Comparing Moderate and High-intensity Interval Training Protocols on Biomarkers in Type 2 Diabetes Patients (D2FIT)

Comparing Moderate and High-intensity Interval Training Protocols on Biomarkers in Type 2 Diabetes Patients

A 12-Month Randomized Control Trial in Patients With Type 2 Diabetes: Comparing Moderate and High-intensity Interval Training Protocols on Biomarkers and Quality of Life

To overcome the lack of knowledge regarding the relative role of different intensities of aerobic training in adults with type 2 (T2D) diabetes, a 12 month randomized controlled trial will be performed to assess and compare the impact of two exercise groups: 1- high intensity interval training (HIIT) with resistance training; 2- moderate continuous training (MCT) with resistance training; and 3- a standard counseling home based control group; on hemoglobin A1c (HbA1c) as the main outcome, and other selected cardiometabolic, body composition and quality of life markers, as secondary outcomes. This investigation aims to increase the current knowledge on HIIT and the related benefits on diabetes control and treatment in a time saving and physiological efficient framework, which will improve the general health and well-being of the diabetes population. A total of 105 participants with T2D will be recruited from the Lisbon area (35 control, 35 HIIT, and 35 MCT). The investigators hypothesize that high-intensity interval training, compared to moderate continuous training, will optimize the physiological adaptations and quality of life in people with type 2 diabetes.

Contemporary exercise guidelines focus on continuous aerobic exercise using mainly moderate intensity exercises. However, there is growing evidence that HIIT has the same (or even further) benefits, with lower time commitment. This type of exercise has already been tested in T2D patients, using mostly short intervention studies, with significant improvements in relevant outcomes for T2D, such as glucose regulation. On the other hand, no study as yet compared the effects of HIIT and MCT (both combining resistance training, RT) in a long-term study design. Therefore, this study will use a 12 month randomized control trial to assess the effects of an HIIT combined with RT, and MCT combined with RT, in comparison with a control group (home base program), on glycemic control, inflammatory profile, endothelium function, cardiorespiratory fitness, quality of life, and body composition outcomes, in adult males and females with T2D. The sample recruitment is planned to be made using media, mails, and community events. Participants can be considered eligible if age is set between 30 and 75 years old, a body mass index lower than 48 kg/m2, and if they have been diagnosed with T2D (according to the ADA criteria). Further criteria will be made upon their medical history concerning strokes, advanced neuropathy or retinopathy, and other health conditions that may interfere with this study's protocols or otherwise safe exercising. Power and sample size calculations (G-Power, Version 3.1.3) are based on a predicted hemoglobinA1c difference of 0.66 hemoglobinA1c units with an SD of effect of 1.2 hemoglobinA1c units, α=0.05, 1-β=0.80 and an expected dropout rate of 10%. The calculations yielded a minimum sample size of 105 participants (35 in each group). The statistical analysis will be performed using SPSS Statistics (version 22.0, SPSS Inc., an IBM Company, Chicago IL, USA). Baseline differences between the interventions and the control group will be examined using ANOVA, or a non-parametric alternative in case of a non-normalized distribution. Outcome variables will be analyzed using three-way mixed factorial ANOVA. Intention-to-treat analysis will be performed. Simple and multiple regression analysis will be performed to test the relationships among the selected variables. Statistical significance will be set at p<0.05.

The control group will be invited to an orientation session, where it will be provided detailed information concerning their home base exercise program. Additionally, once in every 4 weeks, the control group will meet for thematic sessions regarding diabetes topics, such as, nutrition, physical activity, and clinical complications. Due to ethical reasons, the control group needs to be provided with a standard counseling approach, as suggested in this research project.

MCT Group is designed to have equal energy expenditure when compared with HIIT Group. We standardized the exercise prescription according to body weight (kg), predicting that physical activity guidelines of 150 min peer week moderate intensity is equivalent to 10 kcal/kg of a combined session of RT and MCT. The MCT group will perform continuous cycling 3 days per week, with an exercise intensity of 40 to 59% of the heart rate reserve (HRR). Participants will also perform an RT circuit: 1 set of two pull upper body exercises (seated row and lat pulldown); 1 set of two push upper body exercises (chest press and shoulder press); 1 set of two leg exercises (leg press and one leg lunge); and 1 set of two core exercises (dead bug and regular plank). Each set consisting in 10 to 12 repetitions.

The HIIT program will perform cycle ergometer 3 days a week, and it will be divided into three phases: preparation phase (weeks 1-4), where the participants perform MCT (40-59% of the HRR); transition phase (weeks 5-8), in which the HIIT program is introduced progressively, starting with bouts of 2 minutes at 70% of the HRR, followed by 1 minute at 40-59% of the HRR (weeks 5-6), and finishing with bouts of 80% of the HRR, followed by 1 minute at 40-59% of the HRR (weeks 7-8); training phase (weeks 9-42), where the participants perform 1 minute of exercise at 90% of the HRR, followed by 1 minute resting at 40-59% of the HRR. The HIIT session will have the same energy expenditure as the MCT group, using the 10kcal/kg week target. Participants will also fulfill the same RT as the MCT group.

Blood samples will be collected from an indwelling catheter for the assessment of HbA1c. Samples will be drawn into chilled, heparinized tubes and centrifuged rapidly to avoid glycolysis. HbA1c will be analyzed by immunoassay (auto analyzer Hb9210 Premier A. Menarini diagnostics).

A stress test with ECG and gas analysis will be performed to assess cardiorepiratory fitness and to screen for eventual heart problems, under the supervision of appropriately trained medical staff.

Subjects weight and height will be measured according to standardized procedures. Waist circumference measurements will be done according to the NIH and WHO protocol. To estimate total and intra-abdominal fat mass and fat-free mass, DXA measurements will be made using a total body scan (Hologic Explorer-W, Waltham, USA).

Arterial function assessment will be performed on the right carotid artery using an ultrasound scanner (MyLab One, Esaote, Genova, Italy) and implemented with a previously validated radiofrequency-based tracking of the arterial wall.

Inclusion Criteria: Men and women diagnosed with type 2 diabetes 30-75 years of age BMI < 48 kg/m2 Exclusion Criteria: Documented cardiovascular disease Advanced neuropathy or retinopathy Physical health condition that may interfere with study's protocols or exercising safety

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