Effects of Wearing Facemasks During Brisk Walks: A COVID-19 Dilemma

During the Coronavirus disease 2019 (COVID-19) pandemic, wearing facemasks became obligatory worldwide.

The objective of this study was to evaluate the effects of facemasks on gas exchange.

Healthy adults were assessed at rest and during slow and brisk 5-minute walks, with and without masks. We monitored O₂ saturation, end-tidal carbon dioxide (EtCO₂), and heart and respiratory rates. Participants graded their subjective difficulty and completed individual sensations questionnaires.

Twenty-one participants with a median age of 38 years (range, 29-57 years) were recruited. At rest, all vital signs remained normal, without and with masks. However, during slow and brisk walks, EtCO₂ increased; the rise was significantly higher while wearing masks: slow walk, mean EtCO₂ (mmHg) change +4.5 ± 2.4 versus +2.9 ± 2.3, P = .004; brisk walk EtCO₂ change +8.4 ± 3.0 versus +6.2 ± 4.0, P = .009, with and without masks, respectively. Wearing masks was also associated with higher proportions of participant hypercarbia (EtCO₂ range, 46-49 mmHg) compared with walking without masks, though this was only partially significant. Mean O₂-saturation remained stable (98%) while walking without masks but decreased by 1.2 % ± 2.2 while walking briskly with a mask (P = .01). Mild desaturation (O₂ range, 93% to 96%) was noted during brisk walks among 43% of participants with masks, compared with only 14% without masks (P = .08). Borg's scale significantly increased while walking with a mask, for both slow and brisk walks (P < .001). Sensations of difficulty breathing and shortness of breath were more common while walking with masks.

While important to prevent viral spread, wearing facemasks during brisk 5-minute walks might be associated with mild hypercarbia and desaturation. The clinical significance of these minor gas exchange abnormalities is unclear and should be further investigated.