Healthy Adult ParticipantsNCT07529379
Breathwork and Stress: Investigating the Mechanisms of Action and Effectiveness of Breathing Interventions in Modulating the Psychophysiological Response to Acute Stress Test
A study testing Coherent Breathing (6 bpm) in people with Healthy Adult Participants and Acute Stress Reaction, run by Medical University of Bialystok at 1 site in Poland.
Trial summary
This study investigates whether the psychophysiological benefits of breathing exercises are driven by a specific physiological rhythm (6 breaths per minute) or by the general psychological experience of performing a structured, mindful activity. Read more about this study
- Who is it for?
- Ages 18 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy Adult Participants, Acute Stress Reaction, Stress Biomarkers
- What is being tested?
- Coherent Breathing (6 bpm)
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 100 participants
- Where
- 1 sitePoland
- Study dates
- 7 Apr 2026to 22 Aug 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 60 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Healthy adults
- Aged 18 to 60 years
- Willingness to participate in all study phases, including preparation and laboratory session.
- Professionally active individuals or university students.
Who cannot join
- Severe chronic diseases, including metabolic disorders (e.g., diabetes) and mental disorders.
- Cardiac arrhythmia, history of heart attacks, strokes, or heart surgery.
- Regular use of medications such as anxiolytics or beta-blockers (excluding hormonal contraception)
- Pregnancy.
- Current participation in other scientific experiments.
- Significant previous experience with breathing techniques or current independent breathwork/meditation practice (defined as regular practice for more than 7 days/monthly within the last 12 months).
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- Professional sports practice.
- Raynaud's disease
- Inability to abstain from alcohol, caffeine, and nicotine for the required periods before the experiment
Trial locations and contacts
1 site in 1 country.
Poland1 site
Medical University of Bialystok. Department of Physiology.
Bialystok, Podlaskie Voivodeship, 15-222
About this study
This study investigates whether the psychophysiological benefits of breathing exercises are driven by a specific physiological rhythm (6 breaths per minute) or by the general psychological experience of performing a structured, mindful activity. Researchers aim to determine if "coherent breathing", which is hypothesized to synchronize heart and respiratory rhythms, offers unique physiological protection against stress compared to breathing at a natural pace or simple resting. The main questions it aims to answer are:
- Does slow, steady breathing at 6 breaths per minute lower physical stress markers (like heart rate variability and cortisol) better than faster, but structured breathing or just sitting still?
- Is the calming effect caused by the specific breathing rhythm or simply by performing a structured, relaxing activity?
Read more
Researchers will compare three groups to see if the specific rhythm of "coherent breathing" offers unique benefits:
- Group (Interventional): Coherent Breathing: Slow breathing at 6 breaths per minute.
- Group (Sham Breathing): Regular breathing at 15 breaths per minute (matching a natural pace).
- Spontaneous Breathing (Control Group): Natural, unguided breathing.
Participants will:
- Complete a one-day preparation phase to become familiar with the breathing technique.
- Visit the research center for one experimental session.
- Perform their assigned breathing method before and after a stress test.
- Take the Maastricht Acute Stress Test (MAST), which involves putting a hand in cold water and doing mental math.
- Provide saliva samples and have their heart rate variability, and mood measured multiple times.
Read the detailed description
This three-arm randomized controlled trial is designed to investigate whether the therapeutic benefits of slow-paced breathing stem from specific physiological mechanisms (cardiorespiratory resonance) or non-specific psychological factors, such as attention, expectancy, and structured relaxation.
The study directly compares resonant-frequency breathing against a structurally identical sham intervention and a passive control group.
Experimental Protocol:
The study utilizes the Maastricht Acute Stress Test (MAST) as a highly structured and validated laboratory stressor to capture the dynamic psychophysiological response to acute distress.
The protocol consists of the following phases:
Baseline Phase (BASE): A 5-minute measurement of baseline physiological (HRV - Heart Rate Variability) and psychological (STAI-S - State-Trait Anxiety Inventory-State, VAMS - Visual Analogue Mood Scales) parameters.
First Intervention (10 min): Participants perform their assigned breathing technique or sit quietly to assess the preventive "buffering" effect of the intervention.
