Electromyographic feedback for learning to activate thoracic inspiratory muscles

The utility of EMG feedback for modifying the muscular pattern of breathing was investigated in twenty-four subjects divided into two groups (feedback, no feedback. Each took part in three 20-min training sessions, 24 h apart. All the subjects were instructed to increase the thoracic contribution of inspired gas. The feedback subjects were shown an EMG signal of the inspiratory muscles of the upper thorax and a signal indicating their current breathing phase (inspiration or expiration). The no feedback subjects only saw the breathing phase signal. The subjects' ability to control muscular activity was assessed as the relative increase in EMG from expiration to the subsequent inspiration. Analysis of variance with group and session as factors showed that feedback subjects performed significantly better, although the improvement in performance over the sessions by the two groups was not significantly different. These results lend some support to the clinical use of EMG feedback in breathing therapy aimed at changing the thoracoabdominal distribution of ventilation. However, further research for improving learning is necessary.