Physiological Responses to KN95 Masks Use After Moderate-Intensity Activity (5-Minute Recovery): A Randomized Controlled Trial
Machrumnizar Machrumnizar *
Department of Parasitology, Faculty of Medicine, Universitas Trisakti, Indonesia.
Rulliana Agustin
Undergraduate Medical Program, Faculty of Medicine, Universitas Indonesia, Indonesia.
Nurul Amalia
Department of Parasitology, Faculty of Medicine, Universitas Trisakti, Indonesia.
*Author to whom correspondence should be addressed.
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.
Keywords: KN95 mask, physical activity physiology, cardiopulmonary response, cycling, oxygen saturation, public health