No Respiratory or CV Harm With Cloth Face Masks During Exercise

Stephanie Edwards for Medscape

January 04, 2022

The study covered in this summary was published in as a preprint and has not yet been peer reviewed.

Key Takeaways

  • Wearing a cloth face mask did not cause significant respiratory or cardiovascular changes during exercise, including heart rate, blood pressure, lactate, or oxygen saturation, regardless of exercise intensity.

  • Wearing a cloth face mask during exercise did increase difficulty breathing, and at higher intensities, affected respiratory variables such as inspiratory capacity and respiratory frequency.

  • There were no differences between men and women.

Why This Matters

  • Masks are one of the most effective nonpharmacologic strategies to prevent the spread of COVID-19 and are recommended even during exercise, particularly at indoor gym facilities.

  • These data can influence exercise recommendations for health guidelines during the COVID-19 pandemic and "debunk unfounded allegations of harmful effects of masks during exercise," the researchers conclude.

Study Design

  • This was a crossover study performed at an intrahospital exercise physiology laboratory in São Paulo, Brazil, between April and November 2021.

  • Thirty-five individuals (17 men and 18 women) were analyzed; 31 participants were categorized as active and four as inactive.

  • Participants were investigated using a progressive square-wave test on a motorized treadmill at four different intensities wearing a triple-layered cloth mask or no mask, while several physiologic, metabolic, and perceptual measures were taken.

Key Results

  • Mask wearing had no influence on end-expiratory lung volume (EELV) and EELV/forced vital capacity ratio, heart rate, lactate, blood pressure, or oxygen saturation, irrespective of sex.

  • Mask wearing reduced inspiratory capacity, respiratory frequency at peak but not at baseline, tidal volume except at baseline, ventilatory equivalent for carbon dioxide, time to exhaustion, forced vital capacity at rest, forced expiratory volume in 1 second at rest, and peak expiratory flow at rest, irrespective of sex.

  • Mask wearing increased Tobin index (or shallow breathing index) at peak in women only, end-tidal carbon dioxide pressure except at baseline for both sexes, and subjective feelings of heat, misfitting, discomfort, fatigue, resistance, saltiness, and humidity, irrespective of sex.


  • Participants were required to wear a face mask for breath-by-breath measures over the cloth face mask, which may have increased discomfort and led to some inaccuracies in measurements due to air escaping.

  • The current data may not apply to trained individuals.

  • Since sufficient levels of physical activity prevent morbidities and mortality and improve vaccine immunogenicity, it is important that mask mandates do not lead to a reduction in physical activity.

  • Whether the negative feelings related to the use of masks may result in less adherence to exercise remains to be examined.

  • The influence of mask wearing during exercise in clinical populations warrants investigation.


  • The authors received no specific funding for this work.

  • Bruno Gualano, Gabriel Barreto, Tamires Nunes Oliveira, and Bryan Saunders have been financially supported by Fundação de Amparo à Pesquisa do Estado de São Paulo.

  • Bryan Saunders has also received a grant from Faculdade de Medicina da Universidade de São Paulo.

This is a summary of a preprint research study, "A Cloth Facemask Causes No Major Respiratory or Cardiovascular Perturbations during Moderate to Heavy Exercise," by Bryan Saunders, Bruno Gualano, and colleagues at the Faculty of Medicine of the University of Sao Paulo on MedRxiv provided to you by Medscape. This study has not yet been peer reviewed. The full text of the study can be found on


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