A single bout of high-intensity interval exercise does not increase endothelial or platelet microparticles in stable, physically fit men with coronary heart disease.

High-intensity interval exercise (HIIE) is gaining in popularity in fitness centres, even among coronary heart disease (CHD) patients. However, whether HIIE can have deleterious acute effects on the vasculature in CHD has not been studied. We hypothesized that when compared with moderate-intensity continuous exercise (MICE), a single bout of HIIE could lead to vascular damage and increasing numbers of circulating endothelial and platelet microparticles (EMPs, PMPs) in stable, physically fit CHD patients.Nineteen male CHD patients (aged 62 ± 11 years) underwent, in random order, a single session of HIIE corresponding to 15-second intervals at 100% of peak power output and 15-second passive recovery intervals, and an isocaloric MICE session. EMPs (CD31+ and/or CD62E+ and CD42b-); PMPs (CD42b+); nitrates and nitrites; prostacycline; and troponin T, cardiac form (cTnT), were measured 10 minutes before exercise and 20 minutes, 24 hours, and 72 hours after both exercise sessions.EMPs, PMPs, nitrates and nitrites, prostacycline, and cTnT remained unchanged after both HIIE and MICE exercise sessions. Initial EMP concentration correlated inversely with EMP concentration 20 minutes post exercise, irrespective of exercise modality (r = 0.78, P < 0.0001).A single HIIE session with very short exercise and passive recovery periods appears safe and does not induce changes to markers of endothelial function. Future studies are required to determine the safety of a long-term HIIE training program.