Acute Stress Induction (MAST): A 15-minute structured stressor combining periods of hand immersion in cold water and mental arithmetic under social-evaluative pressure. The water temperature is strictly maintained within the range of 4.5 - 5.5 °C using a TECO chiller to ensure consistent stress induction across all participants.
Post-Stress Recovery (POST): Immediate 5-minute measurement following the conclusion of the MAST protocol.
Second Intervention (10 min): A repeat of the breathing/control protocol to evaluate its impact on psychophysiological recovery.
Final Assessments (END \& FOLLOW): Measurements are taken immediately after the second intervention and following a 15-minute recovery phase to capture the peak glucocorticoid (cortisol) response.
Data Collection and Analysis:
- Heart Rate Variability: RR interval (time duration between successive heartbeats, specifically the time intervals between each R-wave peak) data is collected using a Polar H10 heart rate monitor. To ensure data integrity and redundancy, the signal is recorded simultaneously through two mobile applications: Elite HRV and Kubios HRV. All subsequent advanced HRV analyses, including time-domain, frequency-domain, and non-linear indices (e.g., PNS/SNS Index [Parasympathetic Nervous System Index and Sympathetic Nervous System Index], RMSSD [Root Mean Square of Successive Differences]), are performed using Kubios HRV Scientific software.
- Biochemical Markers: Salivary cortisol levels are measured to assess the hypothalamic-pituitary-adrenal (HPA) axis response using ELISA kits.
- Psychological Scales: Subjective stress and anxiety are tracked using the STAI-VAMS.
Adherence Check: Participant adherence to the paced breathing protocols is verified using the Kubios RESP (respiratory rate estimation) algorithm. This software-based solution extracts respiratory frequency from the RR interval data to confirm that participants maintained the target rates of 6 bpm (breaths per minute) or 15 bpm.
Research Arms:
- Coherent Breathing (6 bpm): Guided nasal diaphragmatic breathing (5.5 s inhale / 5.5 s exhale) focused on inducing cardiorespiratory resonance.
- Sham Breathing (15 bpm): Guided breathing at a natural pace (2 s inhale / 2 s exhale) to control for the effects of a structured intervention.
- Spontaneous Breathing (Control): Passive resting with eyes closed, serving as a neutral baseline for the natural course of the stress response.
- Being tested
- Coherent Breathing (6 bpm), Sham Breathing (15 bpm)
- Keywords
- Breathwork, Coherent Breathing, Resonance Breathing, Heart Rate Variability, Maastricht Acute Stress Test (MAST), Cortisol
- Medical subject headings
- Stress Disorders, Traumatic, Acute
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Coherent Breathing (6 bpm)Behavioural
Also called Resonant Breathing
A 10-minute session of guided nasal diaphragmatic, coherent breathing. Participants follow rhythmic audio bell cues: a low tone for a 5.5-second inhalation and a high tone for a 5.5-second exhalation. Instructions emphasize silent, gentle nasal breathing and abdominal (diaphragmatic) expansion without lifting the shoulders. Participants are asked to focus their attention on the sensations of air flow or abdominal movement throughout the session. The intervention is performed twice: before and after the stress protocol
Sham Breathing (15 bpm)Behavioural
Also called Normal-paced Breathing
A 10-minute session of guided nasal diaphragmatic breathing at a rate of 15 breaths per minute (matching a natural spontaneous pace). Participants follow identical rhythmic audio bell cues as the experimental group: a low tone for a 2.0-second inhalation and a high tone for a 2.0-second exhalation. All other instructions regarding nasal breathing, abdominal mechanics, and mindful attention are identical to the experimental group to ensure structural blinding. The intervention is performed twice: before and after the stress protocol
| Study group | Role | What they receive |
|---|---|---|
| Coherent Breathing (6 bpm) | Experimental | Participants perform 10 minutes of guided nasal diaphragmatic breathing at a rate of 6 breaths per minute (~0.1 Hz). The practice involves a 5.5-second inhalation and 5.5-second exhalation phase, guided by rhythmic audio bell cues (low tone for inhale, high tone for exhale). Participants focus on abdominal movement and sensations of air flow. This intervention is performed twice: once before the acute stressor (MAST) and once during the recovery phase. Receives: Behavioral: Coherent Breathing (6 bpm) |
| Sham Breathing (15 bpm) | Sham comparator | Participants perform 10 minutes of guided nasal diaphragmatic breathing at a rate of 15 breaths per minute, which matches a natural spontaneous breathing pace. The practice involves a 2.0-second inhalation and 2.0-second exhalation phase, guided by identical rhythmic audio bell cues as the experimental arm. This arm mimics the structural and attentional components of the active intervention without inducing cardiorespiratory resonance. Performed twice: before and after the MAST protocol. Receives: Behavioral: Sham Breathing (15 bpm) |
