An interventional study of Cold-water immersion and Warm-water immersion (Control) in Behavior, Stress and Quality of Life, sponsored by German Institute of Human Nutrition. Recruiting at 1 site in Germany. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-21.
Sponsored by German Institute of Human Nutrition · Not applicable, Interventional, and Basic science
The behavioral within-subject cross-over design study "CoVa" aims to investigate the effect of a short-term full-body cold-water immersion vs. warm-water immersion control on value-based choice, psychological well-being, and peripheral physiology.
This randomized within-subject cross-over design behavioral study in cognitive neuroscience will employ an acute peripheral physiological intervention, i.e., a 10-minute full-body cold-water (10-16°C) immersion vs. a control condition (10 min @ 30- 36°C water) on two visits separated by approx. 30 days.
Forty eligible female and male participants will be subject to a head-out full-body cold-water immersion or a warm-water condition (control) on two visits. Participants will perform resting-state and task-based non-invasive electrophysiological recordings of the heart, pulse, respiration, skin conductance, and pupil, will undergo thermographic imaging, pre- and post-immersion blood sampling (4 time points), engage in two computer-based decision-making tasks (reinforcement learning task, risk decision-making task), a brief food choice task, and receive a battery of psychometric questionnaires. The visits are separated by approximately 30 days and do not differ in their timeline except for the primary intervention, i.e., cold vs warm-water immersion, and the medical screening on visit 1.
Exclusion Criteria:
Diagnosed current or former illnesses of
Behavioral: Cold-water immersion
Behavioral: Warm-water immersion (Control)
Single 10-minute acute full-body head-out single arm-out cold-water immersion at 10-16°C on the experimental day
Single 10-minute acute full-body head-out single arm-out cold-water immersion at 30-36°C on the experimental day
Risk propensity
Risk propensity, i.e., the ratio between risky and non-risky choices for each monetary value as measured in the risk decision-making task in the cold-water vs warm-water condition as described in Liu et al. (2021)
Time frame: On day 1 and after 30 days
Behavioral range adaptation
Participants will perform a computer-based reinforcement learning task described in Gueguen et al. (2024) to assess reward sensitivity in different monetary contexts. Behavioral range adaptation, which reflects value range-dependent, relative reward valuation, may be altered if reward processing itself is changed through a potent shift in the physiological state. To test whether reward processing is altered after cold vs warm water exposure, the extent to which range adaptation and reference-point centering occurs will be quantified using computational modeling methods.
Time frame: On day 1 and after 30 days
Food choice
Participants will be provided an ad libitum restaurant-like breakfast meal during which they can order various food items (e.g., bread, yogurts, cookies) in the desired amount. The ingested food type, nutritional value, and amount will be quantified to assess food preference after cold vs warm water exposure by linking the consumed food with a standardized food database (German Nutrient Database, Bundeslebensmittelschlüssel).
Time frame: On day 1 and after 30 days
Heart-rate variability
Task-based and resting-state heart-rate variability, measured with a three-point electrocardiogram (ECG)
Time frame: On day 1 and after 30 days
Heart rate
Task-based and resting-state heart rate, measured with ECG
Time frame: On day 1 and after 30 days
Respiration rate
Task-based and resting-state respiration rate, measured via a respiration belt
Time frame: On day 1 and after 30 days
Relative amplitude of the respiratory signal
Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt
Time frame: On day 1 and after 30 days
Event-related skin conductance responses
Phasic electrodermal activity, measured via electrodermal activity (EDA) electrodes
Time frame: On day 1 and after 30 days
Tonic skin conductance
Tonic task-based and resting-state electrodermal activity, measured with EDA electrodes
Time frame: On day 1 and after 30 days
Pupil dilation
Task-based and resting-state pupil dilation, measured via eye-tracking
Time frame: On day 1 and after 30 days
Skin temperature
Thermographic imaging of the face, full-body, supraclavicular, and scapular area using a thermal camera pre-, during, and post-immersion
Time frame: On day 1 and after 30 days
Plasma concentration of large neutral amino acids
Large neutral amino acid (LNAA) plasma concentration will be assessed via blood sampling at 4 time points (pre-immersion to 120 min post-immersion)
Time frame: On day 1 and after 30 days
Plasma concentration of catecholamines
Catecholamines via blood sampling at 4 time points (pre-immersion to 120 min post-immersion)
Time frame: On day 1 and after 30 days
Plasma concentration of cortisol
Cortisol via blood sampling at 4 time points (pre-immersion to 120 min post-immersion)
Time frame: On day 1 and after 30 days
Identification of epigenetic markers associated with acute cold exposure
Epigenetic markers (micro-RNA) via blood sampling at 4 time points (pre-immersion to 120 min post-immersion)
Time frame: On day 1 and after 30 days
Perceived control
Psychological changes in perceived control, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high perceived control.
