Effects of Heating on Exercise Pressor Reflex in Peripheral Artery Disease: Exercise Ability
NCT ID: NCT03900832
Last Updated: 2025-09-16
Study Results
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Basic Information
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COMPLETED
EARLY_PHASE1
33 participants
INTERVENTIONAL
2019-05-15
2025-07-31
Brief Summary
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Detailed Description
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It has been shown that exercise has benefits for patients with PAD. However, exercise becomes limited due to the pain and fatigue associated with the disease. Moreover, the augmented pressor response to exercise in PAD may increase the risk for the end organ damage (e.g. brain and/or heart). Thus, finding alternate/complimentary interventions that modulate the cardiovascular system and autonomic nervous system, and can be tolerated by the patients, would be beneficial.
One possible intervention is heat exposure, since acute bouts of exercise and acute heat exposure have similar acute effects on both the autonomic and cardiovascular systems. For example, both exercise and heat exposure increase body temperature, increase HR, increase cardiac output (CO), increase left ventricular ejection fraction (EF), and enhance myocardial function. In the peripheral circulation, both exercise and heat exposure increase limb blood flow , muscle blood flow, and skin blood flow. Moreover, recent studies suggest that whole body exposure improves the endothelium function in PAD patients (e.g. activates endothelial progenitor cells CD34+).
However, the effect of heat treatment on the ability of walking of PAD patients has not been examined. Moreover, it is unknown if heating can normalize/decrease the accentuated the pressor responses to exercise in PAD patients.
Conditions
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Study Design
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RANDOMIZED
CROSSOVER
BASIC_SCIENCE
SINGLE
Study Groups
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PAD without heating
Subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Without Heating
Subject will complete walking protocol without any heating procedure
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
PAD warm bath
Subjects will take a warm bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Warm Bath
Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.
The water temperature will be controlled between 38-41°C. Subjects will remain in the tub for ≤ 30 minutes. If the HR increases more than 15 -20 bpm, or a significant BP drop occurs (e.g. BP \>20 mmHg), the subject will be removed from the bath even if the time is \<30 min.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
PAD neutral bath
Subjects will take a neutral bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Neutral Bath
Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.
The water temperature will be controlled between 35 - 37°C. Subjects will remain in the tub for ≤ 30 minutes.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
PAD heating suit
Whole body heating with the suit will be performed. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Heating Suit
The mean skin temperature Tsk will be controlled with a water-perfused suit worn by subjects. Whole-body heating will be accomplished by perfusing warm water (\~ 45 - 50 °C) through the suit to elevate the Tsk to ≤ 38 °C (100 oF). Warm water is through plastic tubes, and subjects' skin will not directly touch warm water. The heating will be continued until the ∆Tcore reaches \~ 0. 6 - 1.0 °C. This may take approximately 60 - 90 min.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
PAD lower limb warm water immersion
Subjects will place their lower legs in warm water. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Lower limb warm water immersion
Subjects will sit on a chair and put their lower legs and feet in a bucket with warm water. The water level will be just below the knees (depth of approximately 40 cm). The water temperature will be monitored and controlled at \~38 - 42 °C throughout the 30 minutes. BP, HR, Tcore, the skin temperature and skin blood flow (e.g. on a thigh and/or forearm) will be measured before, during and after the lower limbs warm water immersion.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
Healthy subjects without heating
Subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Without Heating
Subject will complete walking protocol without any heating procedure
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
Healthy subjects warm bath
Subjects will take a warm bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Warm Bath
Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.
The water temperature will be controlled between 38-41°C. Subjects will remain in the tub for ≤ 30 minutes. If the HR increases more than 15 -20 bpm, or a significant BP drop occurs (e.g. BP \>20 mmHg), the subject will be removed from the bath even if the time is \<30 min.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
Healthy subjects neutral bath
Subjects will take a neutral bath. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Neutral Bath
Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.
The water temperature will be controlled between 35 - 37°C. Subjects will remain in the tub for ≤ 30 minutes.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
Healthy subjects heat suit
Whole body heating with the suit will be performed. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Heating Suit
The mean skin temperature Tsk will be controlled with a water-perfused suit worn by subjects. Whole-body heating will be accomplished by perfusing warm water (\~ 45 - 50 °C) through the suit to elevate the Tsk to ≤ 38 °C (100 oF). Warm water is through plastic tubes, and subjects' skin will not directly touch warm water. The heating will be continued until the ∆Tcore reaches \~ 0. 6 - 1.0 °C. This may take approximately 60 - 90 min.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
Healthy subjects lower limb immersion
Subjects will place their lower legs in warm water. Then, subjects will walk on a treadmill using the Gardner protocol until the patient says they want to stop. BP, HR and NIRS will be continuously measured during Gardner protocol. Skin blood flow, skin temperature and BP will be measured in the supine position before and after the Gardner protocol.