| Spontaneous Breathing (Control) | No intervention | Participants in this passive control group sit quietly with their eyes closed for 10 minutes. They receive initial brief relaxation instructions (two deep breaths with a sigh, body muscles relaxation) but do not receive any specific rhythmic guidance, audio cues, or instructions to modulate their breathing pattern. This arm serves as a baseline to control for the natural course of the stress response and the passage of time. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Root Mean Square of Successive (RMSSD)
The Root Mean Square of Successive Differences (RMSSD) measured in milliseconds (ms). This is a time-domain HRV parameter used to assess parasympathetic nervous system activity. An increase indicates higher parasympathetic activity, while a decrease indicates a stress response.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in PNS Index
This outcome measure is reported as a single composite score (standardized Z-score) representing the aggregated modulation of vagal activity. The final value is automatically calculated by Kubios HRV Scientific software from the mathematical combination of three specific assessments: mean RR interval, RMSSD, and the non-linear SD1 parameter, normalized against a reference database. Only the final aggregated Z-score will be reported as the endpoints for these measures. A value of 0 represents the population average; positive values indicate enhanced parasympathetic tone and recovery capacity.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Salivary Cortisol Concentration
Concentration Measured via enzyme-linked immunosorbent assay (ELISA) in nmol/L. This neuroendocrine marker assesses the activation of the hypothalamic-pituitary-adrenal (HPA) axis. It is used to quantify the objective impact of the breathing intervention on the peak hormonal stress response (typically reaching maximum concentration 15-30 minutes after the stressor).
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in STAI-State score
A validated self-report questionnaire used to measure the current intensity of anxiety, tension, and nervousness. Scores range from 20 to 80, with higher scores indicating greater subjective psychological distress.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Mean HR
Mean heart rate measured in beats per minute (bpm). This serves as a fundamental indicator of physiological arousal and autonomic nervous system activity.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Secondary outcomes (15)
Change in SNS Index
This outcome measure is reported as a single composite score (standardized Z-score) representing the aggregated physiological arousal and sympathetic activity. The final value is automatically calculated by Kubios HRV Scientific software from the mathematical combination of three specific assessments: mean heart rate (HR), Baevsky's Stress Index, and the non-linear SD2 parameter, normalized against a reference database. Only the final aggregated Z-score will be reported as the endpoints for these measures. Positive values indicate sympathetic dominance and physiological arousal, providing a quantitative measure of the "cost" of the stressor and the effectiveness of the intervention in reducing sympathetic overdrive.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Diastolic Blood Pressure (DBP)
Measured in millimeters of mercury (mmHg) using an automated sphygmomanometer. This metric serves as functional hemodynamic endpoint to verify the hypothesis that coherent breathing enhances baroreflex sensitivity and stabilizes blood pressure.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Subjective Stress (VAMS)
A specific assessment of subjective stress intensity. Participants mark their current feeling on a 100 mm visual analogue scale (0-100), where 0 indicates "no stress" and 100 indicates "maximum stress" . Only this individual scale value is reported as the endpoint for this measure.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Mean Heart Rate (Mean HR) during Experimental Blocks
Continuous monitoring of mean heart rate (bpm) during active interventions and stress induction to evaluate real-time physiological reactivity and recovery dynamics.
Measured: Average heart rate measured during three 10-minute periods starting at approximately 10 minutes (First Intervention), 35 minutes (Stress Induction), and 55 minutes after Baseline during the single experimental Day 3.
SNS Index during Stress Induction
This outcome measure is reported as a single composite score (standardized Z-score) representing the aggregated physiological arousal and sympathetic activity. The final value is automatically calculated by Kubios HRV Scientific software from the mathematical combination of three specific assessments: mean heart rate (HR), Baevsky's Stress Index, and the non-linear SD2 parameter, normalized against a reference database. Only the final aggregated Z-score will be reported as the endpoint for this measure.
