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Not yet recruitingNCT07505641ProlEx-ContextUpdated Apr 1, 2026

Breathing and Decision-Making (ProlEx-Context)

An interventional study of Instructed Prolonged Exhalation and Instructed Individualized Eupnea in Breathing Techniques, Stress Management and Decision-Making, sponsored by German Institute of Human Nutrition. Not yet recruiting. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-01.

Sponsored by German Institute of Human Nutrition · Not applicable, Interventional, and Basic science

Phase
Not applicable
Study type
Interventional
Enrollment
50
Allocation
Randomized
Ages
18 Years to 40 Years
Sex
All
01

Study summary

The ProlEx-Context study aims to investigate how a slow-paced breathing technique with prolonged exhalation affects decision-making in the context of acute social stress.

Read the detailed description

The ProlEx-Context study explores how a slow breathing technique with prolonged exhalation can restore decision-making processes after exposure to acute social stress.

Method Overview:

The methods of the study include a guided breathing exercise (prolonged exhalation vs normal breathing rhythm), exposure to acute social stress, peripheral electrophysiology (respiration, pulse, gastric and cardiac rhythms, skin conductance, pupillometry), salivary cortisol sampling, psychological questionnaires, behavioral tasks and functional brain imaging with fMRI.

Participant Overview:

An estimated 50 participants will be invited to this within-subject fMRI study and will be blinded to the stress induction component of this study.

Time frame:

One appointment of approx. 4 hours per person.

Procedure Overview:

Participants will be invited to the testing site at approximately 4 PM. Upon completion of the preparations and placement inside the MRI, the participants will undergo an adapted virtual Trier Social Stress Test (TSST). After completing the TSST, the participants are asked to perform a risk decision-making task inside the MRI, during which they are displayed a visual cue to assist during guided breathing. The participants perform blocks of either normal breathing or prolonged exhalation breathing during performance of the decision-making task in a randomized cross-over-design. During the task, brain activity and peripheral physiological signals, such as the respiration rate, heart rate, skin conductance and pupil dilation are measured. After completion of the first breathing condition (three blocks) and before the second breathing condition, participants will undergo a second TSST. Before and after each TSST, at baseline and after completion of the decision-making task, salivary samples for cortisol assessment are taken. After completion of the decision-making task, participants will be asked to fill out a battery of psychometric questionnaires and reimbursed for their time.

02

Conditions studied

  • Breathing Techniques
  • Stress Management
  • Decision-Making
03

Who can participate

Ages eligible
18 Years to 40 Years
Sexes eligible
All
Accepts healthy volunteers
Yes

Inclusion criteria

  • 18- to 40-year-old men and women
  • Consent to participate
  • Fluent in German
  • Right-handed
  • Physically and mentally healthy without regular medication
  • Body-mass index of 18-25 kg/m2
  • Alcohol consumption of less than 15 glasses a week (equivalent to one glass of wine/beer, a glass of higher-percentage alcohol counts as two glasses of beer)
  • No illegal drug consumption in the week previous to the experiment
  • No smoking
  • No competitive athletes
  • Normal day-night rhythm (no shift work)
  • Normal vision without required vision correction (i.e., glasses, contact lenses; ability to clearly read texts at a distance of up to 50 cm without vision aids)

Exclusion criteria

Exclusion Criteria:

  • Former or current illnesses of:
  • Brain or mind (including anxiety disorders, depression, eating disorders, personality disorders, alcohol, drugs or drug dependence, neurological disorders other than occasional headache, psychiatric or neurological abnormalities)
  • Heart or blood circulation
  • Lung Diseases
  • Other serious past or present medical conditions (for example, metabolic syndrome, diabetes)
  • Current medication and medication over a period of two weeks prior to the examination
  • Other serious health problems or present strong mental or physical stress
  • Current infection or excessive stress
  • Missing consent to receive information about incidental findings from the MRI
  • Tendency to claustrophobia, dizziness, or panic attacks
  • Wearing a non-removable pacemaker, defibrillator, hearing aid, drug pump, neurostimulator or implant with solenoid valve (e.g., artificial bowel outlet)
  • Metal parts or implants inside the body, for example, due to surgery or injury with a metallic foreign object (e.g., hip replacements, artificial joints, heart valves, vessel occlusions or dilatations, surgical clips, bone screws or plates, coil, shunts, catheters, electrodes, coils, radiation sources, shrapnel, projectiles, stents)
  • Having non-removable metal parts or metal-containing devices on or in the body
  • Having ferromagnetic metal parts or implants inside the body (e.g., hip replacements, artificial joints, heart valves, vessel occlusions or dilatations, surgical clips, bone screws or plates, coils, shunts, catheters, electrodes, coils, radiation sources, shrapnel, projectiles, stents)
  • Wearing magnetically fixed implants (e.g. amalgam fillings, glass eye)
  • Professionally or privately being involved in the processing of ferromagnetic metals
  • Large tattoos (whole limbs)
  • Pregnancy
  • Wearing an intra-uterine device
  • Having tinnitus
  • Extensive lung function (e.g. apnoe diver, singer, professional musician with lung-involving instruments)
  • Previous participation in the ProlEx-MRI study (the precursor to the current study)
04

