Acute and chronic effects of moderate intensity continuous training and high intensity interval training on vascular function in female patients after myocardial infarction

Background Moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) are two of the most commonly used training protocols in cardiac rehabilitation programmes for patients with coronary artery disease. However, as safety and efficacy data for these protocols originate largely from studies conducted in male populations, evidence in females remains limited. Furthermore, only a few studies have simultaneously assessed both the acute and chronic effects of these training modalities on vascular function. Purpose The aim of this study was to assess the acute effects of MICT versus HIIT on flow-mediated dilation (FMD), as well as their long-term effects on FMD and arterial stiffness in female post–myocardial infarction patients. Methods In this randomised controlled trial, cardiopulmonary exercise testing was performed in all patients. MICT consisted of 32 minutes of exercise at 75% VO2peak intensity, whereas HIIT consisted of 7 cycles of 1.5 minutes at 80–90% VO2peak followed by 3 minutes at 65–70% VO2peak intensity. FMD was measured at rest and 1 hour after (a) the first and (b) the 36th exercise session to compare the acute and long-term effects of MICT versus HIIT. FMD of the right brachial artery and pulse wave velocity (PWV) of the right common carotid artery were assessed in each patient. A two-factor repeated-measures ANOVA was used to evaluate time × intervention interactions across measurement points. Results Fifty-eight female patients were enrolled in the study (mean age 58 ± 9 years), of whom 53 completed the intervention (n = 25 in the MICT group and n = 28 in the HIIT group). Baseline FMD was 5.0 ± 3.7%, and baseline PWV was 6.6 ± 1.1 m/s. There were no significant acute effects on FMD after either MICT or HIIT (p = 0.335). Long-term effects on resting FMD were significant for both interventions (main effect of time p < 0.001; time × intervention interaction p = 0.892). Long-term effects on 1-hour post-exercise FMD were also significant (main effect of time p = 0.002; interaction p = 0.289). Furthermore, both MICT and HIIT significantly improved PWV, with no significant differences between groups (main effect of time p < 0.001; interaction p = 0.909). Conclusion Both MICT and HIIT appear to be safe and effective training protocols for female post–myocardial infarction patients, with beneficial long-term effects on vascular function.