Measured: Average score measured during one 10-minute period starting at approximately 35 minutes (Stress Induction) after Baseline during the single experimental Day 3.
Change in Standard Deviation of NN intervals (SDNN)
A time-domain metric reflecting the total variability of heart rate rhythm, measured in milliseconds (ms). It represents the overall capacity of the autonomic nervous system to adapt to internal and external stimuli.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
SNS index during Intervention Blocks
This outcome measure is reported as a single composite score (standardized Z-score) representing the aggregated physiological arousal and sympathetic activity. The final value is automatically calculated by Kubios HRV Scientific software from the mathematical combination of three specific assessments: mean heart rate (HR), Baevsky's Stress Index, and the non-linear SD2 parameter, normalized against a reference database. Only the final aggregated Z-score will be reported as the endpoint for these measures.
Measured: Average score measured during two 10-minute periods starting at approximately 10 minutes (First Intervention) and 55 minutes (Second Intervention) after Baseline during the single experimental Day 3.
Change in LF power log (ln LF)
The natural logarithm of the HRV absolute power in the low-frequency band (0.04 - 0.15 Hz).
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Log-transformed High-Frequency HRV Power (ln HF)
The natural logarithm of the HRV absolute power in the high-frequency band (0.15 - 0.40 Hz).
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
PNS Index during Stress Induction
This outcome measure is reported as a single composite score (standardized Z-score) representing the aggregated modulation of vagal activity. The final value is automatically calculated by Kubios HRV Scientific software from the mathematical combination of three specific assessments: mean RR interval, RMSSD, and the non-linear SD1 parameter, normalized against a reference database. Only the final aggregated Z-score will be reported as the endpoint for this measure.
Measured: Average score measured during one 10-minute period starting at approximately 35 minutes (Stress Induction) after Baseline during the single experimental Day 3.
PNS index during Intervention Blocks
This outcome measure is reported as a single composite score (standardized Z-score) representing the aggregated modulation of vagal activity. The final value is automatically calculated by Kubios HRV Scientific software from the mathematical combination of three specific assessments: mean RR interval, RMSSD, and the non-linear SD1 parameter, normalized against a reference database. Only the final aggregated Z-score will be reported as the endpoint for these measures.
Measured: Average score measured during two 10-minute periods starting at approximately 10 minutes (First Intervention) and 55 minutes (Second Intervention) after Baseline during the single experimental Day 3.
Change in Systolic Blood Pressure (SBP)
Measured in millimeters of mercury (mmHg) using an automated sphygmomanometer. This metric serves as functional hemodynamic endpoint to verify the hypothesis that coherent breathing enhances baroreflex sensitivity and stabilizes blood pressure.
Measured: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Subjective Mental Tension (VAMS)
A specific assessment of subjective mental tension intensity. Participants mark their current feeling on a 100 mm visual analogue scale (0-100), where 0 indicates "no tension" and 100 indicates "maximum tension" . Only this individual scale value is reported as the endpoint for this measure.
Measured: At Baseline (0 minutes), and at approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Subjective Calmness (VAMS)
A specific assessment of subjective calmness intensity. Participants mark their current feeling on a 100 mm visual analogue scale (0-100), where 0 indicates "no calm" and 100 indicates "maximum calm" . Only this individual scale value is reported as the endpoint for this measure.
Measured: At Baseline (0 minutes), and at approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Subjective Relaxation (VAMS)
A specific assessment of subjective relaxation intensity. Participants mark their current feeling on a 100 mm visual analogue scale (0-100), where 0 indicates "no relaxation" and 100 indicates "maximum relaxation" . Only this individual scale value is reported as the endpoint for this measure.
Measured: At Baseline (0 minutes), and at approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Apr 2026
- Study start7 Apr 2026
- Primary completion22 Aug 2026
- Study completion22 Aug 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Healthy Adult ParticipantsStudies 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
- Parallel groups
- Model description
- This is a three-arm, single-blinded, randomized sham-controlled trial using a parallel assignment model. Participants are randomly assigned to one of three arms: the active intervention (coherent breathing at 6 breaths per minute), a sham-placebo control (paced breathing at 15 breaths per minute), or a passive control (spontaneous breathing). The study design is specifically intended to isolate the psychophysiological mechanisms of the 6 bpm rhythm from non-specific psychological factors, such as attention and participant expectancy.
