Which Frequency Is Best for Whole Body Vibration?

Various theories exist to answer this question. As you will learn, the short answer is that first, it depends on your exercise goal. Are you trying to relieve tight back muscles, tone up your arms or strengthen your legs? It depends on your body; are you heavy or light, young or old, trained or untrained? All these factors influence what is the perfect frequency for you.

In any case, the underlying goal is to get the vibration machine to activate your muscles and stimulate your connective tissues. There is a specific range of vibration frequencies. Within that range, you should generate the most amount of muscle activation. There’s a good chance the perfect frequency for your exercise goal and your body type exists somewhere in or below that range.

Before we reveal what that range is, let us review ‘how’ this muscle activation comes about.

How whole-body vibration activates muscles

 
A vibration platform repeatedly lifts you up, then drops you down. Those two actions cause movement of your joints and stretching of your muscles. These actions result in physiological effects. That includes an increase in gravitational loading of the spine the vibration of the muscles and the activation of one or more reflexes. Vibration frequency helps determine the intensity of those physiological responses.
 

Vibration plate induced muscular reflex

 
One of many reflexes that assist in the smooth movement of your body. It helps protect it from sudden or unexpected movements. It is activated by stretching muscles along with a special organ inside them called a spindle. The spindle responds to stretch by sending electrical impulses along nerves to the spinal cord. Then back down the same limb to the muscle causing it to contract.

This stretch response occurs in whole-body vibration at frequencies as low as 6Hz (1).
 

What does vibration do to muscles?

 
You might recall seeing an image of a female opera singer shattering widows with her voice as she bellows out a high pitch note. Although this is an old wives tale, the principals behind it are legitimate. All physical objects have a natural frequency at which they resonate. When a physical object vibrates at the same frequency as its natural resonance frequency. It causes the vibrating object to resonate with much larger magnitudes.

Different parts of the body have a natural frequency at which they resonate. The natural frequencies of the soft tissues in the lower extremity range between 10 and 50 Hz (2). Scientists have concluded how you can get the most muscle activation (3). Match the vibration plate frequency with that of the natural resonance frequency of the muscle.

What is the highest frequency for stimulating muscle activity on a vibration machine?

 
Muscle spindles can respond to vibration when applied to a muscle-tendon with frequencies up to 100Hz. This type of direct vibration causes 100 tiny muscle stretches per second. The spindle will respond to each of the 100 stretches (4). Also, the muscle twitched in response to each brief burst from the spindle. Meaning muscles can also be activated up to 100 times a second.

It is also known that the strength of the muscle contraction depends on the number of electrical signals it receives from the brain (voluntary contraction) and/or the Spindle (reflex contraction).

Does this mean that the highest possible frequency will also produce the most muscle activity? The answer is “No” more is only better up to a point.

Ask any vibration plate owner that if you increase the frequency from 30Hz to 50Hz muscle activity gets reduced. The feeling is as if the vibration plate is not working.

Best whole-body vibration frequencies

Finnish researchers (5) may have an explanation for this. They tested whole-body vibration frequencies ranging from 10 – 90Hz. The idea was to see how much G-force is delivered to the ankle, knee, hip and spine. What they found was that the higher the frequency went, the more the vibration was dampened as you travel up the body from the feet towards the spine. They found the greatest accelerations could occur for:

• The ankle at up to 40Hz
• The knee at up to 25Hz
• The hip at up to 20Hz
• The spine at up to 10Hz

They found that exceeding a frequency of 40Hz the transmitted vibration power declined by a factor of 10 to 1000. That means the movement in those body parts is reduced up to 1000 times at very high frequencies.

The bodyweight of a person can also influence how well the vibration is transmitted through their body. In effect, heavier persons have a firmer contact with the platform at all frequencies. Yet in 2010, recommendations from the International Society of Musculoskeletal and Neuronal Interactions (6) made mention of what they refer to as “skidding”. Where the vibration settings become too high and cause the user to skid on the platform.

This can happen at lower frequencies if the person on the machine is very lightweight. You will know it is happening if your feet start sliding around the platform. For example, watch children on a whole-body vibration machine. Even at frequencies below 30Hz, they start sliding around on the platform. Their body is not heavy enough to keep them in firm contact with the platform when it is moving very fast.

Another issue with higher vibration settings. The platform can move so fast that the feet no longer have time to drop down before the platform comes back up again. Like a Hummingbird’s wings; they’re moving so fast they appear to be motionless. The same could be happening with your feet if the vibration platform is moving too fast. If they no longer move up and down, your muscles are no longer getting stretched.

The best frequency of stimulation and muscle contraction

While setting an optimal vibration frequency appears to be an individual setting. One thing is very clear, scientists choose frequencies between 20-45Hz in their research. A review of whole-body vibration research by veteran researcher Jorn Rittweger (7). Revealed that all studies showing positive muscle training effects used frequencies of 20-45Hz.

Clues to why scientists keep choosing to use frequencies in that range come from another of Rittweger’s papers (8) where he states:

“From the experience in our laboratory and by reports from other colleagues, a vibration frequency below 20Hz induces muscular relaxation (we have successfully applied 18 Hz vibration exercise in patients with chronic lower back pain). Whereas there are reports that at frequencies above 50Hz severe muscle soreness and even haematoma may emerge in untrained subjects.”

Does vibration loosen muscles?

Is your goal is to relieve tight muscles or assist with recovery from a tough workout? Then causing the already over-tight muscles to tighten with the largest intensity is not going to help.

At frequencies below 20Hz, particularly if the amplitude is low, you are alternating between small continuous tension to a moderate continuous tension. This rhythmic pulsing not only stimulates blood flow. Which aids in detoxifying the muscles and supplying more nutrients. It also stimulates the part of your nervous system that is active when you fall asleep. You can help this soothing effect with deep slow breathing and if it is safe to do so, closing your eyes.
 
Summary
 
In conclusion, higher vibration frequencies will generate more muscle activity. Only to the point where the vibration is being transmitted effectively. Higher vibration frequencies combined with higher vibration amplitudes will generate most muscle activity. There appear to be good reasons to limit vibration frequencies to less than 50Hz. Frequencies below 20Hz can be used for relieving tight sore muscles and helping with recovery.

References:

(1) Changes in joint angle;
(2) Modification of soft tissue vibrations in the leg by muscular activity;
(3) Simulation of surface EMG for the analysis of muscle activity during whole body vibratory stimulation;
(4) High frequency tendon reflexes in the human soleus muscle;
(5) Transmission of vertical whole body vibration to the human body;
(6) Reporting whole-body vibration intervention studies: recommendations of the International Society of Musculoskeletal and Neuronal Interactions;
(7) Vibration as an exercise modality: how it may work, and what its potential might be;
(8) Acute changes in neuromuscular excitability after exhaustive whole body vibration exercise as compared to exhaustion by squatting exercise;