Physiological effects of exercising at different intensities wearing surgical or double‐layer cotton facemasks compared to not wearing a mask

  1. Fabrício Braga
  2. Gabriel Espinosa
  3. Amanda Monteiro
  4. Beatriz Marinho
  5. Eduardo Drummond

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Abstract

Since the beginning of the SARS‐CoV‐2 pandemic, the community use of facemasks has been widely recommended. However, their use during exercise has raised safety concerns. Thus, we compared the physiological differences between exercising wearing a surgical (SM) or a double‐layer‐cotton (DLC) facemask and not wearing a mask (NM). Sixteen volunteers underwent 4 bouts of cycling‐based exercise, which consisted of two different intensities: light‐to‐moderate and moderate‐to‐high. Facemasks were used as follows: bout‐1 and 4: NM; bout‐2: SM or DLC and bout‐3: DLC or SM. Ventilatory, metabolic, pulmonary gas exchange (PGE) and perceptual variables were collected. At both exercise intensities compared to NM, both facemasks induced similar ventilatory adaptations, increasing inspiratory time and tidal volume and decreasing breathing frequency. Effect sizes (ES) were larger for DLC than for SM. At moderate‐to‐high, both facemasks reduced the minute ventilation, whereas at light‐to‐moderate, it was only seen with DLC. End tidal and mixed CO 2 pressures, as well as the difference between them, increased with both facemasks. Again, ES was larger for DLC than SM. No relevant oxygen saturation drop was observed with both facemaks and exercise intensities. A small ES increament in VO 2 and VCO 2 were seen with both facemasks. Effort perception increased at moderate‐to‐high for both exercise intensities, buth larger EF were with DLC than SM. DLC increased facial temperature during both exercise intensities. In conclusion, ventilatory adjustments imposed during facemask exercise influenced PGE and metabolic and perceptual changes. Larger ES were mostly seen for DLC than SM.

Abbreviations: B f : Breathing frequency.; CPET: Cardiopulmonary exercise test.; CI: Confidence interval.; DLC: Double‐layer cotton.; E T CO 2 : End tidal CO 2 pressure.; ES: Effect size.; ΔE T ‐PECO 2 : Difference between E T CO 2 and PECO 2. ; FMMT: Facemask microclimate temperature.; H R : Heart rate.; IQR: Interquartile range.; NM: No mask.; PECO 2 : Mixed‐expired CO 2 pressure.; RER: Respiratory exchange ratio.; RPE: Rate of perceived effort.; SD: Standard deviation.; SM: Surgical Mask.; SpO 2 : Oxygen saturation.; STP: Subjective thermal perception.; T i /T TOT : Duty cycle.; V E : Minute ventilation.; VCO 2 : Carbon dioxide output.; VO 2 : Oxygen uptake.; V T : Tidal volume.; VT: Ventilatory threshold.

Highlights

  • Facemasks affect the breathing pattern by changing the frequency and amplitude of pulmonary ventilation.

  • The augmented ventilatory work increases VO 2 , VCO 2 , and RPE and promotes nonconcerning drops in SpO 2 and CO 2 retention.

  • Increased inspiratory and expiratory pressure can account for the reduction in pulmonary physiological dead space.

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  1. Version published to 10.1080/17461391.2022.2065928
  2. ScreenIT

    SciScore for 10.1101/2020.12.11.20203224: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementConsent: After providing written informed consent, they submitted to the two-day protocol outlined.
    IRB: This study was approved by the Ethics Committee of the Hospital Federal de Bonsucesso under protocol number 33487920.9.0000.5253.
    Randomizationnot detected.
    BlindingIn order to blind the volunteers from the mask they were using, a cloth frame was placed on the border of the flow sensor (figure 2-C).
    Power Analysisnot detected.
    Sex as a biological variableSixteen healthy volunteers (7 women) were recruited among amateur cyclists screened in our sport medicine clinic within the previous 12 months.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Some limitations should be pointed out. First, and in our opinion the most relevant, is external validation. In real life, a non-negligible amount of the ventilatory flow, either with TNT or DLC, does not pass through the FM and flows by their borders otherwise. Thus, our FM exercising model was more obstructive, and changes should probably not be this large in practice. However, as physiological exercise effects are volume and intensity dependent, we can consider that a similar effect can arise during longer exercise with less restrictive FM. Second, our population was composed of healthy young people, so we do not recommend extrapolating these results to older and unhealthy populations. Third, as two volunteers failed to complete all sets of exercise, the research became underpowered for showing some post hoc differences at the higher intensity exercise level. Wearing a FM while exercising triggers several physiological adaptations, all of which are more pronounced with DLC than with TNT. Frequency, amplitude and mostly the time domain of pulmonary ventilation must suit higher upper airway resistance. This breakdown in the usual breathing pattern increases VO2, HR and RPE and promotes a non-concerning drop in SpO2. Nevertheless, CO2 exchange also adapts. Rebreathing and an increased gas exchange surface elicited by alveolar recruitment are hypothesized. By reducing heat dissipation, face temperature increased but did not contribute to an increased thermal sensation, althoug...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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  3. Version published to 10.1101/2020.12.11.20203224v1 on medRxiv