Vibration therapy is the application of low frequency vibrations to the body, either targeted locally or the whole body, generally between 15 and 300 Hz depending on the desired effect [1]. When the whole body is targeted, this is called whole body vibration therapy, whereas targeted vibrations are referred to as local vibration therapy.
The focus of this article will be local vibration therapy. It has been repeatedly shown to reduce pain, increase oxygenation of the blood and muscles, circulation and blood flow, local temperature of tissues subjected to vibrations and activation of muscle metabolism enzymes [1]. Other effects include relaxation of myofascial tissues, systemic relaxation as shown through heart rate variability, increased bone growth and density, as well as improved muscle strength and flexibility [1][2][3].
How do the Devices Work?
Localized vibration devices are generally wearable, handheld, or a machine where the user rests the targeted body part for vibration to be applied.
Local vibration roller device
Vibration therapy devices use mechanical movements, such as motors, to produce vibrations at specific frequencies. Important characteristics for these devices include frequency (Hz) and amplitude, which is the measure of strength of the vibrations.
Researchers indicate that frequency is the most important factor by far, as different reactions and interactions occur within the body at different frequencies. The devices operate at relatively low frequencies, between anywhere from 15 to 300 Hz, or vibrations per second. These ranges are where the most effective responses have been seen [1][4].
The vibration sessions can last longer than whole body vibration, ranging from 5 minutes to 60 minutes or longer.
What does it Do to the Body?
Vibration therapy, as mentioned above, has various effects on the body, such as impacting muscle, blood flow, bone, and reducing pain. The vibrations applied to the body are received and absorbed by the body, transferring this vibrational energy to the body’s cells which then convert it into other forms of energy [5]. This energy is primarily picked up by neurons, which then convert these oscillations to electrical signals and are carried to the remainder of the nervous system [1][4].
There are also other biochemical changes which occur as a result of localized vibration therapy, which is hypothesized to be a result of some interaction between the cell nucleus (oscillating due to the vibrations) and the cellular cytoskeleton [6].
Mechanisms of Muscular Effects
For the impact to the muscles, which includes muscle strength, flexibility, and soreness, there is a term called tonic vibration reflex (TVR) to describe how the muscles react to the vibrations with reflexive contractions [1][7].
This reactivity of muscles occurs because the vibrations are able to selectively stimulate muscle spindles (sensory neurons) locally in the muscles which then trigger the stimulation of alpha-motoneurons (control muscle movement) in response to the detections of contractions [1][2][7].
Mechanisms of Analgesic (Pain Reducing) Effects
The primary theory for the analgesic effects of vibration therapy is what is known as Gate Control Theory. This is the theory that non-painful, or non-noxious, stimuli can override the pain signals received by the brain. This theory also applies to the sensation of itch.
We will explore this further in the next article.
