Integrative Breathing Therapy: A Multidimensional Framework for Unified Airway Function and Its Application to Orofacial Myology and Obstructive Sleep Apnea

Abstract

Background/Objectives: Breathing efficiency and stability depend on the integrated function of biochemical, biomechanical, and psychophysiological processes across the unified upper and lower airway. Clinical interventions often address these domains in isolation, which may limit treatment outcomes. The primary objective of this article is to present Integrative Breathing Therapy (IBT) as a clinically applicable, multidimensional framework for training unified airway function. A secondary objective is to illustrate how this framework can inform clinical reasoning in orofacial myology and behavioural management of obstructive sleep apnea. Method: This article presents a clinical synthesis of physiological theory, neuroplasticity research, and applied breathing therapy to describe the theoretical and clinical foundations underpinning the Integrative Breathing Therapy (IBT) framework. Multidimensional phenotyping is used to organise dominant biochemical, biomechanical, and psychophysiological contributors to breathing inefficiency, with obstructive sleep apnea presented as a clinical example. Results: This synthesis outlines a unified airway model linking multidimensional phenotyping to targeted intervention selection. The IBT framework provides a structured approach for integrating biomechanical coordination, ventilatory control, and psychophysiological regulation within clinical practice. The obstructive sleep apnea exemplar demonstrates how phenotype-informed mapping can support clinical reasoning and guide individualised intervention strategies within OM and related behavioural approaches. Conclusions: Integrative Breathing Therapy offers a clinically grounded, multidimensional model for functional breathing optimisation that aligns unified airway training with principles of neural adaptation and systems-based clinical reasoning. This framework supports phenotype-guided clinical decision-making and provides a coherent structure for addressing breathing inefficiency and airway instability across a range of clinical populations, including those treated with orofacial myology and behavioural OSA therapies.

1. Introduction

Breathing and airway dysfunction are increasingly recognised as multidimensional problems that may require multidisciplinary and comprehensive interventions. Despite advances in orofacial myofunctional therapy (OMT) and related approaches, clinicians often lack an integrated framework that connects nasal function, tongue and upper-airway behaviour, breathing pattern regulation, and the training processes required for sustainable change, particularly in more complex patients.

This article outlines the IBT approach to breathing and airway rehabilitation, organised around three core concepts: the unified breathing system; the multidimensional nature of breathing; and the application of neuroplasticity principles to the retraining of dysfunctional patterns. This perspective aligns with current directions in OMT while extending them, offering additional conceptual tools for understanding and addressing nasal breathing difficulties, upper-airway impairment, and conditions such as sleep-disordered breathing.

2. The Evolving Landscape of Orofacial Myofunctional Therapy

Orofacial Myofunctional Therapy (OMT) has traditionally focused on the tongue, lips, jaw, and related oral behaviors, using targeted exercises to improve muscle coordination, optimize oral postures, and eliminate dysfunctional habits. Most foundational protocols define OMT within this local orofacial scope, though more recent models have begun to integrate broader airway and systemic considerations, including nasal breathing, craniofacial growth, and sleep-disordered breathing [1].

While the importance of nasal breathing has long been acknowledged within OMT, correction of mouth breathing has traditionally focused on establishing normalized tongue and lip posture, improving orofacial muscle function, and addressing maladaptive oral habits. More recently, emerging protocols have placed greater emphasis on nasal breathing function itself, including airflow mechanics, breathing pattern regulation, and the integration of respiratory and postural control, particularly in the context of sleep-disordered breathing and craniofacial development. This evolution provides an important bridge to the broader, multidimensional focus of IBT described in this article [2,3,4].

A parallel trend within OMT is the growing emphasis on neurological re-education as the foundation for restoring orofacial and nasal breathing function. This shift has expanded OMT beyond mechanical exercise drills toward more comprehensive, system-aware protocols [5].

3. Integrative Breathing Therapy (IBT): A Systems-Based Complement to OMT

Building on these developments within OMT, Integrative Breathing Therapy (IBT) is described here as a systems-based framework that situates orofacial function within the regulation of the unified breathing system as a whole.

