Effects of Wearing an N95 Respirator or Cloth Mask Among Adults at Peak Exercise: A Randomized Crossover Trial | Infectious Diseases | JAMA Network Open | JAMA Network
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Figure.  The Mixed-Effects Model Overall Main Effect of Mask Condition on Peak Exercise Oxygen Uptake (Peak V̇O2) Adjusted for the Covariate Effect of Perception of Breathing Resistance
The Mixed-Effects Model Overall Main Effect of Mask Condition on Peak Exercise Oxygen Uptake (Peak V̇O2) Adjusted for the Covariate Effect of Perception of Breathing Resistance

Reported peak V̇O2 for mask conditions reflect rest-to-peak exercise changes in oxygen saturation that occurred as compared with the no mask condition.

Table.  Exercise Physiological and Subjective Responses
Exercise Physiological and Subjective Responses
1.
Centers for Disease Control and Prevention. COVID-19 guidance for unvaccinated people: how to protect yourself & others. Accessed November 24, 2020. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html
2.
World Health Organization. Critical preparedness, readiness and response actions for COVID-19: interim guidance. Published November 4, 2020. Accessed November 24, 2020. https://www.who.int/publications/i/item/critical-preparedness-readiness-and-response-actions-for-covid-19
3.
Fletcher  GF, Ades  PA, Kligfield  P,  et al; American Heart Association Exercise, Cardiac Rehabilitation, and Prevention Committee of the Council on Clinical Cardiology, Council on Nutrition, Physical Activity and Metabolism, Council on Cardiovascular and Stroke Nursing, and Council on Epidemiology and Prevention.  Exercise standards for testing and training: a scientific statement from the American Heart Association.   Circulation. 2013;128(8):873-934. doi:10.1161/CIR.0b013e31829b5b44 PubMedGoogle ScholarCrossref
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    Research Letter
    Nutrition, Obesity, and Exercise
    June 30, 2021

    Effects of Wearing an N95 Respirator or Cloth Mask Among Adults at Peak Exercise: A Randomized Crossover Trial

    Author Affiliations
    • 1Center of Sports Medicine, Department of Orthopaedics, Orthopaedic and Rheumatology Institute, Cleveland Clinic, Cleveland, Ohio
    • 2Center of Obesity and Medical Weight Loss, Endocrinology and Metabolism Institute Cleveland Clinic, Cleveland, Ohio
    • 3Section of Clinical Cardiology, Miller Family Heart, Vascular and Thoracic Institute, Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio
    • 4Department of Pulmonary and Critical Care Medicine, Respiratory Institute, Cleveland Clinic, Cleveland, Ohio
    • 5Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio
    • 6Section of Preventive Cardiology and Rehabilitation, Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Miller Family Heart, Vascular and Thoracic Institute, Cleveland Clinic, Cleveland, Ohio
    JAMA Netw Open. 2021;4(6):e2115219. doi:10.1001/jamanetworkopen.2021.15219
    Introduction

    For the majority of apparently healthy adults, mask wearing while at rest or during activities of daily living is recommended to be safe and effective for reducing the risk of person-to-person airborne transmission of SARS-Cov-2.1,2 Original research has yet to find evidence showing an effect of mask wearing on clinical indicators of exercise safety.3 In this study, we tested whether mask wearing during exercise stress testing (EST) to peak exhaustion provokes clinically indicated safety concerns.

    Methods

    In this randomized crossover trial (ClinicalTrials.gov Identifier: NCT04415879), 20 never-smoker, apparently healthy, recreationally active men and women participated in treadmill EST under each of the experimental conditions: no mask, N95 (3M 8200 N95 respirator), and cloth mask (Boco Gear PM2.5 activated carbon filter). A random number generator determined the order whereby experimental conditions would be performed. Participants provided voluntary verbal and written informed consent during study enrollment and prior to EST.

    The Cleveland Clinic institutional review board reviewed and approved this study in accordance with the Declaration of Helsinki. The trial protocol is available in Supplement 1. The design and execution of this study also followed the Consolidated Standards of Reporting Trials (CONSORT) reporting guideline for crossover trials. A full description of the study methods, including the CONSORT flow diagram, can be viewed in the eAppendix of Supplement 2.

    Individualized EST had participants self-select a constant treadmill belt speed that would be used across experimental conditions. Treadmill grade always increased from 0.0% to 2.0% at minute 2; and thereafter by 1.0% each minute until achieving peak exhaustion. Heart rate, rating of perceived exertion, and oxyhemoglobin saturation measurements were acquired throughout EST. Peak exercise oxygen uptake (V̇O2) was derived based on the Fitness Registry and the Importance of Exercise National Database equation using treadmill belt speed and grade. The subjective experience of wearing or not wearing a mask was also evaluated immediately postexercise using a perceptions instrument questionnaire. Established clinical indicators were used to evaluate exercise safety.3

    The independent experimental condition effect on continuous variables was tested using mixed-effects analysis of variance modeling. The randomized EST order was set as a random effect in models. Two-tailed significance was determined using an alpha level set at .05. Statistical analysis was performed using SAS statistical software version 9.4 (SAS Institute) from October to December 2020.

