NCT Number: NCT07529379
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:
1. Group (Interventional): Coherent Breathing: Slow breathing at 6 breaths per minute. 2. Group (Sham Breathing): Regular breathing at 15 breaths per minute (matching a natural pace). 3. 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.
Interested in participating?
Request Info18 year–60 year
All sexes
Interventional
Not applicable
Bialystok, Podlaskie Voivodeship, 15-222, Poland
Location status: Recruiting
Adam Siebieszuk, Master
PRINCIPAL_INVESTIGATOR
Department of Physiology, Medical University of Bialystok
CONTACT
Marcin Baranowski, PhD
SUB_INVESTIGATOR
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:
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:
Healthy volunteers accepted: Yes
Only the study team can determine whether someone qualifies for participation.
Inclusion criteria
Exclusion criteria
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
Other names: Resonant 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
Other names: Normal-paced Breathing
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.
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.
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).
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.
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.
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 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.
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.
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.
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 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.
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.
Continuous monitoring of mean heart rate (bpm) during active interventions and stress induction to evaluate real-time physiological reactivity and recovery dynamics.
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.
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.
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 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.
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.
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.
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 natural logarithm of the HRV absolute power in the low-frequency band (0.04 - 0.15 Hz).
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 natural logarithm of the HRV absolute power in the high-frequency band (0.15 - 0.40 Hz).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Time frame: At Baseline only (at the start of the Preparation Phase on Day 1).
A 21-item self-report instrument used to characterize the participants' baseline psychological distress over the past week. Subscales for Depression, Anxiety, and Stress (scores 0-21 each) will serve as covariates to analyze the interaction between baseline state and intervention results.
Time frame: At Baseline only (at the start of the experimental session on Day 3).
Measures the participant's stable tendency to respond with anxiety. Scores range from 20 to 80. This trait measure will be used to analyze how personality-level anxiety influences the physiological response to the stressor and breathing tasks.
Time frame: Average respiratory rate 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.
Objective verification of respiratory frequency (breaths per minute) derived from RR interval data using the Kubios RESP algorithm. This measurement is used as a manipulation check to confirm participant adherence to the assigned breathing protocols (6 bpm for the experimental group and 15 bpm for the sham group) and to ensure the internal validity of the experimental blocks.
Contact information is provided by the study sponsor or research team.
Medical University of Bialystok
Other
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