While myofunctional interventions primarily focus on tongue, lip, and facial muscle function to support nasal breathing and oral posture, IBT applies these principles across broader physiological, neurological, and behavioural contributors to habitual breathing patterns and airway stability.

IBT conceptualises breathing both as a therapeutic regulator and as a function requiring retraining—using breathing practices to influence autonomic and physiological regulation while simultaneously rehabilitating dysfunctional breathing mechanics and patterns. IBT explicitly assumes that all effective training depends on neuroplastic change in neural circuits supporting breathing, but for clinical reasoning it differentiates three overlapping targets: (1) sensory retraining (e.g., interoceptive and exteroceptive awareness of breathing and orofacial function), (2) autonomic state regulation (e.g., modulating arousal and autonomic balance through specific breathing styles), and (3) behavioural habit retraining of breathing and orofacial patterns. Drawing on neuroplasticity principles, IBT treats breathing as an integrated behavioural process shaped by biomechanical, biochemical, and psychophysiological influences. This systems perspective is particularly relevant in conditions involving upper-airway compromise, including sleep-disordered breathing.

Within this framework, IBT is organized around three core principles:

• The unified breathing system—acknowledging functional continuity from the nasal and orofacial structures through the pharynx, thorax and pelvic floor, such that changes in one region may influence function across the system. This perspective is consistent with osteopathic descriptions of five interconnected ‘diaphragms’—the tentorium cerebelli, tongue, thoracic inlet, respiratory diaphragm and pelvic floor—which together form co-dependent planes involved in respiration, circulation and postural support [6].
• A multidimensional model of breathing—assessing breathing-related dysfunction across biomechanical, biochemical, and psychophysiological dimensions, each contributing to breathing efficiency, airway stability, and adaptive capacity.
• Sensory–autonomic–behavioral retraining—employing graded and varied breathing practice, sensory training for interoceptive accuracy, attentional modulation, behavioural reinforcement, and nervous system regulation to influence habitual breathing patterns and to promote longer-term functional adaptation. These interventions are designed with the expectation of neuroplastic change, but are described in terms of their primary clinical targets for clarity.

Together, these principles situate orofacial interventions within a broader systems framework that considers airway mechanics, respiratory physiology, and neural regulation.

4. Unified Breathing System

In systems-oriented approaches to breathing rehabilitation, it is useful to view the airway as a single connected functional unit. The respiratory tract, from the nose to the lungs, shares mechanical, inflammatory, and neural pathways, such that dysfunction in one region can influence function in others.

The concept of the unified airway describes the functional integration of the upper airway (nose, oral cavity, pharynx, tongue, larynx) and lower airway (trachea, bronchi, lungs). These regions are linked through shared inflammatory mechanisms, similar tissue responses, and coordinated neural control [7]. In the following paragraphs, I outline key shared inflammatory and neuromuscular features of the unified airway. Table 1 then summarises these components and their primary functions as a synthesis of the preceding text.

4.1. Linked Inflammatory Responses

The respiratory tract functions as a continuous biological system, such that inflammation in the nasal or sinus tissues (e.g., allergic rhinitis) can affect the lower airway, including asthma and OSA [8]. Shared inflammatory mediators and structural changes help explain the frequent coexistence of upper- and lower-airway conditions, supporting the clinical relevance of whole-airway perspectives [9].

4.2. Integrated Neuromuscular Control

Effective breathing depends on coordinated activity between the tongue, pharyngeal muscles, diaphragm, and rib cage. These structures function as an integrated system rather than as isolated components, with continuous sensory–motor feedback shaping airway patency and ventilation [10]. During inspiration, for example, reflex activation of the tongue increases the aperture of the upper airway and contributes to airway stabilisation, while coordinated engagement of the diaphragm and intercostal muscles supports airflow and ventilation demands [11,12].

Disruption of this coordination, through chronic stress, inflammation, oxidative stress, dysfunctional breathing or sleep-related breathing disorders, can impair the timing and magnitude of upper-airway muscle activation [13]. In obstructive sleep apnoea, reduced and poorly co-ordinated tongue-muscle activity during sleep is commonly observed and contributes to airway collapse and increased apnea–hypopnea index (AHI) [14].

