Following completion of this chapter, the student will be able to:
- Define biofeedback and identify its uses in a clinical setting.
- Contrast the various types of biofeedback instruments.
- Explain physiologically how the electrical activity generated by a muscle contraction can be measured using an electromyograph (EMG).
- Break down how the electrical activity picked up by the electrodes is amplified, processed, and converted to meaningful information by the biofeedback unit.
- Differentiate between visual and auditory feedback.
- Outline the equipment setup and clinical applications for biofeedback.
Electromyographic biofeedback is a modality that seems to be gaining increased popularity in clinical settings. It is a therapeutic procedure that uses electronic or electromechanical instruments to accurately measure, process, and feedback reinforcing information via auditory or visual signals.1 In clinical practice, it is used to help the patient develop greater voluntary control in terms of either neuromuscular relaxation or muscle reeducation following injury.32
Electromyography (EMG) is a clinical technique that involves recording of the electrical activity generated in a muscle for diagnostic purposes. It involves a sophisticated electrodiagnostic study performed in an EMG laboratory, which uses either surface or needle electrodes for measuring not only electrical activity in muscle but also various aspects of nerve conduction. An electromyogram is a graphic representation of those electrical currents associated with muscle action. EMG is widely used in the diagnosis of a variety of neuromuscular disorders. Certainly EMG would not be considered a therapeutic modality.31
|Biofeedback instruments measure:|
- peripheral skin temperature;
- finger phototransmission;
- skin conductance activity;
- electromyographic activity.
The small portable biofeedback units that will be discussed in this chapter also measure electrical activity in the muscle and are in fact small electromyographs. The discussion in this chapter will be limited to the information on EMG necessary for the clinician to understand to be able to effectively incorporate biofeedback techniques into clinical practice.
The term biofeedback should be familiar because all clinicians routinely serve as instruments of biofeedback when teaching a therapeutic exercise or in coaching a movement pattern. Using feedback can help the patient to regain function of a muscle that may have been lost or forgotten following injury.2 Feedback includes information related to the sensations associated with movement itself as well as information related to the result of the action relative to some goal or objective. Feedback refers to the intrinsic information inherent to movement, including kinesthetic, visual, cutaneous, vestibular, and auditory signals collectively termed as response-produced feedback. However, it also refers to extrinsic information or some knowledge of results that is presented verbally, mechanically, or electronically to indicate the outcome of some movement performance. Therefore, feedback is ongoing, in a temporal sense, occurring before, during, and after any motor or movement task. Feedback from some measuring instrument that provides moment-to-moment information about a biologic function is referred to as biofeedback.3...