The longitudinal association between asthma severity and physical fitness among new York City public school youth.

Severe persistent childhood asthma is associated with low physical activity and may be associated with poor physical fitness. Research on the asthma severity-fitness association longitudinally and across sociodemographic subgroups is needed to inform fitness interventions targeting youth with asthma. We evaluated the relationship between asthma severity (categorized as severe, mild, or no asthma) and subsequent fitness in New York City (NYC) public school youth enrolled in grades 4-12 using the NYC Fitnessgram dataset (2010-2018). Longitudinal mixed models with random intercepts were fit to test the association between asthma severity and one-year lagged fitness z-scores by clustering repeated annual observations at the student level. Models were adjusted for sex, race/ethnicity, grade level, poverty status, time, and stratified by sociodemographic factors. The analytic sample included 663,137 students (51% male; 31% non-Hispanic Black, 40% Hispanic; 55% in grades 4-8, 70% high poverty; 87%, 11% and 1% with no, mild, and severe asthma, respectively). Students with severe asthma and mild asthma demonstrated -0.19 (95% CI, -0.20 to -0.17) and - 0.10 (95% CI, -0.11 to -0.10), respectively, lower fitness z-scores in the subsequent year relative to students without asthma. After stratifying by demographics, the magnitude of the asthma severity-fitness relationship was highest for non-Hispanic white vs. all other racial/ethnic subgroups, and was similar across sex, grade level, and household poverty status. Overall, we observed an inverse longitudinal relationship between asthma severity and subsequent fitness among urban youth, particularly non-Hispanic Whites. Future research should examine how neighborhood-level factors impact the asthma severity-fitness relationship across racial/ethnic subgroups.