Abstract

Background. Neural gating of respiratory sensations (NGRS) is studied using respiratory-related evoked potentials (RREP) in the electroencephalogram (EEG). It is characterized as the RREP N1 peak amplitude ratio of the second stimulus (S2) over the first stimulus (S1) of paired inspiratory occlusions. NGRS has been suggested to decrease with increasing dyspnea, reflecting increased respiratory awareness. Aims. We aimed to validate a new paradigm to study NGRS during increasing levels of exercise-induced dyspnea. Methods. Ten healthy adults (19±4 yrs) exercised on a cycle ergometer at increasing intensities, calibrated as 10%, 40% and 70% of their individual maximum work rate (each intensity 2x5 min in counterbalanced order), followed by Borg ratings of dyspnea intensity/unpleasantness. Brief paired inspiratory occlusions were presented every 2-6 breaths to evoke the RREP in the EEG during cycling, with ventilation continuously measured. Results. Ratings of dyspnea intensity (p<.001) and unpleasantness (p<.001) as well as the S1 (p<.05) and S2 (p<.01) N1 amplitudes significantly increased with increasing work rate. We did observe lower NGRS with increasing work rate, but this did not reach statistical significance (p=.42). Conclusions. We present a new paradigm that successfully evokes exercise-induced dyspnea while allowing for the concurrent measurement of NGRS. This paradigm has improved ecological validity for an exercise context compared to resistive loaded breathing. Further studies can use a larger sample size to determine whether NGRS decreases with increasing levels of exercise-induced dyspnea, and can use this paradigm to study dyspnea mechanisms in patients with respiratory conditions.