Impact of Physical Activity Intensity on Stroke Risk in Middle-aged and Older Adults
Authors: Bai Zetai , Li Mei , Meng Liying , Zhang Chen , Wang Zheyi , Kong Deyuan , Wu Guanzhao 
Published: June 2024

Background
The relationship between weekly physical activity intensity and the incidence of initial stroke among middle-aged and elderly populations remains uncertain. Therefore, this study endeavors to elucidate this association through an analysis of a nationally representative cohort study.To contrast the incidence rates of initial stroke among participants engaging in varying levels of physical activity intensity with those leading sedentary lifestyles.
Methods
Cox regression analysis was employed to investigate the relationship between the intensity of physical activity and stroke incidence. Multimodel Cox regression analysis was conducted to evaluate the risk of initial stroke occurrence among patients with chronic diseases across varying levels of physical activity intensity. Restricted cubic splines were utilized to explore the correlation between overall physical activity and first stroke incidence, while mediation effects analysis was employed to elucidate the impact of highly active physical activity on first stroke occurrence through cardiovascular indicators. Subgroup analysis further delved into the relationship between highly active physical activity and initial stroke occurrence within diverse population subsets.
Results
Over a 7-year follow-up period, among the 4,380 participants (mean baseline age of 58 ± 9 years; 1,997 females), 300 individuals experienced a stroke, constituting 6.8% of the cohort. Of these cases, 43 (8.9%) occurred in sedentary participants, 173 (7.37%) in active individuals, and 84 (5.42%) in highly active individuals. In the overall population, the lowest risk of first stroke was observed at 13,045 MET-minutes/week of total physical activity. Following adjustment for potential confounders, highly active physical activity was found to significantly reduce the risk of first stroke (hazard ratio [HR], 0.52; 95% confidence interval [CI], 0.30 to 0.92). Furthermore, multivariate logistic regression revealed that highly active physical activity was associated with a decreased risk of first stroke (odds ratio [OR], 0.45; 95% CI, 0.36 to 0.55). Among participants with chronic diseases, those with hypertension demonstrated a reduced risk of first-ever stroke with highly active physical activity (HR, 0.55; 95% CI, 0.31 to 0.96), whereas such a benefit was not observed in other chronic conditions. Adjusting for confounding factors revealed that highly active physical activity might mitigate the risk of first stroke through mediating effects involving cardiovascular indicators, including blood pressure (effect, -0.003; 95% CI, -0.018 to -0.003), HDL (effect, -0.003; 95% CI, -0.018 to -0.005), BMI (effect, -0.001; 95% CI, -0.009 to -0.001), and TyG index (effect, -0.001; 95% CI, -0.008 to 0.000). Subgroup analyses, adjusted for confounders, revealed that compared to sedentary behavior, highly active physical activity was associated with a reduced risk of first-ever stroke in men (HR, 0.41; 95% CI, 0.22 to 0.75), individuals without heart disease (HR, 0.52; 95% CI, 0.33 to 0.82), and overweight individuals (HR, 0.40; 95% CI, 0.21 to 0.79).
Conclusions
These findings suggest that participation in highly active physical activity may mitigate the risk of first stroke among middle-aged and elderly individuals through modulation of cardiovascular indicators.