Effects of face masks on the multiple dimensions and neurophysiological mechanisms of exertional dyspnea

Introduction: During the coronavirus disease 2019 (COVID-19) pandemic, public health officials have widely adopted the use of face masks (FM) to limit the spread of infection. Despite consistent evidence that FMs increase dyspnea (i.e., breathlessness), no studies have examined the multidimensional components of dyspnea or the physiological mechanisms of dyspnea with FMs. Methods: In a randomized cross-over design, sixteen healthy individuals (n=9 females, 25±3 y) completed three testing sessions separated by ≥48 h. Each visit included a maximal incremental cycling test where visits 2 & 3 were randomized to either FM or control condition. Dyspnea intensity and unpleasantness were assessed using the 0-10 Borg scale and the Multidimensional Dyspnea Profile (MDP) was administered immediately following exercise. Crural diaphragmatic electromyography (EMGdi), esophageal pressure (Peso), and transdiaphragmatic pressure (Pdi) were measured via a specialized catheter to estimate neural respiratory drive and respiratory muscle pressures respectively. Results: Dyspnea unpleasantness was significantly greater with the FM at the highest equivalent submaximal work rate (HESWR) (2.5±2.0 vs. 1.5±1.5 Borg 0-10 units, P=0.01) and at peak exercise (7.8±2.1 vs. 5.9±3.4 Borg 0-10 units, P=0.01) with no differences in dyspnea intensity ratings throughout exercise compared to control. There were also significant increases in the sensory quality of “smothering/air hunger” (P=0.01) and the emotional response of “anxiousness” (P=0.04) in the FM condition. There were significant increases in EMGdi (P=0.001) and esophageal pressure swings (P=0.006) at the HESWR but no differences in heart rate, peripheral oxygen saturation or breathing frequency throughout exercise with FMs compared to control. Conclusions: Our findings suggest that FMs negatively impact the affective domain of dyspnea during exercise and increase neural respiratory drive and respiratory muscle effort requirements during exercise, although the impact on other cardiopulmonary responses are minimal.Medicine, Faculty ofGraduat