HIIT Improves Left Ventricular Exercise Response in Adults with Type 2 Diabetes

Type 2 diabetes is associated with reduced left ventricular reserve. It is unclear whether exercise training improves left ventricular function in people with type 2 diabetes. PURPOSEThis study aimed to determine whether 3 months of high-intensity interval training (HIIT) improves left ventricular function during exercise in adults with type 2 diabetes. METHODSParticipants performed a V˙O2peak test and received a DXA scan and total blood volume measurement at baseline. Left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and left ventricular stroke volume (LVSV) were then measured at rest and during low- and moderate-intensity semirecumbent exercise in adults with type 2 diabetes before and after 3 months of HIIT (n = 11) or no training (control) (n = 5). The effects of HIIT were determined using repeated-measures ANOVA. RESULTSHIIT increased V˙O2peak by approximately 15% (P < 0.002) but did not change body composition or total blood volume. LVESV decreased and LVEDV and LVSV increased from rest to moderate-intensity exercise in both groups at baseline (all P < 0.01). Three months of HIIT increased LVEDV (P = 0.008) and LVSV (P = 0.02) at all conditions, but there was no difference in controls (all P > 0.05). HIIT augmented the reduction in LVESV from rest to moderate-intensity exercise (P < 0.04), but LVESV was unchanged in controls. Increased LVEDV explained 51% of the change in LVSV after HIIT intervention. Mitral inflow parameters and mitral annular velocities were unaffected by HIIT (all P > 0.05). CONCLUSIONSHIIT training increased the LVSV response to exercise in adults with type 2 diabetes. These data suggest that HIIT can improve LV filling and emptying during exercise and reverse early cardiac consequences of type 2 diabetes.