4.3. Relevance for Breathing Retraining Approaches

The concept of the unified airway provides a useful framework for breathing retraining approaches such as Integrative Breathing Therapy (IBT). Training diaphragmatic activity and lower respiratory mechanics can alter airflow regulation and respiratory muscle coordination across the airway, including the upper airway. Likewise, improvements in nasal and upper airway obstruction may reduce respiratory effort and support restoration of a more functional breathing pattern. This bidirectional interaction suggests that breathing-based interventions may influence both airway function and breathing pattern through integrated mechanical and neural pathways.

In individuals with functional breathing disorders, disruption at one level of the airway, whether mechanical, inflammatory, or neural, may therefore contribute to maladaptive breathing patterns across the system, reinforcing symptoms despite the absence of structural pathology.

Table 1. Structures and Features of the Unified Airway.

Component	Includes	Primary Functions	Shared Features
Upper Airway (Extrathoracic)	Nose, mouth, nasopharynx, oropharynx, laryngopharynx, tongue, larynx	- Conditions, filters, and humidifies incoming air - Regulates airflow through modulation of upper airway resistance, including vocal-fold and supraglottic cotributions - Supports phonation and speech - Protects lower airway	- Similar epithelial and inflammatory responses - Integrated neuromuscular control with muscles of lower airway. - Shares neural pathways with lower airway. - Dysfunction can influence lower airway behavior.
Lower Airway (Thoracic)	Trachea, bronchi, bronchioles, alveoli	- Conducts air to the lungs - Gas exchange (alveolar)	- Linked inflammatory mechanisms with upper airway disease. - Shares sensory and autonomic innervation with upper airway. - Dysfunction can influence upper airways.
Primary Muscles of Breathing	Diaphragm, intercostals	- Generate pressure gradients by changing thoracic volume - Main drivers of quiet breathing	- Work synergistically with both upper, thoracic and pelvic structures to regulate airflow and support ventilation within an integrated pressure system.
Secondary (Accessory) Muscles of Breathing	Sternocleidomastoid, scalenes, upper trapezius, pectoralis minor, abdominal muscles	- Provide additional thoracic and abdominal expansion or compression during increased demand or dysfunction	- Often recruited when airway or breathing control is compromised; their activity reflects system-wide respiratory and postural integration, including intra abdominal and pelvic pressure regulation.

Primary functions and shared features are summarised from current descriptions of upper and lower airway physiology and unified airway models [15,16,17].

Table 1. Structures and Features of the Unified Airway.

Component	Includes	Primary Functions	Shared Features
Upper Airway (Extrathoracic)	Nose, mouth, nasopharynx, oropharynx, laryngopharynx, tongue, larynx	- Conditions, filters, and humidifies incoming air - Regulates airflow through modulation of upper airway resistance, including vocal-fold and supraglottic cotributions - Supports phonation and speech - Protects lower airway	- Similar epithelial and inflammatory responses - Integrated neuromuscular control with muscles of lower airway. - Shares neural pathways with lower airway. - Dysfunction can influence lower airway behavior.
Lower Airway (Thoracic)	Trachea, bronchi, bronchioles, alveoli	- Conducts air to the lungs - Gas exchange (alveolar)	- Linked inflammatory mechanisms with upper airway disease. - Shares sensory and autonomic innervation with upper airway. - Dysfunction can influence upper airways.
Primary Muscles of Breathing	Diaphragm, intercostals	- Generate pressure gradients by changing thoracic volume - Main drivers of quiet breathing	- Work synergistically with both upper, thoracic and pelvic structures to regulate airflow and support ventilation within an integrated pressure system.
Secondary (Accessory) Muscles of Breathing	Sternocleidomastoid, scalenes, upper trapezius, pectoralis minor, abdominal muscles	- Provide additional thoracic and abdominal expansion or compression during increased demand or dysfunction	- Often recruited when airway or breathing control is compromised; their activity reflects system-wide respiratory and postural integration, including intra abdominal and pelvic pressure regulation.

