Does wearing a facemask decrease arterial blood oxygenation and impair exercise tolerance?

Introduction: Concerns have been raised that COVID-19 face coverings compromise lung function and pulmonary gas exchange to the extent that they produce arterial hypoxemia and hypercapnia during high intensity exercise resulting in exercise intolerance in recreational exercisers. This study therefore aimed to investigate the effects of a surgical, flannel or vertical-fold N95 masks on cardiorespiratory responses to incremental exercise. Methods: This investigation studied 11 adult males and females at rest and while performing progressive cycle exercise to exhaustion. We tested the hypotheses that wearing a surgical (S), flannel (F) or horizontal-fold N95 mask compared to no mask (control) would not promote arterial deoxygenation or exercise intolerance nor alter primary cardiovascular variables during submaximal or maximal exercise. Results: Despite the masks significantly increasing end-expired peri-oral %CO2 and reducing %O-2, each similar to 0.8-2% during exercise (P < 0.05), our results supported the hypotheses. Specifically, none of these masks reduced submaximal or maximal exercise arterial O-2 saturation (P = 0.744), but ratings of dyspnea were significantly increased (P = 0.007). Moreover, maximal exercise capacity was not compromised nor were there any significant alterations of primary cardiovascular responses (mean arterial pressure, stroke volume, cardiac output) found during sub-maximal exercise. Conclusion: Whereas these results are for young healthy recreational male and female exercisers and cannot be applied directly to elite athletes, older or patient populations, they do support that arterial hypoxemia and exercise intolerance are not the obligatory consequences of COVID-19-indicated mask-wearing at least for cycling exercise.

Automated summary

The study found that wearing masks during exercise may increase end-expired peri-oral %CO2 and decrease %O2, but did not impact arterial oxygen saturation. Ratings of dyspnea increased, but maximal exercise capacity was not compromised and primary cardiovascular responses remained unchanged during submaximal exercise.