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

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 CO₂ 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 VO₂ and VCO₂ 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_TCO₂: End tidal CO₂ pressure.; ES: Effect size.; ΔE_T-PECO₂: Difference between E_TCO₂ and PECO_2.; FMMT: Facemask microclimate temperature.; H_R: Heart rate.; IQR: Interquartile range.; NM: No mask.; PECO₂: Mixed-expired CO₂ pressure.; RER: Respiratory exchange ratio.; RPE: Rate of perceived effort.; SD: Standard deviation.; SM: Surgical Mask.; SpO₂: Oxygen saturation.; STP: Subjective thermal perception.; T_i/T_TOT: Duty cycle.; V_E: Minute ventilation.; VCO₂: Carbon dioxide output.; VO₂: 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 VO₂, VCO₂, and RPE and promotes nonconcerning drops in SpO₂ and CO₂ retention.

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

GRAPHICAL ABSTRACT

KEYWORDS:

• Cardiovascular/Cardiorespiratory
• performance
• physiology

Consent for publication

The author hereby fully consents to publication of this paper in APNM.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical standards

The Research Ethics Committee of the Hospital Federal de Bonsucesso (Expedient number: 4.120.822, 29/06/2020) approved the study, which was registered at the National Council of Research Ethics in accordance with the 1964 Helsinki declaration. Informed consent was obtained from all participants included in the study.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.