Return to training in the COVID-19 era: The physiological effects of face masks during exercise

COVID-19 outbreak has a profound impact on almost every aspect of life. Universal masking is recommended as a means of source control. Routinely exercising in a safe environment is an important strategy for healthy living during this crisis. As sports clubs and public spaces may serve a source of viral transmission, masking may become an integral part of physical activity. This study aimed to assess the physiological effects of wearing surgical masks and N95 respirators during short-term strenuous workout. This was a multiple cross-over trial of healthy volunteers. Using a standard cycle ergometry ramp protocol, each subject performed a maximal exercise test without a mask, with a surgical mask, and with an N95 respirator. Physiological parameters and time to exhaustion were compared. Each subject served his own control. Sixteen male volunteers (mean age and BMI of 34 +/- 4 years and 28.72 +/- 3.78 kg/m(2), respectively) completed the protocol. Heart rate, respiratory rate, blood pressure, oxygen saturation, and time to exhaustion did not differ significantly. Exercising with N95 mask was associated with a significant increase in end-tidal carbon dioxide (EtCO2) levels. The differences were more prominent as the load increased, reaching 8 mm Hg at exhaustion (none vs N95,P = .001). In conclusion, in healthy subjects, short-term moderate-strenuous aerobic physical activity with a mask is feasible, safe, and associated with only minor changes in physiological parameters, particularly a mild increase in EtCO2. Subjects suffering from lung diseases should have a cautious evaluation before attempting physical activity with any mask.