heart rate variability and blood pressure response to low-intensity endurance exercise training plus blood flow restriction in individuals with mild hypertension: a randomized controlled clinical trial

Background: given limited available data and information gaps related to the effects of endurance exercise along with blood flow restriction (bfr) on the heart. this study examined the effects of low-intensity endurance exercise training (ex) alone and bfr on blood pressure (bp), electrocardiogram (ecg), heart rate variability (hrv), and heart rate recovery time (hrrt) in participants with grade 1 hypertension.methods: in this randomized double-blind clinical trial, 43 hypertensive participants, 50-65 years old, were randomly divided into three groups: ex+bfr, ex, and the control (con) group. the training program was conducted three times weekly for 10 weeks in spring 2024 at kerman university of medical sciences. before and 24 hours after the intervention, hrv parameters, bp, ecg, and hrrt were assessed.results: the ex and ex+bfr groups showed a significant increase in root mean square of successive differences between normal heartbeats (rmssd) (p=0.008, p=0.002), standard deviation of successive differences (sdsd) (p=0.008, p=0.002),  and the standard deviation of the poincaré plot ratio (sd1/sd2) (p=0.0004, p=0.0002), and a reduced low frequency to high frequency ratio (lf/hf) (p=0.013 and p=0.007) compared to con group, respectively. the ex+bfr group demonstrated a greater positive effect on frequency-domain parameters of hrv. in addition, both the ex and ex+bfr groups showed a significant reduction in hrrt (p=0.0001 vs. relevant baseline), mean arterial blood pressure (map) (p=0.0001), and prolonged pr interval (p=0.038 and p=0.035, respectively) and shortened qrs complex compared to the con group.conclusion: this study demonstrates that combining low-intensity endurance exercise with bfr exerts a positive effect on cardiovascular parameters such as bp, ecg, hrrt, and demonstrates superior effects on hrv compared to exercise alone in individuals with mild hypertension.