Recommendations for EMG biofeedback & NeXus 10

Whether the client is an athlete aiming to improve performance or someone struggling with stress EMG biofeedback can be a useful approach.  The principle of EMG training is normally to provide the client with enhanced information about his or muscle tension in a particular area, hoping that with repeated training this will facilitate improved control of the muscle. Relaxation of excess and inappropriate tension is the usual goal.  As with all biofeedback approaches the aim is to bring about improved awareness of a physiological state that is "normally" not in our conscious awareness. This provides a step in the direction of improved control.

Recording EMG from the trapezius muscles - a common site for tension and stress

Electrodes are attached to the skin over the muscle being targeted for change, and connected to the EXG sensor of the NeXus system. Muscles may be targeted anywhere on the body, including the forehead, neck, shoulders, back, jaws, arm, legs. The insertable vaginal sensor and rectal sensor can be used to target pelvic muscles and rectal muscles respectively.

Common sources of EMG artefact

The magnitude and nature of the tiny electrical signals emitted by the muscles are proportional to the degree of contraction. These are amplified and displayed in the BioTrace software. It is necessary to understand and minimise any artefacts that can currupt the date.

There are lots of possiblities for feedback. For example the visual display may be digits, polygraph-style lines, or changes in colors or patterns. An audio tone may indicate changes in muscle tension by a rising or falling tone, or by a change in frequency of a beep. The NeXus systems allow for the recording of average muscle tension over a specified time interval.

After some instruction, the client is allowed quiet practice time during which he or she attempts to lower the measured muscle tension, using the biofeedback signal as a guide.  The clinician suggests various ways to relax, helps deal with obstacles to learning, keeps track of progress, and generally facilitates the learning process.

Home practice is often a good idea, since the goal is to learn better control of the muscles without the aid of biofeedback monitoring. One or more criteria are usually set as goals of training: for instance, staying below two microvolt for the upper shoulder. Speed of recovery from contraction is another common criterion, and also keeping muscle tension lower during movement.

The frequency of sessions varies, and may be once-twice per week or less often. Biofeedback is considered a temporary learning aid, and as the client becomes more sensitive to internal sensations and learns to read his body better, the biofeedback training becomes less necessary.

The duration of this learning process varies from person to person, but might typically take one to three months. Duration is best determined by achieving the criteria rather than by number of sessions. Symptoms are usually tracked with home diaries, and this helps the client to understand which activities and situations increase muscle tension. Self-regulation eventually begins to become habitual: goals such as keeping the shoulders low or the jaw loose require less and less conscious involvement.

Recommended Hardware

The following hardware is recommended when looking to apply EMG biofeedback with the popular NeXus 10 biofeedback unit running Biotrace+ software.

The requirements for EMG biofeedback with a NeXus 10