Primary functions and shared features are summarised from current descriptions of upper and lower airway physiology and unified airway models [15,16,17].

5. The Multidimensional Nature of Breathing

Breathing is a complex, adaptive behaviour that emerges from interactions across multiple physiological and psychological domains. In frameworks such as Integrative Breathing Therapy (IBT), breathing is conceptualised as multidimensional, shaped primarily by three interrelated systems: the biochemical, biomechanical, and psychophysiological dimensions [18]. Each dimension influences the others, and dysfunction in any domain can affect overall respiratory function. Recognising these interconnections provides a framework for assessment and intervention that goes beyond approaches focused on isolated aspects of breathing.

5.1. Biochemical Dimension

This dimension encompasses gas exchange, chemosensitivity to carbon dioxide, acid–base regulation, and metabolic demand. Alterations in CO₂ sensitivity, chronic over-breathing, or breath-holding habits can influence respiratory drive and contribute to sympathetic arousal, airway instability, and symptoms such as dyspnoea or dizziness. Breathing exercises targeting biochemical function include controlled nasal breathing, slow relaxed breathing, and CO₂ tolerance exercises, which may be performed with or without biofeedback [19].

5.2. Biomechanical Dimension

The biomechanical dimension refers to structural and movement-based aspects of breathing, including ribcage mobility, diaphragmatic function, postural alignment, upper-airway mechanics, and orofacial contributions to airflow. Restrictions or inefficiencies in these systems can lead to compensatory patterns such as upper-chest breathing, excessive accessory muscle use, or oral breathing, which may disrupt airflow and autonomic regulation. Interventions may include manual therapy, postural and motor retraining, upper-airway and nasal muscle rehabilitation, and breathing exercises designed to restore relaxed, flexible, and functional breathing patterns.

5.3. Psychophysiological Dimension

This dimension reflects the influence of emotional state, autonomic regulation, stress reactivity, attentional patterns such as hypervigilance, and fear-conditioned responses to breathing. Factors such as chronic stress, heightened threat sensitivity, perfectionism, or trauma can reinforce high-effort breathing strategies, including bracing, rapid shallow breathing, or highly irregular breathing with involuntary breath-holding during cognitive load. Addressing this dimension may involve autonomic downregulation strategies, interoceptive training, cognitive reframing, and neuroplasticity-informed habit change to support more adaptable respiratory patterns.

While each dimension contributes uniquely to overall function, these domains are inseparable in practice. Biochemical dysregulation can drive mechanical rigidity, mechanical inefficiencies can increase psychophysiological load, and stress physiology can influence both chemistry and movement. Considering all three dimensions may therefore support more precise assessment and the development of personalised therapeutic pathways.

Finally, the multidimensional model interfaces directly with neuroplastic mechanisms: each domain—biochemical, biomechanical, and psychophysiological—modulates both sensory (afferent) and motor (efferent) control of the unified airway, providing a foundation for integrated, adaptive interventions.

6. Mechanisms of Neuroplasticity: The Whole-System Approach

The following subsections summarise key neuroplastic mechanisms through which breathing and airway function may adapt to training. Neuroplasticity—the nervous system’s capacity to reorganise neural connectivity and function in response to experience—is central to effective breathing and airway rehabilitation [20]. These adaptive processes involve interacting biomechanical, biochemical, and neural pathways and exhibit learning and memory effects shaped by prior patterns of stimulation [21].

6.1. Breathing Brain Connections

Breathing rhythms influence neural activity across multiple brain regions and can support adaptive change. Respiratory cycles coordinate oscillatory activity in areas including the olfactory bulb, parietal cortex, amygdala, and medial prefrontal cortex (mPFC). Inhalation and exhalation modulate neuronal timing involved in interoception, emotional processing, and action preparation, generating respiration-modulated brain oscillations (RMBO) [22].

