A Cloth Facemask Causes No Major Respiratory or Cardiovascular Perturbations during Moderate to Heavy Exercise

Objectives

To investigate whether wearing a cloth facemask could affect physiological and perceptual responses to exercise at distinct exercise intensities in non-trained men and women.

Methods

In a crossover design, participants (17 men and 18 women) underwent a progressive square-wave test at four intensities (i. at 80% of the ventilatory anerobic threshold [80%VAT]; ii. at VAT; iii. at the respiratory compensation point [RCP]; iv. at exercise peak [Peak] to exhaustion), with or without a triple-layered cloth mask (Mask or No-Mask). Several physiological, metabolic and perceptual measures were analyzed.

Results

Mask reduced inspiratory capacity at all exercise intensities vs. No-Mask (p<0.0001), irrespective of sex. Mask reduced respiratory frequency vs. No-Mask (p=0.001) at Peak (−8.3 breaths·min^-1; CI: -5.8, -10.8), RCP (−6.9 breaths·min^-1; CI: -4.6, -9.2) and VAT (−6.5 breaths·min^-1; CI: -4.1, -8.8), but not at Baseline or at 80%VAT. Mask also reduced tidal volume (p<0.0001) at both RCP (−0.5L; CI: -0.3, -0.6) and Peak (−0.8L; CI: -0.6, -0.9), but not at Baseline, 80%VAT or VAT. Shallow breathing index was increased with Mask at Peak compared to No-Mask (11.3; CI: 7.5, 15.1), but not at any other intensities. Mask did not change heart rate, lactate, ratings of perceived exertion, blood pressure or oxygen saturation.

Conclusions

Wearing a cloth facemask during exercise at moderate to heavy intensities is unlikely to incur significant respiratory or cardiovascular changes, irrespective of sex. These data can inform new exercise recommendations for health during the COVID-19 pandemic and debunk unfounded allegations of harmful effects of masks during exercise. <ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://ClinicalTrials.gov">ClinicalTrials.gov</ext-link>: <ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="clintrialgov" xlink:href="NCT04887714">NCT04887714</ext-link>

What are the new findings?

• <label>✓</label>

  Using a progressive square-wave test, we showed that wearing a cloth facemask during exercise increased breathing difficulty, but this was dependent upon the exercise intensity.

• <label>✓</label>

  Respiratory variables (e.g., inspiratory capacity, respiratory frequency, shallow breathing index) were affected at higher rather than lower intensities.

• <label>✓</label>

  Mask wearing did not change heart rate, lactate, ratings of perceived exertion, blood pressure or oxygen saturation at any exercise intensity.

• <label>✓</label>

  There were no substantial sex differences on the effects of mask wearing during exercise.

How might it impact on clinical practice in the future?

• <label>✓</label>

  These data can debunk unfounded allegations on harmful effects of masks during exercise, and help inform new exercise recommendations for health during the COVID-19 pandemic, particularly where facemasks remain necessary.