whole body vibration therapy
Whole Body Vibration: Potential Benefits in the Management of Pain and Physical Function
Growing evidence supports the use of this treatment tool, in combination with exercise, for improving flexibility, bone density, balance, strength, and pulmonary rehabilitation.
Whole body vibration (WBV) is a form of treatment that has been shown to have an important role in increasing neuromuscular performance, improving muscular strength, balance, gait mechanics, and quality of life. The technique involves standing and holding positions, or performing prescribed exercises, on a platform that is vibrating at a programmed frequency, amplitude, and magnitude of oscillation. WBV was first introduced in the clinical setting to enhance bone-mineral density in patients with osteoporosis, and has since expanded to help improve strength and neuromuscular activation in more sedentary populations, such as older adults; to decrease pain and fatigue levels in patients with fibromyalgia syndrome; to improve postural control and functional mobility in patients with multiple sclerosis;10 and to improve gait mechanics in patients with Parkinson’s disease. The benefits of WBV may also apply to pulmonary strength and body composition, which are reviewed in this article. In fact, within recent years, WBV therapy has emerged in the field of research as a possible method for pain relief across multiple conditions.
While the technique is still relatively new and requires further research to determine full efficacy and sustainability, the therapy has been indicated across the literature as an effective, noninvasive, non-pharmacological, relatively easy-to-use, and comparatively inexpensive therapy that could provide relief from chronic pain, as described herein.
WBV for Chronic Pain Conditions
Pain is a primary symptom of osteoarthritis (OA), diabetic peripheral neuropathy (DPN), and fibromyalgia. Whole body vibration has demonstrated a high adherence rate, which is not often the case for many interventions used to help treat individuals with chronic pain.9
Research by Park and colleagues concluded that individuals suffering from chronic pain produced by knee OA found relief after practicing WBV therapy in conjunction with a home-based exercise program. More specifically, the individuals that participated in WBV therapy and home-based exercise had reduced pain intensity when compared to those who practiced only home-based exercise.
A case study by Hong and colleagues14 examined patients with DPN who experienced slight numbness, mild tingling sensations, and severe pain on a daily basis – including one male patient who struggled to put pressure on his feet due to pain and needed to frequently sit or lay down. In this particular patient, WBV therapy was used as an interventional method to relieve his pain. The therapy decreased his pain after each session for an average of three hours. The patient also reported less pain over time. Kessler and Hong15 examined the effects of this case on a larger scale study. Similarly, their research indicated WBV was effective at lowering pain over time in individuals suffering from DPN.
Alentorn-Geli and colleagues9 examined the effects of WBV therapy on fibromyalgia patients. Not only did their results support WBV therapy for chronic pain, but interestingly, there was a 0% dropout rate among participants.
In regard to chronic pain that is not associated with a particular disease or disorder, such as low back pain (LBP), Gusi and colleagues examined the effects of WBV on this type of pain. Research indicated evidence for WBV relieving back pain, but also suggested that additional investigations be conducted (detailed below).
Flexibility: WBV for Older Adults & Athletes
For decades, kinesiologists have studied the effects of flexibility on body performance, pain, strength, and quality of life. It has been observed that the more flexibility an individual displays, the more lengthened the muscle group becomes, and this lengthening may lead to fewer feelings of body stress and pain. The "sit-n-reach test," for example, came to fruition during a time when the prevalence of LBP was emerging frequently. The test was used to measure hamstring flexibility and trunk flexion ability. It has been theorized that if an athlete possesses a greater range of motion, then the possibility of injuries on the field will be lower.
Older adults have improved function when static stretching programs are adopted and consistently followed, also leading to an increase in quality of life. Therefore, it may be advantageous to find a tool that provides easy, quick, and less intense forms of stretching, while also providing equal to or greater increases in joint range of motion (ROM) than traditional static stretching alone.
Whole body vibration may offer a unique exposure mechanism to the nervous system that inhibits the proprioceptors from being overactivated and, in turn, may leave the muscle in a lengthened, more relaxed position. This phenomenon is often observed during static and dynamic flexibility training programs. The rapid vibrations appear to desensitize the muscle spindles which allows the muscle cells to lengthen without excessive static stretching. Dynamic stretching techniques are typically performed through deep ROM, held for a short period of time, and performed rather quickly to provide increased ROM through neural mechanisms.22 Research has demonstrated that WBV platforms may provide the body with a stimulus similar to that of a dynamic stretching routine.
