal effect. This is important since muscle growth occurs faster than angiogenesis. This may be used to help vessels and other tissues adapt closer to the rate of muscles to ensure tensile strength is sufficient rather than muscles only growing through metabolic processes (study combining it with blood flow restricted training anyone?).
- Increases flexibility when combined with static stretching. The evidence for this goes both ways, but there is evidence suggesting WBV causes a rise in muscle temperature which allows the muscle to be better stretched. Those who did not receive WBV did not improve as much.
- Decreases excessive muscle tone, particularly in those with cerebral palsy and multiple sclerosis. Individuals immediately saw a reduction in muscle tone (measured by H and M wave electromyography). Tone immediately began normalizing, with the largest decrease at 3 minutes. There is a lot of evidence for those with CP and MS, however I did not encounter any studies on healthy individuals or athletes in regard to muscle tone decrease.

What the Evidence Says it Doesn't Do
- Increase muscle deoxygenation for replication of muscle fatigue to stimulate muscle growth. People thought because more blood was found in local regions, that is was because muscles were unloading oxygen more. This was not true when they measured it. If it was true, the hopes would be they could trick the body into adapting metabolically rather than loading a muscle.
​- Decrease self-reported pain for individuals with osteoarthritis. Pain was not  reported to have decreased when WBV was used for 6 weeks. This was particularly in the knee.
- Decrease self-reported stiffness for individuals with osteoarthritis. Stiffness was not reported to decrease with WBV for 6 weeks. This was particularly in the knee.
- Increases airway clearance and functional mobility in individuals with chronic obstructuve pulmonary disease (COPD). Chest wall vibrations are an affective way to assist in airway clearance for individuals with COPD, however WBV showed now improvements in ability to to clear airways. Also, as mentioned above, functional mobility is not increased because the musculoskeletal system is not the limiting factor for COPD patients.
- Increase muscle strength. Activation was increased according to EMG, however when squats and vertical jump were performed 5-10 minutes after WBV, there was no significant difference in strength or jump height. Just because a muscle is activated does not garuantee its maximum strength can improve.
- Increase muscle size. WBV affects the body and tissues more neurologically, and therefore does not increase muscle size. Even when paired with resistive exercises, there was no difference in those who used WBV, and those who did not. It would just decrease the amount of muscle lost, mainly due to the resistance exercise.

Guidelines on Use
- Do NOT use it for patients with upper body disorders involving wrist extensors, wrist flexors, grip, and carpal tunnel. High frequency vibrations aggravate symptoms in these disorders and syndromes.
- Amplitudes should be within 2-4mm. Others may work however most studies were within these limits.
- Frequency should be within 20-30Hz. Others may work however most studies were within these limits. For tone reduction in patients with MS and CP, a progression from 20Hz to 40Hz over 8 weeks was used.
- No contraindications have been released besides wrist conditions. Just to be safe, it is best to assume it is contraindicated for individuals with cancer, pregnancy, rheumatoid arthritis, and those with poor balance and weak grip (risk of falls if they can not hold on to handle bars).
- For angiogenesis, dynamic and loaded exercises are preferred (squats, lunges, etc.).
- For muscle activation, static exercises is preferred (isometrics). Calf activation was best at a 0-60 degree isometric squat, and quad activation was best at a 90 degree isometric squat. Ankle dorsiflexion or plantarflexion had no significant difference on activation of the quadriceps.
- For muscle activation and balance improvements, 3 sets of 60 seconds, with 60 seconds rest between sets, is appropriate.
- For tone reduction, 3 minutes has the peak reduction in tone, however experimenters did 10 minutes without any negative effects.

The Power Plate 5 is the most popular WBV machine seen in sports performance facilities.

The Swiss Swing is a LBV machine making its way into sports performance facilities.

So, What Does This All Mean? What Do I Do?
- For the practitioner: There seems to be a lot of benefits such as decreased muscle tone, increased balance, increased angiogenesis, increased flexibility potential, and assistance in activation in quad dysfunction after ACLR. A lot of the research was done on the lower extremity, but if you take the concepts to the upper extremity, you may get similar results. The machines however, are very expensive ($3000+); there may be better ways to achieve each of the benefits via manual therapy and exercise selection. Ultimately it would come down to the cost of whether you want to purchase one or not. Today the most popular machines seen in performance facilities are pictured above.

- For the public: Most athletes use them during their soft tissue routine, and as a way to prime their nervous system since there is evidence that it activates muscles by neural pathways. Athletes also do variations of core exercises on them since they act as a unstable surface, and there is a lot of evidence supporting more core activation on unstable surfaces. If they are in a commercial gym, they may be worth using in the beginning or at the end of sessions for the above purposes. As far as strengthening and increasing muscle size goes, resistance training without them is fine. There are also other ways to prime your motor system and decrease muscle tone, but research has not compared these methods with WBV. It is not worth the cost to buy a machine for home use, unless you have CP or MS. Time-wise, it would most likely take the same amount if you substituted your soft tissue work rather than added to your routine. Also consider if you even need soft tissue work every session.

References
1) Beijer, A., Degens, H., Weber, T., Rosenberger, A., Gehlert, S., Herrera, F., Kohl-Bareis, M., Zange, J., Bloch, W., and Rittweger, J. (2105). Microcirculation of skeletal muscle adapts differently to a resistive exercise intervention with and without superimposed whole-body vibrations. 35: 425 – 435

2) Cheng, H.K., Yu, Y., Wong, A.M., Tsai, Y., and Ju, Y. (2015) Effects of an eight-week whole body vibration on lower extremity muscle tone  and function in children with cerebral palsy. Research in Developmental Disabilities. 38: 258 - 261

3) Kacoglu, C. and Gurol, B. 2016. Effect of body position during whole body vibration on acute jumping performance. Baltic Journal of sport and health sciences. 3(102): 8-12

4) Pamukoff, D.N., Piestrimone, B., Ryan, E.D., Lee, D.R., Brown, L.E., and Blackburn, J.T. 2016. Whole body vibration improves early rate of torque development in individuals with ACL reconstruction. Journal of Strength and Conditioning Research. 

5) Wang, P., Yang, X., Yang, Y., Yang, L., Zhou, Y., Liu, C., Reinhardt, J.D., He, C. 2015. Effects of whole body vibration on pain, stiffness and physical functions in patients with knee osteoarthritis: a systematic review and meta-analysis. Clinical Rehabilitation. 29 (10): 939-951.

6) Yang, X., Zhou, Y., Wang, P., He, C., He, H. (2016). Effects of whole body vibration on pulmonary function, functional exercise capacity, and quality of life in people with chronic obstructive pulmonary disease: a systematic review. Clinical Rehabilitation. 30(5): 419 – 431
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