Time frame: On day 1 and after 30 days
Perceived freedom
Psychological changes in perceived freedom, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high perceived freedom.
Time frame: On day 1 and after 30 days
Perceived stress
Psychological changes in perceived stress, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high perceived stress.
Time frame: On day 1 and after 30 days
State of flow
Psychological changes in perceived state of flow, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating a high state of flow.
Time frame: On day 1 and after 30 days
Self-efficacy
Psychological changes in self-efficacy, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high self-efficacy.
Time frame: On day 1 and after 30 days
Perceived pain
Psychological changes in perceived pain, measured semi-continuously via self-reports throughout the experimental day. Measures range from 0% (not at all) to 100% (very much) with 100% indicating high perceived pain.
Time frame: On day 1 and after 30 days
Emotions
Psychological changes in emotions and their bodily origins, measured via self-reports pre- and post-immersion. Measures will be drawn on a virtual body using an adapted version of the Nummenmaa et al. (2014) emBODY tool with red color indicating increased perception and blue indicating decreased perception.
Time frame: On day 1 and after 30 days
Positive affect and negative affect questionnaire
Psychological changes in affect, measured semi-continuously via the Positive Affect Negative Affect (PANAS) questionnaire to be filled out pre- and post-immersion. Measures for each item range from 1 (not at all) to 5 (very much) with 5 indicating the highest feeling perceived at the moment.
Time frame: On day 1 and after 30 days
Trait autonomy questionnaire
Trait autonomy is assessed via the Basic Psychological Need Satisfaction and Frustration Scale (BPNSFS). Measures range from 1 (not at all true) to 5 (totally true) with 5 indicating the highest score.
Time frame: On day 1 and after 30 days
Emotion regulation questionnaire
Emotion regulation, assessed via the Emotion Regulation Questionnaire (ERQ). Measures range from 1 (not at all true) to 7 (totally true) with 7 indicating the highest score.
Time frame: On day 1 and after 30 days
Causality orientation questionnaire
Causality orientation, assessed via the General Causality Orientations Scale (GCOS). Measures range from 1 (very unlikely) to 6 (very likely) with 6 indicating the highest probability of responding as the item describes in the vignette scenario.
Time frame: On day 1 and after 30 days
Delay discounting questionnaire
Delay discounting is assessed via the Delay Discounting Test by Kirby. Response options to each item are binary with one option corresponding to an immediate reward (e.g., 14 EUR today) and the second option corresponding to a higher but delayed reward (e.g., 19 EUR in 60 days).
Time frame: On day 1 and after 30 days
Interoceptive awareness questionnaire
Interoceptive awareness, assessed via the Multidimensional Assessment of Interoceptive Awareness (MAIA) questionnaire. Measures range from 0 (never) to 5 (always) with 5 indicating the highest response.
Time frame: On day 1 and after 30 days
Generalized self-efficacy questionnaire
Generalized self-efficacy, assessed via the Self-Efficacy Scale (SWE). Measures range from "not at all true", "hardly true", "moderately true" and "exactly true". A higher score, indicated by a preference for "exactly true", indicated more self-efficacy.
Time frame: On day 1 and after 30 days
Trait and state anxiety questionnaire
Trait and state anxiety, assessed via the State-Trait Anxiety Inventory (STAI-S and STAI-T). State anxiety is assessed on a scale from 1 (not at all) to 8 (very much) with a higher score indicating high state anxiety. Trait anxiety is assessed on a scale from 0 (almost never) to 3 (almost always) with a higher score indicating high trait anxiety.
Time frame: On day 1 and after 30 days
Well-being questionnaire
Psychological well-being is assessed via the short version of the Warwick-Edinburgh Mental Well-Being Scale (SWEMWBS). Responses range from "never" to "always" on a 5-point scale with a high score indicating higher mental well-being in the past two weeks.
Time frame: On day 1 and after 30 days
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German Institute of Human Nutrition