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 100 participants (actual)
Sponsor and investigators
- Lead sponsor
- Medical University of Bialystok
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07529379
- Sponsor's protocol ID
- APK.002.107.2024
- Status last verified
- Mar 2026
- First submitted
- 18 Mar 2026
- Last updated
- 21 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Anonymized individual participant data that underlie the results reported in the published article (including HRV parameters, cortisol levels, and psychological scale scores) will be made available from the corresponding author upon reasonable request. Raw physiological signal files will not be shared to protect participant privacy. Data will be provided in a standardized tabular format (e.g., Excel or CSV).
Publications
Dick TE, Hsieh YH, Dhingra RR, Baekey DM, Galan RF, Wehrwein E, Morris KF. Cardiorespiratory coupling: common rhythms in cardiac, sympathetic, and respiratory activities. Prog Brain Res. 2014;209:191-205. doi: 10.1016/B978-0-444-63274-6.00010-2.
PubMed 24746049Sevoz-Couche C, Laborde S. Heart rate variability and slow-paced breathing:when coherence meets resonance. Neurosci Biobehav Rev. 2022 Apr;135:104576. doi: 10.1016/j.neubiorev.2022.104576. Epub 2022 Feb 12.
PubMed 35167847Siebieszuk A, Plonski AF, Baranowski M. Breathwork for Chronic Stress and Mental Health: Does Choosing a Specific Technique Matter? Med Sci (Basel). 2025 Aug 13;13(3):127. doi: 10.3390/medsci13030127.
PubMed 40843749Smeets T, Cornelisse S, Quaedflieg CW, Meyer T, Jelicic M, Merckelbach H. Introducing the Maastricht Acute Stress Test (MAST): a quick and non-invasive approach to elicit robust autonomic and glucocorticoid stress responses. Psychoneuroendocrinology. 2012 Dec;37(12):1998-2008. doi: 10.1016/j.psyneuen.2012.04.012. Epub 2012 May 18.
PubMed 22608857Shilton AL, Laycock R, Crewther SG. The Maastricht Acute Stress Test (MAST): Physiological and Subjective Responses in Anticipation, and Post-stress. Front Psychol. 2017 Apr 19;8:567. doi: 10.3389/fpsyg.2017.00567. eCollection 2017.
PubMed 28469586
Study at a glance
From the registry record, last updated by the sponsor on 21 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Breathwork and Stress: Investigating the Mechanisms of Action and Effectiveness of Breathing Interventions in Modulating the Psychophysiological Response to Acute Stress Test
- ClinicalTrials.gov ID
- NCT07529379
- Acronym / sponsor ID
- APK.002.107.2024
- Keywords
- Breathwork, Coherent Breathing, Resonance Breathing, Heart Rate Variability, Maastricht Acute Stress Test (MAST), Cortisol
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 100 participants (actual)
- Lead sponsor
- Medical University of BialystokUniversity, hospital or other
- Study start
- 7 Apr 2026 (actual)
- Primary completion
- 22 Aug 2026 (actual)
- Study completion
- 22 Aug 2026 (actual)
- First posted
- 14 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study investigates whether the psychophysiological benefits of breathing exercises are driven by a specific physiological rhythm (6 breaths per minute) or by the general psychological experience of performing a structured, mindful activity. Researchers aim to determine if "coherent breathing", which is hypothesized to synchronize heart and respiratory rhythms, offers unique physiological protection against stress compared to breathing at a natural pace or simple resting. The main questions it aims to answer are:
- Does slow, steady breathing at 6 breaths per minute lower physical stress markers (like heart rate variability and cortisol) better than faster, but structured breathing or just sitting still?
- Is the calming effect caused by the specific breathing rhythm or simply by performing a structured, relaxing activity?
Researchers will compare three groups to see if the specific rhythm of "coherent breathing" offers unique benefits:
- Group (Interventional): Coherent Breathing: Slow breathing at 6 breaths per minute.
- Group (Sham Breathing): Regular breathing at 15 breaths per minute (matching a natural pace).
- Spontaneous Breathing (Control Group): Natural, unguided breathing.
Participants will:
- Complete a one-day preparation phase to become familiar with the breathing technique.
- Visit the research center for one experimental session.
