View Full Version : Muscular Pains/Vibration Frequency etc

08-29-1998, 04:21 PM
Hand held vibrators which run off the mains supply are widely known and
widely available. I think there is no doubt that the may fairly often
give some relief for people with what may be loosely called muscular
pains. The relief is obtained during the application, and does not
usually last for long afterwards

I believe the vibration generated is twice the mains frequency. In
Europe this will be at 100 Hz in North America 120 Hz.

But are these frequencies the optimum ? Has the effect using other
frequencies been tested in relation to the degree of pain relief
achieved ?

Apart from this would some degree of frequency modulation be useful ?

There are also on the market pillows which contain a source of
vibration. When the person has such a pillow behind them and leans back
a switch in the pillow is pressed and the vibration starts. I have
examined one such pillow. Inside is a unit containing two large 1.5.Volt
batteries, the switch and the source of the vibration. As far as I can
see this is a small DC motor carrying on its shaft an eccentric weight.
This is a simple effective and cheap system.

The one I have measured, which had new batteries, gave a vibration of
about 70 Hz with some harmonics.
As the voltage of the batteries drops the frequency will drop and the
force generated will drop, perhaps being proportional to the square of
the frequency.

Is 70 Hz better than 100 Hz. or is the frequency not critical ?

It seems to me that the parameters used have been chosen for both of
the types discussed above more for the ease of manufacture rather than
for the optimum effect. It is is of course possible that the relief is
only minimally dependent on frequency over a fairly wide range.

If you also have views as to the mechanism by which the relief is
obtained it can sometimes be substantial, please let me know.

Observations could be made with one of the larger moving coil vibrators
where the current passed and frequency can be accurately controlled.
These instruments are comparatively expensive. A suitable one would be
physically large and probably impracticable for routine use but might be
used to answer some of these questions on a research basis.

I will probably post the replies I consider significant

Geoffrey Walsh

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