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 intensities between three "iso-work" protocols: (a) a high intensity interval training protocol (HIIT), (b) a higher intensity continuous protocol (CON) and (c) a lower intensity continuous protocol (CON) 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 with 3 min of recovery at 50% VO, a CON protocol corresponding to 70% VO and a CON protocol corresponding to 50% VO. Cardiopulmonary data were collected by an online gas analysis system. The HIIT and CON elicited higher cardiorespiratory responses compared to CON with no differences between them ( > 0.05). In HIIT and CON, patients exercised longer at >80% and >90% VO. The completion rate was 100% for the three protocols. Not any adverse events were observed in either protocol. Both HIIT and CON elicited a stronger physiological stimulus and required shorter time than CON. Both HIIT and CON also induced comparable hemodynamic responses and ventilatory demand.