- Perform their assigned breathing method before and after a stress test.
- Take the Maastricht Acute Stress Test (MAST), which involves putting a hand in cold water and doing mental math.
- Provide saliva samples and have their heart rate variability, and mood measured multiple times.
Detailed description
This three-arm randomized controlled trial is designed to investigate whether the therapeutic benefits of slow-paced breathing stem from specific physiological mechanisms (cardiorespiratory resonance) or non-specific psychological factors, such as attention, expectancy, and structured relaxation.
The study directly compares resonant-frequency breathing against a structurally identical sham intervention and a passive control group.
Experimental Protocol:
The study utilizes the Maastricht Acute Stress Test (MAST) as a highly structured and validated laboratory stressor to capture the dynamic psychophysiological response to acute distress.
The protocol consists of the following phases:
Baseline Phase (BASE): A 5-minute measurement of baseline physiological (HRV - Heart Rate Variability) and psychological (STAI-S - State-Trait Anxiety Inventory-State, VAMS - Visual Analogue Mood Scales) parameters.
First Intervention (10 min): Participants perform their assigned breathing technique or sit quietly to assess the preventive "buffering" effect of the intervention.
Acute Stress Induction (MAST): A 15-minute structured stressor combining periods of hand immersion in cold water and mental arithmetic under social-evaluative pressure. The water temperature is strictly maintained within the range of 4.5 - 5.5 °C using a TECO chiller to ensure consistent stress induction across all participants.
Post-Stress Recovery (POST): Immediate 5-minute measurement following the conclusion of the MAST protocol.
Second Intervention (10 min): A repeat of the breathing/control protocol to evaluate its impact on psychophysiological recovery.
Final Assessments (END \& FOLLOW): Measurements are taken immediately after the second intervention and following a 15-minute recovery phase to capture the peak glucocorticoid (cortisol) response.
Data Collection and Analysis:
- Heart Rate Variability: RR interval (time duration between successive heartbeats, specifically the time intervals between each R-wave peak) data is collected using a Polar H10 heart rate monitor. To ensure data integrity and redundancy, the signal is recorded simultaneously through two mobile applications: Elite HRV and Kubios HRV. All subsequent advanced HRV analyses, including time-domain, frequency-domain, and non-linear indices (e.g., PNS/SNS Index [Parasympathetic Nervous System Index and Sympathetic Nervous System Index], RMSSD [Root Mean Square of Successive Differences]), are performed using Kubios HRV Scientific software.
- Biochemical Markers: Salivary cortisol levels are measured to assess the hypothalamic-pituitary-adrenal (HPA) axis response using ELISA kits.
- Psychological Scales: Subjective stress and anxiety are tracked using the STAI-VAMS.
Adherence Check: Participant adherence to the paced breathing protocols is verified using the Kubios RESP (respiratory rate estimation) algorithm. This software-based solution extracts respiratory frequency from the RR interval data to confirm that participants maintained the target rates of 6 bpm (breaths per minute) or 15 bpm.
Research Arms:
- Coherent Breathing (6 bpm): Guided nasal diaphragmatic breathing (5.5 s inhale / 5.5 s exhale) focused on inducing cardiorespiratory resonance.
- Sham Breathing (15 bpm): Guided breathing at a natural pace (2 s inhale / 2 s exhale) to control for the effects of a structured intervention.
- Spontaneous Breathing (Control): Passive resting with eyes closed, serving as a neutral baseline for the natural course of the stress response.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 3
- Model description
- This is a three-arm, single-blinded, randomized sham-controlled trial using a parallel assignment model. Participants are randomly assigned to one of three arms: the active intervention (coherent breathing at 6 breaths per minute), a sham-placebo control (paced breathing at 15 breaths per minute), or a passive control (spontaneous breathing). The study design is specifically intended to isolate the psychophysiological mechanisms of the 6 bpm rhythm from non-specific psychological factors, such as attention and participant expectancy.