Nasal and oral breathing engage partially distinct neural pathways [23,24]. While both influence baroreflex-related brain rhythms—particularly at slower breathing rates around 0.1 Hz—nasal airflow uniquely entrains activity via olfactory pathways. Projections from the olfactory bulb reach limbic and cortical regions involved in emotion, memory, and learning, including the amygdala, piriform cortex, and mPFC [25]. These pathways provide a plausible neurophysiological basis through which nasal breathing retraining may influence emotional regulation, anxiety, and cognitive clarity.

Consistent with this view, subjective nasal obstruction is associated with elevated anxiety even in the absence of clear structural pathology [26]. Rhinitis has also been linked to increased risk of depression, and olfactory impairment is associated with depressive symptoms, memory deficits, and cognitive decline [27,28]. While these associations do not establish causality, they highlight the close relationship between nasal sensory input, breathing, and brain function.

Attending to sensations of smell, nasal airflow, body movement, and sound increases respiration-linked sensory input and may enhance afferent signalling through olfactory and trigeminal pathways. Training olfactory awareness and mindful attention to nasal sensation may therefore support mood regulation and cognitive function, particularly in individuals with reduced nasal sensory engagement. Within IBT, conscious smelling and mindful nasal attention are incorporated as components of functional nasal rehabilitation, informed by evidence of sensory deafferentation associated with reduced nasal use [4].

6.2. Sensory and Motor Pathways of Neuroplasticity

Adaptive plasticity of the unified airway depends on sensory (afferent) signals from the nose, upper and lower airways, and chemoreceptors that project to the brain’s respiratory control centers. These inputs coordinate motor (efferent) output through the hypoglossal, phrenic, and intercostal nerves, enabling the tongue, pharynx, diaphragm, and chest wall to function as a single unit [29].

Afferent information related to O₂, CO₂, pH, and mechanical stretch is conveyed primarily via the vagus (X) and glossopharyngeal (IX) nerves to the nucleus tractus solitarius (NTS). Trigeminal (V) inputs from nasal and facial receptors signal airflow and resistance, influencing breathing patterns and upper-airway muscle drive [30].

Motor pathways to the upper airway run predominantly through the hypoglossal nerve (XII), while the phrenic and intercostal nerves supply the diaphragm and rib cage. The respiratory central pattern generator (rCPG) provides an important source of respiratory-related drive to these motor pools, contributing to coordination between tongue, diaphragm and chest-wall behaviour. However, studies of hypoglossal motoneurons show that tongue muscle activity is shaped by a complex convergence of respiratory premotor inputs, chemosensory and mechanosensory feedback, and sleep–wake-dependent neuromodulation, rather than by a simple uniform rhythmic signal. IBT therefore treats the tongue and upper airway muscles as respiratory effectors whose function reflects this multi-level central control [7,12].

From a neuroplasticity perspective, breathing retraining can be understood as modulation of afferent sensory input to influence central respiratory control and downstream motor output. Specific breathing modifications preferentially engage different sensory pathways: attention to nasal airflow enhances trigeminal input; changes in lung volume, breathing rate, or inspiratory–expiratory ratios influence vagal mechanoreceptors; and breath-holding or controlled hypoventilation engages chemoreceptor-based afferent systems. Respiratory muscle training further alters afferent feedback and motor drive through phrenic and intercostal pathways.

Together, these strategies enable graded, task-specific engagement of sensory–motor circuits and support adaptive neuroplastic change within the unified breathing system.

6.3. Adaptive Long-Term Facilitation

A key mechanism of neuroplastic change in breathing is long-term facilitation (LTF), a form of serotonin- and adenosine-dependent synaptic plasticity that enhances baseline activation of phrenic and hypoglossal motoneurons, increasing respiratory pump and upper-airway muscle tone [31,32]. Fluctuations in oxygen, carbon dioxide, and mechanical load modulate this response and shape motor output to both upper and lower airway muscles [33].

LTF may be adaptive or destabilising depending on chemoreceptor sensitivity, ventilatory drive, and background CO₂ levels [34]. Mild intermittent hypoxia within a controlled range can enhance airway stability when ventilatory drive is not excessive and CO₂ is maintained within normal physiological limits [35]. In contrast, hypocapnia reduces neural drive—particularly to upper-airway muscles—while excessive hypoxia or hypercapnia, as seen in severe OSA, may impair coordination and plasticity [36].

