The effects of cloth face masks on cardiorespiratory responses and VO(2) during maximal incremental running protocol among apparently healthy men

We aimed to determine the effects of wearing a cloth face mask on cardiorespiratory response, peak oxygen uptake (Vo(2)), 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(m)) was measured and calculated as an integral P(m) to assess respiratory muscle effort. Maximal minute ventilation was 13.4 ± 10.7% lower in the CFM condition than in the CON condition (P < 0.001). The peak Vo(2) (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(m) was significantly higher (P = 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, Vo(2) remained unchanged. Exercise tolerance also decreased slightly.