| Arm | Type | Receives |
|---|---|---|
| Coherent Breathing (6 bpm) | Experimental | Behavioral: Coherent Breathing (6 bpm)Participants perform 10 minutes of guided nasal diaphragmatic breathing at a rate of 6 breaths per minute (~0.1 Hz). The practice involves a 5.5-second inhalation and 5.5-second exhalation phase, guided by rhythmic audio bell cues (low tone for inhale, high tone for exhale). Participants focus on abdominal movement and sensations of air flow. This intervention is performed twice: once before the acute stressor (MAST) and once during the recovery phase. |
| Sham Breathing (15 bpm) | Sham comparator | Behavioral: Sham Breathing (15 bpm)Participants perform 10 minutes of guided nasal diaphragmatic breathing at a rate of 15 breaths per minute, which matches a natural spontaneous breathing pace. The practice involves a 2.0-second inhalation and 2.0-second exhalation phase, guided by identical rhythmic audio bell cues as the experimental arm. This arm mimics the structural and attentional components of the active intervention without inducing cardiorespiratory resonance. Performed twice: before and after the MAST protocol. |
| Spontaneous Breathing (Control) | No intervention | –Participants in this passive control group sit quietly with their eyes closed for 10 minutes. They receive initial brief relaxation instructions (two deep breaths with a sigh, body muscles relaxation) but do not receive any specific rhythmic guidance, audio cues, or instructions to modulate their breathing pattern. This arm serves as a baseline to control for the natural course of the stress response and the passage of time. |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Healthy adults
- Aged 18 to 60 years
- Willingness to participate in all study phases, including preparation and laboratory session.
- Professionally active individuals or university students.
Key exclusion criteria (9 listed)
- Severe chronic diseases, including metabolic disorders (e.g., diabetes) and mental disorders.
- Cardiac arrhythmia, history of heart attacks, strokes, or heart surgery.
- Regular use of medications such as anxiolytics or beta-blockers (excluding hormonal contraception)
- Pregnancy.
- Current participation in other scientific experiments.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Coherent Breathing (6 bpm)Also: Resonant BreathingA 10-minute session of guided nasal diaphragmatic, coherent breathing. Participants follow rhythmic audio bell cues: a low tone for a 5.5-second inhalation and a high tone for a 5.5-second exhalation. Instructions emphasize silent, gentle nasal breathing and abdominal (diaphragmatic) expansion without lifting the shoulders. Participants are asked to focus their attention on the sensations of air flow or abdominal movement throughout the session. The intervention is performed twice: before and after the stress protocol | Behavioural | Coherent Breathing (6 bpm) |
| Sham Breathing (15 bpm)Also: Normal-paced BreathingA 10-minute session of guided nasal diaphragmatic breathing at a rate of 15 breaths per minute (matching a natural spontaneous pace). Participants follow identical rhythmic audio bell cues as the experimental group: a low tone for a 2.0-second inhalation and a high tone for a 2.0-second exhalation. All other instructions regarding nasal breathing, abdominal mechanics, and mindful attention are identical to the experimental group to ensure structural blinding. The intervention is performed twice: before and after the stress protocol | Behavioural | Sham Breathing (15 bpm) |
Primary outcome
Change in Root Mean Square of Successive (RMSSD)
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
The Root Mean Square of Successive Differences (RMSSD) measured in milliseconds (ms). This is a time-domain HRV parameter used to assess parasympathetic nervous system activity. An increase indicates higher parasympathetic activity, while a decrease indicates a stress response.
Change in PNS Index
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
This outcome measure is reported as a single composite score (standardized Z-score) representing the aggregated modulation of vagal activity. The final value is automatically calculated by Kubios HRV Scientific software from the mathematical combination of three specific assessments: mean RR interval, RMSSD, and the non-linear SD1 parameter, normalized against a reference database. Only the final aggregated Z-score will be reported as the endpoints for these measures. A value of 0 represents the population average; positive values indicate enhanced parasympathetic tone and recovery capacity.
Change in Salivary Cortisol Concentration
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Concentration Measured via enzyme-linked immunosorbent assay (ELISA) in nmol/L. This neuroendocrine marker assesses the activation of the hypothalamic-pituitary-adrenal (HPA) axis. It is used to quantify the objective impact of the breathing intervention on the peak hormonal stress response (typically reaching maximum concentration 15-30 minutes after the stressor).
Change in STAI-State score
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
A validated self-report questionnaire used to measure the current intensity of anxiety, tension, and nervousness. Scores range from 20 to 80, with higher scores indicating greater subjective psychological distress.
Change in Mean HR
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Mean heart rate measured in beats per minute (bpm). This serves as a fundamental indicator of physiological arousal and autonomic nervous system activity.
