Effect of a 16-day Hot and Cold Acclimation on Adaptive Responses and Health-related Indicators

Time Course of Adaptive Responses in Humans During a 16-day Hot and Cold Acclimation Program, and Its Effect on Health-related Indicators

There are no previous studies of the effects of a combination of whole-body immersions in hot and cold baths on adaptive responses and health-related markers. Thus, the primary aim of this project is to determine whether interventions consisting of whole body immersion in hot and cold baths over 16 days develop heat and/or cold adaptation by remodeling thermoregulatory, metabolic, cardiovascular and physiological responses, and the secondary aim is to determine if current cold-hot acclimation has any effects on physical and mental health-related markers.

Study Overview

• Status: Recruiting
• Conditions: Healthy
• Intervention / Treatment: Other: 16-day hot and cold acclimation

• Study Type: Interventional
• Enrollment (Estimated): 31
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Laura Jarutienė; Phone Number: +37069009956; Email: laura.jarutiene@stud.lsu.lt
• Study Contact Backup: Name: Rima Solianik; Phone Number: +37069009956; Email: rima.solianik@lsu.lt

Study Locations

• Lithuania
  • Kaunas, Lithuania, LT-44221
    • Recruiting
    • Lithuanian Sports University
    • Contact: Diana Reklaitienė, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• young, healthy, non-obese males and females;
• nonsmoker;
• no needle phobia;
• not taking medication and/or dietary supplements that may affect experimental variables.

Exclusion Criteria:

• neurological, cardiovascular, metabolic, and/or inflammatory diseases, or conditions that could be worsened by exposure to acute thermal stimuli and that could affect experimental variables;
• involvement in temperature manipulation program for ≥ 3 months;
• attendance at any excessive formal physical exercise or sports program.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: 16-day hot and cold acclimation; Healthy young subjects will participate in a 16-days hot and cold acclimation program. During cold procedure, the participant will be immersed in 14° water bath in semi recumbent position up to the level of the manubrium for 5-min, and during hot procedure, the participant will be immersed in 45° water bath in semi recumbent position up to the level of the manubrium for 5-min.

