Effects Of Vibration Training on the Brain (Academic)

Written by Gabriel Ettenson, MS, PT

As a physical therapist and fitness enthusiast, I’ve experienced firsthand, and secondhand through my patients, the sense of euphoria, clarity and enhanced vitality that comes from using a whole body vibration platform for training or therapeutic purposes. This form of exercise, which is referred to as vibration training (VTr) and vibration therapy (VTh), has demonstrated potential to improve bone density, balance responses, arterial circulation and muscle strength.1-4These benefits have been described in numerous studies for the past 15 years. Recently however, as interest from the world of western medicine has increased, we’ve seen new and exciting potential for this technology, including treatment of neurological diseases.

In a study from the University of Miami, researchers demonstrated that after a 1-month whole body vibration therapy program subjects with incomplete spinal cord injuries could increase walking speed, cadence, step length and consistency of intra-limb coordination.5It’s clear that clinicians should look beyond the categorical musculoskeletal effects and explore more intricate and potentially more profound roles of VTr and VTh to positively influence functions of the central nervous system (CNS). Through a better understanding of these neurophysiological mechanisms, this technology’s existing applications can be better clarified. In addition, further developments of its potential relevance may touch many areas, such as pain management, neuroendocrine function, mood alteration and memory, and improvement of the efficiency and strength of neurophysiological pathways. The purpose of this article is to explore the role of VTr and VTh to help promote increased serotonergic activity, neurogenesis through expression of brain derived neurotrophic factor (BDNF), and the associated, rapid release of enkephalins and endorphins into the bloodstream.

The primary mechanisms by which this form of exercise interacts with the human body is through the tonic vibratory reflex (TVR). This reflex, a subject of great interest amongst researchers, occurs in response to the bombardment of the CNS by vibrational input and the resulting repeated muscle spindle excitation. The result is a more complicated version of the tonic stretch reflex. In the case of the TVR, the reflex includes polysynaptic pathways and the need for modulation by specific descending pathways that control posture and muscle tone.6Although many pathways exert an influence over this modulation activity, the primary pathways are the vestibulospinal and reticulospinal tracts.

The reticulospinal tract, an extrapyramidal tract, originates in the reticular formation. The reticular formation is a loose network of neurons in the brainstem. Through the excitatory mechanisms provided by TVR and a whole body vibration platform, the raphe nuclei, which are primary stores of serotonin in the brain, are activated. This activation results in increased serotonergic pathway activity and serotonin release. Serotonin, a neurotransmitter, is responsible for mood elevation, feelings of ecstasy, increased sexual desire and function, increased motivation and improved sleep.7

FIBROMYALGIA APPLICATIONS

Low serotonin levels have been linked to depression, weight gain, sleep disorders, migraine headaches and restless leg syndrome. The largest group that may benefit from increased serotonin production are those that suffer from fibromyalgia. Recent studies have shown that a common characteristic between fibromyalgia patients is low serotonin levels. As a result, studies with medications designed to reduce the reuptake of serotonin in the brain have provided insight into potential causes and treatment of fibromyalgia.8 Lower serotonin levels also signal the release of substance P, which is responsible for transmitting pain signals through the CNS and may be responsible for the increased pain sensitivity in fibromyalgia. The potential to use VTh and VTr as a pain treatment modality demands further investigation.

A RECIPRICOL RELATIONSHIP

The reciprocal relationship between serotonergic activity and the expression of BDNF has been established.9As serotonin levels rise in the brain, BDNF expression is encouraged. As BDNF expression in the brain increases, serotonergic activity and serotonin release is supported. BDNF, a neurotrophin, acts on neurons of the CNS and the peripheral nervous system. Its role is to encourage the growth and differentiation of new neurons, while protecting existing neurons and increasing the efficiency of communication. This process is neurogenesis.

Until recently, clinicians believed the brain matured at age 25 and nerve cells didn’t divide or replicate. However, recent studies have shown that the adult brain can generate new brain cells.10This finding is the foundation behind neuroplasticity. Neurogenesis occurs in the hippocampus, where higher learning and memory occurs; its the location associated with Alzheimer’s disease, epilepsy and post-traumatic stress disorder. Potential applications of promoting neurogenesis to occur in the adult brain are endless and treatment modality should be considered and explored.

A TONIC VIBRATORY REFLEX

Returning to the influence of the TVR on the raphe nuclei, there’s also an association with enkephalin release through the interaction with enkephalin interneurons in the spinal cord.11Enkephalins, sometimes used interchangeably with the term endorphins, are naturally occurring opioids in the body. When released, they’re responsible for blocking pain and reducing nociceptor activity by binding to opioid receptors in the brain. The association between exercise and enkephalin and endorphin release is what’s been referred to as a “runner’s high.” This arguably addictive condition has been the subject of debate for many years. However, recent research in Germany using positive emission topography has confirmed the real existence of this phenomenon.12Besides potential applications for pain management by increasing production of enkephalins, the ability to create an “addiction to exercise” holds potential for fighting the war against obesity.

POINTING TO THE FUTURE

Like exploring quantum physics and the activities of subatomic particles, understanding the physiological mechanisms by which the CNS works has improved significantly in recent years. As it has improved, however, the potential for these physiological mechanisms to occur differently than we have understood in the past has also proven to be much greater. These pathways through which whole body vibration may interact with the body have been demonstrated in clinical research. A clinical demonstration of how these pathways occur in response to VTr and VTh is still needed.

The technological applications can be far reaching and as we continue to pursue and refine the clinical significance of whole body vibration, we may be able to break through barriers that still exist in rehabilitation. Along the way, we need to improve the wealth of knowledge that has already been established in western and eastern medicine, and in the osteopathic and health and fitness communities. Together, we can move to the next stage of fighting disease, improving quality of life for patients and encouraging the pursuit of eliminating disability, reducing health care costs and building stronger, more efficient “mind-body” neural connectivity.