Study design

Phase
Not applicable
Primary purpose
Basic science
Allocation
Randomized
Intervention model
Crossover assignment
Masking
None (open label)
Enrollment
50 participants (estimated)

Study arms

  • Experimental
    Prolonged Exhalation Breathing

    Participants are required to perform a specific voluntarily controlled breathing pattern directed by visual cues. The core characteristic is a systematic lengthening of the expiratory phase relative to the inspiratory phase. Specifically, participants are instructed to inhale for 2 seconds and prolong their exhalation to 8 seconds

    Behavioral: Instructed Prolonged Exhalation

  • Experimental
    Eupnea Breathing (Normal)

    Eupnea (Normal breathing) condition: In this control condition, participants maintain their spontaneous respiratory rhythm. The pacing for eupnea is individualized for each participant, based on their natural breathing frequency sampled during representative non-interventional intervals of the session (e.g., baseline or post-stress recovery periods). This ensures the control condition reflects the participant's characteristic physiological state within the experimental context.

    Behavioral: Instructed Individualized Eupnea

Interventions

  • BehavioralInstructed Prolonged Exhalation

    Participants are required to perform a specific instructed breathing pattern directed by visual cues. The core characteristic is a systematic lengthening of the expiratory phase relative to the inspiratory phase. Specifically, participants are instructed to inhale for 2 seconds and prolong their exhalation to 8 seconds.

  • BehavioralInstructed Individualized Eupnea

    Instructed Individualized Eupnea: In this control condition, participants are instructed to match their breath to a visual cue that is calibrated to their own characteristic natural respiratory frequency. This frequency is sampled during representative non-interventional phases of the session to capture the participant's individual baseline eupnea pace within the experimental context.

05

What researchers measure

Primary outcomes

  1. Risk propensity

    The dependent variable will be trial-wise gamble acceptance (accept vs. reject of a 50% gamble), which will be mainly analyzed using a binomial generalized linear mixed-effects model (GLMM) to compare the Prolonged Exhalation and Eupnea conditions under acute stress.

    Time frame: On day 1.

  2. Task-related BOLD Signals

    Task-related changes in blood-oxygen-level-dependent (BOLD) signals measured using functional magnetic resonance imaging (fMRI).

    Time frame: On day 1.

  3. Structural T1-weighted MRI

    High-resolution T1-weighted structural images measured using magnetic resonance imaging (MRI).

    Time frame: On day 1.

  4. Relative amplitude of the respiratory signal

    Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt and nasal airflow sensor.

    Time frame: On day 1.

  5. Respiration rate

    Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt and nasal airflow sensor.

    Time frame: On day 1.

  6. Heart rate

    Task-based and resting-state heart rate, measured with ECG

    Time frame: On day 1.

  7. Heart-rate variability

    Task-based and resting-state heart-rate variability, measured with a three-point electrocardiogram (ECG)

    Time frame: On day 1.

  8. Gastric myoelectrical activity

    Resting-state and task-based gastric myoelectrical activity, measured using cutaneous electrogastrography (EGG).

    Time frame: On day 1.

  9. Tonic skin conductance

    Tonic task-based and resting-state electrodermal activity, measured with EDA electrodes

    Time frame: On day 1.

  10. Event-related skin conductance responses

    Phasic electrodermal activity, measured via electrodermal activity (EDA) electrodes

    Time frame: On day 1.

  11. Salivary Cortisol Levels

    Concentration of cortisol in saliva (measured in nmol/L). This indexes the HPA-axis response to the Trier Social Stress Test (TSST). We will compare the cortisol trajectory

    Time frame: On day 1.

  12. Pupil dilation

    Task-based and resting-state pupil dilation, measured via eye-tracking

    Time frame: On day 1.

Secondary outcomes

  1. Response Times

    The average time (in milliseconds) taken by participants to make a choice in each trial.

    Time frame: On day 1.

  2. Self-reported levels of stress

    Self-reported levels of stress will be measured via a Visual Analog Scale (VAS) ranging from 0 to 100. A score of 0 represents "not at all" and 100 represents "extremely high."