Additional studies have examined the acute effects of WBV and measured flexibility after a single exposure. Results have indicated that brief exposure to whole body vibration may acutely improve flexibility when compared to stable ground stretching. Whole body vibration has also been shown to be an adequate warm-up for athletes prior to competition. Overall, the technique has proven to be an adequate training tool to produce greater improvements in flexibility than traditional stable ground-based stretching, allowing the inhibition of the muscle spindle activity to cause muscle relaxation.
Bone Density: WBV as a Possibility for Osteoporosis Patients
Whole body vibration provides a unique stimulus to the body, in that it utilizes and magnifies body weight during a vibrational oscillation. Currently, WBV platforms produce a large range of amplitudes, where some vibrate with vertical displacement at ~4 mm and some oscillate to provide ~20 mm of displacement. Although each platform may stimulate bone growth, it could be expected that a platform with a larger amplitude would potentially manipulate the body weight in a more aggressive manner, which would lead to an increase in bone fortification.
In general, any bone marrow density increases experienced from WBV exercises may be attributed to a similar type of adaptation to plyometric and resistance training. The most effective way to stimulate bone to restructure and strengthen is to provide the body with a stimulus that causes the bone to slightly bend. If an aggressive force is sent through the bone, it will stimulate osteoblast production and initiate the redirection of calcium to the bone shaft. This type of stimulation is commonly experienced during resistance training. Therefore, resistance weight training is often recommended to osteoporotic individuals as it can slightly cause bone to bend and reform. Similarly, plyometric exercises provide an aggressive stimulus that causes the bones to quiver, bend, and undergo the same strengthening restructuring as resistance training.
In fact, plyometrics may be considered the more aggressive exercise due to the amplification of body weight with each jump. An individual’s body weight may be amplified by up to 10 times depending on the height of the jump. This amplified body weight is then sent into the limbs, joints, and muscles of the lower body which cause the bones to quiver. When compared to a low-amplitude platform, WBV exercises performed on a high amplitude platform would be expected to amplify the body weight more and may initiate the same bone deformations as a resistance exercise or a plyometric jump. Multiple studies have demonstrated improvements in bone density while using a low-amplitude vibration platform, however, research is currently being conducted on a high-amplitude vibration platform.
Overall, the majority of research investigating the use of WBV to treat osteoporosis has indicated that there are no improvements in bone density. However, the literature cited in the paragraph above investigated the effects of a low-amplitude, high-frequency WBV stimulus which may not cause much bone deformation during training compared to a high-amplitude vibration stimulus. High-amplitude WBV theoretically could produce more body perturbations which could lead to greater improvements in bone density. In general, traditional studies that have demonstrated improvements in bone density from other anaerobic exercise sessions have demonstrated changes in BMD in about a year. However, to the authors' knowledge, there have been no WBV studies to date that engaged participants in vibration training for more than one year.
Contrary to previous belief, osteoporosis may not be the leading cause of hip fractures in the mainstream population. Instead, recent literature shows that poor balance may be emerging as a primary cause of hip injuries (read about pain care and risk fall in the elderly). If individuals had better balance overall, it is possible that the number of falls might decrease, thus avoiding injury from ground forces. Balance is discussed in more detail in the next section.
Balance is a multifaceted ability that may influence physical capabilities over the lifespan. For example, inadequacies in balance during infancy may result in limited mobility while middle-aged and older adults that lack balance generally report a decrease in quality of life due to the inability to live independently. Among other factors, a lack of nervous system flexibility, hip tightness, and hip weakness may be attributed to poor balance at any age. Whole body vibration training provides the body with a form of exercise that may help to improve all of these factors and has been shown through research to improve balancing tasks.
When the body is in contact with a WBV training device, the vibratory wave is transmitted through the limb, which contacts the platform and is sent up the body to the joint. Once the vibratory wave reaches the joint, the muscles and tendons at the joint are slightly and rapidly shifted, causing a brief contraction and relaxation of the musculature. The rapid stretch causes the muscle spindle to engage, which causes the stretch reflex to activate and cause a reflexive contraction of the muscle. The mobilization and contraction of all the hip musculature during the vibrations are likely to lead to increased hip strength and flexibility, both of which are needed to improve balance.
Strength: WBV for Aging Adults with Increased Immobility
As a whole, the human neuromuscular system is a complex entity that delivers electrical charges to the muscles from the high brain centers. There are many factors that may alter the effects of this system, including intensity of physical exercise, the amount of stress on the body, and how often the exercise pattern is changed. The main indicator of a highly functioning nervous system is the high force production of the muscles, which are associated with the body’s ability to move more weight.
Infants may be perceived as possessing a high strength-to-mass ratio due to the cellular freshness of the structures and the high conductivity of the nervous system. However, after a certain age, the nervous system passes its peak and begins to become a poor conductor of movement impulses. This results in the system becoming slower and weaker. It has been reported that anaerobic exercises, such as plyometric exercise, may provide a resistance great enough to cause adaptational improvements in this regard.
