Low-intensity Resistance Exercise and Diet on Arterial Function and Blood Pressure

Study Overview
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Brief Summary
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Obesity is a major risk factor for premature arterial abnormalities including high blood pressure and increased stiffness. Previous studies have shown that weight loss via lifestyle modifications is associated with a decrease in large artery (aorta) stiffness. However, along with decreases in fat mass, hypocaloric diet reduces muscle mass. Low-intensity resistance exercise training (LIRET) results in similar increases in muscle mass and strength than those observed after high-intensity resistance exercise. The investigators hypothesis is that weight loss via diet combined with LIRET would additively reduce arterial stiffness and blood pressure (BP) in obese women. The investigators also hypothesize that the improved arterial function with weight loss would be associated with beneficial changes in the main mechanisms involved in BP regulation.

Detailed Description
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The purpose of the study is to examine the effects of 12 weeks of low-intensity resistance exercise training (LIRET) and diet on arterial function, autonomic function, and body composition in obese women with high blood pressure (BP). Specific aims of the study are to: To evaluate the extent to which diet and LIRET will improve body composition assessed by changes in fat mass and lean mass using dual-energy x-ray absorptiometry and waist circumference. To investigate that combined diet and LIRET are more efficacious than either treatment alone in ameliorating cardiovascular disease risk factors by assessing arterial stiffness (aortic, systemic, and leg), aortic BP and wave reflection, and autonomic function (heart rate variability, vascular sympathetic activity [low-frequency power of systolic BP variability], and baroreflex sensitivity). Circulating levels of adipocytokines (adiponectin and leptin) and endothelial-derived vasodilators (NO metabolites [NOx] and prostacyclin) and vasoconstrictors (endothelin-1 and prostaglandin F2α) will be assessed as secondary outcome variables.

Official Title
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Effects of Low-intensity Resistance Exercise Training and Diet on Central Hemodynamics and Arterial Stiffness in Obese Middle-aged Women With High Blood Pressure

Conditions
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Obesity, Pre-hypertension, Hypertension

Intervention / Treatment
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* Other: Resistance exercise training
* Other: Hypocaloric diet
* Other: Resistance exercise training & diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Female 40 to 65 years of age Body mass index of 27-39.9 Sedentary or low active (less than 2 hr per wk) Exclusion Criteria: Younger than 40 or older than 65 years of age Body mass index lower than 27, or 40 or higher Physically active or competitively active Smoker Systolic blood pressure higher than 140 mmHg Use of hormone replacement therapy of less than 1 yr Use of calcium channel blocker or beta blockers Type 1 diabetes Uncontrolled type 2 diabetes

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Resistance exercise training<br>Lower-body exercises 3 times per wk for 12 wk | Other: Resistance exercise training<br>* The low intensity resistance exercise training intervention consists of lower-body resistance exercise (machines) 3 times per wk for 12 wk. Two sets the first 2 wk and 3 sets the rest of the intervention, at 40% of the estimated 1 repetition maximum, for 17 to 23 repetitions, with 1 minute of rest in between sets.<br>|
| Experimental: Hypocaloric diet<br>This arm involves 12 wk of the standard Nutrisystem foods plan complemented by fresh produce and dairy. Subjects consume breakfast, lunch, dinner, and one (women) or two (men) snacks per day. | Other: Hypocaloric diet<br>* The hypocaloric diet intervention consists of 12 wk of the standard Nutrisystem foods plan complemented by fresh produce and dairy. Subjects consume breakfast, lunch, dinner, and one (women) or two (men) snacks per day.<br>|
| Experimental: Resistance exercise training & diet<br>Lower-body exercise training and diet | Other: Resistance exercise training & diet<br>* Combination of low intensity resistance exercise training and hypocaloric diet<br>|
| No Intervention: Control<br>This arm involves not making any change to the subject's lifestyle at the moment of the start of the intervention and for 12 wk. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood pressure | Non-invasive measures of brachial and aortic blood pressure | 12 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Autonomic Function | Heart rate variability, vascular sympathetic activity [low-frequency power of systolic BP variability], and spontaneous baroreflex sensitivity will be assessed from electrocardiogram and beat-by-beat digital blood pressure | 12 weeks | 
| Endothelial Function | By measuring circulating levels of adipocytokines (adiponectin and leptin) and endothelial-derived vasodilators (NO metabolites [NOx] and prostacyclin) and vasoconstrictors (endothelin-1 and prostaglandin F2α) | 12 weeks | 
| Body Composition | By measuring fat mass and lean soft tissue mass from dual-energy x-ray absorptiometry and waist circumference | 12 weeks | 
| Arterial Stiffness | Using pulse wave velocity of the aorta, systemic, and legs | 12 weeks | 
| Pressure Wave Reflection | Using the augmentation index from radial tonometry | 12 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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low intensity resistance exercise training, hypocaloric diet, prehypertension, hypertension, obesity, arterial function, arterial stiffness, pulse wave velocity, autonomic function, endothelial function, adipocytokines