Mild intermittent hypoxia has therefore been explored as a therapeutic stimulus in conditions such as sleep apnoea and asthma [20]. This can be delivered through controlled breath-holding practices or Intermittent Hypoxia Training (IHT) using specialised devices. When carefully titrated, IHT may promote adaptive LTF and normalise chemosensitivity, potentially improving upper-airway muscle responsiveness [37,38]. However, these effects are highly protocol-dependent, and inappropriate dosing may increase loop gain or respiratory instability, particularly in individuals with severe OSA or motor control disorders [39].

In addition to hypoxic stimuli, increased respiratory load—such as higher inspiratory pressure or lung volume—can strengthen hypoglossal motor output and support airway patency, as occurs during exercise or with inspiratory resistance training [40,41].

Overall, carefully dosed modulation of hypoxia, CO₂, and mechanical load can induce adaptive neuroplastic changes in breathing and upper-airway control. While these mechanisms provide a plausible foundation for therapeutic intervention, clinical application—particularly in OSA—remains an emerging field requiring individualised protocols and further research [35,42].

7. Clinical Application of IBT’s Multidimensional Neuroplasticity Approach: Sleep Apnea

In this section, the general IBT framework described above is applied to obstructive sleep apnea (OSA) as an example of how unified airway concepts, multidimensional phenotyping, and neuroplasticity-informed training can guide clinical reasoning. Dysfunctional breathing in sleep apnea can act as both a contributor to, and a consequence of, the condition. Biomechanical, biochemical, and psychophysiological drivers often overlap and interact, leading to the persistence of disordered breathing patterns and related symptoms [43,44]. These patterns reflect a combination of adaptive and maladaptive changes across both the upper and lower airways [45]. While adaptive neuroplastic changes support airway stability and efficient coordination, maladaptive patterns may reinforce airway collapsibility, ventilatory instability, and symptom expression. Sleep apnea therefore provides a clear illustration of the unified airway and multidimensional framework underpinning breathing rehabilitation, highlighting the need for individualized interventions that reinforce adaptive neuroplastic change across the respiratory system.

Taken together, these concepts support a phenotype-guided approach to breathing rehabilitation in sleep apnea. Within this approach, sleep apnea is understood through the lens of a unified airway, assessed using a multidimensional framework, and addressed through interventions designed to reinforce adaptive neuroplastic change. The sections that follow outline how unified airway function, multidimensional phenotyping, and phenotype-specific intervention pathways can be integrated to guide targeted breathing rehabilitation.

7.1. Unified Airway and Functional Coordination

The unified airway model recognises the nose, pharynx, larynx, and lower airway as an integrated functional system. Anatomical, neural, and inflammatory interdependence means that dysfunction in one region can destabilise others, contributing to airway collapsibility and ventilatory inefficiency. For this reason, IBT treats nasal function as foundational, supporting airflow regulation, sensory feedback, and neuromotor coordination. Upper airway retraining is embedded within respiratory timing, diaphragmatic mechanics, and posture, ensuring that airway support is trained as a coordinated, cycle-linked function rather than as isolated muscle strength work.

7.2. Neuroplasticity-Informed Training

Respiratory and upper airway control networks are activity-dependent and highly plastic. IBT incorporates phase-locked breathing interventions designed to reinforce adaptive coordination across the upper and lower airway. Tongue, soft palate, and pharyngeal activation are specifically trained in synchrony with both inspiratory and respiratory phases, with the aim of enhancing integration between hypoglossal, phrenic, and intercostal motor output. Mindful attention to sensory input, carbon dioxide modulation, and carefully titrated hypoxic exposure are also employed to further support long-term facilitation and stabilization of airway motor control.