15 secondary outcomes
Change in SNS Index
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Diastolic Blood Pressure (DBP)
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Subjective Stress (VAMS)
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Mean Heart Rate (Mean HR) during Experimental Blocks
Time frame: Average heart rate measured during three 10-minute periods starting at approximately 10 minutes (First Intervention), 35 minutes (Stress Induction), and 55 minutes after Baseline during the single experimental Day 3.
SNS Index during Stress Induction
Time frame: Average score measured during one 10-minute period starting at approximately 35 minutes (Stress Induction) after Baseline during the single experimental Day 3.
Change in Standard Deviation of NN intervals (SDNN)
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
SNS index during Intervention Blocks
Time frame: Average score measured during two 10-minute periods starting at approximately 10 minutes (First Intervention) and 55 minutes (Second Intervention) after Baseline during the single experimental Day 3.
Change in LF power log (ln LF)
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Log-transformed High-Frequency HRV Power (ln HF)
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
PNS Index during Stress Induction
Time frame: Average score measured during one 10-minute period starting at approximately 35 minutes (Stress Induction) after Baseline during the single experimental Day 3.
PNS index during Intervention Blocks
Time frame: Average score measured during two 10-minute periods starting at approximately 10 minutes (First Intervention) and 55 minutes (Second Intervention) after Baseline during the single experimental Day 3.
Change in Systolic Blood Pressure (SBP)
Time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Subjective Mental Tension (VAMS)
Time frame: At Baseline (0 minutes), and at approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Subjective Calmness (VAMS)
Time frame: At Baseline (0 minutes), and at approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Change in Subjective Relaxation (VAMS)
Time frame: At Baseline (0 minutes), and at approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 21 Oct 2026.
- Background: PubMed 24746049Dick TE, Hsieh YH, Dhingra RR, Baekey DM, Galan RF, Wehrwein E, Morris KF. Cardiorespiratory coupling: common rhythms in cardiac, sympathetic, and respiratory activities. Prog Brain Res. 2014;209:191-205. doi: 10.1016/B978-0-444-63274-6.00010-2.
- Background: PubMed 35167847Sevoz-Couche C, Laborde S. Heart rate variability and slow-paced breathing:when coherence meets resonance. Neurosci Biobehav Rev. 2022 Apr;135:104576. doi: 10.1016/j.neubiorev.2022.104576. Epub 2022 Feb 12.
- Background: PubMed 40843749Siebieszuk A, Plonski AF, Baranowski M. Breathwork for Chronic Stress and Mental Health: Does Choosing a Specific Technique Matter? Med Sci (Basel). 2025 Aug 13;13(3):127. doi: 10.3390/medsci13030127.
- Background: PubMed 22608857Smeets T, Cornelisse S, Quaedflieg CW, Meyer T, Jelicic M, Merckelbach H. Introducing the Maastricht Acute Stress Test (MAST): a quick and non-invasive approach to elicit robust autonomic and glucocorticoid stress responses. Psychoneuroendocrinology. 2012 Dec;37(12):1998-2008. doi: 10.1016/j.psyneuen.2012.04.012. Epub 2012 May 18.
- Background: PubMed 28469586Shilton AL, Laycock R, Crewther SG. The Maastricht Acute Stress Test (MAST): Physiological and Subjective Responses in Anticipation, and Post-stress. Front Psychol. 2017 Apr 19;8:567. doi: 10.3389/fpsyg.2017.00567. eCollection 2017.
- Individual participant dataSharing planned: Yes. Anonymized individual participant data that underlie the results reported in the published article (including HRV parameters, cortisol levels, and psychological scale scores) will be made available from the corresponding author upon reasonable request. Raw physiological signal files will not be shared to protect participant privacy. Data will be provided in a standardized tabular format (e.g., Excel or CSV).
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Coherent Breathing (6 bpm) in people with Healthy Adult Participants and Acute Stress Reaction, run by Medical University of Bialystok at 1 site in Poland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 21 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Poland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Root Mean Square of Successive (RMSSD) (time frame: Measured at 5 time points: at Baseline (0 minutes), and approximately 25, 45, 60, and 75 minutes after Baseline during the single experimental session on Day 3.). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07529379, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Oct 2026.