Whole body vibration (WBV) is a mechanical stimulation characterized by an oscillatory motion. The parameters that determine its stress factor (intensity) are frequency, amplitude and magnitude of these oscillations. The displacement of each oscillatory motion determines amplitude (measured in millimeters or mm) of vibration, the repetition rate or cycles of oscillation per second, create the frequency (measured in hertz or Hz) and the acceleration factor indicates the magnitude (measured in g-forces or g).
Low frequency, low amplitude WBV has been studied with subjects exercising on vibrating platforms that produce sinusoidal vibrations (see Figures 1A and 1B). Frequencies tend to range from 15 to 44Hz and displacements from three to 10mm, thus acceleration factors (magnitudes) of 1.8 to 15g. Where the Earth’s gravitational field is equal to 1g (9.81 m.s-2), WBV provides perturbations of the gravitational field over a specified course of time.
Mechanisms and Effects on Human Performance
Vibration stimulates muscle spindle activation, and the rapid continual firing of this mechanism, due to vibration, is known as the Tonic Vibrational Reflex (TVR). TVR is determined greatly by the amount of pre-tension existing in the muscle; thus, movement selection and execution are crucial in determining efficacy of outcomes. This is exactly the reason why “isometric” execution often has more impact on improving strength and power than “dynamic” execution of the same movement pattern (i.e., a squat).
Furthermore, effects are also proportional to the load imposed by the vibration (i.e., total g-forces). In normal conditions, muscles exposed to the daily g-force(s) of Earth are capable of maintaining their performance capabilities and capacities. When gravitational load is reduced and falls below 1g (microgravity), a marked decrease in both muscle mass and function is observed. Comparatively, if gravitational load is increased to readings above 1g (hypergravity), a concurrent increase in muscle cross-sectional area and functional capacity occur. Exercise programs designed with the goal of improving strength and power must induce an increased gravitational load (hypergravity). Such programs have been shown to produce adaptive responses to human muscle that are both morphological and neurophysiological.
WBV research in athletic, geriatric and populations living with disability has shown marked improvements in static, dynamic and explosive strength and power. These are significant findings as such improvements are both acute and chronic in nature. Particularly of interest is that WBV is eliciting functional power outcomes, safely and effectively, without many of the traditional concerns for high mass, high impact and high stress loading. Obviously such factors are crucial where musculoskeletal systems (both active and passive) are less tolerant of these high mechanical and morphological stresses. Current research shows not only improved strength in elderly populations but also much needed speed of movement (see Figure 3), again proving WBV as a safe and effective exercise intervention for the elderly. Equally importantly is the drastic reduction in time required to achieve these outcomes: as little as 12 to 15 minutes training per session, two to three times per week.
Enhanced neuromuscular performance post vibration is related to an increased sensitivity of the stretch reflex. However, it is important to note that vibration is also perceived by Golgi Tendon Organs, skin, joints and other secondary endings. This results in further improvements in flexibility, joint stabilization, sensory motor feedback (proprioception) and body awareness. Combined, these functions are the crux of establishing Active Daily Living lifestyles and functional independence as well as establishing optimal performance and injury prevention. Also of note here is the fact that WBV may be used for purposes of pain reduction. The de-sensitization of nocioceptive feedback will positively affect all above mentioned functions: strength, power, posture, balance, flexibility, etc. The mechanisms for this pain inhibition and/or reduction is a most complex area, yet it can probably be attributed to vibrations impact on the Pain Gate Control Theory as well as the Muscle Spasm Cycle. It is also my opinion that WBV is helping to balance the Autonomic Nervous System, particularly restoring Parasympathetic (PNS) drive. Thus, it is a powerful pain inhibitor through creating an environment for positive change on many systems.
Concurrent to functional strength and power improvements, WBV is a most effective form of fighting bone loss and osteoporosis. Studies have been performed in both animal and human populations showing an improvement in bone mineral. Excitingly, new research, has shown significant (1.5 percent) increase in hip area bone mineral density, as well as muscle strength and postural control, in post menopausal women. These findings present an exciting solution for ever worsening problems in our aging population: osteoporosis, loss of postural control and balance, bone fractures from falls and difficult and incomplete recovery from traumatic falls. So effective is WBV that its impact is being achieved at the knee, hip and spine as well as utilized to expedite orthopedic injury recovery from traumatic surgery. These bone outcomes are due to the combined factors of muscle pull on the skeleton (25 to 50 times per second = a HUGE amount of tension but with little impact forces!), the revascularization of the intraosseous matrix, the enhanced anabolic hormonal profiles (see next paragraph) and the magnitude of load (remember that hypergravity creates overload!). This breakthrough on bone remodeling and density is far more reaching than simply fighting bone loss; it is a powerful tool in expediting orthopedic recovery from trauma and surgery as well as optimizing regeneration from training or competition stress.
Hormonal factors are intrinsically linked to both neuromuscular and morphological adaptations. Indeed, changes in gravitational load will inevitable involve neural and hormonal responses. Studies in astronauts have shown that microgravity will produce a decline in androgen and human growth hormone, primarily due to reduced musculoskeletal tension, loss of hydrostatic pressure and altered sensory motor systems. In contrast, an increase in gravitational load (WBV) has been shown to increase human growth hormone, testosterone and IGF-1. Furthermore, WBV is decreasing cortisol response post exercise. This reduction carries implications regarding prevention of atrophy (muscular, skeletal and neural) as well as balancing the autonomic nervous system. In short, the increased force generating capacity and enhanced proprioceptive qualities from WBV are creating an anabolic environment in which recovery, regeneration and growth can occur. Again, this is of paramount importance in all populations as we now live in highly stressed external and internal environments where catabolism is the norm. We must remember that exercise is a STRESS. This stress only becomes positive if we create an environment for positive (anabolic) change (i.e., supercompensation). For many, if not most, people this is not the case. Anything that naturopathically enhances our anabolic hormones aids in this.
