Purpose: although the acute physiological responses to continuous exercise have been well documented in CHD patients, no previous study has examined the responses to high-intensity intermittent exercise in these patients. The purpose of this study was to compare the physiological responses to a high-intensity interval exercise (HIIE) protocol versus a moderate-intensity continuous exercise (MICE) protocol of similar energy expenditure in CHD patients.
Methods: twenty patients with stable CHD (19 males and 1 female, 62 ± 11 yr) were assigned in random order to a single session of HIIE corresponding to 15-s intervals at 100% of peak power output (PPO) and 15-s passive recovery intervals and, 2 wk later, to an isocaloric MICE corresponding to 70% of PPO.
Results: both protocols were equivalent in terms of energy expenditure. The HIIE protocol resulted in lower mean ventilation (P < 0.001) for a small difference in metabolic demand. All participants preferred the HIIE mainly because the perceived exertion measured by the Borg scale was lower (P < 0.05). No elevation of serum concentration of troponin T was found in all participants at baseline and at 20 min and 24 h after the exercise sessions, thus excluding the presence of any exercise-induced myocardial injury in our patients.
Conclusions: when considering physiological responses, safety, and perceived exertion, the HIIE protocol seemed to be well tolerated and more efficient in this group of stable CHD patients.