Effects of Diaphragmatic Breathing Retraining in Combat Sport Athletes With Dysfunctional Breathing Patterns

Condition(s) studied

Investigational drug(s) / intervention(s)

Diaphragmatic breathing training exercise: Participants will complete one session of diaphragmatic breathing correction. During the session, verbal instruction, manual facilitation, and corrective feedback will be used to guide participants toward a more diaphragmatic breathing pattern. Participants will be instructed to breathe with relaxed shoulders and neck, increase lower rib cage and abdominal expansion, and minimize upper-chest dominant breathing. The intervention is designed to examine the immediate effects of breathing correction on breathing pattern characteristics, diaphragm function, postural alignment, and core stability-related outcomes.

Usual training: Participants continue their regular sport-specific training schedule. They receive non-specific limb stretching and general exercise education but no structured breathing exercises or breathing instruction during the study period.

Study summary

Combat sport athletes often need to maintain a guarded posture, stabilize the trunk, react quickly, and control balance during contact or unexpected movement. These demands may be related not only to strength and conditioning, but also to the coordination between breathing and postural control. The diaphragm is the main muscle for breathing and also contributes to trunk stability through its role in pressure regulation and deep core control. However, dysfunctional breathing patterns, such as upper-chest dominant breathing, reduced lower rib expansion, or poor coordination between the chest and abdomen, may interfere with this function.

The purpose of this study is to examine dysfunctional breathing patterns in combat sport athletes and to investigate whether diaphragmatic breathing retraining can improve breathing patterns, diaphragm function, core stability, postural control, and sport-related performance. This study will first screen athletes from combat and non-combat sports to determine the prevalence of dysfunctional breathing. Combat sport athletes will then complete laboratory tests to examine the relationship between breathing pattern, posture, diaphragm function, core stability, and postural control. In the intervention part of the study, combat sport athletes with dysfunctional breathing will be randomly assigned to diaphragmatic breathing retraining plus usual training or usual training only. The study will compare the two groups to determine whether adding diaphragmatic breathing retraining provides additional benefits. The study will also examine whether the changes are maintained after training and whether baseline measures can help identify athletes who respond better to the program.

Eligibility

Primary outcome measure(s)