7.3. Multidimensional Phenotyping and Intervention Pathways

Assessment considers the relative contribution of three interacting dimensions—biochemical, biomechanical, and psychophysiological—mapped to the key physiological traits described in obstructive sleep apnea, including ventilatory control instability (high loop gain), impaired responsiveness of upper airway dilator muscles, and a low arousal threshold [46].

Biochemical factors include ventilatory control instability and heightened carbon dioxide sensitivity, which may contribute to oscillatory breathing and ventilatory overshoot. Biomechanical factors encompass ribcage and diaphragmatic mechanics, tongue posture, pharyngeal compliance, and habitual oral breathing, influencing passive airway collapsibility and the effectiveness of upper airway muscle recruitment. Psychophysiological factors include autonomic tone, arousal threshold, and threat sensitivity, which modulate respiratory control, sleep continuity, and arousal propensity. These dimensions rarely occur in isolation; rather, their interaction reflects the trait overlap and heterogeneity commonly observed in obstructive sleep apnea.

Once nasal breathing has been established and baseline breathing patterns stabilised (as outlined in the unified airway and neuroplasticity-informed training sections), IBT interventions are guided by the dominant physiological trait profile. In presentations characterised by elevated loop gain or carbon dioxide intolerance, intervention prioritises stabilisation of ventilatory control through breathing pattern retraining and CO₂ tolerance work, consistent with approaches aimed at reducing ventilatory instability; mild intermittent hypoxia may be introduced cautiously once baseline regulation improves. Where impaired responsiveness of upper airway dilator muscles predominates, training emphasises biomechanical and neuromuscular retraining of the tongue and pharyngeal musculature in synchrony with the breathing cycle, supporting improved airway muscle recruitment during vulnerable phases of respiration. In mixed presentations involving heightened arousal propensity and ventilatory dysregulation, intervention integrates slow, cycle-linked breathing, autonomic downregulation, and interoceptive training, consistent with trait-based strategies aimed at increasing arousal threshold, alongside airway retraining to support respiratory stability.

Across phenotypes, nasal breathing rehabilitation and stabilisation of baseline breathing patterns remain a consistent foundation, supporting unified airway function and facilitating adaptive coordination across the respiratory system.

Table 2. Trait-Informed Multidimensional Phenotyping and IBT-Guided Intervention Pathways in Sleep Apnea.

Dominant Phenotype	Primary Dimension	Key Features	IBT informed Intervention Focus
Elevated loop gain/ventilatory control instability	Biochemical (with psychophysiological interaction)	Heightened CO2 sensitivity, ventilatory overshoot, oscillatory breathing patterns, frequent respiratory arousals	Breathing pattern retraining to support ventilatory stability; CO2 tolerance work as described in neuroplasticity-informed training; cautious introduction of mild intermittent hypoxia once baseline breathing regulation improves
Impaired responsiveness of upper airway dilator muscles	Biomechanical (with neural drive interaction)	Reduced or poorly timed tongue and pharyngeal muscle activation, increased airway collapsibility, oral breathing tendency	Phase-locked retraining of tongue, soft palate, and pharyngeal musculature synchronised with the breathing cycle, consistent with unified airway and airway neuromuscular training sections; resistance-based respiratory loading where appropriate
Low arousal threshold with ventilatory dysregulation	Psychophysiological with ventilatory dysregulation (with biochemical and biomechanical overlap)	Heightened autonomic tone, increased arousal propensity, sleep fragmentation, variable breathing patterns	Slow, cycle-linked breathing; autonomic downregulation and interoceptive training as outlined in psychophysiological regulation sections; airway retraining to support respiratory stability

Traits are adapted from established physiological models of obstructive sleep apnea, including ventilatory control instability (loop gain), upper airway muscle responsiveness, and arousal threshold. Suggested IBT intervention foci are extrapolated from existing literature on breathing retraining, intermittent hypoxia, and orofacial myofunctional and airway-focused therapies [42,46].

summarises the IBT phenotype-guided rehabilitation framework for sleep apnea, illustrating how unified airway concepts, trait-informed phenotyping, and neuroplasticity-informed training principles are integrated to guide targeted breathing rehabilitation.

