Acute Cardiorespiratory Responses to Different Exercise Modalities in Chronic Heart Failure Patients—A Pilot Study

The purpose of this study was to compare the acute cardiorespiratory responses and time spent above different %VO(2peak) intensities between three “iso-work” protocols: (a) a high intensity interval training protocol (HIIT), (b) a higher intensity continuous protocol (CON(70)) and (c) a lower intensity continuous protocol (CON(50)) in patients with chronic heart failure (CHF). Ten male CHF patients (aged 55.1 ± 16.2 years) performed in separate days a single session of a HIIT protocol consisted of 4 sets × 4 min cycling at 80% VO(2peak) with 3 min of recovery at 50% VO(2peak), a CON(70) protocol corresponding to 70% VO(2peak) and a CON(50) protocol corresponding to 50% VO(2peak). Cardiopulmonary data were collected by an online gas analysis system. The HIIT and CON(70) elicited higher cardiorespiratory responses compared to CON(50) with no differences between them (p > 0.05). In HIIT and CON(70), patients exercised longer at >80% and >90% VO(2peak). The completion rate was 100% for the three protocols. Not any adverse events were observed in either protocol. Both HIIT and CON(70) elicited a stronger physiological stimulus and required shorter time than CON(50). Both HIIT and CON(70) also induced comparable hemodynamic responses and ventilatory demand.