Other: 16-day hot and cold acclimation; Acclimation program will consist of 8 brief cold water immersions (CWI; 14°C 5 min) and 8 hot water immersions (HWI; 45°C 5 min). Heat and cold sessions will be performed on separate days (i.e., 1st day hot exposure, 2nd day cold exposure, 3rd day hot exposure, etc.).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in body mass and body composition (kg)	Body mass and composition (in kg) will be evaluated using Tanita Body Composition Analyzer (Japan).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in skinfold thickness (mm)	Skinfolds thickness (in mm) will be measured using a skinfold caliper (Saehan, Korea) at 10 sites and the mean subcutaneous fat thickness will be calculated.	Before acclimation (1st day), 2 days and 2 weeks after the end of acclimation (44 th and 51st day)
Change in substrate oxidation	Oxygen consumption (VO2) and carbon dioxide (VCO2) output will be measured using Cortex METALYZR® 3B, Leipcig, Germany), and the respiratory quotient (RQ = VCO2 / VO2) will be computed to determine substrate utilisation. The RQ values for fat is assumed as 0.7, for protein is assumed as 0.8 and for carbohydrate isassumed as 1.0.	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in ventilation (l/min)	Ventilation (in l/min) will be measured using Cortex METALYZR® 3B, Leipcig, Germany).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in breathing frequency (t/min)	Breathing frequency (in t/min) will be measured using Cortex METALYZR® 3B, Leipcig, Germany).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in heart rate (bpm)	Heart rate (in bpm) will be recorded using a heart rate sensor with a chest strap (Polar, Finland) or Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in blood pressure (mmHg)	Systolic and diastolic blood pressure (in mmHg) will be measured using PROVIEW 10 Compact Patient Monitor (Germany).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in mean arterial pressure (mmHg)	The mean arterial pressure (MAP; in mmHg) will be estimated using the formula: MAP = DP + 1/3(SP - DP) or MAP = DP + 1/3(SP - DP), where SP is systolic bood pressure and DP is diastolic blood pressure.	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in stroke volume (ml)	Stroke volume (in ml) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in contractility index	Contractility index will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in ventricular ejection time (ms)	Ventricular ejection time (in ms) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in end diastolic volume (ml)	End diastolic volume (in ml) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in testosterone concentration (µg/dl)	The saliva samples will be collected to measure testosterone level (in µg/dl) using an ELISA kits and a Spark multimode microplate reader (Tecan, Austria).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in female sex hormones concentration (pg/mL)	The venous 17beta-estradiol and progesterone (in pg/mL), follicle stimulating hormone and luteinizing hormone will be measured using an ELISA kits and a Spark multimode microplate reader (Tecan, Austria).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in salivary cortisol concentration (µg/dl)	The saliva samples will be collected to measure cortisol level (in µg/dl) using an ELISA kits and a Spark multimode microplate reader (Tecan, Austria)..	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in cytokines concentrations (pg/ml)	The venous tumor necrosis factor alpha, interleukin-6 and IL-1 beta (in pg/ml) will be measured using an ELISA kits and a Spark multimode microplate reader (Tecan, Austria).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in lipid profile (mmol/l)	Blood samples will be collected to measure lipid profile (in mmol/l) (total cholesterol, high density and low density cholesterol, triglycerides) using a CardioChek PA analyzer (USA).	Before acclimation (1st day),during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in catecholamines concentration (ng/ml)	The venous adrenaline and noradrenaline concentrations (in ng/ ml) will be measured using enzyme-linked immunosorbent assay kits and a Spark multimode microplate reader (Tecan, Austria).	Before acclimation (1st day),during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in insulin concentration (μIU/ml)	The venous insulin concentrations (in μIU/ml) will be measured using enzyme-linked immunosorbent assay kits and a Spark multimode microplate reader (Tecan, Austria)	Before acclimation (1st day), 2nd day and 2 weeks after the end of acclimation (44th and 51st days)
Change in glucose tolerance (mmol/l)	The glucose concentration (in mmol/l) will be measured using a On-call GK dual meter (Acon Laboratories, USA).	Before acclimation (1st day), 2nd day and 2 weeks after the end of acclimation (44th and 51st days)
