Evaluation of a Respiratory Muscle Biofeedback Procedure–Effects on Heart Rate and Dyspnea

Abstract

Patients with respiratory diseases or anxiety frequently complain about dyspnea, which may be partly related to chronic tension of respiratory muscles and/or dynamic hyperinflation. In two experiments we tested a biofeedback technique that recorded electromyographic (EMG) activity from a bipolar surface electrode placement over the right external intercostal muscles with visual signal feedback. Healthy participants were tested in their ability to alter the signal. Heart rate was measured continuously throughout training trials. In the second experiment, dyspnea was rated on a modified Borg scale after each trial. Participants were able to increase their EMG activity considerably while heart rate and dyspnea increased substantially. Changes in EMG activity were achieved mostly by manipulating accessory muscle tension and/or altering breathing pattern. Thus, the technique is capable of altering respiratory muscle tension and associated dyspnea. Further studies may test the procedure as a relaxation technique in patients with respiratory disease or anxiety.

Respiratory Muscle Tension as Symptom Generator in Individuals With High Anxiety Sensitivity

“…In a pilot study with healthy individuals, we used electromyogram (EMG) biofeedback targeting the tension levels of intercostal muscles (12). Our findings showed substantial increases in dyspnea during periods of tension.…”

“…Our sample was also limited in that we only recruited from an undergraduate student population. Participants' qualitative reports of our pilot study also suggested that more than one respiratory muscle site was activated by the biofeedback task, with some participants describing in the debriefing session maneuvers such as tension of chest muscles and/or the shoulders or abdomen to manipulate the biofeedback signal (12). With regard to our measures of respiratory muscle tension, as with any surface electrode placement, we did not measure the activity of individual muscles but more nonspecific activity at a particular muscle site (51).…”

“…EMGs were measured with the Biopac System (Biopac Systems Inc., Goleta, CA), using surface electrodes (inner diameter, 18 mm) with a bipolar placement on the left external intercostal muscle of the second and third intercostal spaces (12,15). Leg muscle EMG was measured simultaneously with a bipolar placement of electrodes on the left calf (approximate left gastrocnemius placement; 16).…”