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

Ophir Bar-On, MD; Yulia Gendler, PhD; Patrick Stafler, MD; Hagit Levine, MD; Guy Steuer, MD; Einat Shmueli, MD; Dario Prais, MD; Meir Mei-Zahav, MD


J Am Board Fam Med. 2021;34(4):798-801. 

In This Article

Abstract and Introduction


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

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

Methods: 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.

Results: 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.

Conclusion: 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.


During the Coronavirus disease 2019 (COVID-19) pandemic, facemasks became ubiquitous worldwide to protect against viral spread.[1–3] Concurrently, warnings against mask potential harmful effects, including hypoxemia and hypercarbia, appeared. The World Health Organization stated[4] that "people should not wear masks while exercising," yet no real-life experimental supporting evidence was found. This study evaluated the effects of a standard surgical facemask on respiratory physiology in healthy individuals.