Comparable Improvements in Heart Rate Recovery Following Short-Term High-Intensity and Moderate-Intensity Interval Training in Patients with Cardiovascular Disease

Objective: Heart rate recovery (HRR) is a validated prognostic marker in cardiovascular disease (CVD). This study evaluated and compared the effects of 4-week high-intensity interval training (HIIT) and moderate-intensity interval training (MIIT) on post-exercise HRR in patients with CVD. Methods: A total of 1,020 CVD patients undergoing cardiac rehabilitation (Jan 2021-May 2024) were screened, and 209 who completed 12 sessions and cardiopulmonary exercise tests were included (HIIT: 82; MIIT: 127). The mean ages were 55.2 (HIIT) and 52.9 years (MIIT), with females comprising 34.1% and 34.6%, respectively. The MIIT protocol included four 8-min cycling bouts (RPE 12– 14) with 2-min active recovery, while HIIT involved 20– 25 × 30-s high-intensity bouts (RPE 14– 15) alternating with 30-s low-intensity recovery. Results: Both interventions significantly improved HRR (HIIT: 3.1± 8.7 bpm, P = 0.002; MIIT: 3.0± 10.0 bpm, P = 0.001), with no between-group difference ( P = 0.816). Peak VO 2 similarly increased in both groups (HIIT: 3.3± 2.8; MIIT: 3.0± 3.6 mL·kg − 1 ·min − 1 ; P < 0.001). Other related measures were also notably improved ( P < 0.05). Multivariable regression analysis revealed that the change in HRR was inversely associated with the change in resting heart rate in both HIIT (β = − 0.227, P = 0.04) and MIIT (β = − 0.318, P < 0.001) cohorts. Conclusion: Both short-term HIIT and MIIT comparably enhance HRR in patients with CVD, highlighting the clinical applicability of interval training as an efficient option for patients with limited time availability. However, the retrospective design limits causal inference and requires confirmation in future studies.