Effects of wearing a surgical face mask on cardiac biomarkers, respiratory function, and perceptual responses during exercise in a hot and humid climate at different intensities: a randomized crossover trial

Ongoing concerns have been raised about wearing face masks during exercise, yet large-scale experimental studies, particularly conducted under heat, are lacking. We aimed to investigate the effects of wearing a surgical face mask during exercise on cardiac biomarkers, respiratory function, and perceptual responses in a hot and humid condition at various intensities. A total of 98 participants (mean age, 20.4 years; 29 women) completed six separate experimental trials in a randomized order that consisted of exercising on a treadmill at light, moderate, or vigorous intensity with or without a surgical face mask (each trial, 15 min), in a climatic chamber set at 30 ± 1 ℃ and 70 ± 3% humidity. Cardiorespiratory and perceptual responses were measured pre- and post-exercise, continuously during exercise, and post-exercise only. Cardiac biomarkers including creatine kinase myocardial band (CK-MB), N-terminal pro-brain natriuretic peptide, and troponin T values were higher at post-exercise, with CK-MB higher following high-intensity than light-intensity exercise, despite no significant effects of mask use. Similarly, blood pressure, lactate, and flow-mediated dilation levels, as well as mean value of forehead temperature, core-temperature, heart rate, and respiratory exchange ratio showed no significant difference with or without surgical face mask, although these values were generally higher at higher intensities and/or significantly increased post-exercise. Most respiratory parameters and perceived discomfort levels tended to show negative effects post-exercise with a surgical face mask under this condition. Wearing a surgical face mask for 15 min during exercise in hot and humid conditions had limited effects on cardio-related parameters but significantly affected respiratory function and increased discomfort, particularly at high intensities. This study was registered in the Chinese Clinical Trial Registry (#ChiCTR2100053144).