Comparing Surgical And N95 Mask Use On Resting Metabolic Rate In Healthy Young Adults

While face masks knowingly reduce the spread of respiratory pathogens, other effects remain controversial. Few studies have examined physiological changes while wearing face masks at rest. PURPOSE: To examine the effect of wearing surgical and N95 masks on resting metabolic rate (RMR) in healthy young adults at rest. Secondarily, heart rate (HR), oxygen consumption (VO₂), carbon dioxide production (VCO₂), and respiratory exchange ratio (RER) with macronutrient substrates were analyzed. METHODS: This prospective, randomized crossover study was IRB approved. Eligible subjects were men and women between 18-55 years old with no history of a respiratory/metabolic disease or claustrophobia, and were recruited from a convenience sample. Macronutrient substrates, VO₂, VCO₂, RMR, RER, and HR were recorded using indirect calorimetry under a canopy. Subjects fasted overnight for ≥8 hours. The first trial recorded baseline measurements without a face mask, then surgical mask and N95 mask trials were recorded in a randomized order. Each trial was 15 minutes, with a rest between conditions. Comfort levels were measured after each condition using a Likert scale, and open-ended responses were recorded. Repeated measures ANOVA with post-hoc Holm-Bonferroni correction was used to analyze the mean values of the final 10 minutes of each trial. RESULTS: Twenty-two subjects (age 24.6 ± 2.94, 14 women) signed written consent and completed the study. RMR (kcal/day), VO₂ (mL/min), and VCO₂ (mL/min) were significantly lower in the surgical mask condition when compared with no face mask (1843.0 ± 340.3 vs. 1899.6 ± 360.5, p = 0.005; 276.0 ± 51.6 vs. 283.8 ± 53.6, p = 0.007; 184.9 ± 34.0 vs. 193.2 ± 39.3, p = 0.011, respectively). VCO₂ was also lower in the N95 mask condition when compared with no face mask (186.9 ± 37.6 vs. 193.2 ± 39.3, p = 0.049), while RMR and VO₂ were not significantly different (1866.5 ± 368.4 vs. 1899.6 ± 360.5, p = 0.11; 279.7 ± 55.4 vs. 283.8 ± 53.6, p = 0.19, respectively). No changes were found in HR, RER, or macronutrient substrates between conditions. CONCLUSION: Surgical masks had a more significant impact on RMR compared to N95 masks in healthy, young adults at rest.