Endothelial function following interval exercise plus low-calorie diet treatment in obese females

We determined if interval exercise plus a low-calorie diet (LCD + INT) increases endothelial function more than an energy-matched LCD. Obese women (47.2 ± 2.6y, 37.5 ± 1.3kg/m² ) were randomized to 13 days of a LCD (n = 12; mixed meals of ~ 1200kcal/d) or LCD + INT (n = 13; 12 supervised 60-min INT bouts of 3 min at 90% and 50% HR_peak ). LCD + INT subjects received 350kcal postexercise to equate energy availability with LCD. Fitness (VO₂ peak) and body composition (BodPod) were determined and a 120 min, 75 g oral glucose tolerance test was performed to examine fasting and postprandial flow-mediated dilation (FMD, endothelial function), respiratory exchange ratio (RER) via indirect calorimetry as well as glucose and insulin incremental area under the curve (iAUC_120min ). LCD + INT increased VO₂ peak (P = 0.02) compared with LCD, and both treatments decreased fat mass (P < 0.001) and insulin iAUC_120min (P = 0.03). There was no overall treatment effect on fasting or iAUC_120min FMD. However, in participants who increased fasting endothelial function after each treatment (Δ > 50%; LCD n = 5, LCD + INT n = 7), LCD + INT increased fasted (P = 0.005) and decreased iAUC_120min (P = 0.003) FMD compared with LCD. Enhanced fitness correlated with increased fasting FMD (r = 0.43, P = 0.03) and diminished FMD iAUC_120min (r = -0.44, P = 0.03). Decreased FMD iAUC_120min correlated with reduced glucose iAUC_120min (r = 0.64, P = 0.001) as well as increased 60-min RER (r = -0.42, P = 0.04). Low baseline fasting and iAUC_120min FMD was also linked to enhanced fasting and iAUC_120min FMD post-treatment (r = -0.71, P < 0.001; r = -0.89, P < 0.001, respectively). In conclusion, increasing fitness via INT may increase the effect of LCD on lowering cardiovascular disease risk in obese women.