Mechanomyogram

The mechanomyogram (MMG) is the mechanical signal observable from the surface of a muscle when the muscle is contracted. At the onset of muscle contraction, gross changes in the muscle shape cause a large peak in the MMG. Subsequent vibrations are due to oscillations of the muscle fibres at the resonant frequency of the muscle.

Signal Characteristics
The MMG is a low frequency vibration that may be observed when a muscle is contracted using suitable measuring techniques.

Measurement Techniques
It can be measured using an accelerometer or a microphone placed on the skin over the belly of the muscle. When measured using a microphone is may be termed the acoustic myogram.

Uses
The MMG may provide a useful alternative to the electromyogram (EMG) for monitoring muscle activity. It has a higher signal-to-noise ratio than the surface EMG and thus can be used to monitor muscle activity from deeper muscles without using invasive measurement techniques. It is currently the subject of research activity into prosthetic control and assistive technologies for the disabled.