Artery Function Responses to Heat Therapy and Exercise Training

November 8, 2022 updated by: McMaster University

The Effects of 8 Weeks of Lower Limb Heat Therapy, Moderate-intensity Cycling Exercise, or Both on Vascular Function in Young, Healthy Males and Females

This study will explore the effects of 8 weeks of local leg heat therapy, exercise training, or both on measures of vascular function, cardiorespiratory fitness, and muscle strength in young, healthy individuals. Participants will be allocated into either a control group that will maintain their regular physical activity habits; or into one of three training groups: heat therapy will involve lower limb warm water immersion, exercise training will involve moderate-intensity cycling, and combined training will involve both performed in sequential order.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

A between-groups interventional design will be used in a cohort of 80 young, healthy males and females 18-35 years old. Interested individuals will be invited to the lab for a screening and familiarization visit (1 hr), in which participants will be introduced to various lab testing protocols to ensure proper performance and tolerance during experimental data collection sessions. Participants will be randomized into one of four groups for an 8-week intervention period: (1) no training (CON), (2) lower limb heat therapy (HEAT), (3) moderate intensity cycling training (EX), or (4) combined training (HEATEX). CON will involve maintenance of regular physical activity habits. HEAT will involve 45 minutes of lower limb hot water immersion (42 °C) using a custom-made heating apparatus 3x/week. EX will involve of 45 minutes of cycling on an ergometer at 40-59% VO2reserve 3x/week. HEATEX will require participants to perform 3x/week of exercise training and heat therapy consecutively and in that order, such that each session is 90 minutes in duration. In total, all groups except CON will be expected to complete 24 intervention sessions. Vascular function will be characterized by measures of endothelial function, arterial stiffness, arterial structure, central hemodynamics, arterial blood flow and shear, and endothelial cell nitric oxide production. Muscle and metabolic adaptations will be characterized by measures of cardiorespiratory fitness, body composition, muscle strength and thickness, and fasting glucose and insulin. Inflammatory profile will be characterized by concentrations of interleukins, heat shock proteins, and cortisol. Thermal physiological adaptations will be characterized by measures of core and skin temperature and sweat rate. Perceptual responses will be characterized by measures of thermal comfort and sensation, calmness, alertness, mood, affect, and ratings of perceived exertion. Intervention adherence will be tracked throughout the intervention period. For the acute investigation (3-hr visit), outcome measures will be assessed before and immediately following the first and last training session. For the chronic investigation (2-hr visit), outcome measures will be assessed at weeks 0, 2, 4, 6, and 8 of the intervention period.

Study Type

Interventional

Enrollment (Actual)

60

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Ontario
      • Hamilton, Ontario, Canada, L8S 4L8
        • McMaster University Vascular Dynamics Lab

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 35 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Apparently healthy (i.e., no cardiovascular, musculoskeletal, or metabolic disease)
  • 18-35 years old
  • Recreationally and/or physically active

Exclusion Criteria:

  • History of cardiovascular, musculoskeletal, or metabolic disease
  • Regular smoking and/or vasoactive drug use

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
No Intervention: Control
Participants will be asked to maintain their regular physical activity habits for the duration of the 8-week intervention period.
Experimental: Heat therapy
Participants will be asked to undergo 45 minutes of lower limb hot water immersion (42 degrees C) 3 times per week for 8 weeks.
Other: Heat therapy
Lower limb warm water immersion (42 degrees C)
Experimental: Exercise training
Participants will be asked to undergo 45 minutes of moderate-intensity cycling exercise (~40-59% VO2 reserve) 3 times per week for 8 weeks.
Other: Exercise training
Moderate-intensity cycling exercise (~40-59% VO2 reserve)
Experimental: Combined training
Participants will be asked to undergo 90 minutes of moderate-intensity cycling exercise and lower limb hot water immersion sequentially 3 times per week for 8 weeks.
Other: Heat therapy
Lower limb warm water immersion (42 degrees C)
Other: Exercise training
Moderate-intensity cycling exercise (~40-59% VO2 reserve)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Brachial artery endothelial function
Time Frame: Change in endothelial function from week 0 to 8
Flow-mediated dilation (FMD) is a measure of the ability of the artery to dilate in response to elevated shear stress, and represents endothelial function. For this technique, a pressure cuff will be wrapped around the forearm and then inflated to ~200 mmHg for 5 minutes to occlude blood flow through the artery site. Doppler ultrasound (Vivid q, GE Medical Systems, Horten, Norway) and a 12 MHz linear array probe will be used to measure artery diameter before cuff inflation (rest), before cuff deflation (ischemia), and for three minutes after cuff deflation (reactive hyperemia). Images of the BA will be collected in Duplex mode and obtained proximal to the antecubital fossa. FMD will be calculated using this formula: FMD% = ((peak diameter-baseline diameter)/baseline diameter) × 100%.
Change in endothelial function from week 0 to 8
Arterial stiffness
Time Frame: Change in arterial stiffness from week 0 to 8
Pulse wave velocity (PWV) is a measure of the speed at which a pulse travels between two superficial artery sites, and represents arterial stiffness. For this outcome, applanation tonometers (i.e., micromanometer-tipped probes) (SPT-301, Millar Instruments, Houston, Texas, USA) will be used to detect and transmit pulse pressure wave forms at the carotid, femoral, and dorsalis pedis or tibialis posterior arteries. PWV will be calculated between the carotid-femoral arteries and femoral-foot arteries to quantify central and peripheral arterial stiffness, respectively, using this general formula: PWV = distance/pulse transit time.
Change in arterial stiffness from week 0 to 8

