Author(s): JIANG, C., XU, L.2, HU, M.3, PANG, Y.Q.1, LU, Y.Q.1, JI, J.N.2, YIN, W.F.2, Institution: SOUTHWEST PETROLEUM UNIVERSITY, Country: CHINA, Abstract-ID: 1100

INTRODUCTION:
Amid rapid population aging, rising asthma burden in middle-aged and older adults is a critical public health issue. Physical activity is modifiable and low-cost, yet evidence on new-onset asthma remains limited. This national cohort study prospectively examined total and intensity-specific physical activity in relation to new-onset asthma.
METHODS:
Using 2011–2020 data from the China Health and Retirement Longitudinal Study, we included participants aged ≥45 years at baseline who were free of asthma, had complete physical activity data, and had follow-up information on asthma (n=3454). Baseline physical activity was assessed using the validated International Physical Activity Questionnaire, which captured daily duration (mins/day) and weekly frequency (days/week) across activity intensities. TPA was calculated as MET-minutes/week and categorized into quartiles. New-onset asthma was defined as the first self-reported asthma based on physician diagnosis during the follow-up. Kaplan–Meier methods were used to compare cumulative incidence, and Cox proportional hazards models with stepwise covariate adjustment were fitted; restricted cubic splines were applied to examine dose–response relationships. Three models were specified: Model 1 adjusted for age, sex, education, marital status, and residence; Model 2 additionally adjusted for body mass index, waist circumference, sleep duration, smoking status, and alcohol consumption; Model 3 further adjusted for hypertension, diabetes, dyslipidemia, liver disease, kidney disease, and heart disease.
RESULTS:
Cumulative incidence differed across TPA quartiles (log-rank P=0.045). After full adjustment, the highest TPA quartile was associated with a lower risk of new-onset asthma compared with the lowest quartile (HR 0.64, 95% CI 0.42–0.96; P=0.031; P for trend=0.030). Moderate-intensity physical activity (MPA) duration showed a more consistent inverse association: relative to 0–10 min/day, risk was significantly lower at 120–239 mins/day (HR 0.49, 95% CI 0.30–0.79; P=0.004) and remained reduced at ≥240 mins/day (HR 0.70, 95% CI 0.50–0.99; P=0.048; P for trend=0.011; log-rank P=0.003). No significant differences were observed for walking or vigorous-intensity physical activity (VPA) duration. Regarding frequency, each additional day per week of MPA was associated with a lower risk (HR 0.94, 95% CI 0.90–0.98; P=0.001), whereas associations for walking and VPA frequency were not significant after full adjustment.
CONCLUSION:
Habitual MPA was significantly associated with a lower risk of new-onset asthma among middle-aged and older adults, and TPA should be maintained at a high level overall per week. In contrast, walking and VPA showed no significant protective associations, suggesting that MPA may offer the most favorable balance of safety, effectiveness, and long-term feasibility. Promoting regular moderate-intensity activity could serve as a practical, non-pharmacological approach for primary asthma prevention and control in ageing societies.