Effects of Passive Heat Therapy on Oxygen Consumption and Cardiovascular Fitness in Adults
Condition: Heart Failure; Heart Diseases; Cardiovascular Diseases; Endothelial Dysfunction
MeSH terms: Cardiovascular Diseases; Heart Diseases
Study type: Interventional

Summary: 
      The purpose of this study is to determine if enhanced endothelial arterial distensibility
      observed with heat therapy translates into improved cardiorespiratory fitness. The following
      aims are proposed: Aim 1: to determine if chronic heat therapy results in improvements in
      cardiovascular function. Aim 2: To examine potential mechanism(s) of action of heat therapy
      in cardiovascular function.
    

Detailed description: 
      The National Institute of Health recognizes heart failure as a major public health problem
      with a prevalence of over 5.8 million Americans and 23 million people worldwide. Commonly
      prescribed medications to treat the symptoms associated with this disease are expensive and
      many are not covered by major health insurance companies. There is a critical need to develop
      novel treatment and prevention strategies for heart failure. Emerging research highlights the
      benefits of heat therapy (HT) on metabolic and cardiovascular disease risk. The Geiger
      laboratory has demonstrated that in obese rats fed a high- fat diet for 12 weeks, weekly HT
      restored whole body glucose tolerance and skeletal muscle insulin sensitivity. The first
      comprehensive investigation of long-term HT in young, sedentary humans resulted in improved
      endothelial function and hemodynamics that were on par with what is typically observed with
      exercise training in previously sedentary subjects. The purpose of this pilot study is to
      determine if the enhanced endothelial arterial distensibility observed with HT translates
      into improved cardiorespiratory fitness. The following aims are proposed:

      Aim 1: To determine if chronic HT results in improvements in cardiovascular function. The
      study team hypothesizes that repeated HT will result in improvement in hemodynamic variables
      related to arterial distensibility (blood pressure, stroke volume, stroke volume variation,
      cardiac index and systemic vascular resistance) and that these changes translate to improved
      cardiovascular function as measured by VO2max.

      Aim 2: To examine potential mechanism(s) of action of HT in cardiovascular function. The
      study team hypothesizes that HT may exerts its beneficial effects via the effect of heat
      shock proteins (HSPs) on Nitric Oxide (NO) bioavailability. This will be tested by measuring
      HSPs, NO mediators and inflammatory markers at baseline and post-intervention. There is
      rapidly growing interest in the use of HT as a global therapeutic approach and alternative or
      complementary therapy to exercise training for patients with chronic disease. Study findings
      would be clinically significant as both men and women with higher cardiorespiratory fitness
      (as indicated by maximal oxygen consumption, VO2max) are at lower risk for cardiovascular
      disease.

      These studies will be the first to examine the ability of chronic heat therapy to increase
      cardiorespiratory fitness as measured by maximal oxygen consumption, VO2max. These findings
      could lead to HT as a simple and effective tool for improving cardiovascular health in a
      variety of populations, particularly those with exercise limitations and comorbid disease
      states like type 2 diabetes, dementia and cardiovascular disease.
    

Intervention name(s): Heat Therapy Treatment
Intervention type(s): Behavioral
Intervention description(s): Subjects will undergo 10 hot water immersions of 40.5 degrees Celsius for approximately 45 minutes per session over 14 days. Subjects will be immersed up to the shoulder until rectal temperature reacher 38.5 degrees Celsius (approximately 15-20 minutes). Subjects will then remain in the water bath submerged at waist level to maintain between 38.5 to 39.0 degrees Celsius for another 30 minutes. Following hot water immersion, subjects will be monitored for 10 minutes, or until temperature falls below 38.5 degrees Celsius.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Heat Therapy