    Results

    Of 20 participants, there were 9 women (45%); the mean (SD) age and mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) for women in the sample were 35 (11) years and 25.1 (4.2), respectively, which did not differ significantly from the men in the sample (39 [11] years and 25.0 [2.4], respectively). Performing EST with a mask yielded lower peak V̇O2 and heart rates as compared with no mask. Regardless of experimental condition, no participant demonstrated a clinical indication requiring EST termination prior to voluntary cessation associated with the achievement of peak exhaustion.

    Univariate comparisons of physiological responses to EST in the Table consistently demonstrated exercise tolerance was the highest during the EST and no mask trial. However, symptoms were consistently severest during EST with a mask (eg, mean [SD] exercise duration was 591 [145] seconds without a mask vs 548 [147] seconds with a cloth mask vs 545 [141] seconds with an N95 mask; analysis of variation [ANOVA] P = .047). Perceived breathing resistance was the strongest symptom and unique to EST with a mask (eg, the median [interquartile range {IQR}] scores for subjective responses [0-10, with higher scores indicating worse symptoms] for breathing resistance were 0.0 [0.0-0.0] without a mask vs 7.0 [5.3-8.0] with a cloth mask vs 7.0 [5.5-8.3] with an N95 mask; ANOVA P < .001; the median [IQR] scores for feeling humid were 0.0 [0.0-1.0] without a mask vs 6.3 [3.5-7.8] with a cloth mask vs 7.0 [5.5-8.0] with an N95 mask; ANOVA P < .001). Adjusting comparisons of peak V̇O2 for perceived breathing resistance resulted in no significant experimental condition main effect (Figure).

    Discussion

    This crossover trial found that perceived breathing resistance at peak exercise is uniquely and significantly elevated when EST is performed while wearing a mask. Performing EST with a mask yielded lower peak V̇O2 and heart rates as compared with no mask. However, each experimental condition resulted in peak exercise values that generally remained within normal limits, and no EST required termination due to clinically indicated safety concerns. Thus, although it is possible that wearing a mask exerted a physical limitation on exercise capacity, the clinical relevance of such a possibility is not supported by these data.

    A limitation of this study was the lack of exercise ventilation and gas exchange data collected during EST. This limited our ability to potentially identify where a major physiological limitation to exercise occurred during masked trials. However, having access to these data would likely not have changed the conclusion that performing EST with a mask is generally clinically safe but likely to provoke exaggerated symptoms. The subjective experience of high breathing resistance should not be overlooked as being potentially impactful to reducing how well individuals are able to perceptually tolerate vigorous-to-peak intensity exercise.

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    Article Information

    Accepted for Publication: April 20, 2021.

    Published: June 30, 2021. doi:10.1001/jamanetworkopen.2021.15219

    Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2021 Kampert M et al. JAMA Network Open.

    Corresponding Author: Matthew Kampert DO, MS, Center of Sports Medicine, Department of Orthopaedics, Orthopaedic and Rheumatology Institute, 5555 Transportation Blvd, Garfield Heights, OH 44125 (kamperm@ccf.org).

    Author Contributions: Dr Kampert had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

    Concept and design: Kampert, Singh, Sahoo, Van Iterson.

    Acquisition, analysis, or interpretation of data: Kampert, Sahoo, Han, Van Iterson.

    Drafting of the manuscript: Kampert, Sahoo, Van Iterson.

    Critical revision of the manuscript for important intellectual content: All authors.

    Statistical analysis: Sahoo, Han, Van Iterson.

    Obtained funding: Kampert, Sahoo.

    Administrative, technical, or material support: Kampert, Sahoo.

    Supervision: Kampert, Singh, Sahoo, Van Iterson.

    Conflict of Interest Disclosures: None reported.

    Funding/Support: Funding support was provided by Joseph Parambil and The Brentwood Foundation solely to cover the cost of purchasing the masks used in this study.

    Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

    Disclaimer: The results of the present study do not constitute endorsement by the American College of Sports Medicine.

    Data Sharing Statement: See Supplement 3.

    References
    1.
    Centers for Disease Control and Prevention. COVID-19 guidance for unvaccinated people: how to protect yourself & others. Accessed November 24, 2020. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html
    2.
    World Health Organization. Critical preparedness, readiness and response actions for COVID-19: interim guidance. Published November 4, 2020. Accessed November 24, 2020. https://www.who.int/publications/i/item/critical-preparedness-readiness-and-response-actions-for-covid-19
    3.
    Fletcher  GF, Ades  PA, Kligfield  P,  et al; American Heart Association Exercise, Cardiac Rehabilitation, and Prevention Committee of the Council on Clinical Cardiology, Council on Nutrition, Physical Activity and Metabolism, Council on Cardiovascular and Stroke Nursing, and Council on Epidemiology and Prevention.  Exercise standards for testing and training: a scientific statement from the American Heart Association.   Circulation. 2013;128(8):873-934. doi:10.1161/CIR.0b013e31829b5b44 PubMedGoogle ScholarCrossref
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