• Breathing Pattern_ Total Faulty Breathing Scale (TFBS) Score — Baseline (Day 1), Day 1 (immediately after first session), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Breathing pattern severity assessed using the Total Faulty Breathing Scale (TFBS), a structured observational tool scored 0-12. Higher scores indicate greater breathing dysfunction. Assessed during 10 cycles of quiet and 10 cycles of deep breathing in standing. Also supported by Manual Assessment of Respiratory Motion (MARM).
• Trunk Flexor Endurance _ McGill Curl-Up Hold Test — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Description: Isometric trunk flexor endurance measured as hold time during the McGill Curl-Up Test. A longer time indicates greater endurance. Unit of Measure: seconds
• Back Extensor Endurance _Biering-Sørensen Test — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Isometric back extensor endurance measured as hold time during the Biering-Sørensen Test. A longer time indicates greater endurance. Unit of Measure: seconds
• Movement Speed_10-Meter Sprint Time — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Time to complete a 10-meter maximal sprint from a combat/two-point stance, measured with electronic timing gates. Lower time indicates better performance. Unit of Measure: seconds
• Agility _ T-Test Time — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Time to complete the agility T-test course (sprint forward, lateral shuffles, backward run around 4 cones in a T-shape). Lower time indicates better multidirectional agility. Unit of Measure: seconds
• Visual Motor Reaction Time _ BlazePod System — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Average reaction time to randomly illuminated light pods during a standardized protocol from a fighting stance, using the BlazePod system (BlazePod Ltd.). Lower time indicates faster reaction. Unit of Measure: milliseconds
• Dynamic Balance _ Y Balance Test Composite Score — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Maximum normalized reach distance in the anterior, posteromedial, and posterolateral directions during single-leg stance on the Y-Balance Test. Unit of Measure: percent of leg length
• Reactive Postural Control - Time to Stabilization — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Time to stabilization of center of pressure after an unexpected anterior pulling perturbation (10% body weight), measured via force plate. Lower time indicates better reactive postural control. Unit of Measure: seconds
• Reactive Postural Control - Trunk/Pelvis Angular Displacement — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Angular displacement of the trunk and pelvis during the stabilization phase following an unexpected anterior pulling perturbation, measured via 3D motion capture. Unit of Measure: degrees
• Reactive Postural Control - Trunk/Pelvis Angular Velocity — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Angular velocity of the trunk and pelvis during the stabilization phase following an unexpected anterior pulling perturbation, measured via 3D motion capture. Unit of Measure: degrees per second
• Reactive Postural Control - Peak Ground Reaction Force — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Peak ground reaction force during the stabilization phase following an unexpected anterior pulling perturbation, measured via force plate. Unit of Measure: percent of body weight
• Reactive Postural Control - COP Path Length — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Total center-of-pressure trajectory length during the stabilization phase following an unexpected anterior pulling perturbation, measured via force plate and normalized to foot length. Unit of Measure: mm
• Reactive Postural Control - Trunk Muscle Onset Latency — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  EMG onset latency of trunk muscles relative to perturbation onset, measured via surface electromyography. Unit of Measure: milliseconds
• Reactive Postural Control - Trunk Muscle EMG Amplitude — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Normalized EMG amplitude of trunk muscles during the early stabilization phase following an unexpected anterior pulling perturbation. Unit of Measure: percent of MVIC
• Maximal Inspiratory Pressure (MIP) — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion) Secondary
  Global inspiratory muscle strength was measured in cmH₂O using a gas pressure gauge (Galemed Corporation). Participants exhale maximally, then inhale forcefully against the gauge for ≥1 second with a nose clip applied.
• Maximal Expiratory Pressure (MEP) — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Global expiratory muscle strength is measured using a gas pressure gauge. Participants inhale maximally, then exhale forcefully against the gauge for ≥1 second. Unit of Measure: cmH₂O
• Diaphragmatic Excursion — Baseline (Day 1), Day 1 (immediately after first session), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Maximum diaphragmatic excursion during maximal inspiration and expiration, measured by M-mode ultrasonography with a 1-5 MHz convex transducer in the right mid-clavicular subcostal region. Unit of Measure: cm
• Diaphragmatic Thickening Fraction — Baseline (Day 1), Day 1 (immediately after first session), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Diaphragmatic thickening fraction calculated from B-mode ultrasound measurements of diaphragm thickness at end-maximal inspiration and end-maximal expiration, using a 4-12 MHz linear transducer at the zone of apposition. Unit of Measure: percent
• Proactive Core Stability - Time to Stabilization — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Time to stabilization of center of pressure after single-leg drop landing, measured via force plate. Lower time indicates better proactive core stability. Unit of Measure: seconds
• Proactive Core Stability - Trunk/Pelvis Angular Displacement — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Angular displacement of the trunk and pelvis during the stabilization phase following single-leg drop landing, measured via 3D motion capture. Unit of Measure: degrees
• Proactive Core Stability - Trunk/Pelvis Angular Velocity — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Angular velocity of the trunk and pelvis during the stabilization phase following single-leg drop landing, measured via 3D motion capture. Unit of Measure: degrees per second
• Proactive Core Stability - Peak Ground Reaction Force — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Peak ground reaction force during the stabilization phase following single-leg drop landing, measured via force plate. Unit of Measure: percent of body weight
• Proactive Core Stability - COP Path Length — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Total center-of-pressure trajectory length during the stabilization phase following single-leg drop landing, measured via force plate and normalized to foot length. Unit of Measure: mm
• Proactive Core Stability - Trunk Muscle EMG Amplitude — Baseline (Day 1), Week 8 (post-intervention), Week 16 (8 weeks after intervention completion)
  Normalized EMG amplitude of trunk muscles during the early stabilization phase following single-leg drop landing. Unit of Measure: percent of MVIC

Trial sites (1)

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