7.4. Integration with Conventional Therapies

IBT is not positioned as a replacement for continuous positive airway pressure (CPAP), oral appliances, neuromodulation devices, or orofacial myofunctional therapy (OMT), but as a complementary, phenotype-informed approach. By addressing nasal function, ventilatory control stability, and behavioural and autonomic regulation, IBT may support tolerance to conventional therapies, reduce residual ventilatory instability, and assist functional adaptation beyond periods of device dependence.

Framed within established physiological trait models of obstructive sleep apnea, IBT aims to complement device-based and mechanical interventions by targeting modifiable contributors to breathing instability that may not be fully addressed by structural support alone.

7.5. Clinical Implications for Orofacial Myofunctional Therapy Practice

From an orofacial myofunctional therapy perspective, the IBT framework provides a broader explanatory context for variability in patient response to conventional protocols. Traditional OMT approaches emphasise strengthening and coordination of the tongue, lips, and orofacial musculature to support nasal breathing and airway patency. However, residual symptoms or unstable gains may persist when breathing pattern regulation, ventilatory control instability, or heightened psychophysiological arousal are not concurrently addressed.

A multidimensional, trait-informed approach encourages clinicians to consider whether apparent non-compliance, fatigue, or plateauing reflects underlying physiological contributors such as elevated loop gain, impaired timing or responsiveness of upper airway dilator muscles, or psychophysiological factors including hypervigilance and low arousal threshold. In such cases, excessive emphasis on isolated or high-load muscle activation may inadvertently increase respiratory effort or sympathetic activation, potentially undermining airway stability.

Within the IBT framework, myofunctional retraining is reframed as a task of coordination and timing embedded within the breathing cycle rather than as isolated strength-based exercise. Integrating nasal breathing rehabilitation, respiratory pacing, and autonomic regulation strategies may improve tolerance to orofacial exercises and enhance carryover into sleep and daily function. This perspective also supports flexible dosing, sequencing, and progression of exercises based on individual regulatory capacity and dominant physiological trait profile.

For OMT practitioners, incorporating unified airway assessment and multidimensional screening may refine clinical reasoning, improve matching of patients to specific intervention strategies, and reduce variability in outcomes. Rather than replacing established myofunctional techniques, IBT offers a complementary framework that situates them within whole-system breathing regulation and training-informed adaptation.

7.6. Limitations and Future Directions

This article presents a clinically informed synthesis rather than a definitive treatment protocol. Although the framework draws on established research in respiratory physiology, airway control, autonomic regulation, and training-related neuroplasticity, evidence specific to IBT as an integrated intervention in sleep apnea remains emergent and is largely extrapolated from related fields.

Future research should include controlled studies of phenotype-guided breathing interventions, mechanistic investigations linking breathing pattern modification to airway stability during sleep, and comparative evaluations alongside conventional orofacial myofunctional therapy and device-based treatments. As this evidence base develops, phenotype-guided IBT frameworks may offer clinicians a structured, evidence-informed approach to tailoring breathing rehabilitation in sleep apnea.

8. Conclusions

Integrative Breathing Therapy (IBT) offers a clinically grounded, multidimensional framework that brings together unified airway concepts, breathing biomechanics, ventilatory control, autonomic regulation, and orofacial function within a single systems-based model for practice. By organising assessment and intervention around biochemical, biomechanical, and psychophysiological dimensions, and then applying this structure in a phenotype-guided way—as illustrated with obstructive sleep apnea—IBT supports more targeted selection and sequencing of sensory, autonomic, and behavioural breathing interventions. For orofacial myofunctional therapists, this perspective reframes tongue and orofacial retraining as coordination- and timing-focused tasks embedded within the breathing cycle and supported by nasal rehabilitation and autonomic regulation, rather than as isolated strength exercises. Positioned alongside CPAP, oral appliances, neuromodulation, and conventional OMT, IBT is proposed not as a replacement but as a complementary clinical reasoning framework that may help explain variability in treatment response, facilitate integration of therapies, and guide future research on personalised, whole-system breathing rehabilitation in sleep-disordered and dysfunctional breathing populations.