Cardiovascular Risk Factor, Metabolic Syndrome, Obesity, Polycystic Ovary Syndrome, PreDiabetes, Prehypertension
Conditions
Keywords
heat therapy, blood pressure, oral glucose tolerance test, adipose tissue, muscle sympathetic nerve activity
Brief summary
Traditional medical treatments are often based on research done exclusively in males, and recent research efforts in the physiology community have highlighted critical sex differences in disease presentation and progression. For example, the relative risk of fatal heart disease is 50% greater in obese, diabetic women as compared to their male counterparts, and women appear to respond differently to lifestyle interventions such as exercise compared with men. Chronic passive heat exposure (hot tub use) provides alternative or supplemental therapeutic potential for improving cardiovascular and metabolic health in obese women. In addition, passive heat exposure may offer specific cellular protection from stresses like a lack of blood flow (ischemia), which is the primary cause of fatal coronary heart disease. This study is investigating the possible cardiovascular and metabolic health benefits of chronic passive heat exposure, and whether regular hot tub use (3-4 days per week for 8-10 weeks) may reduce obese womens' cardiometabolic risk. The investigators are examining cardiovascular health through blood pressure, blood vessel stiffness, sympathetic ('fight or flight') activity, and responsiveness to stresses like increased or decreased blood flow. The investigators are also examining metabolic health through an oral glucose tolerance test and a subcutaneous fat biopsy. The goal of this research is to develop a therapy targeted toward the specific health needs and complications of obese women, in an effort to improve cardiovascular and metabolic health and provide therapeutic alternatives in this high-risk population.
Interventions
BEHAVIORALHeat therapy
Regular hot tub use
Sponsors
American Heart Association
University of Oregon
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
SINGLE (Outcomes Assessor)
Masking description
It was not possible to blind the subject or PI to treatment group, but all measures that were collected were analyzed offline by a blinded investigator.
Intervention model description
Subjects were matched for age and BMI, then assigned to either a heat therapy intervention or time control (no intervention, just outcomes assessment at matched timepoints).
Eligibility
Sex/Gender
FEMALE
Age
18 Years to 40 Years
Healthy volunteers
No
Inclusion criteria
* Age 18-40 * Body mass index (BMI) between 30-45 kg/m2. * Willing to maintain consistent diet and activity patterns through the study * Willing to refrain from food, physical activity, supplements, and medications as required before testing days * Willing to refrain from blood donations over the course of the study
Exclusion criteria
* overt cardiovascular disease or diabetes * medications that affect blood vessel function (i.e. Spironolactone), insulin sensitivity (Metformin), or blood coagulation (i.e. Warfarin) * Recent rectal, anal, or vaginal surgery * pregnant, breastfeeding, or trying to conceive within 6 months.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| diastolic blood pressure | through study completion, an average of 10 weeks | Resting supine blood pressure, measured in triplicate with median recorded |
| oral glucose tolerance test | through study completion, an average of 10 weeks | glucose and insulin responses to a 75-g, 2-hr oral glucose tolerance test after a 12+hr fast |
| systolic blood pressure | through study completion, an average of 10 weeks | Resting supine blood pressure, measured in triplicate with median recorded |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| muscle sympathetic nerve activity burst frequency | through study completion, an average of 10 weeks | recording of sympathetic nerve traffic during supine rest, quantified as burst count per minute |
| arterial wall thickness (carotid) | through study completion, an average of 10 weeks | intimal thickness of common carotid artery assessed using doppler ultrasonography |
| flow mediated dilation | through study completion, an average of 10 weeks | flow-mediated dilation of brachial artery, expressed as % change in diameter. A measure of endothelial function. |
| flow mediated dilation after ischemia-reperfusion | through study completion, an average of 10 weeks | flow-mediated dilation of brachial artery, expressed as % change in diameter, following 20 minute ischemia-20 minute reperfusion. A measure of vascular tolerance to ischemia-reperfusion stress. |
| Abdominal subcutaneous fat biopsy | through study completion, an average of 10 weeks | Adipose tissue sample analyzed for insulin signaling, markers of inflammation, and heat shock protein expression |
| arterial wall thickness (femoral) | through study completion, an average of 10 weeks | intimal thickness of superficial femoral artery assessed using doppler ultrasonography |
| dynamic arterial compliance (carotid) | through study completion, an average of 10 weeks | arterial compliance of common carotid artery measured using ultrasonography |
| dynamic arterial compliance (femoral) | through study completion, an average of 10 weeks | arterial compliance of superficial femoral artery measured using ultrasonography |
Other
| Measure | Time frame | Description |
|---|---|---|
| C-reactive protein | through study completion, an average of 10 weeks | serum measurement of high-sensitivity C-reactive protein, global inflammatory marker |
| Cholesterol panel | through study completion, an average of 10 weeks | serum measurement of cholesterol |
Countries
United States
Outcome results
None listed