Breathing TechniquesProlEx-ContextNCT07505641
Breathing and Decision-Making (ProlEx-Context)
A study testing Instructed Prolonged Exhalation and Instructed Individualized Eupnea in people with Breathing Techniques and Stress Management, run by German Institute of Human Nutrition.
Trial 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 more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Breathing Techniques, Stress Management, Decision-Making
- What is being tested?
- Instructed Prolonged Exhalation and Instructed Individualized Eupnea
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 50 participants
- Where
- No sites listed yet
- Study dates
- 1 Apr 2026to 1 Apr 2027
- Phase
- Interventional
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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
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- 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)
Who cannot join
- 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
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- 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)
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
Wenhao Huang contact
About this study
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.
- Conditions
- Breathing Techniques, Stress Management, Decision-Making
- Being tested
- Instructed Prolonged Exhalation, Instructed Individualized Eupnea
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Instructed Prolonged ExhalationBehavioural
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.
Instructed Individualized EupneaBehavioural
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.
| Study group | Role | What they receive |
|---|---|---|
| Prolonged Exhalation Breathing | Experimental | 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 Receives: Behavioral: Instructed Prolonged Exhalation |
| Eupnea Breathing (Normal) | Experimental | 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. Receives: Behavioral: Instructed Individualized Eupnea |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: On day 1.
Task-related BOLD Signals
Task-related changes in blood-oxygen-level-dependent (BOLD) signals measured using functional magnetic resonance imaging (fMRI).
Measured: On day 1.
Structural T1-weighted MRI
High-resolution T1-weighted structural images measured using magnetic resonance imaging (MRI).
Measured: On day 1.
Relative amplitude of the respiratory signal
Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt and nasal airflow sensor.
Measured: On day 1.
Respiration rate
Task-based and resting-state relative respiratory amplitude, measured via a respiratory belt and nasal airflow sensor.
Measured: On day 1.
Heart rate
Task-based and resting-state heart rate, measured with ECG
Measured: On day 1.
Heart-rate variability
Task-based and resting-state heart-rate variability, measured with a three-point electrocardiogram (ECG)
Measured: On day 1.
Gastric myoelectrical activity
Resting-state and task-based gastric myoelectrical activity, measured using cutaneous electrogastrography (EGG).
Measured: On day 1.
Tonic skin conductance
Tonic task-based and resting-state electrodermal activity, measured with EDA electrodes
Measured: On day 1.
Event-related skin conductance responses
Phasic electrodermal activity, measured via electrodermal activity (EDA) electrodes
Measured: On day 1.
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
Measured: On day 1.
Pupil dilation
Task-based and resting-state pupil dilation, measured via eye-tracking
Measured: On day 1.
Secondary outcomes (22)
Response Times
The average time (in milliseconds) taken by participants to make a choice in each trial.
Measured: On day 1.
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."
Measured: On day 1.
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."
Measured: On day 1.
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."
Measured: On day 1.
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."
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1
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.
Measured: On day 1.
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.
Measured: On day 1
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.
Measured: On day 1.
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.
Measured: On day 1
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
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.
Measured: On day 1.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Apr 2026
- Study start1 Apr 2026 (estimated)
- Primary completion1 Apr 2027 (estimated)
- Study completion1 Apr 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (23)Papers the sponsor has linked to this study.
- Other trials for Breathing TechniquesStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- German Institute of Human Nutrition
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Prof. Dr. Soyoung Q Park, German Institute of Human Nutrition
- Investigators
- Soyoung Q Park, Prof. Dr., Principal investigator, German Institute of Human Nutrition Potsdam-Rehbruecke
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07505641
- Sponsor's protocol ID
- ProlEx-Context
- Other IDs
- 88/2025 107/2025
- Acronym
- ProlEx-Context
- Status last verified
- Dec 2025
- First submitted
- 13 Mar 2026
- Last updated
- 1 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- 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.
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 1770969Backhaus 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 12217446Buysse 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 2748771Craig 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 12900694Heimberg 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