    Time frame: On day 1.

  3. Self-reported levels of tension

    Self-reported levels of tension will be measured via a Visual Analog Scale (VAS) ranging from 0 to 100. A score of 0 represents "not at all" and 100 represents "extremely high."

    Time frame: On day 1.

  4. Self-reported levels of heart feeling

    Self-reported levels of heart feeling will be measured via a Visual Analog Scale (VAS) ranging from 0 to 100. A score of 0 represents "not at all" and 100 represents "extremely high."

    Time frame: On day 1.

  5. Self-reported levels of stomach feeling

    Self-reported levels of stomach feeling will be measured via a Visual Analog Scale (VAS) ranging from 0 to 100. A score of 0 represents "not at all" and 100 represents "extremely high."

    Time frame: On day 1.

  6. State and Trait Anxiety questionnaires

    trait and state anxiety, assessed via the State-Trait Anxiety Inventory (STAI-S and STAI-T). State anxiety is assessed on a scale from "not at all" to "very much" on an 8-point scale, and trait anxiety is assessed on a scale from 0 to 3, with higher scores indicating higher anxiety.

    Time frame: On day 1.

  7. Affect questionnaire

    Positive and negative affect, assessed via the Positive and Negative Affect Schedule (PANAS). Responses range from "not at all" to "extremely" on a 5-point scale (from 0 to 5). Higher positive affect scores indicate greater positive affect, and higher negative affect scores indicate greater negative affect.

    Time frame: On day 1.

  8. Depression questionnaire

    Depressive symptoms, assessed via the Beck Depression Inventory (BDI). Items are rated from 0 to 3 based on how the participant felt during the past week including today, with higher scores indicating greater depressive symptoms.

    Time frame: On day 1.

  9. Personality questionnaire

    Personality traits, assessed via the Big Five Inventory (BFI-10). Responses range from "strongly disagree" to "strongly agree" on a 5-point scale (from 1 to 5). Higher subscale scores indicate greater levels of the corresponding personality trait.

    Time frame: On day 1.

  10. Impulsivity questionnaire

    Impulsivity, assessed via the Barratt Impulsivity Scale (BIS-15). Items are rated on a scale from 1 to 4, with higher scores indicating greater impulsivity.

    Time frame: On day 1.

  11. Self-control questionnaire

    Self-control, assessed via the Brief Self-Control Scale (BSCS). Responses range from "not at all" to "very much" on a 5-point scale (from 0 to 5), with higher scores indicating greater self-control.

    Time frame: On day 1.

  12. Behavioral inhibition and activation questionnaire

    Behavioral inhibition and activation, assessed via the BIS/BAS scales. Items are rated on a scale from 1 to 4, with higher scores indicating stronger inhibition or activation tendencies.

    Time frame: On day 1.

  13. Interoceptive awareness questionnaire

    Interoceptive awareness, assessed via the Multidimensional Assessment of Interoceptive Awareness (MAIA). Responses range from "never" to "always" on a 6-point scale (from 0 to 5). Higher subscale scores indicate greater self-reported interoceptive awareness in the corresponding domain.

    Time frame: On day 1

  14. Perceived stress questionnaire

    Perceived stress, assessed via the Perceived Stress Questionnaire (PSQ). Responses range from "almost never" to "usually" on a 4-point scale (from 0 to 5), referring to the past 4 weeks, with higher scores indicating greater perceived stress.

    Time frame: On day 1.

  15. Self-efficacy questionnaire

    General self-efficacy, assessed via the Self-Efficacy Scale (SES). Responses range from "not at all true" to "exactly true" on a 4-point scale (from 1 to 4), with higher scores indicating greater self-efficacy.

    Time frame: On day 1

  16. Mental well-being questionnaire

    Mental well-being, assessed via the Warwick-Edinburgh Mental Well-Being Scale (WEMWBS). Responses range from "never" to "always" on a 5-point scale (from 1 to 5), with higher scores indicating greater mental well-being over the past 2 weeks.

    Time frame: On day 1.

  17. Loneliness questionnaire

    Loneliness, assessed via the UCLA Loneliness Scale. Responses range from "not at all" to "completely" on a 5-point scale (from 1 to 5), with higher scores indicating greater loneliness.

    Time frame: On day 1

  18. Resilience questionnaire

    Resilience, assessed via the Brief Resilience Scale (BRS). Responses range from "strongly disagree" to "strongly agree" on a 5-point scale (from 0 to 5), with higher scores indicating greater resilience.

    Time frame: On day 1.

