The journal of sport and exercise medicine
British Journal of Sports Medicine 2008;39:585-589; doi:10.1136/bjsm.2008.016857
Copyright © 2005 BMJ Publishing Group Ltd &
British Association of Sport and Exercise Medicine.
Whole body vibration exercise: oscillatory or vertical vibration?
M Cardinale1, J Wakeling2
1 College of Life Sciences and Medicine, University of Aberdeen, Aberdeen, Scotland, UK and British Olympic Medical Institute, Northwick Park Hospital, London, UK
2 The Royal Veterinary College, Structure and Motion Laboratory, North Mymms, Herts AL9 7TA, UK
What is the principle of side-oscillating vibration?
With side-oscillating vibration the rapid involuntary muscle activation occurs as with other types of vibratory equipment, but the core principle is slightly different. The 'see-saw' motion of the foot-plate induces muscle activation in strict alternation - which means that the muscles on one side of the body are first activated, and then relaxed as the activation shifts to the other side of the body. Non-pivotal equipment induces muscles activation on both sides of the body simultaneously which compresses the two bones of any joint together. Repeating this compression at high frequency is unnatural for the body and induces a high load as you are being repeatedly jumped, with joints placed under stress. Also, under a linear pattern of movement involuntary muscles are not engaged.
With side-alternating vibration the load is in fact lower then when walking, the core muscles are engaged, and the neuro-muscular system is trained to fire muscles as we should in natural exercise - through an alternating crisscross pattern.
This mobilizes joints and has a highly balancing effect. When people first step off their feedback is most frequently a feeling of being lighter, a symptom of distributing their standing load both vertically through more of their spine and also in greater balance over left and right sides.
A Spinal Analysis Machine (SAM) that chiropractors and other practitioners use for postural examination, amongst other features includes twin scales that demonstrate the difference in weight between the right and left sides of the body. Remarkably just 3 minutes exhibits a marked improvement, reducing imbalance by up to 100%.
So the fundamental principle is this: Through voluntary exercise you carry your entire physiological history, imbalances and injuries - which means that you inevitably stress one side more and allow the other side to lag, exaggerating your existing condition. But through involuntary, alternating muscle work you take your body through equal travel on both sides, activate involuntary muscle, mobilize areas that are not engaging in voluntary movement, significantly improve balance and return immobile areas to mobility.
Muscle contraction as a result of linear movement
A vertical vibration machine simulates a jump for the user. In this scenario muscles on both sides of the body contract simultaneously. The load on the body is very high, around 600% (6x the body weight of the user). The repetition of this impact makes certain postures unsuitable, as well as limiting the suitability of this technology to people who are already quite fit. Anyone with joint issues particularly any condition of the spine typically finds this movement pattern uncomfortable and often painful.
Muscle contraction as a result of oscillatory movement
The muscles effected when using an oscillatory vibration machine are contracted alternately - the same muscles on both sides of the body are never engaged at the same time. This alternating sequence means that the load on the body from vibration training with an oscillatory type platfom is approximately +30% of your body weight. This compares with +50% induced under the condition of ordinary walking and makes oscillatory vibration training a mere fifth of the load induced with linear equipment
When we first explain this to people we are often asked about bone development... "isn't bone built under high/impacting forces?" we are asked. This line of questioning comes from a degree of flaw in understanding. External load and impact on the body is not typically beneficial. The forces applied to our bones to which the bone adapts are forces caused by the muscles - applied during every day living - not caused by external influences. This becomes clear when you picture how the muscles work as levers between the majority of our bones, and are not involved under compression stress. Thus every-day loads should maintain our skeletal health. To compensate for bone resorption / bone-matter depletion / osteoporosis, the stress on the bones has to be above the every-day level but not intense by any measure. Thus the +30% load of oscillatory training may be used to regain muscle force and stimulate the addition of new bone material.
What oscillatory vibration training cannot achieve that linear / vertical vibratory systems can is improvement in 'jump height', a well studied benefit of those systems - which explains their use by American football and basketball teams. This is unlikely to be of interest to most home users.
Off the platform, oscillatory training provides real world benefit as the alternating pattern of muscle work has been precisely demonstrated to the neuromuscular system, developing balance, proprioception and an even-form whether standing, walking or exercising.
The benefits to the side-alternating platform is obvious
As the rhythmic movement of the platform reaches the tops of your legs, the pelvis is gently mobilized rather then compacted. Then, all your pelvic and core muscles at the front and trunk of you torso are activated and developed, while the snake-like movement repeats throughout your spinal vertebrae - mobilizing, clearing stagnant fluids & inflammation, and allowing fresh oxygenated blood to enter. Just three minutes will typically alleviate back pain.
Users find oscillating platforms far more comfortable then vertical vibration platforms. In particular, the vertical vibration system easily reaches the skull and can lead to discomfort, disorientation and nausea. Conversely the side-alternating platform produces a rhythmic snake-like movement throughout the body mimicking natural gait. Both systems effectuate an involuntary stretch reflex but oscillatory vibration training offers advantages that vertical vibration training cannot achieve from a simple standing posture.
• Tensor and flexor muscles are activated alternately causing immediate activation of your core muscles, toning your abdomen.
• A natural movement pattern similar to walking encourages improved posture (walking activates alternate muscles on either side of the body, never the same muscle on right and left sides).
• Reduced head vibrations - vertical vibrations exit via the head whilst oscillatory vibrations are dampened in the core abdominal region.
• Users can adjust the amplitude simply by moving their feet closer or further apart. This would have no affect on a vertical vibration plate where the amplitude is fixed.