Vibration therapy may sound hokey. Growing up it was a belt around the backside attached to a machine that made you shake and shimmy as a weight loss tool. Today it can be a whole body machine to a handheld one that targets specific sites. Recent studies show it just might help those of us who suffer from chronic pain.
Some of that research comes from the Russian space program when their astronauts, returning from space, were found to have a significantly higher risk for bone loss and fractures. This was due to the lack of gravity in space. Without this naturally occurring force on Earth, astronauts lose 1-2% of their bone mineral density every month. For short flights it has a minimal affect but longer stays in space can create serious consequences. The body is constantly breaking down old bone via osteoclasts and replacing it via osteoblasts with new bone. On Earth these occur at the same rate, but as we grow older, or live in a microgravity environment, like space, this process changes and breakdown out paces formation. They found vibration therapy helped to strengthen bone mass and muscles so well that even NASA jumped on board and still uses it to this day.
Whether it’s applied to the entire body e.g. lying on a bed or just local to the area of concern e.g. the calf, elbow, or hand, vibrations makes the underlying muscles contract and relax. The direction of vibration may determine the benefits as well. It appears vertical vibrations are most effective for producing the most rapid muscle contractions.
Vibration therapy sets up this oscillating mechanical stimulation by establishing a rhythmic movement through different mechanisms e.g. sound or ultrasonic waves, pulse electromagnetic fields, electrical stimulation, shock waves or motor driven devices.
All substances vibrate at a specific internal frequency. Pluck a guitar string, drum or rubber band and the frequency of vibration is intrinsic to the material, tension and surrounding compression that supports the structure. In the body our connective tissues provide the tension. It starts in the skin, which then stimulates mechanoreceptors- sense organs or cells that respond to mechanical stimuli such as touch or sound- in the muscles, tendons, joints, and ligaments. When applying vibration to the legs while weight bearing it passes through the bones to all the tendons, muscles and cells in its path.
This occurs everyday with all our normal activities- sitting, standing and walking. These mechanical forces set up vibrations, usually between 10 to 20 hertz, that then promote remodeling, cellular and tissue growth. Below this mechanical strain threshold muscles atrophy and bone gets reabsorbed. When the minimum is reached, growth occurs. It also increases circulation and blood flow which increases oxygen uptake in the tissues. Over time this decreases osteoclast activity (bone destruction), and increases growth hormone expression. It also has been shown to increase production of osteoblasts- cells that actually make bone. That’s why just walking, stretching and mobilizing can decrease the damage and/or progression osteoporosis can cause.
A great example is orthopedists who prefer not to immobilize a fracture of the humerus (the long bone in the upper arm). It turns out mild activity causes the shoulder muscles that are attached along the long bone to the elbow to vibrate. This creates micro tensions that actually encourage bone to remodel faster than if it was put in a cast. Gentle activity acts like a plucked guitar string, causing a mechanical signal that exceeds the mechanical strain threshold, which then promotes cellular growth. But like everything in the body a precise balance must be honored. Higher or prolonged levels at this threshold can actually cause damage by constricting blood flow.
Pain is transmitted from the periphery to the spinal cord and then to the brain. A perfect example is how the nerve endings wrapped around the taste buds (papillae) on the tongue transmit touch, heat, and pain through a series of pathways to the same areas of the brain. Research shows stimulation of specific nerves such as when we eat chili peppers can actually reduce pain because the strongest signals inhibit the weaker ones. If we are overwhelmed with the hot pepper response and it’s ultimate numbing effect, other, less strong pain signals are diminished. Vibration therapy incorporates this same effect as another way to decrease pain and improve mobilization.
In several studies muscle strength improved in those who performed vibration training as compared to those who didn’t. In one they observed an 18 pound increase in leg extension strength. In another the vibration group had significantly better standing long jump scores, a measurement of lower body strength.
Other studies showed delayed onset muscle soreness was diminished when local vibration therapy was used prior to exercising. 5 minutes of vibration was equivalent to 15 minutes of massage which then increased blood flow and oxygenation reducing lactic acid production and inflammation. And combined vibration and traction therapy were more effective than traction alone.
Recent studies showed frequencies below 20 Hz reduced low back pain by inducing muscle relaxation and improving strength in the abdominal and back extensor muscles. In one study, just three months of 2-3 fifteen minute sessions per week showed clinically significant improvement in pain levels.
Processes like plantar fasciitis, arthritis, fibromyalgia, over use injuries and chronic pain syndromes benefited as well. One study followed patients suffering from chronic pain for 18 months. Over half said their pain was improved after using vibration therapy in 15-45 minutes sessions, several times a week. Benefits were prolonged when followed by 10 minute ice sessions.
It even was shown to significantly boost metabolic expenditures- the net amount of energy available to meet the demands of every day function e.g. metabolism, growth and reproduction- when added to a twenty minute exercise program.
Studies have shown when sitting or standing on vibrating plates, balance and tone actually improved by remodeling chronic or damaged tissue and reducing pain over time. This could have a dramatic impact on speeding up the healing process in minor injuries but even more importantly it could improve damage in peripheral nerves that cause neuropathic numbness, pain and weakness in the extremities. There are three times the mechanoreceptors in the feet than the hands. When they are anesthetized, as happens with neuropathic pain, balance is significantly reduced. Vibration therapy has been shown to amplify signals in the soles of the feet which then improves balance and kinesthetic awareness- the ability to feel and control our movements in space. All of which leads to not only decreased pain but falls and injuries.
It should be used with caution if you’re pregnant, take anticoagulants, have advanced cardiovascular or diabetic disease.
More research is needed to better understand the benefits of vibration therapy. But as a benign addition to other proven modalities, when used safely, it could be a great addition to our pain relief arsenal.