Sistema FMUSP-HC: Faculdade de Medicina da Universidade de São Paulo (FMUSP) e Hospital das Clínicas da FMUSPGUARDIEIRO, Natalia MendesBARRETO, GabrielMARTICORENA, Felipe MiguelOLIVEIRA, Tamires NunesOLIVEIRA, Luana Farias dePINTO, Ana Lucia de SaPRADO, Danilo Marcelo Leite doSAUNDERS, BryanGUALANO, Bruno2023-08-162023-08-162023JOURNAL OF PHYSICAL ACTIVITY & HEALTH, v.20, n.1, p.35-44, 20231543-3080https://observatorio.fm.usp.br/handle/OPI/54557Purpose: Investigate whether a cloth facemask could affect physiological and perceptual responses to exercise at distinct exercise intensities in untrained individuals. Methods: Healthy participants (n = 35; 17 men, age 30 [4] y, and 18 women, age 28 [5] y) underwent a progressive square wave test at 4 intensities: (1) 80% of ventilatory anaerobic threshold; (2) ventilatory anaerobic threshold; (3) respiratory compensation point; and (4) exercise peak (Peak) to exhaustion, 5-minute stages, with or without a triple-layered cloth facemask (Mask or No-Mask). Several physiological and perceptual measures were analyzed. Results: Mask reduced inspiratory capacity at all exercise intensities (P < .0001). Mask reduced respiratory frequency (P = .001) at Peak (-8.3 breaths-min-1; 95% confidence interval [CI], -5.8 to -10.8), respiratory compensation point (-6.9 breaths-min-1; 95% CI, - 4.6 to -9.2), and ventilatory anaerobic threshold (-6.5 breaths-min-1; 95% CI, -4.1 to -8.8), but not at Baseline or 80% of ventilatory anaerobic threshold. Mask reduced tidal volume (P < .0001) only at respiratory compensation point (-0.5 L; 95% CI, - 0.3 to -0.6) and Peak (-0.8 L; 95% CI, -0.6 to -0.9). Shallow breathing index was increased with Mask only at Peak (11.3; 95% CI, 7.5 to 15.1). Mask did not change HR, lactate, ratings of perceived exertion, blood pressure, or oxygen saturation. Conclusions: A cloth facemask reduced time to exhaustion but had no major impact on cardiorespiratory parameters and had a slight but clinically meaningless impact on respiratory variables at higher intensities. Moderate to heavy activity is safe and tolerable for healthy individuals while wearing a cloth facemask. ClinicalTrials.gov: NCT04887714.engrestrictedAccessmaskCOVID-19 pandemicoxygen saturationlactatephysical-activityoxygen-uptakedysanapsisarticleCopyright HUMAN KINETICS PUBL INC10.1123/jpah.2022-0145Public, Environmental & Occupational Health1543-5474