Heat Therapy and Cardiometabolic Health in Obese Women (CMH)

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.

Study Overview

• Status: Completed
• Conditions: Obesity; Polycystic Ovary Syndrome; Metabolic Syndrome; PreDiabetes; Prehypertension; Cardiovascular Risk Factor
• Intervention / Treatment: Behavioral: Heat therapy

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Oregon
    • Eugene, Oregon, United States, 97403
      • University of Oregon

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 40 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Female

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Heat Therapy; Subjects assigned to heat therapy underwent 30 1-hour hot tub sessions over 8-10 weeks (3-4 per week). The hot tub was set to 40.5 Celsius, and core temperature and heart rate were monitored throughout each session.Subjects were instructed to not make any other dietary or lifestyle changes.Cardiovascular and metabolic health assessments were made Pre (0 heat sessions), mid (after 14-16 heat sessions, ~4-5 weeks), and post (after all 30 heat sessions; ~8-10 weeks).	Behavioral: Heat therapy; Regular hot tub use
No Intervention: Time Control; Subjects were monitored at matched timepoints (start of study, 4-5 weeks, and 8-10 weeks) but not exposed to any intervention. Subjects were instructed to not make any dietary or lifestyle changes.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
systolic blood pressure	Resting supine blood pressure, measured in triplicate with median recorded	through study completion, an average of 10 weeks
diastolic blood pressure	Resting supine blood pressure, measured in triplicate with median recorded	through study completion, an average of 10 weeks
oral glucose tolerance test	glucose and insulin responses to a 75-g, 2-hr oral glucose tolerance test after a 12+hr fast	through study completion, an average of 10 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
muscle sympathetic nerve activity burst frequency	recording of sympathetic nerve traffic during supine rest, quantified as burst count per minute	through study completion, an average of 10 weeks
arterial wall thickness (carotid)	intimal thickness of common carotid artery assessed using doppler ultrasonography	through study completion, an average of 10 weeks
arterial wall thickness (femoral)	intimal thickness of superficial femoral artery assessed using doppler ultrasonography	through study completion, an average of 10 weeks
dynamic arterial compliance (carotid)	arterial compliance of common carotid artery measured using ultrasonography	through study completion, an average of 10 weeks
dynamic arterial compliance (femoral)	arterial compliance of superficial femoral artery measured using ultrasonography	through study completion, an average of 10 weeks
flow mediated dilation	flow-mediated dilation of brachial artery, expressed as % change in diameter. A measure of endothelial function.	through study completion, an average of 10 weeks
flow mediated dilation after ischemia-reperfusion	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.	through study completion, an average of 10 weeks
Abdominal subcutaneous fat biopsy	Adipose tissue sample analyzed for insulin signaling, markers of inflammation, and heat shock protein expression	through study completion, an average of 10 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
C-reactive protein	serum measurement of high-sensitivity C-reactive protein, global inflammatory marker	through study completion, an average of 10 weeks
Cholesterol panel	serum measurement of cholesterol	through study completion, an average of 10 weeks

Collaborators and Investigators

• Sponsor: University of Oregon
• Collaborators: American Heart Association

Study record dates

Study Major Dates

• Study Start (Actual): September 8, 2015
• Primary Completion (Actual): April 30, 2018
• Study Completion (Actual): July 1, 2018

Study Registration Dates

• First Submitted: August 20, 2018
• First Submitted That Met QC Criteria: August 21, 2018
• First Posted (Actual): August 23, 2018

Study Record Updates

• Last Update Posted (Actual): August 23, 2018
• Last Update Submitted That Met QC Criteria: August 21, 2018
• Last Verified: August 1, 2018

More Information

Terms related to this study

• Keywords: blood pressure; oral glucose tolerance test; adipose tissue; muscle sympathetic nerve activity; heat therapy
• Additional Relevant MeSH Terms: Pathologic Processes; Cardiovascular Diseases; Vascular Diseases; Glucose Metabolism Disorders; Metabolic Diseases; Neoplasms; Endocrine System Diseases; Disease; Ovarian Cysts; Cysts; Ovarian Diseases; Adnexal Diseases; Gonadal Disorders; Insulin Resistance; Hyperinsulinism; Polycystic Ovary Syndrome; Syndrome; Metabolic Syndrome; Prehypertension
• Other Study ID Numbers: 08282015.026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No