  19. Social anxiety questionnaire

    Social anxiety, assessed via the Liebowitz Social Anxiety Scale (LSAS). Fear and avoidance are each rated on a scale from 0 to 3, with higher scores indicating greater social anxiety.

    Time frame: On day 1.

  20. Autism traits questionnaire

    Autism-related traits, assessed via the Autism-Spectrum Quotient (AQ-k). Items are rated on a 4-point scale (from 1 to 4), with higher scores indicating greater endorsement of autism-related traits.

    Time frame: On day 1.

  21. Physical activity questionnaire

    Physical activity, assessed via the International Physical Activity Questionnaire - Short Form (IPAQ-SF). The questionnaire assesses the number of days and time spent in vigorous activity, moderate activity, walking, and sitting over the past 7 days, considering activities performed for at least 10 minutes without interruption. Higher values indicate greater reported activity or sedentary time in the respective domain.

    Time frame: On day 1.

  22. Sleep quality questionnaire

    leep quality, assessed via the Pittsburgh Sleep Quality Index (PSQI). The questionnaire assesses sleep habits over the past 4 weeks, including sleep timing, duration, disturbances, and subjective sleep quality. Several items are rated on 4-point scales, with higher scores indicating poorer sleep quality.

    Time frame: On day 1.

06

Study locations

No study locations are listed for this record.

