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NCT Number: NCT04026126

Effects of Passive Heat Therapy on Oxygen Consumption and Cardiovascular Fitness in Adults

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.

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Key information

Conditions

Heart Failure Body Temperature Changes Cardiovascular Diseases Endothelial Dysfunction Heart Diseases Heat Stress Disorders Hyperthermia Pathological Conditions, Signs and Symptoms Signs and Symptoms Wounds and Injuries

Age range

50 year–75 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Kansas Medical Center

Kansas City, Kansas, 66160, United States

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Exclusion criteria

  • Current major cardiovascular disease (i.e.: recent myocardial infarction (heart attack), stroke, angina pectoris, high grade coronary vasculopathy or atherosclerosis, severe valvular disease, cardiac dysrhythmia that requires treatment.
  • Current treatment with steroids or immunosuppressive agents
  • Cancer
  • Serious liver disease
  • End-stage renal disease
  • Judgement by medical provider that heat therapy poses an undue burden or risk
  • Women who are pregnant or plan to become pregnant

Treatment and study plan

Heat Therapy Treatment

Behavioral

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.

Primary outcomes

  1. Change in Blood Pressure

    Time frame: Blood pressure will be assessed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit). As a safety measure only, blood pressure will be monitored during every heat therapy treatment.

    Systolic and diastolic blood pressure will be monitored using the noninvasive Clearsight (Edward Lifesciences, Irvine, CA) monitor, which incorporates a disposable, single use fingertip cuff.

  2. Change in Stroke Volume

    Time frame: Stroke volume will be assessed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit).

    Stroke volume will be monitored using the noninvasive Clearsight (Edward Lifesciences, Irvine, CA) monitor incorporates a disposable, single use fingertip cuff.

  3. Change in Stroke Volume Variation

    Time frame: Stroke volume variation will be assessed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit).

    Stroke volume variation will be monitored using the noninvasive Clearsight (Edward Lifesciences, Irvine, CA) monitor incorporates a disposable, single use fingertip cuff.

  4. Change in Cardiac Index

    Time frame: Cardiac index will be assessed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit).

    Cardiac index will be monitored using the noninvasive Clearsight (Edward Lifesciences, Irvine, CA) monitor incorporates a disposable, single use fingertip cuff.

  5. Change in Systemic Vascular Resistance

    Time frame: Systemic vascular resistance will be assessed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit).

    Systemic vascular resistance will be monitored using the noninvasive Clearsight (Edward Lifesciences, Irvine, CA) monitor incorporates a disposable, single use fingertip cuff.

  6. Change in Maximum Oxygen Consumption (VO2max)

    Time frame: VO2max assessment will be performed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit).

    Maximum oxygen consumption (VO2max) will be measured using the Bruce Ramp protocol. The Bruce Ramp protocol is a standardized treadmill exercise commonly used in clinical laboratories.

  7. Change in Concentration of Heat Shock Proteins

    Time frame: Blood analyses will be performed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit).

    Serum levels of heat shock proteins (HSP72, HSP25) and the primary heat shock protein transcription factor (HSF1) will be assessed for change post heat therapy treatment.

  8. Change in Concentration of Nitric Oxide

    Time frame: Blood analyses will be performed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit).

    Nitric oxide (NO) bioavailability will be assessed for change post heat therapy treatment by measuring nitric oxide and endothelial nitric oxide synthase (eNOS).

  9. Change in Concentration of Pro/Anti-inflammatory Markers

    Time frame: Blood analyses will be performed at baseline and 24-48 hours after the last heat therapy session (end of study, ~2.5 weeks after first study visit).

    Pro/anti-inflammatory markers (IL1ra, IL-10, IL-8, IFN, and CRP) will be assessed for change post heat therapy treatment.

Sponsors and collaborators

Lead sponsor

University of Kansas Medical Center

Other

Collaborators

  • National Institute of General Medical Sciences (NIGMS)

Registry information

Important dates

Study start
2019
Primary completion
2021
Study completion
2021
First posted
Jul 19, 2019
Registry last updated
Oct 17, 2022

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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