Physiological Responses to KN95 Masks Use After Moderate-Intensity Activity (5-Minute Recovery): A Randomized Controlled Trial

Abstract

Aims: To evaluate the cardiopulmonary effects of wearing KN95 respirators compared with a standard surgical mask during moderate-intensity outdoor cycling, and to explore potential sex-based differences in physiological responses. Study Design: This was a randomized parallel-group controlled trial conducted in an outdoor field environment at the Sudirman Central Business District (SCBD), Jakarta, Indonesia, from October to November 2022. Methodology: Thirty-two healthy, physically active adults were randomly assigned (1:1) to wear either a KN95 mask (n = 16) or a standard surgical mask (n = 16) while cycling 8 km at a constant speed of 15 km/h (~30 minutes). Heart rate (HR), respiratory rate (RR), and oxygen saturation (SpO₂) were measured five minutes post-exercise. Independent t-tests compared groups, and ANCOVA adjusted for age, sex, and body mass index (BMI). Effect sizes were calculated using Cohen’s d and partial η². Gender-stratified analyses were conducted exploratorily. Results: Compared with a standard surgical mask, KN95 use significantly increased HR (+14.4 bpm; p = 0.003; d = 1.15) and RR (+5.1 breaths/min; p = 0.013; d = 0.94), and reduced SpO₂ (–0.8%; p = 0.019; d = 0.88). Adjusted analyses confirmed these associations (partial η² range: 0.189–0.295). All effect sizes were large. Oxygen saturation remained within clinically acceptable ranges in both groups. Exploratory subgroup analyses suggested sex-related trends in physiological responses; however, no statistically significant interaction effects were observed, and these findings should be interpreted cautiously given the limited sample size. Conclusion: KN95 respirators impose measurable cardiopulmonary strain during moderate-intensity cycling compared with standard surgical masks. While these effects were physiologically tolerable for healthy adults during short-duration activity, the findings have implications for individuals with limited cardiopulmonary reserves and for public health guidance in contexts requiring both infection control and physical activity promotion.