Abstract: OBJECTIVE: Masks are one of the most important defenses against the virus. However, the impact of wearing masks during daily activities or sports on respiratory and circulatory function remains controversial. A comprehensive quantitative evaluation of the effects of mask-wearing on human heart rate, oxygen saturation and end-expiratory carbon dioxide by Meta-analysis was conducted. The effects of wearing different types of masks at different exercise intensities and time of exercise on the human respiratory and circulatory system were explored. 
METHODS: By February 2023, with “mask, face mask, N95, training, sports, running, walking, cycling” as the Chinese search terms and “masks, respiratory protective devices, N95 respirators, surgical face masks, exercise, resistance training, explosive training, muscle exercises” as English search terms, the experimental studies addressing the influence of exercise with a mask on hemodynamic indexes were retrieved from CNKI, Web of Science, PubMed, Cochrane Library and WanFang databases. The outcome indicators included three continuous variables - exercise center rate, blood oxygen saturation and end-expiratory carbon dioxide. Stata16.0 software was used to analyze the outcome indicators of the included literature. The PEDro scale was used as a quality assessment tool, and the funnel plot was used to analyze the impact of publication bias.
RESULTS: Totally 25 articles involving 857 healthy children and adults were included in this Meta-analysis. The overall methodological quality was high, with 22 studies scoring 6 points on the PEDro scale, 2 studies scoring 7 points and 1 study scoring 8 points. The meta-analysis results showed that compared with the control group, exercise with masks had no significant effect on heart rate (SMD=0.02, 95%CI: -0.11 to 0.15, P=0.81), but increased end-expiratory carbon dioxide (SMD=0.60, 95%CI: 0.37 to 0.83, P=0.00), decreased oxygen saturation (SMD=-0.28, 95%CI: -0.47 to -0.09, P=0.03). Intensity and duration were the factors that affected the heterogeneity between studies. Wearing a mask during high-intensity exercise significantly increased heart rate (SMD=-0.20, 95%CI: -0.36 to -0.04, P=0.02). The effect of high-intensity and short-time exercise on blood oxygen saturation was significantly higher than that of other exercises (SMD=-0.40, 95%CI: -0.70 to -0.10; SMD=-0.25, 95%CI: -0.45 to -0.04). For end-expiratory carbon dioxide, maintaining a certain intensity and increasing the exercise time or increasing the intensity further increased the index significantly, reaching a moderate effect size (SMD=0.61, 95%CI: 0.06 to 1.15; SMD=0.58, 95%CI: 0.04 to 1.13).
CONCLUSION: Existing evidence suggests that exercise with masks may have the adverse effect of increasing end-expiratory carbon dioxide and decreasing blood oxygen saturation. The influence of different exercise test time and intensities on the three outcome indexes was different. Wearing a mask during high-intensity exercise can significantly increase heart rate and decrease blood oxygen saturation. Maintaining moderate intensity for a long period or further increasing the intensity of exercise will lead to increased end-expiratory carbon dioxide levels.

Key words: surgical mask, N95 mask, blood oxygen saturation, exercise center rate, exercise test, end-expiratory carbon dioxide, Meta-analysis