The Effect of Heat Exposure on Physiological Markers

Not Applicable

Completed

• Conditions: Healthy Adult Male

• Registration Number: NCT07064512
• Lead Sponsor: Lithuanian Sports University

Brief Summary

This study is the first to examine the effects of core temperature elevation on kynurenine pathway (KP) metabolites in healthy young males. It was hypothesized that rise in core temperature due to both pasive heating and exercise will initiate a stress response, affecting the concentration of KP metabolites. Additionally, it was expected that the exercise would produce more pronounced effects due to the increased cardiovascular, mechanical, and metabolic demands associated with it. Thus, the the main purpose of the present study was to investigate and to compare the effects of two distinct heat stress modalities on KP metabolites.

Detailed Description

Not available

Study Timeline

• Study Start: 2021-01-11
• Primary Completion: 2021-03-12
• Study Completion: 2021-03-12
• Status Verified: 2025-07
• Study First Submitted: 2025-07-11
• Study First Submitted QC: 2025-07-11
• Study First Posted: 2025-07-14
• Last Update Submitted: 2025-07-14
• Last Update Posted: 2025-07-17

Recruitment & Eligibility

• Status: COMPLETED
• Sex: Male
• Target Recruitment: 11

Inclusion Criteria

• healthy adults;
• age between 18 - 36 years;
• physically active (exercising 2-3 times per week);
• non-smoking.

Exclusion Criteria

• a body mass index (BMI) > 30 kg/m2;
• neurological, cardiovascular, metabolic, and/or inflammatory diseases, or conditions that could be worsened by exposure to interventions and that could affect experimental variables;
• involvement in temperature manipulation program for ≥ 3 months.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Primary Outcome Measures

Name	Time	Method
Rectal temperature (°C)	Day 1 (during both heating modalities until Tre reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	Rectal temperature (in °C) was measured using a thermocouple (Rectal Probe, Ellab, Denmark) inserted to a depth of 12 cm past the anal sphincter.
Change in plasma metabolites of the kynurenine pathway (μm)	Day 1 (every 0.5 °C until rectal temperature (Trec) reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	An ultra-performance liquid chromatography-tandem mass spectrometry system (UPLC-MS/MS) was 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.
Changes in catecholamines concentration (ng/mL)	Day 1 (every 0.5 °C until rectal temperature (Trec) reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	The venous adrenaline and noradrenaline concentrations (in ng/mL) was measured using enzyme-linked immunosorbent assay kits and a Spark multimode microplate reader (Tecan, Austria).
Changes in salivary cortisol concentration (µg/dL)	Day 1 (every 0.5 °C until rectal temperature (Trec) reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	The saliva samples was collected to measure cortisol level (in µg/dL) using an ELISA kits and a Spark multimode microplate reader (Tecan, Austria).
Change in heart rate (bpm)	Day 1 (during both heating modalities until Tre reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	Heart rate (in bpm) was recorded using a heart rate sensor with a chest strap (Polar, Finland).
Change in physiological strain index	Day 1 (every 0.5 °C until rectal temperature (Trec) reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	A physiological strain index (PSI) was 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 every 0.5°C of the heat exposure and Tre0 and HR0 are the initial measurements.
Change in glucose (mmol/L)	Day 1 (every 0.5 °C until rectal temperature (Trec) reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	The glucose concentration (in mmol/L) was measured using an automatic blood glucose meter Glucocard X-mini-Plus (Arkray Inc, Japan).
Change in lactate (mmol/L)	Day 1 (every 0.5 °C until rectal temperature (Trec) reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	The lactate concentration (in mmol/L) was measured using an Accutrend Plus System (Roche, Germany).
Changes in prolactin concentration (ng/mL)	Day 1 (every 0.5 °C until rectal temperature (Trec) reached 39°C, followed by a recovery phase until Trec reached 37.5°C)	The venous prolactin (in ng/mL) was measured using enzyme-linked immunosorbent assay kit and a Spark multimode microplate reader (Tecan, Austria).

Trial Locations

Locations (1)

Lithuanian Sports University; 🇱🇹 Kaunas, Lithuania