AUTHOR=Boff Winston , da Silva Antonio M. , Farinha Juliano B. , Rodrigues-Krause Josianne , Reischak-Oliveira Alvaro , Tschiedel Balduino , Puñales Marcia , Bertoluci Marcello C. 

TITLE=Superior Effects of High-Intensity Interval vs. Moderate-Intensity Continuous Training on Endothelial Function and Cardiorespiratory Fitness in Patients With Type 1 Diabetes: A Randomized Controlled Trial

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00450

DOI=10.3389/fphys.2019.00450

ISSN=1664-042X

ABSTRACT=<p>This study aimed to compare the effect of high-intensity interval training (HIIT) with moderate-intensity continuous training (MCT) on endothelial function, oxidative stress and clinical fitness in patients with type 1 diabetes. Thirty-six type 1 diabetic patients (mean age 23.5 ± 6 years) were randomized into 3 groups: HIIT, MCT, and a non-exercising group (CON). Exercise was performed in a stationary cycle ergometers during 40 min, 3 times/week, for 8 weeks at 50–85% maximal heart rate (HR<sub>max</sub>) in HIIT and 50% HR<sub>max</sub> in MCT. Endothelial function was measured by flow-mediated dilation (FMD) [endothelium-dependent vasodilation (EDVD)], and smooth-muscle function by nitroglycerin-mediated dilation [endothelium-independent vasodilation (EIVD)]. Peak oxygen consumption (VO<sub>2peak</sub>) and oxidative stress markers were determined before and after training. Endothelial dysfunction was defined as an increase &lt; 8% in vascular diameter after cuff release. The trial is registered at <ext-link ext-link-type="uri" xlink:href="http://clinicaltrials.gov" xmlns:xlink="http://www.w3.org/1999/xlink">ClinicalTrials.gov</ext-link>, identifier: NCT03451201. Twenty-seven patients completed the 8-week protocol, 9 in each group (3 random dropouts per group). Mean baseline EDVD was similar in all groups. After training, mean absolute EDVD response improved from baseline in HIIT: + 5.5 ± 5.4%, (<italic>P</italic> = 0.0059), but remained unchanged in MCT: 0.2 ± 4.1% (<italic>P</italic> = 0.8593) and in CON: −2.6 ± 6.4% (<italic>P</italic> = 0.2635). EDVD increase was greater in HIIT vs. MCT (<italic>P</italic> = 0.0074) and CON (<italic>P</italic> = 0.0042) (ANOVA with Bonferroni). Baseline VO<sub>2peak</sub> was similar in all groups (<italic>P</italic> = 0.96). VO<sub>2peak</sub> increased 17.6% from baseline after HIIT (<italic>P</italic> = 0.0001), but only 3% after MCT (<italic>P</italic> = 0.055); no change was detected in CON (<italic>P</italic> = 0.63). EIVD was unchanged in all groups (<italic>P</italic> = 0.18). Glycemic control was similar in all groups. In patients with type 1 diabetes without microvascular complications, 8-week HIIT produced greater improvement in endothelial function and physical fitness than MCT at a similar glycemic control.</p>