Lower limb warm water immersion
Subjects will sit on a chair and put their lower legs and feet in a bucket with warm water. The water level will be just below the knees (depth of approximately 40 cm). The water temperature will be monitored and controlled at \~38 - 42 °C throughout the 30 minutes. BP, HR, Tcore, the skin temperature and skin blood flow (e.g. on a thigh and/or forearm) will be measured before, during and after the lower limbs warm water immersion.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
Interventions
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Without Heating
Subject will complete walking protocol without any heating procedure
Warm Bath
Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.
The water temperature will be controlled between 38-41°C. Subjects will remain in the tub for ≤ 30 minutes. If the HR increases more than 15 -20 bpm, or a significant BP drop occurs (e.g. BP \>20 mmHg), the subject will be removed from the bath even if the time is \<30 min.
Neutral Bath
Subjects will sit in a warm bathtub with water up to their shoulders, while one arm will be out of water for BP and HR measurement. The water temperature and internal temperature (Tcore), BP and HR will be measured throughout the bath.
The water temperature will be controlled between 35 - 37°C. Subjects will remain in the tub for ≤ 30 minutes.
Heating Suit
The mean skin temperature Tsk will be controlled with a water-perfused suit worn by subjects. Whole-body heating will be accomplished by perfusing warm water (\~ 45 - 50 °C) through the suit to elevate the Tsk to ≤ 38 °C (100 oF). Warm water is through plastic tubes, and subjects' skin will not directly touch warm water. The heating will be continued until the ∆Tcore reaches \~ 0. 6 - 1.0 °C. This may take approximately 60 - 90 min.
Lower limb warm water immersion
Subjects will sit on a chair and put their lower legs and feet in a bucket with warm water. The water level will be just below the knees (depth of approximately 40 cm). The water temperature will be monitored and controlled at \~38 - 42 °C throughout the 30 minutes. BP, HR, Tcore, the skin temperature and skin blood flow (e.g. on a thigh and/or forearm) will be measured before, during and after the lower limbs warm water immersion.
Gardner walking protocol
The Gardner protocol begins at 2 mph and 0% grade for 2 minutes. The grade increases by 2% every 2 minutes (the speed remains 2 mph) until the subject says they want to stop or 22 minutes maximum. BP and HR will also be measured throughout the protocol.
Eligibility Criteria
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Inclusion Criteria
* Capable of giving informed consent
* Any race or ethnicity
* Men and women age 21- 85 years (inclusive)
* Fluent in written and spoken English
Patients with peripheral arterial disease (PAD)
* Diagnosed with PAD (i.e., ankle-brachial index below 0.9)
* Fontaine stage II or less - no pain while resting
* Satisfactory history and physical exam
Healthy subjects
* Satisfactory history and physical examination
* Free of acute medical conditions
Exclusion Criteria
* Age \< 21 years
* Pregnant or nursing women
* Decisional impairment
* Prisoners
For patients with PAD
* History of CAD with symptoms of unstable angina or myocardial infarction (\<6 months)
* History of epilepsy or seizure disorders
For healthy subjects
• Any other chronic diseases (heart, lung, neuromuscular disease or diabetes)
21 Years
85 Years
ALL
Yes
Sponsors
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Milton S. Hershey Medical Center
OTHER
Responsible Party
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Jian Cui
Associate Professor of Medicine
Principal Investigators
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Jian Cui
Role: PRINCIPAL_INVESTIGATOR
Penn State College of Medicine
Locations
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Penn State Milton S. Hershey Medical Center
Hershey, Pennsylvania, United States
Countries
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References
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Cui J, Blaha C, Sinoway LI. Whole body heat stress attenuates the pressure response to muscle metaboreceptor stimulation in humans. J Appl Physiol (1985). 2016 Nov 1;121(5):1178-1186. doi: 10.1152/japplphysiol.00212.2016. Epub 2016 Oct 7.
Cui J, Blaha C, Moradkhan R, Gray KS, Sinoway LI. Muscle sympathetic nerve activity responses to dynamic passive muscle stretch in humans. J Physiol. 2006 Oct 15;576(Pt 2):625-34. doi: 10.1113/jphysiol.2006.116640. Epub 2006 Jul 27.
Cui J, Boehmer J, Blaha C, Sinoway LI. Muscle sympathetic nerve activity response to heat stress is attenuated in chronic heart failure patients. Am J Physiol Regul Integr Comp Physiol. 2017 Jun 1;312(6):R873-R882. doi: 10.1152/ajpregu.00355.2016. Epub 2017 Mar 22.
Cui J, Muller MD, Blaha C, Kunselman AR, Sinoway LI. Seasonal variation in muscle sympathetic nerve activity. Physiol Rep. 2015 Aug;3(8):e12492. doi: 10.14814/phy2.12492.
Other Identifiers
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STUDY00005798
Identifier Type: -
Identifier Source: org_study_id
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