The aim of this non-inferiority study was to determine whether wearing a non-woven mask during exercise results in inferior peak oxygen uptake (Peak V ・ O 2 /kg) compared to not wearing a mask. METHODS: A total of 29 healthy young men (age 20.7 ± 0.8 years, BMI 21.8 ± 3.0 kg/m 2 ) underwent cardiopulmonary exercise tests using a ramp protocol, with and without wearing a non-woven mask. The evaluation indices included V ・ O 2 /kg, carbon dioxide output (V ・ CO 2 ), heart rate (HR), respiration rate (RR), minute ventilation (V ・ E), end-tidal oxygen tension, end-tidal carbon dioxide tension, transcutaneous oxygen saturation, and the Borg scale for dyspnea and lower extremity fatigue. A non-inferiority test for Peak V ・ O 2 /kg was conducted to compare the non-woven mask condition with the no-mask condition. RESULTS: The results of the non-inferiority test showed that Peak V ・ O 2 /kg (mean difference [95% confidence interval], 1.08 [-0.77 to 2.93]) was within the upper limit of the non-inferiority margin (3.5 mL/kg/min), indicating that wearing a non-woven mask during exercise is not inferior to exercising without a mask in terms of Peak V ・ O 2 /kg. CONCLUSION: This study demonstrates that wearing a non-woven mask during exercise does not result in decreased Peak V ・ O 2 /kg compared to exercising without a mask.