Body composition and body mass are an increasing concern as we now have more obesity, android obesity, diabetes and diseases of toxicity than ever before. WBV has a tremendous impact on the metabolic demand of exercise, both during and following. A muscle firing rate of 30 to 50 times per second (Hz) in multiple directions (planes) will not only increase type 1 (slow) fibers usage, but it will activate those type II (fast) fibers that are so desperately needed for real morphological change. By utilizing fast twitch fibers (WBV), the metabolic demand during and post exercise will be greater. Research has shown WBV to be as much as 25 percent more compared to traditional resistance training. Considering that fast twitch muscle fibers are linked to increases in testosterone and human growth hormone, it makes great sense that WBV increases metabolic demand and initiates and anabolic response. Subsequently, testosterone and human growth hormone will in turn positively impact on one’s basal metabolic rate as well as tissue repair and recovery. The net result is increased muscle mass, decreased body fat and improved weight loss and maintenance.
As the body is forced to react and respond to the expedited muscle activity, the circulatory system is similarly overloaded. Indeed, research shows WBV to increase muscle blood volume by as much as 100 percent. With this increased muscle blood volume comes a stimulation of the lymphatic drainage system. Combined, these two systems of circulation provide optimal nutrient and energy exchange at the metabolic level as well as an enhanced waste product and toxin removal. In themselves, these are very significant findings, yet they will also carry integrated benefits on flexibility, morphological changes, pain reduction and body composition (fat cells house toxins!). This explains why so many clinical environments are witnessing elevated immune function in those patients and clients that utilize WBV.
Many traditional exercise interventions for health, wellness and performance have had to overcome varied and persistent obstacles; thus, participation and adherence rates of physical activity and exercise (especially in the elderly population) are decreasing. These factors are complex and transient, yet include; access, resources, time, poor outcomes (results), pain/dysfunction (exacerbated) and confusion (what, how and when to use).
This technology and science is not only supported by research based evidence but a wealth of global practice based evidence which now has WBV at the core of applied health practices in sports medicine, physical therapy, chiropractic care, athletic training, beauty and wellness worldwide.
For a modality that has been proven to be fast (12 to 20 minutes) and effective (strength, power, balance, bone, pain, hormones, pain reduction, etc), WBV is providing exercise intervention with an innovative application for optimal health, wellness and performance. As part of an integrated approach to exercise programs, WBV offers a very powerful and holistic set of tools.
- A. Abercromby, W. Amonette, et al. Effects of knee flexion angle on neuromuscular responses to whole body vibration. Presented Abstract at NSCA National Conference, July 7th, 2005.
- A. Abercromby, W. Amonette, et al. Neuromuscular responses to two whole body vibration modalities during dynamic squats. Presented Abstract at NSCA National Conference, July 7th, 2005.
- J. D. Bastian, W. Franz. Effects of Whole Body Vibration after arthroscopic reconstruction of the ACL. German Journal of Sports Medicine (2006) V56, No. 7: 228.
- C. Bosco, M. Cardinale, O. Tsarpela. Influence of vibration on mechanical power and electromyogram activity in human arm flexor muscles. Eur J Appl Physiol (1999) 79: 306-311.
- C. Bosco, M. Cardinale, et al. The influence of whole body vibration on jumping performance. Biology of Sport (1998) V15, N3: 157-164.
- C. Bosco, M. Cardinale, et al. Hormonal responses to whole body vibration in men. Eur J Appl Physiol (2000) V81: 449-454.
- J. Duchateau et al. Neural adaptations with chronic activity patterns in able-bodied humans. Am. J. Phys. Med. Reh. 81: in press 2002.
- M. Cardinale, C. Bosco. The use of vibration as an exercise Intervention. Exercise and Sport Sciences Reviews (2003) 3-7.
- Jordan, M, et al. Vibration Training: An Overview of the Area, Training Consequences, and future considerations. Journal of Strength and Conditioning Research (2005), V19, N2: 459-466.
- K. Kerschan-Schindl, et al. Whole body vibration exercise leads to alterations in muscle blood volume. Clinical Physiology (2001) V21, N3: 377-382.
- J. Mester, H. Kleinoder, Z. Yue. Vibration training: benefits and risks. J Biomech, (2005) Apr 30.
- M Roelants, C. Delecluse, S. Verschueren. Whole body vibration training increases knee-extension strength and speed of movement in older women. JAGS (2004) 52: 901-908.
- J. Rittweger, D. Felsenberg, et al. Treatment of chronic low back pain with lumbar extension and whole body vibration exercise. SPINE (2002) V27, N17: 1829-1834.
- J. Rittweger, G. Beller, D. Felsenberg. Acute physiological effects of exhaustive whole body vibration exercise in men. Clinical Physiology (2001) V20, N2: 134 – 142.
- S. Verschueren. M. Roelents, C. Delecluse, S. Swinnen, et al. Effect of 6-month whole body vibration training on hip density, muscle strength and postural control in post-menopausal women: A randomized controlled pilot study. Journal of Bone and Mineral Research (2003) V19, N3: 352-359.