The effects of cloth face masks on cardiorespiratory responses and VO2 during maximal incremental running protocol among apparently healthy men

<jats:title>Abstract</jats:title><jats:p>We aimed to determine the effects of wearing a cloth face mask on cardiorespiratory response, peak oxygen uptake (<jats:italic>V</jats:italic>o<jats:sub>2</jats:sub>), respiratory muscle effort, and exercise tolerance during incremental exercise. The study had a randomized crossover design: 11 apparently healthy young men performed the Bruce protocol treadmill test in two conditions, wearing a cloth face mask (CFM) and without CFM (CON), in random order. Minute ventilation and oxygen uptake were measured using a mass spectrometry metabolic analyzer; cardiac output (CO) was measured using an impedance CO monitor; and mouth pressure (P<jats:sub>m</jats:sub>) was measured and calculated as an integral P<jats:sub>m</jats:sub> to assess respiratory muscle effort. Maximal minute ventilation was 13.4 ± 10.7% lower in the CFM condition than in the CON condition (<jats:italic>P</jats:italic> < 0.001). The peak <jats:italic>V</jats:italic>o<jats:sub>2</jats:sub> (52.4 ± 5.6 and 55.0 ± 5.1 mL/kg/min in CFM and CON, respectively) and CO were not significantly different between the two conditions. However, the integral value of P<jats:sub>m</jats:sub> was significantly higher (<jats:italic>P</jats:italic> = 0.02), and the running time to exhaustion was 2.6 ± 3.2% lower (P = 0.02) in the CFM condition than in the CON condition. Our results suggest that wearing a cloth face mask increased respiratory muscle effort and decreased ventilatory volume in healthy young men; however, <jats:italic>V</jats:italic>o<jats:sub>2</jats:sub> remained unchanged. Exercise tolerance also decreased slightly.</jats:p>