Exercise Capacity and Perceived Exertion on Treadmill Stress Test Performed While Wearing vs Without a Surgical Mask: A Randomized Clinical Trial in Healthy Adults

Background: The graded exercise treadmill stress test (GXT) is among the most frequently performed tests in cardiology. The COVID-19 pandemic led many healthcare facilities to require patients to wear a mask during the test. This study evaluated the effect of wearing a surgical face mask on exercise capacity and perceived exertion. Methods: In this prospective, randomized crossover trial, 35 healthy adults performed a GXT using the Bruce protocol while wearing a surgical mask, and without a mask. The primary outcome was exercise capacity in metabolic equivalents (MET), and the secondary outcome was exercise perception on the modified Borg scale (from 0 to 10). Effort duration, heart rate, oxygen saturation, and blood pressure were also analyzed. Results: Exercise capacity was reduced by 0.4 MET (95% confidence interval [CI] -0.7 to -0.2) during the GXT with a mask (11.8 +/- 2.7 vs 12.3 +/- 2.5 MET, P = 0.001), and the final perceived effort increased by 0.5 points (95% CI 0.2 to 0.8; 8.4 +/- 1.3 vs 7.9 +/- 1.6, P = 0.004). Effort duration was cut down by 24 seconds (CI -0:39 to -0:09; 10:03 +/- 2:30 vs 10:27 +/- 2:16 [minutes:seconds], P = 0.003). Oxygen saturation was slightly lower at the end of the test when participants wore a mask. No significant differences occurred in heart rate or blood pressure during the test. Conclusion: Wearing a surgical mask causes a statistically significant decrease in exercise capacity and increase in perceived exertion. This small effect is not clinically significant for the interpretation of test results.