Comparison of the Time-Course and Magnitude of Cardiorespiratory Responses to Superimposed Surgical Masks or N95 Respirators during 20-min Treadmill Walking

Abstract

Wearing medical barriers has recently expanded from healthcare to public settings, and could increase dead space and facilitate rebreathing of expired air resulting in heat accumulation, hypercapnia, and hypoxia, particularly during physical activity. We recently showed that participants wearing surgical masks (SM) and N95 respirators (N95) over 60-min during seated rest had mild and immediately reversible (a) increases face microclimate temperature, (b) increases in the pressure of end-tidal (PET)CO2, (c) decreases in PETO2, but (d) no differences in peripheral oxygen saturation (SpO2). Previous publications showed conflicting results of superimposed barrier wearing during physical activity, and there are limited studies that assessed face microclimate temperature and end-tidal gases, particularly comparing superimposed SM and N95. We hypothesized that participants wearing SM and N95 will experience mild face microclimate hyperthermia, hypoxia, and hypercapnia during 3mph treadmill walking. Participants (n=18; 8F) randomly wore (a) no barrier (NB), (b) SM or (c) N95 during a 10-min standing baseline, 20-min treadmill walking (3 mph), and a 10-min standing recovery. We continuously measured face microclimate temperature (thermistor), end tidal gases (PETCO2, PETO2; oro-nasal cannula), SpO2 (peripheral pulse oximeter). Average 20-min PETCO2 (higher; p<0.0001, P=0.0001) and PETO2 (lower; P=0.0003, P=0.0178) were significantly from baseline for both SM and N95, respectively. The delta between the 20-min average compared to the baseline data was not statistically significant for PETCO2 or PETO2 in all three conditions, except for ΔPETCO2 NB vs. N95 (higher; P=0.0344). Additionally, there was no difference in SpO2 across all barrier conditions during exercise. These mild physiological effects may account for qualitative reports of shortness of breath and increased perceived exertion while wearing barriers during physical activity. However, these effect-magnitudes are not physiologically-meaningful, and are immediately reversed upon cessation of exercise and/or barrier removal. NSERC. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.