Change in plasma metabolites of the kynurenine pathway (μm)	An ultra-performance liquid chromatography-tandem mass spectrometry system (UPLC-MS/MS) will be used to measure venous plasma levels of tryptophan, kynurenine, kynurenic acid, 3-hydroxy-kynurenine, quinolinic acid, nicotinamide and picolinic acid (in μm). The UPLC-MS/MS system uses a Xevo TQ-XS triple quadrupole mass spectrometer (Waters) with a Z-spray electrospray interface, and the system operates in electrospray positive multiple reaction monitoring mode.	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in body temperature (°C)	Rectal temperature (in °C) will be measured using a thermocouple (Rectal Probe, Ellab, Denmark) inserted to a depth of 12 cm past the anal sphincter, skin temperature (in °C) will be measured with thermistors (Skin/Surface Probe, DM852, Ellab) at four sites: supraclavicular, back, thigh, and forearm, and right lateral gastrocnemius muscle temperature (in °C) will be measured using a needle microprobe (MKA; Ellab).	During baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in body mass index (kg/m^2)	The body mass index (in kg/m^2) will be defined as the body mass divided by the square of the body height.	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in body surface area (m^2)	The participant's body surface area (BSA) (in m^2) will be estimated using the following equations: BSA = 128.1 ×weight^0.44 × height^0.60 for males and BSA = 147.4 ×weight^0.47 × height^0.55 for females.	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in substrate oxidation (g/day)	Carbohydrate and fat oxidation (in g/day) will be measured using Cortex METALYZR® 3B, Leipcig, Germany).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in resting energy expenditure (kcal/day)	The resting energy expenditure (REE; in kcal/day) will be computed using the following equation: REE = [3.941 × (VO2) + 1.106 × (VCO2)] × 1440	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in metabolic heat production (W)	The metabolic heat production (MHP; in W) will be computed using the equation: MHP = (281.65 + 80.65 × RQ) × VO2.	during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days)
Change in heart rate variability (ms)	R-R intervals (in ms) in supine resting will be recorded using a Polar heart ratesensor (Finland) and simultaneously transferred to Polar Pro Trainer 5 software (Finland)	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in heart rate variability (time domain) (ms)	Heart rate variability data will be analyzed using Kubios heart rate variability analysis software (Finland). In the time domain that reflects general heart rate variability (HRV), the standard deviation of normal-to-normal intervals (SDNN; estimate of overall HRV) and the root mean square of successive differences (RMSSD; estimate of short-term components of HRV will be assessed (in ms).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in heart rate variability (time domain) (Ln)	Heart rate variability data will be analyzed using Kubios heart rate variability analysis software (Finland). In the time domain that reflects general heart rate variability (HRV), the standard deviation of normal-to-normal intervals (SDNN; estimate of overall HRV) and the root mean square of successive differences (RMSSD; estimate of short-term components of HRV) will be assessed and logarithmically transformed (Ln) to correct the skewness of distribution.	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in heart rate variability (frequency domain) (ms^2)	Heart rate variability data will be analyzed using Kubios heart rate variability analysis software (Finland). In the frequency domain that measures the more specific contribution of the autonomic nervous system branch, low-frequency (LF; estimates sympathetic and parasympathetic activity) and high-frequency (HF; estimates parasympathetic activity) powers in absolute units (in m^2) will be assessed.	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in heart rate variability (frequency domain) (Ln)	In the frequency domain that measures the more specific contribution of the autonomic nervous system branch, low-frequency (LF; estimates sympathetic and parasympathetic activity) and high-frequency (HF; estimates parasympathetic activity) powers will be assessed and logarithmically transformed (Ln) to correct the skewness of distribution.	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in stroke volume index (ml/m^2)	Stroke volume index (in ml/m^2) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in cardiac output index (l/min//m^2)	Cardiac output (in l/min/m^2) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in cardiac output index (l/min)	Cardiac output (in l/min) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in ventricular ejection fraction (percent)	Ejection fraction (in percent) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in systemic vascular resistance (dyn.s/cm5.m^2)	Systemic vascular resistance (in dyn.s/cm5.m^2) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in cardiac work index (kg.m/m^2)	Cardiac work index (in kg.m/m^2) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in early diastolic filling ratio (percent)	Early diastolic filling ratio (in percent) will be recorded using Physioflow hemodynamic monitor (France).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in complete blood count (10^9/L)	Complete blood count with 5 different white blood count components (absolute neutrophils, lymphocytes, monocytes, eosinophils, basophils) analysis (in 10^9/L) will be performed using an automated Mythic 60 hematology analyzer (Switzerland).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in complete blood count (percent)	Complete blood count with 5 different white blood count components (absolute neutrophils, lymphocytes, monocytes, eosinophils, basophils) analysis (in percent) will be performed using an automated Mythic 60 hematology analyzer (Switzerland).	Before acclimation (1st day), during baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days), and 2 weeks after the end of acclimation (51st day)
