Greater improvement in cardiorespiratory fitness using higher-intensity interval training in the standard cardiac rehabilitation setting.

PURPOSE: We tested the hypothesis that higher-intensity interval training (HIIT) could be deployed into a standard cardiac rehabilitation (CR) setting and would result in a greater increase in cardiorespiratory fitness (ie, peak oxygen uptake, (·)VO2) versus moderate-intensity continuous training (MCT). METHODS: Thirty-nine patients participating in a standard phase 2 CR program were randomized to HIIT or MCT; 15 patients and 13 patients in the HIIT and MCT groups, respectively, completed CR and baseline and followup cardiopulmonary exercise testing. RESULTS: No patients in either study group experienced an event that required hospitalization during or within 3 hours after exercise. The changes in resting heart rate and blood pressure at followup testing were similar for both HIIT and MCT. (·)VO2 at ventilatory-derived anaerobic threshold increased more (P < .05) with HIIT (3.0 ± 2.8 mL·kg⁻¹·min⁻¹) versus MCT (0.7 ± 2.2 mL·kg⁻¹·min⁻¹). During followup testing, submaximal heart rate at the end of stage 2 of the exercise test was significantly lower within both the HIIT and MCT groups, with no difference noted between groups. Peak (·)VO2 improved more after CR in patients in HIIT versus MCT (3.6 ± 3.1 mL·kg⁻¹·min⁻¹ vs 1.7 ± 1.7 mL·kg⁻¹·min⁻¹; P < .05). CONCLUSIONS: Among patients with stable coronary heart disease on evidence-based therapy, HIIT was successfully integrated into a standard CR setting and, when compared to MCT, resulted in greater improvement in peak exercise capacity and submaximal endurance.