Since WBV exercises use gravity as a possible way to increase weight bearing on the body, it may provide a resistance stimulus for the muscles and nervous system for several repetitive short durations or time. During each wave, the body is minimally propelled vertically and then returned to the normal platform height during the next vibratory wave. The painful lactic acid build up felt during a traditional anaerobic set is not common during a vibration exercise set due to the myogenic effect of the skeletal muscle pump. This makes for a unique training stimulus, one that can overload the muscles and nervous system, yet does not fatigue as quickly due to a delay in lactic acid build-up.
In a study conducted by Bogaerts and colleagues, it was shown that a year-long body weighted WBV training program produced similar results to a traditional strength training program in older adult men.
Therefore, the amplification of the body weight seemed to serve as a sufficient stimulus to maintain the nervous system conductivity.
Wang and colleagues concluded that the addition of WBV exercise to a traditional strength and conditioning program increased the strength of track athletes. It also has been hypothesized that WBV stimuli may enhance recovery by providing a rest for the muscle tissues while still providing stimulation to the nervous system. It has been theorized that this process allows the athlete to continue through a periodization cycle while resting the muscles and not allowing the nervous system to become deconditioned. Although tested primarily in athletes, WBV may offer an optimal training tool for the older adult population in which the nervous system has become deconditioned, leading to movement inabilities.
Pulmonary Rehabilitation: WBV for COPD
The most studied pulmonary complication in terms of WBV benefit has been chronic obstructive pulmonary disease (COPD). Early forms of WBV were localized chest wall vibrations (CWV). The effectiveness of CWV has been supported in individuals with COPD, with improvement in breathlessness. The movements of CWV in the management of dyspnea might be related to the activation of muscle spindles in the intercostal muscles.
More recently, WBV has demonstrated improved quality of life and exercise capacity in those with COPD.49-54 WBV does not exacerbate perceived dyspnea55 and may safely improve clinical parameters of the patient with COPD. Researchers also have found little to no negative side effects of the technique in COPD patients, and thus, WBV has been highly recommended as a component of pulmonary rehabilitation when treating.
However, a systematic review by Yang and colleagues concluded that, as of 2016, there was insufficient evidence to support the use of WBV to improve pulmonary function in patients with COPD. The authors pointed out that it was difficult to compare WBV interventions as each study in the review used a slight variation of the treatment.
In patients who have had lung transplants, WBV significantly improved quality of life, maximal workload, vital capacity, and aerobic workouts; however, peak cough flow and forced expiratory volume showed no significant change due to WBV. WBV may, therefore, offer a safe and feasible treatment to rehabilitate post-surgical patients after intensive care unit (ICU) treatment in those with COPD.
Low Back Pain: WBV as a Cause or Cure?
Whole body vibration has been a particular area of contention as it relates to low back pain (LBP). At particular frequencies, vibration has been demonstrated as a factor in the cause of low back pain. Early studies established an association between WBV and LBP in primarily occupational exposure, including as a result of prolonged sitting in a vehicle.
More recent research has shown that, at frequencies below 20 Hz, vibration may actually reduce LBP by inducing muscle relation and improving the strength of abdominal and back extensor muscles.61,62 Research led by Yang and Maddalozzo has further supported the evidence that WBV may be effective in managing LBP. Specifically, a distinction was made between WBV therapy and whole body vibrations that may be experienced passively.
For example, Kaeding and colleagues proposed that there are substantial negative effects of occupational WBV that individuals may experience while driving a vehicle for long periods of the day. The frequency and amplitude of these passive vibrations are often considerably higher than would be while experiencing WBV as a therapy. Researchers concluded that WBV therapy was an effective, safe, and suitable intervention that requires little infrastructure, time, and/or investment.
Overall, whole body vibration appears to be a promising, complementary, easy-to-integrate tool for the management of certain types of chronic pain, physical functioning and mobility, bone strength, and balance. Benefits of WBV therapy, when combined with exercise, appear to be even more promising.
Healthcare professionals are urged to take a serious investigation into the promising effects of WBV in regard to sedentary, rehabilitating, chronic pain, and older adult populations as the aforementioned effects of WBV show support of offering a low-impact, low-stress method to help recondition individuals. These factors, along with increased functional mobility and decreased pain, may be the main proponents to high adherence to WBV treatment protocols. The evidence WBV has demonstrated on individual health measures warrants further investigation into its effectiveness as a method for relieving pain and improving overall strength and physical function.