Effect of Passive Heat Therapy on Metabolism

Study Overview
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Brief Summary
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The goal of this prospective interventional study is to examine if repeated brief hot stimuli affects glucose metabolism and substrate oxidation in young non-obese adults. Young adult participants were asked to participate in fourteen 5-min procedures involving whole body passive heating at 45°C water. The main question it aims to answer is: Does repeated brief noxious heat stimuli is sufficient to improve glucose tolerance, insulin sensitivity, and fat oxidation in young non-obese adults?

Detailed Description
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No studies yet addressed whether brief heat stimuli could be viable time-efficient alternative approach in order to improve glucose metabolism and fat oxidation. Consequently, we aimed to examine the ability of brief noxious heat stimuli to improve glucose tolerance, insulin sensitivity, and fat oxidation in young adults. Non-obese males and females completed fourteen 5-min sessions involving whole body passive heating at 45°C water. Changes in catecholamines, cytokines, substrate oxidation, resting energy expenditure, glucose tolerance and insulin response were assessed.

Official Title
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Effect of Repeated Brief Passive Heat Therapy on Metabolism in Healthy Young Adults

Conditions
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Healthy

Intervention / Treatment
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* Procedure: Heat therapy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: healthy non-obese (BMI between 18.5 and 29.9 kg/m2) males and females; no diseases, or conditions that could be worsened by exposure to acute hot water and affect experimental variables; no participation in any excessive formal physical exercise or sports program, temperature manipulation program or exposure to extreme temperatures. Exclusion Criteria: smokers; obesity (BMI greater than 30 kg/m2); needle phobia; taking medication and/or dietary supplements that may affect experimental variables.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Heat therapy<br>14 heat sessions of whole-body immersed in a 45°C water bath for 5 minutes. | Procedure: Heat therapy<br>* 14 heat sessions, during each session subjects were fully immersed in a 45°C water bath for 5 minutes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in catecholamines concentration (ng/mL) | The venous plasma adrenaline and noradrenaline concentrations (in ng/mL) were measured using enzyme-linked immunosorbent assay kits and a Spark multimode microplate reader | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Changes in cytokines concentration (pg/mL) | The venous serum interleukin-6 and tumor necrosis factor alpha concentrations (in pg/mL) were measured using enzyme-linked immunosorbent assay kits and a Spark multimode microplate reader | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in glucose concentration (mmol/L) | The venous glucose concentration (in mmol/L) was measured using a Glucocard X-mini plus meter. | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in insulin concentration (μIU/mL) | The venous serum insulin concentrations (in μIU/mL) were measured using enzyme-linked immunosorbent assay kits (Cat. No. E-EL-H2237, Elabscience, China) and a Spark multimode microplate reader (Tecan, Austria). | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in insulin sensitivity | Indices for insulin sensitivity/resistance assessment were computed using the homeostatic model assessment for insulin resistance, quantitative insulin-sensitivity check index (QUICKI), and the Matsuda insulin sensitivity index were calculated. | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in substrate oxidation | Oxygen consumption (VO2) and carbon dioxide (VCO2) output on a breath-by breath basis using a stationary MetaLyzer® 3B spiroergometry system (Cortex Biophysik GmbH) was measured at rest, and the respiratory quotient (RQ=VCO2/VO2) was computed to determine substrate utilisation. | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in fat oxidation (g/min | Oxygen consumption (VO2) and carbon dioxide (VCO2) output on a breath-by breath basis using a stationary MetaLyzer® 3B spiroergometry system (Cortex Biophysik GmbH) was measured at rest, and the fat oxidation (FATox; g/min) was calculated by using the equation: FATox = 1.67 × VO2 - 1.67 × VCO2, | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in fat oxidation (g/min) | Oxygen consumption (VO2) and carbon dioxide (VCO2) output on a breath-by breath basis using a stationary MetaLyzer® 3B spiroergometry system (Cortex Biophysik GmbH) was measured at rest, and the carbohydrate oxidation (CARBox; g/min) was calculated by using the equation: CARBox = 4.55 × VCO2 - 3.21 × VO2 | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in resting energy expenditure (kcal/day) | Oxygen consumption (VO2) and carbon dioxide (VCO2) output on a breath-by breath basis using a stationary MetaLyzer® 3B spiroergometry system (Cortex Biophysik GmbH) was measured at rest, and the resting energy expenditure (REE; kcal/day) was calculated by using the Weir equation: REE = (3.941(VO2) + 1.106(VCO2)) × 1440. | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in body mass (kg) | Body mass (in kg) was evaluated using Tanita Body Composition Analyzer. | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in fat mass (kg) | Fat mass (in kg) was evaluated using Tanita Body Composition Analyzer. | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in fat mass (%) | Fat mass (in %) was evaluated using Tanita Body Composition Analyzer | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in fat free mass (kg) | Fat free mass (in kg) was evaluated using Tanita Body Composition Analyzer | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in fat free mass (%) | Fat free mass (in %) was evaluated using Tanita Body Composition Analyzer | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in body mass index (kg/m2) | Body mass index (in kg/m2) was evaluated using Tanita Body Composition Analyzer | Pre-condition, post-condition (after 14 days), and after 1 month recovery | 
| Change in oxygen consumption and carbon dioxide output (mL/min) | Oxygen consumption and carbon dioxide output (in mL/min) on a breath-by breath basis using a stationary MetaLyzer® 3B spiroergometry system (Cortex Biophysik GmbH) was measured at rest. | Pre-condition, post-condition (after 14 days), and after 1 month recovery |