Change in anxiety and depression (points)	The level of anxiety and depression (in points) will be defined using Hospital Anxiety and Depression scale. Scale scores range from 0 to 21, with higher scores indicating more severe symptoms.	Before acclimation (1st day), 2nd day and 2 weeks after the end of acclimation (44th and 51st days)
Change in physiological strain index	A physiological strain index (PSI) will be used to indicate heat strain. PSI = 5 x (Tret - Tre0) x (39.5 - Tre0)^-1+ 5 x (HRt - HR0) x (180 - HR0)^-1, where rectal temperature (Tre) t and heart rate (HR) t are simultaneous measurements taken at the end of the heat exposure and Tre0 and HR0 are the initial measurements.	During baseline provocative heat test (8th or 15th day), during acclimation (from 22 to 37th days), during repeated provocative heat test (41st or 42nd days)
Change in cold strain index	A cold strain index (CSI) will be used to indicate cold strain. CSI = 6.67 x (Tre t - Tre 0) x (35 - Tre 0)^-1 + 3.33 x (Tsk t - Tsk 0) x (20 - Tsk 0)^-1, where rectal temperature (Tre) 0 and skin temperature (Tsk) 0 are initial measurements and Tre t and Tsk t are simultaneous measurements taken at the end of the cold exposure.	During baseline provocative cold test (8th or 15th day), during acclimation (from 22 to 37th days), during repeated provocative cold test (41st or 42nd days)
Change in root mean square (RMS) amplitude (mV)	Root mean square (RMS) amplitude (in mV) of pectoralis major muscle indicating shivering intensity will be measured using a surface EMG (Biometrics, UK).	During baseline provocative cold test (8th or 15th day), during acclimation (from 22 to 37th days), during repeated provocative cold test (41st or 42nd day)
Change in pain sensations	The pain sensation will be evaluated using numeric pain scale ranging from 0 (no pain) to 10 (worst possible pain).	During baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st or 42nd day)
Change in thermal sensations (points)	The thermal sensation will be evaluated using 9-point scale. The rating of thermal sensation range from 1 (very cold) to 9 (very hot), with 5 being neutral.	During baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st or 42nd day)
Change in shivering/sweating (points)	The shivering/sweating rate will be evaluated using 7-point scale. The rating of shivering/sweating range from 1 (heavily sweating) to 7 (vigorously shivering), with 4 being neutral.	During baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st or 42nd day)
Change in thermal comfort (points)	The thermal comfort will be evaluated using 4-point scale. The rating of thermal comfort range from 0 (neutral) to 3 (very uncomfortable).	During baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st or 42nd day)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Height (m)	Height (in m) will be measured using a Harpenden anthropometer set (Holtain Ltd, UK)	Before acclimation (1st day)
Change in physical activity (in h)	MotionWatch 8 actigraph will estimate the time spent in sedentary, light, moderate, or vigorous activity	3 days before first assessment, during 16-day acclimation period and during 2 week post-acclimation period.
Change in sleep (in h)	Sleep statistics (in h) including total hours of sleep and the time spent in different sleep stages will be assessed with MotionWatch 8 actigraph.	3 days before first assessment, during 16-day acclimation period and during 2 week post-acclimation period.
Change in oxygen saturation (percent)	Oxygen saturation (in percent) will be measured using Proview 10 Compact Patient Monitor (Germany).	During baseline provocative tests (8th and 15th day), during acclimation (from 22 to 37th days), during repeated provocative tests (41st and 42nd days)

Collaborators and Investigators

• Sponsor: Lithuanian Sports University
• Investigators: Principal Investigator: Laura Jarutienė, Lithuanian Sports University

Study record dates

Study Major Dates

• Study Start (Actual): April 4, 2024
• Primary Completion (Estimated): April 4, 2029
• Study Completion (Estimated): April 4, 2029

Study Registration Dates

• First Submitted: March 28, 2024
• First Submitted That Met QC Criteria: March 28, 2024
• First Posted (Actual): April 4, 2024

Study Record Updates

• Last Update Posted (Estimated): April 15, 2024
• Last Update Submitted That Met QC Criteria: April 11, 2024
• Last Verified: April 1, 2024

More Information

Terms related to this study

• Other Study ID Numbers: LithuananianSportsU-17

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