Low back pain, being one of the most disabling musculoskeletal conditions, can pose major threat to healthy aging by limiting physical, mental, and functional capabilities. Low-back pain can lead to an increased number of medical leaves (up to an average of 15.5%) reduced work productivity as well as increase economic burden. In the US, the combination of direct medical healthcare expenditure and loss of work productivity due to low-back pain have been estimated to be as high as 635$ billion annually. It is estimated that prevalence of common low-back pain in a lifetime ranges between 60-70% in developed countries, with the one year prevalence at 15%-45% and an adult incidence of 5% per year. Factors that seem to have contributed the most to the increase in prevalence of low-back pain are as such; educational status, type of occupation, job satisfaction, obesity, psychosocial factors as well as psychological factors such as stress and depression.
Low-back pain may present as back pain alone or back pain with referring symptoms down the leg. The most common cause of low back pain is non-specific as they are poorly localized while other specific causes are either from structural origin or are pathological based.
That being said, mild cases of low-back pain are rarely disabling and may not require care. Approximately 50% of mild new/acute cases tends to recover within a few weeks. However, if not well managed, recurrences of pain are common and can show persistence. Studies show that at least 60% of chronic low-back pain patients would continue to have pain after a year.
The recurrence and lack of recovery for certain populations of low-back pain patients can probably be associated with the lack of neuromuscular control/reduction of proprioception of low back muscles. Proprioception is the body’s ability to sense joint position, movement and action mediated by the central nervous system through sensory receptors in the muscles and joints. Proprioception is a key component for neuromuscular control and joint stability. In essence, lack of proprioception ability affects normal coordinated movement.
Additionally, the lack of joint stability restricts strength, endurance & flexibility which altogether increase risk of injury. Studies have found that there is a link between lumbar proprioception deficit and the reoccurrence of low-back pain. low-back pain patients has been shown to have a lower accuracy for detecting changes in trunk position as well as displayed a higher trunk repositioning error during sitting position compared to a pain-free individual. Proprioceptive deficit has also been thought to be the consequence and the cause of re-injury. The observed impairment in trunk proprioception in low-back pain patient is thought to be caused by combination of events such as the traumatic damage of tissues, progressive muscle fatigue, and/or the overactivation of sensory receptors which directly affects neuromuscular control.
The general principles of low-back pain clinical management aim to provide pain relief in addition to minimising disability. Most clinical practice recommends exercise intervention to reduce pain and improve overall function in low-back pain patients. Over the recent years, therapeutic vibration has gained popularity as a complementary therapy to exercise and is advocated as an alternative choice of treatment to relieve pain, improving function and quality of life in low-back pain patients. Vibration therapy has been widely utilised to improve proprioceptive function in athletic and non-athletic population and has an impact on improving muscular function for young and older population.
Different frequencies of vibration have been studied to provide different types of effect. Vibrational stimulus of 60-100 Hz can induce involuntary muscle contraction through the activation of proprioceptive sensory system while stimulus between 30-50Hz as well as 100-120Hz may offer effect of muscle relaxation and pain relief. It has been theorized that therapeutic vibration can induce pain relief via pain gate control mechanism and muscle relaxation. According to the pain gate theory, low intensity focal vibration can activate large fibers ((A-β fibers)) and prevent small fibers (A-δ or C fibers) from transmitting pain signal to the central nervous system.
Low frequency vibration ranging between 30-50Hz has been noted to interrupt the pain-spasm-pain vicious cycle by inducing muscle relaxation. Studies have shown that both focal and whole body vibration has the ability of inducing muscle relaxation. Taking into consideration that most cases of low-back pain would present with paravertebral muscle spasm, repeated use of therapeutic vibration may prevent the build-up of muscle tension that may attribute to low-back pain.
Vibration therapy can improve neuromuscular control through stimulation of sensory receptors via muscle spindle which then increases the frequency of signal to the brain thus increasing recruitment of previously inactive muscle fibres (Bagheri et al, 2012). Apart from that, previous studies have shown that therapeutic vibration can increase excitation of spinal and supraspinal functions leading to an improved sensory nervous system which directly controls the muscle fibre recruitment.
Apart from varying frequencies, therapeutic vibration can be generated either as non-stochastic (non-random) or stochastic (random) vibratory pattern. Non stochastic vibratory pattern are created by linear (simple) frequency vibrations and is commonly applied in most vibration training devices in the market. On the other hand, stochastic vibratory pattern is created by non-linear frequency vibrations making it complex and unpredictable.
The Proxomed SRT Zeptor (SRT=Stochastic Resonance Therapy) ) is currently the only device in the market which applies stochastic vibrations. In comparison, training with randomized vibratory pattern would prove to be superior to non-randomized vibratory pattern due to the erratic nature of stochastic vibrations. An individual will not be able to anticipate the upcoming stochastic vibratory pattern hence constantly challenging the body. Such will provoke an interaction of different types of neurophysiologic sensors ultimately increasing muscular activity and improving neuromuscular coordination. Its potential for improving sensorimotor performance makes it beneficial for variety of scenarios that requires balancing capabilities from day to day fall prevention to performance based sport activities. Such qualities make stochastic vibration a valuable intervention for injury prevention and also conditioning.
At Rehamed Therapy, stochastic vibration is implemented in our Unexpected Disturbance Program (UDP) during the final phase of rehabilitation before returning to sport. Taking into consideration that most fall/injury incidents tend to happen unexpected, using random vibrations as part of training serve as an unpredictable environment thus mirroring real life situations. Notably, previous studies that have implemented UDP with stochastic vibrations into the final phase of rehabilitation showed improved conditioning and postural control.
The difference in effectiveness between stochastic and non-stochastic applications has been demonstrated in studies involving Parkinson patients with postural instability. While studies on the use of non-stochastic vibrations for Parkinson were conflicting, studies using stochastic vibrations were consistent showing improvement in postural stability.
Clinical application of therapeutic vibration on low back pain has been demonstrated in previous studies. One study in particular compared the effects of whole body vibration (WBV) exercise program with a general exercise program on individuals with chronic Non-specific low-back pain (NS-LBP) after 12 weeks.
84 subjects aged between 18- 60 years old were randomly allocated into the WBV group (intervention) and the general exercise group (control). The primary outcome measures were pain intensity and functional disability measured through Visual Analogue Scale and Oswestry Disability Index. Additionally, they also included lumbar joint position sense, quality of life and Global perceived effect as secondary measures.
At the end of the program, individuals who had undergone the WBV program demonstrated significant positive effects in terms of pain relief, functional disability, quality of life and perception of treatment effect compared to those who undergone general exercise program. Notably, the intervention group demonstrated an additional average reduction of 30% on Visual Analogue Scale and additional reduction of 12% on Oswestry Disability Index scores compared to the control group. In addition, individuals from WBV group showed 50% better accuracy on lumbar joint positioning test than those from general exercise group attributing to better proprioceptive capabilities. Finally, 75% of the participants in the intervention group reported good perception towards their treatment better than control group (36%).
These results resonate with previous studies that utilized a similar protocol. Such positive findings prove that a weekly exercise program in combination with vibration therapy is beneficial for patients with chronic NS-LBP.
Rehamed Therapy employes vibration therapy is one of the alternative choices of treatment utilized for low back pain patients, due to its beneficial effects on pain relief and function. Such combination of effects makes it versatile and suitable to be used throughout the pain continuum (from acute to chronic). That being said, regular therapy with therapeutic vibrations may improve many abilities of a human body (muscular function, bone health and functional capability).