Dose–Response Effects of Low-Intensity Exercise on Cardiovascular Adaptations: An 8-Week Randomized Controlled Trial

Background: Cardiovascular diseases (CVDs) are the leading cause of mortality worldwide. While moderate- and high-intensity exercise are well-documented for cardiovascular benefits, the dose–response effects of low-intensity exercise remain underexplored. Objective: To investigate the dose–response relationship between varying durations of low-intensity exercise and cardiovascular adaptation over 8 weeks. Methods: Forty sedentary healthy adults (18–30 years) were randomized into four groups (n = 10 each): Control (CG), 15-minute (LI-15), 30-minute (LI-30), and 45-minute (LI-45) low-intensity exercise groups. Participants exercised five days per week at 40–50% of HRmax for 8 weeks. Primary outcomes were resting heart rate (RHR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate variability (HRV; RMSSD). Data were analyzed using repeated-measures ANOVA and linear regression modeling. Results: Significant time × group interactions were observed for RHR (p < .01), SBP (p < .05), and HRV (p < .01). The LI-45 group showed the greatest improvements, followed by LI-30 and LI-15. Linear regression confirmed a significant dose–response relationship between exercise duration and cardiovascular adaptation (R² = .42–.58). Conclusion: Low-intensity exercise produces dose-dependent cardiovascular adaptations, with longer durations providing greater physiological benefits. These findings suggest low-intensity exercise as a practical intervention for cardiovascular health promotion.