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Cardiorespiratory fitness
Time Frame: Change in cardiorespiratory fitness from week 0 to 8
VO2peak represents the maximum rate of oxygen consumption that the body can attain, and is reliant on both oxygen delivery to muscles and oxygen utilization by muscles. In this VO2peak test, participants will cycle on a cycle ergometer (Excalibur Lode B.V., Groningen, The Netherlands) at an intensity that begins at 50 W and progressively increases at a rate of 1 W every 2 seconds until volitional exhaustion or a pedaling cadence < 60 rpm. A mask equipped with a breath-by-breath gas analyzer (Quark CPET, COSMED, Rome, Italy) will be worn to obtain the ratio of CO2 produced to O2 consumed, and a HR monitor (Polar Electro Oy, Kempele, Finland) will be worn to monitor HR throughout the duration of the test. VO2peak will be calculated using this formula: VO2peak = (VI * FIO2) - (VE * FEO2).
Change in cardiorespiratory fitness from week 0 to 8
Body composition
Time Frame: Change in body composition from week 0 to 8
Body composition tests measure the proportions of fat mass and fat-free mass in the body. Participants will have their body composition assessed through air displacement plethysmography (BodPod). This method is non-invasive and involves ~5 minutes of sitting still and quietly as the measurement is completed.
Change in body composition from week 0 to 8
Muscle strength
Time Frame: Change in muscle strength from week 0 to 8
Knee extensor muscle strength will be assessed with an isokinetic dynamometer (Biodex). Participants will be familiarized with the testing procedures before assessment. Participants will be seated with restraining straps secured over the trunk, pelvis, and thigh; arms will be crossed over their chest. The axis of the dynamometer will be aligned with the axis of rotation of the knee joint. Participants will be asked to kick out repeatedly against the arm of the machine, and the force produced will be recorded.
Change in muscle strength from week 0 to 8
Metabolic blood markers
Time Frame: Change in metabolic markers from week 0 to 8
Fasting insulin and glucose will be measured in blood plasma and serum.
Change in metabolic markers from week 0 to 8
Core temperature
Time Frame: Change in core temperature from week 0 to 8
Core temperature will be measured using a wireless telemetric pill during the acute experimental testing visits, and tympanic and rectal thermometry during all experimental testing visits. Participants will be instructed to swallow the pill with water 2-3 hours prior to each testing session.
Change in core temperature from week 0 to 8
Endothelial cell nitric oxide production markers
Time Frame: Change in endothelial nitric oxide production from week 0 to 8
Endothelial nitric oxide synthase protein content and activity, and nitric oxide and superoxide anion production will be measured in human umbilical vein endothelial cell cultures bathed in serum collected from the study.
Change in endothelial nitric oxide production from week 0 to 8
Heat shock protein mRNA and content
Time Frame: Change in heat shock proteins from week 0 to 8
HSP72 and HSP90 will be measured in blood plasma and serum.
Change in heat shock proteins from week 0 to 8

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

McMaster University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

July 13, 2021

Primary Completion (Actual)

June 18, 2022

Study Completion (Actual)

June 18, 2022

Study Registration Dates

First Submitted

October 2, 2020

First Submitted That Met QC Criteria

October 8, 2020

First Posted (Actual)

October 19, 2020

Study Record Updates

Last Update Posted (Actual)

November 9, 2022

Last Update Submitted That Met QC Criteria

November 8, 2022

Last Verified

November 1, 2022

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • HEATEX

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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