Physical activity in children with asthma: Associations with climatic, environmental, anthropometric and clinical parameters.

<bold>Background:</bold> Among children with asthma, the associations of environmental and other parameters with physical activity remain unclear. This study quantified the daily physical activity of children with asthma living in Cyprus and Greece and evaluated its association with climatic, environmental, personal, and clinical parameters. <bold>Methods:</bold> Physical activity (“total steps” and “steps outside”) and personal and clinical (age, sex, BMI, asthma symptom control, atopy status, and lung function) data were prospectively collected from children with asthma continuously wearing a smartwatch for three months, which recorded physical activity and geolocation data. Daily temperature, precipitation, and air pollution levels (PM₁₀ and PM_2.5) were available from local monitoring stations. Adjusted mixed effect regression models were used to assess the relationship between the examined parameters and physical activity. <bold>Results:</bold> The median number of daily steps was 9706 (IQR: 2026, 13034). We observed a decrease of 796 steps (95%CI: -1080, -511) during precipitation days compared to non-precipitation days and a decrease of 10 steps (95%CI: -18.20, −0.92) for every μg/m³ increase in mean PM₁₀ daily levels. Additionally, we identified a strong inverted U-shaped relationship between temperature and daily steps. Male sex demonstrated a positive association (β: 1012, 95% CI:83, 1941), while BMI z-score was negatively associated with daily steps, especially during cold days (β: -561, 95%CI: -920, -202). <bold>Conclusion:</bold> Precipitation, PM10, female sex, and BMI were negatively associated with physical activity, while the relationship with temperature was characterised by an inverse U-shape.