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Completed

NCT Number: NCT07504718

The Effect of Cold Exposure on Physiological Markers

The goal of this observational study is to examine how different physiological markers change over a two-day period after long-duration whole-body cold-water immersion in healthy young men and women. Specifically, the study aims to address the following questions:

* How do kynurenine pathway metabolites change after cold exposure? * How do stress markers change after cold exposure? * How do cytokine levels change after cold exposure? * How do white blood cells count and distribution change after cold exposure?

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Key information

Conditions

Healthy Adult Participants

Age range

18 year–36 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Lithuanian Sports University

Kaunas, LT-44221, Lithuania

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Healthy adults;
  • Age between 18 and 36 years;
  • No excessive sporting activities;
  • No participation in any temperature-manipulation program or exposure to extreme temperatures within the past 12 weeks.

Exclusion criteria

  • Smokers;
  • Use of medication that could affect natural thermoregulation;
  • Body mass index greater than 30 kg/m²;
  • History of asthma, neurological conditions, cardiovascular disease, or any condition that could be adversely affected by cold exposure.

Treatment and study plan

Cold water immerssion

Other

This intervention consisted of intermittent whole-body immersion in 14 °C water. After 20 min of immersion, the subject exited from the bath and rested for 10 min by sitting in the room environment, and then the same procedure was repeated. The cold stress continued until 170 min in total (120 min maximum total immersion time).

Primary outcomes

  1. Change in plasma metabolites of the kynurenine pathway (μm)

    Time frame: 2 days

    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.

  2. Body temperature (°C)

    Time frame: 1 day

    Rectal temperature (in °C) was measured using a thermocouple (Rectal Probe, Ellab, Denmark) inserted to a depth of 12 cm past the anal sphincter, skin temperature (in °C) was measured with thermistors (Skin/Surface Probe, DM852, Ellab).

  3. Cold strain index

    Time frame: 1 day

    A cold strain index (CSI) was 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.

  4. Free cortisol concentration (µg/dl)

    Time frame: 2 days

    The saliva samples was collected to measure free cortisol level (in µg/dl) using an ELISA kit and a Spark multimode microplate reader (Tecan, Austria).

  5. Cytokines concentrations (pg/ml)

    Time frame: 2 days

    The venous tumor necrosis factor alpha and interleukin-6 (in pg/ml) were measured using an ELISA kits and a Gemini Analyzer (Stratec Biomedical GmbH, Birkenfeld, Germany)

  6. Total cortisol concentration (nmol/l)

    Time frame: 2 days

    The venous total cortisol consentration (in nmol/l) was measured using an ELISA kit and an automated enzyme immunoassay analyzer (AIA-2000; Tosoh Corp., Tokyo, Japan).

  7. Catecholamines concentration (ng/ml)

    Time frame: 2 days

    The venous adrenaline and noradrenaline concentrations (in ng/ ml) were measured using an Elisa kit and a Spark multimode microplate reader (Tecan, Austria).

  8. Complete blood count (10^9/L)

    Time frame: 2 days

    Complete blood count with 5 different white blood count components (absolute neutrophils, lymphocytes, monocytes, eosinophils, basophils) analysis (in 10^9/L) was performed using an automated hematology analyzer (XE-5000, Sysmex Corp, Kobe, Japan).

  9. Glucose (mmol/l)

    Time frame: 2 days

    The glucose concentration (in mmol/l) was measured using a Cardiocheck PA analyzer (Polymer Technology Systems Inc, Indianapolis, IN, USA).

Sponsors and collaborators

Lead sponsor

Lithuanian Sports University

Other

Registry information

Official study title

The Effect of Cold Water Immersion on Physiological Markers

Important dates

Study start
2013
Primary completion
2018
Study completion
2018
First posted
Apr 1, 2026
Registry last updated
Apr 7, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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