Temperature exposure and time adolescents spend in physical activity across intensity levels

Background: Environmental factors such as temperature may influence how much time adolescents spend being active, but evidence remains limited. We aimed to evaluate the relationship between same-day temperature exposure and accelerometer-measured time spent in physical activity at different intensities in adolescents in two European cohorts. Methods: We used data from 1316 Dutch adolescents (mean age [standard deviation]: 12.7 [1.5] years, Generation R Study, 2015–2018) and 531 Spanish adolescents (13.6 [2.3] years, INMA Project, 2017–2022). Ambient residential-level daily temperature at 100 × 100-m resolution was estimated using the UrbClim model. Daily light, moderate, and vigorous physical activity duration was measured with wrist-worn accelerometers up to nine consecutive days. Cohort-specific distributed lag mixed-effect models assessed same-day temperature effects on physical activity, adjusting for temperatures in the two previous days. Results: Adolescents spend more time in light and moderate physical activity on warmer days. In Generation R, light activity increased by up to 10.9 (95% confidence interval = 4.7, 17.0) minutes and moderate activity by 4.8 (1.2; 8.4) minutes at the 95th versus 5th percentile (21.5 vs. 2.3ºC). In INMA, increases were 16.3 (3.8, 28.9) and 14.2 (6.1, 22.4) minutes, respectively (25.1 vs. 7.7ºC). No associations were observed for vigorous activity. Conclusion: Warmer temperatures were associated with more time spent in light and moderate, but not vigorous, physical activity in Dutch and Spanish adolescents. These findings highlight the importance of considering ambient temperature when designing activity interventions, particularly in the context of climate change.