THE EFFECT OF CHEST-WALL TRANSCUTANEOUS ELECTRICAL NERVE-STIMULATION ON DYSPNEA

We studied the effects of transcutaneous electrical nerve stimulation (TENS) over the chest wall on breathlessness in normal subjects during exercise. Eleven male subjects performed a progressive incremental ex ercise test to break point on four consecutive days. TENS (continuous form, frequency 100 Hz, pulse width 200 mu s) was applied during three of these tests - over the second intercostal spaces during inspiratio n ('in phase' with the underlying inspiratory muscle contraction) or e xpiration ('out of phase' with contraction) or over the deltoid muscle s during inspiration (control), and not on the fourth occasion in rand om order. Breathlessness (Borg scale), heart rate, respiratory frequen cy, tidal volume, minute ventilation and minute oxygen uptake were mea sured. No significant differences were found for any of the measured v ariables between the four study days. We conclude that TENS under thes e circumstances has no effect on the sensation of breathlessness or on the measured physiological variables in normal subjects during exerci se.