Measuring muscles

Researchers in human movement science and neuro-physiologists at NTNU have developed a new method for measuring muscle activity that is both painless and that provides tremendous amounts of information. The method is called multi-channel surface EMG, and it has a range of useful functions in diagnosing diseases, in rehabilitation, and in physical training.
Pain, exhaustion, or weakening in muscular activity may sometimes be the result of neuro-muscular diseases. Such diseases are diagnosed by measuring electric signals in the muscle in question. Neuro-physiologists have done this for a century now – either by inserting needles straight into the muscle, or by measuring muscle activity by attaching a double set of electrodes (surface EMG) to the skin.

The first of these methods is painful, and it provides only limited amounts of information from a restricted area. The second method is unreliable because muscle signals can be distorted by signals from the skin and from fatty tissue.
Multi-channel surface EMG was developed in the Netherlands by Karin Roeleveld and others. At present Roeleveld is working with the Programme for Sports Science at NTNU, where she is conducting further research into this method, with particular focus on the computer analysis.
The apparatus is a square block with 130 small electrode points. Once this has been attached to a muscle, and the patient is instructed to make certain movements, the information about the muscle is sent straight to a computer brain.

“The smallest unit we can analyse is called a motor unit. Such a unit consists of one single neuron in the spinal marrow with a pathway to the muscle fibre. The aim is to obtain the best image possible of these units: when they are used, how they change in relation to the degree of illness, tiredness, exercise, pain, or ageing,” Roeleveld explains.
Before this method can be put into clinical use in hospitals, however, the systems for computer analysis must be improved. Presently, it takes too much time to process the large quantities of data which are collected by the multi-channel surface EMG system.
So far, this technology is to be found only two places in the world: in Amsterdam and in Trondheim.

By Lisa Olstad