07

References and documents

Publications

  • Freitag, C. M., Retz-Junginger, P., Retz, W., Seitz, C., Palmason, H., Meyer, J., ... & von Gontard, A. (2007). Evaluation der deutschen version des Autismus-Spektrum-Quotienten (AQ)-die Kurzversion AQ-k. Zeitschrift für klinische Psychologie und Psychotherapie, 36(4), 280-289.
  • Döring, N., & Bortz, J. (1993). Psychometrische Einsamkeitsforschung: Deutsche Neukonstruktion der UCLA Loneliness Scale. Zeitschrift für Klinische Psychologie, 22(3), 224-233.
  • Lang, G. & Bachinger, A. Validation of the German Warwick-Edinburgh Mental Well-Being Scale (WEMWBS) in a community-based sample of adults in Austria: a bi-factor modelling approach. J Public Health 25, 135-146 (2017).
  • Grimm, J. State-trait-anxiety inventory nach Spielberger. Deutsche Lang- und Kurzversion. Methodenforum der Universität Wien: MF-Working Paper (2009).
  • Schwarzer, R., Bäßler, J., Kwiatek, P., Schröder, K., & Zhang, J. X. (1997). The assessment of optimistic self-beliefs: comparison of the German, Spanish, and Chinese versions of the general self-efficacy scale. Applied Psychology, 46(1), 69-88.
  • Fliege, H., Rose, M., Arck, P., Levenstein, S. & Klapp, B. F. (2001). Validierung des "Perceived Stress Questionnaire" (PSQ) an einer deutschen Stichprobe. Diagnostica, 47, 142-152.
  • Janke, S., & Glöckner-Rist, A. (2014). "Deutsche Version der Positive and Negative Affect Schedule (PANAS)" in Zusammenstellung sozialwissenschaftlicher Items und Skalen, GESIS (Mannheim, Germany).
  • Strobel, A., Beauducel, A., Debener, S., & Brocke, B. Eine deutschsprachige Version des BIS/BAS-Fragebogens von Carver und White. [A German version of Carver and White's BIS/BAS scales.]. Zeitschrift für Differentielle und Diagnostische Psychologie 22, 216-227 (2001).
  • Meule, A., Vögele, C. & Kübler, A. Psychometrische Evaluation der deutschen Barratt Impulsiveness Scale - Kurzversion (BIS-15). Diagnostica 57, 126-133 (2011).
  • Rammstedt, B., Kemper, C.J., Klein, M.C., Beierlein, C., & Kovaleva, A. (2013). Eine kurze Skala zur Mes-sung der fünf Dimensionen der Persönlichkeit. Methoden, Daten, Analysen, 7(2), S. 233-249.
  • Hautzinger M. [The Beck Depression Inventory in clinical practice]. Nervenarzt. 1991 Nov;62(11):689-96. German. PubMed 1770969 ↗
  • Backhaus J, Junghanns K, Broocks A, Riemann D, Hohagen F. Test-retest reliability and validity of the Pittsburgh Sleep Quality Index in primary insomnia. J Psychosom Res. 2002 Sep;53(3):737-40. doi: 10.1016/s0022-3999(02)00330-6. PubMed 12217446 ↗
  • Buysse DJ, Reynolds CF 3rd, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989 May;28(2):193-213. doi: 10.1016/0165-1781(89)90047-4. PubMed 2748771 ↗
  • Craig CL, Marshall AL, Sjostrom M, Bauman AE, Booth ML, Ainsworth BE, Pratt M, Ekelund U, Yngve A, Sallis JF, Oja P. International physical activity questionnaire: 12-country reliability and validity. Med Sci Sports Exerc. 2003 Aug;35(8):1381-95. doi: 10.1249/01.MSS.0000078924.61453.FB. PubMed 12900694 ↗
  • Heimberg RG, Horner KJ, Juster HR, Safren SA, Brown EJ, Schneier FR, Liebowitz MR. Psychometric properties of the Liebowitz Social Anxiety Scale. Psychol Med. 1999 Jan;29(1):199-212. doi: 10.1017/s0033291798007879. PubMed 10077308 ↗
  • Chmitorz A, Wenzel M, Stieglitz RD, Kunzler A, Bagusat C, Helmreich I, Gerlicher A, Kampa M, Kubiak T, Kalisch R, Lieb K, Tuscher O. Population-based validation of a German version of the Brief Resilience Scale. PLoS One. 2018 Feb 13;13(2):e0192761. doi: 10.1371/journal.pone.0192761. eCollection 2018. PubMed 29438435 ↗
  • Mehling WE, Acree M, Stewart A, Silas J, Jones A. The Multidimensional Assessment of Interoceptive Awareness, Version 2 (MAIA-2). PLoS One. 2018 Dec 4;13(12):e0208034. doi: 10.1371/journal.pone.0208034. eCollection 2018. PubMed 30513087 ↗
  • Sproesser G, Strohbach S, Schupp H, Renner B. Candy or apple? How self-control resources and motives impact dietary healthiness in women. Appetite. 2011 Jun;56(3):784-7. doi: 10.1016/j.appet.2011.01.028. Epub 2011 Feb 4. PubMed 21296115 ↗
  • Tom SM, Fox CR, Trepel C, Poldrack RA. The neural basis of loss aversion in decision-making under risk. Science. 2007 Jan 26;315(5811):515-8. doi: 10.1126/science.1134239. PubMed 17255512 ↗
  • Porcelli AJ, Delgado MR. Stress and Decision Making: Effects on Valuation, Learning, and Risk-taking. Curr Opin Behav Sci. 2017 Apr;14:33-39. doi: 10.1016/j.cobeha.2016.11.015. PubMed 28044144 ↗
  • De Couck M, Caers R, Musch L, Fliegauf J, Giangreco A, Gidron Y. How breathing can help you make better decisions: Two studies on the effects of breathing patterns on heart rate variability and decision-making in business cases. Int J Psychophysiol. 2019 May;139:1-9. doi: 10.1016/j.ijpsycho.2019.02.011. Epub 2019 Mar 1. PubMed 30826382 ↗
  • Bae D, Matthews JJL, Chen JJ, Mah L. Increased exhalation to inhalation ratio during breathing enhances high-frequency heart rate variability in healthy adults. Psychophysiology. 2021 Nov;58(11):e13905. doi: 10.1111/psyp.13905. Epub 2021 Jul 20. PubMed 34289128 ↗
  • Allen AP, Kennedy PJ, Dockray S, Cryan JF, Dinan TG, Clarke G. The Trier Social Stress Test: Principles and practice. Neurobiol Stress. 2016 Nov 12;6:113-126. doi: 10.1016/j.ynstr.2016.11.001. eCollection 2017 Feb. PubMed 28229114 ↗

Individual participant data

Plan to share: Undecided — A decision regarding sharing of individual participant data (IPD) has not yet been made. The dataset includes behavioral, physiological, and neuroimaging data, and any future data sharing will be subject to institutional policies and applicable data protection regulations. Data sharing options will be evaluated following study completion.

08

Registry details

Key details

Study ID
NCT07505641
Lead sponsor
German Institute of Human Nutrition
Responsible party
Prof. Dr. Soyoung Q Park (Prof. Dr., German Institute of Human Nutrition) — Principal investigator
First posted
Apr 1, 2026
Start date
Apr 1, 2026 (estimated)
Primary completion
Apr 1, 2027 (estimated)
Completion
Apr 1, 2027 (estimated)
Last update
Apr 1, 2026

Study contacts

Soyoung Q Park, Prof. Dr.
Contact
soyoung.park@dife.de
+49 033200 88 2510
Wenhao Huang
Contact
Wenhao.Huang@dife.de
Soyoung Q Park, Prof. Dr.
principal investigator · German Institute of Human Nutrition Potsdam-Rehbruecke

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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