Effects of Combined Thoracic and Diaphragmatic Breathing on Cognitive and Psycho-Physiological Functions

May 27, 2026 updated by: National Taiwan University Clinical Trial Center

The Effects of Combined Thoracic Expansion Exercises and Slow Diaphragmatic Breathing on Cognitive Function, Brain Activation, Psychological Status, and Head-Shoulder Posture in Healthy Adults

This study aims to investigate the effects of a combined thoracic expansion exercise (TEE) and slow diaphragmatic breathing (SDB) program on cognitive function, brain activation, psychological status, and head-shoulder posture in healthy young adults.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

60

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  1. age between 18 to 30 years with at least a high school education to ensure baseline cognitive task comprehension
  2. the ability to adhere to verbal instructions
  3. no regular participation in formal breathing exercise or mindfulness training within the past six months.

Exclusion Criteria:

  1. a history of musculoskeletal, cardiovascular, or cerebrovascular diseases which may interfere this study
  2. history of respiratory disease or recent respiratory infection
  3. diabetes mellitus with neuropathy, peripheral neuropathy, or other neurological disorders
  4. major surgery within the past six months
  5. Current or past major psychiatric disorders or cognitive impairment
  6. use of medications significantly affecting cerebral hemodynamics or autonomic function (e.g., beta-blockers, vasodilators) within the past 2 weeks
  7. use of psychotropic medications or substances known to alter cerebral blood flow, neural activation, or autonomic regulation (e.g., antidepressants, antipsychotics, anxiolytics, stimulants, or sedative-hypnotics).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: rhythmic breathing exercise group
The rhythmic breathing exercise group will perform 10 minutes of thoracic expansion exercises followed by 15 minutes of progressive diaphragmatic breathing (4-s inhalation/6-s exhalation) to facilitate parasympathetic dominance.
Other: thoracic expansion exercises and slow diaphragmatic breathing
4-week supervised training program, consisting of three 30-minute sessions per week. Thoracic expansion exercises consists of chest wall stretching and mobility drills. Followed by 15 minutes of progressive slow diaphragmatic breathing (4-s inhalation/6-s exhalation).
Sham Comparator: natural breathing exercise group
The natural breathing exercise group performed sham thoracic expansion exercises and sham slow diaphragmatic breathing
Other: Sham Block
During sham TEE, participants perform comfortable thoracic movements without foam rollers or specific breathing coordination. During sham SDB, they maintain a spontaneous, natural respiratory rhythm in relaxed postures. Crucially, the sham protocol lacks the rhythmic pacing (4:6s), diaphragmatic depth cues, and resistance-based progression required to trigger the neuro-cognitive "respiratory-brain" axis.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change from baseline in Working Memory
Time Frame: Baseline, Week 5 (post-intervention)
Assessed by the 2-back task. The outcome is calculated as the change in accuracy (percentage of correct responses) and reaction time. Accuracy range from 0% to 100%. Higher accuracy and lower reaction time indicate better working memory capacity.
Baseline, Week 5 (post-intervention)
Change from baseline in Inhibitory Control
Time Frame: Baseline, Week 5 (post-intervention)
Measured by the Stop-signal task (SST). The outcome is the change in Stop-Signal Reaction Time (SSRT) in milliseconds. SSRT values typically range from 100 to 500 milliseconds, with lower scores (faster reaction time) indicating better inhibitory control.
Baseline, Week 5 (post-intervention)
Change from baseline in Mental Set Shifting
Time Frame: Baseline, Week 5 (post-intervention)
Assessed using the Wisconsin Card Sorting Test (WCST). The outcome include the number of categories achieved, perseverative errors and set-loss errors. Higher number of categories achieved, lower perseverative errors and set-loss errors indicate better cognitive flexibility and set-shifting ability.
Baseline, Week 5 (post-intervention)
Change from baseline in Short-Term Memory
Time Frame: Baseline, Week 5 (post-intervention)
Assessed using the Corsi Block-Tapping Task. The outcome is Corsi span score. The Corsi span is defined as the longest sequence accurately reproduced by participants. Scores range from 0 to 9 blocks, with higher scores indicating better short-term memory capacity.
Baseline, Week 5 (post-intervention)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Heart Rate Variability (HRV)
Time Frame: Baseline and Week 5 (post-intervention)
HRV will be assessed as a non-invasive marker of autonomic nervous system (ANS) flexibility and neurovisceral integration, reflecting the dynamic regulation of the prefrontal-vagal pathway. Higher HRV serves as a physiological indicator of superior executive function and emotional regulation, whereas lower values are linked to autonomic dysregulation and cognitive fatigue. Data will be captured using a validated Polar H10 chest strap and the Elite HRV application for precise R-R interval detection. Outcome measurement include time-domain indices (SDNN, RMSSD), frequency-domain measures (HF, LF, and LF/HF ratio), and non-linear metrics (SD1, SD2). Increased RMSSD and HF power will be interpreted as enhanced parasympathetic modulation, providing the physiological foundation for improved attentional control and neural efficiency.
Baseline and Week 5 (post-intervention)
Change in Posture Alignment
Time Frame: Baseline and Week 5 (post-intervention)
  1. Craniovertebral angle (CVA) Measured from a lateral-view in a relaxed standing position. Participants look forward and maintain a comfortable stance during image acquisition. The CVA is the angle between a line connecting the tragus of the ear to the C7 spinous process and a horizontal line passing through C7. A Smaller angle indicates more severe forward head posture.
  2. Acromion-to-table distance (ATD) While supine, the vertical distance between the posterior aspect of the acromion and the table surface is measured. A larger distance indicates increased rounded shoulder posture or thoracic kyphosis.
Baseline and Week 5 (post-intervention)
Change in Psychological status
Time Frame: Baseline and Week 5 (post-intervention)
The Traditional Chinese version of Depression Anxiety Stress Scales-21 (DASS-21) will be used to assess negative emotional states including depression, anxiety, and stress. DASS-21 contains 21 items, with 7 items assigned to each subscale. Participants rate their symptoms over the past week on a 4-point scale ranging from 0 ("did not apply to me at all") to 3 ("applied to me very much or most of the time") in each question. Subscale scores are obtained by summing the 7 items and multiply by two within each domain, with higher scores indicating greater severity of emotional distress.
Baseline and Week 5 (post-intervention)
Change in Brain Activation
Time Frame: Baseline and Week 5 (post-intervention)
Brain activation in the prefrontal cortex, primary motor cortex, supplementary motor area, and premotor cortex during tasks is assessed using functional near-infrared spectroscopy (fNIRS). The specific metric reported is the change in the concentration of oxygenated hemoglobin (HbO). Higher HbO values indicate increased regional cerebral blood flow and higher brain activation.
Baseline and Week 5 (post-intervention)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Taiwan University Clinical Trial Center

Investigators

  • Principal Investigator: Yan Ci Liu, School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

May 25, 2026

Primary Completion (Estimated)

February 1, 2027

Study Completion (Estimated)

February 1, 2027

Study Registration Dates

First Submitted

May 11, 2026

First Submitted That Met QC Criteria

May 27, 2026

First Posted (Actual)

June 2, 2026

Study Record Updates

Last Update Posted (Actual)

June 2, 2026

Last Update Submitted That Met QC Criteria

May 27, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 202603092RIN

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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