SIGNAL VS. NOISE IN PHYSICAL THERAPY

What Physical Therapy Has Been Getting Wrong-and the Science That Points Us Forward

A precision framework for separating clinical signal from professional noise across manual therapy, therapeutic exercise, and neuromuscular control

THE PROBLEM: A DISCIPLINE RICH IN TECHNIQUE, POOR IN SIGNAL

Physical therapy is, in many respects, a discipline undergoing active change. The clinical literature and empirical evidence has never been richer. Imaging, mechanobiology, and behavioral science have provided frameworks that would have been unrecognizable to clinicians even twenty years ago. And yet, in the average outpatient clinic on any given Tuesday morning, patients are receiving care built on biomechanical metaphors from the 1960s, compliance-dependent home programs that most won’t complete, and neuromuscular protocols anchored to motor control theories that the research community has quietly moved past (or validated).

The gap between what the science says and what happens in practice is not just the void in knowledge problem, it’s a signal-to-noise problem. Physical therapy as a profession generates enormous amounts of both. The challenge for health system leaders, payers, and clinicians who want to drive genuine outcomes is learning to distinguish one from the other.

We cannot question the clinical efficacy of PT. The evidence is clear that it does. The question is which parts work, why they work, and whether the profession can adminster the intellectual discipline to shed what it cannot defend.

This post maps that differentiation across three core domains of physical therapy practice-manual therapy, therapeutic exercise, and neuromuscular control. At the conclusion, we should explore the broader organizational and systemic implications for health systems as they navigate an increasingly value-driven care. In each case, the structure is the same: identify the signal the science actually supports, name the noise that has accumulated around it, and consider what separating the two would demand of clinicians and executives alike.

MANUAL THERAPY: THE SIGNAL IS NEUROLOGICAL, THE NOISE IS STRUCTURAL

What the Evidence Actually Says

For decades, the dominant story told about manual therapy-spinal manipulation, joint mobilization, soft tissue work-was a biomechanical one (or at least on the tissue level). Adjustments corrected subluxations. Mobilizations restored joint play. PPIVM, PAVM. I recently taught a kinesiology course. All of this is very much a part of CAPTA supported curriculum. The therapeutic value of a skilled clinician’s hands on a patient’s body is explained through tissue mechanics: you are moving something that is stiff, tight ore restricted, releasing something that was compressed, freeing something that had adhered(don’t get me started on adhesions). It was a logical story. It was also, as the accumulating neurophysiological evidence now makes plain, largely incorrect.

A 2025 systematic review published in the Journal of Clinical Medicine, reviewed randomized controlled trials on spinal manual therapy techniques, found consistent evidence that the primary short-term effects of these interventions operate through the central and autonomic nervous systems-not through the mechanical disruption of articular structures. Across included trials, spinal manipulative therapy produced measurable changes in pain perception thresholds, autonomic markers including heart rate variability and skin conductance, and central sensitization metrics. The structural changes traditionally invoked to explain these effects were largely not demonstrated.

A living review of manual therapy mechanisms published in PLOS ONE in 2025, drawing on systematic, narrative, and scoping reviews through September 2024, cataloged the entire volume of literature and proposed mechanisms and found that neurological, neuroimmune, neurovascular, and neurotransmitter-level effects represented the most consistent and replicable findings across the literature (Alanez et al., 2025). Biomechanical mechanisms-tissue movement, fluid loading, articular realignment-remained theoretically proposed but empirically underspecified. The central nervous system, in short, is where manual therapy lives.

CNS > Joints

Neurophysiological changes documented following spinal manual therapy include altered pain thresholds, autonomic nervous system responses, and CNS activation patterns-effects inconsistent with purely biomechanical explanations.

Jupin et al., 2025, J. Clin. Med.; Alanez et al., 2025, PLOS ONE

The Noise That Has Accumulated

The noise in manual therapy is theoretical inertia. The profession has retained-and, in many instances, doubled down on-explanatory frameworks-palpatory diagnosis of structural asymmetry, segmental assessment, and targeted joint manipulation-that the evidence does not support as primary mechanisms. This matters because the story told to justify them shapes clinical reasoning in ways that produce real downstream harm.

When a clinician believes they are correcting structural dysfunction, they design a treatment episode accordingly: they identify the dysfunctional segment, apply the specific technique to that segment, and reassess the structural finding. There is an entire body of literature on diagnostic labeling we can cover at a later time (and also on clinical uncertainty). The nervous system-the actual site of therapeutic action-is not part of this loop. Patients are informed, implicitly or explicitly, that their tissue is damaged or misaligned, that expert detection of that damage is necessary, and that only the clinician’s hands can correct it. This model creates clinical dependency and nocebo effects that are now among the best-documented barriers to recovery in musculoskeletal pain.

When a patient leaves a manual therapy session believing their spine is ‘fixed’ until it ‘goes out’ again, the clinician has used a neurological tool to deliver a structural belief-and that belief may cause more harm than the technique causes benefit.

The organizational implication is clear: health systems investing in manual therapy as a service line need to assess not just whether their clinicians can perform techniques competently, but whether the explanatory models their clinicians use are coherent with what the science supports. A technically skilled manipulator operating from an outdated theoretical framework is a clinical liability, not an asset.

THERAPEUTIC EXERCISE: THE SIGNAL IS MECHANICAL LOAD, THE NOISE IS PRESCRIPTION COMPLEXITY

What the Evidence Says

Of all the interventions in the physical therapy toolkit, therapeutic exercise has the deepest and most durable evidence base. But the strength of that evidence is concentrated in a specific mechanism-mechanical loading and the downstream biological cascades it triggers-that has become obscured under layers of prescription complexity, specificity requirements, and compliance architecture that the science does not justify. Yes, specificity rarely matters in tx.

The biological case for load as the primary therapeutic signal is now well established. Mechanotransduction-the conversion of mechanical stimuli at the cellular level into biochemical cascades governing tissue remodeling, collagen synthesis, and structural adaptation-is the central mechanism by which exercise produces tissue-level change. A 2024 review in Cell Physiology and Biochemistry demonstrated that tensile loading in tendinopathic tissue, which is roughly 20% of all musculoskeletal complaints, stimulates tenocyte reorganization, collagen fiber alignment along stress trajectories, and gap junction-mediated intercellular communication that drives coordinated repair (Gögele et al., 2024).

The clinical implication is simple and linear: the most important variable in a therapeutic exercise prescription is not the exercise. It is the load. Whether that load is delivered through an isometric contraction, an eccentric protocol, a progressive resistance program, or a functional movement pattern matters far less than whether the tissue in question is receiving sufficient mechanical stimulus to activate the repair cascade. The exercise is the delivery vehicle. Load is the drug.

Load = Signal

Mechanical loading stimulates collagen synthesis, fiber realignment, and structural tissue repair through well-characterized mechanotransduction pathways-independent of exercise modality or movement pattern specificity.

Gögele et al., Cell Physiol. Biochem., 2024; ScienceDirect Mechanobiology Review, 2025

The Noise: Compliance Architecture and False Specificity

Against this clean biological signal, the profession has erected an elaborate structure of noise. Home exercise programs remain a foundational component of physical therapy delivery, yet adherence data consistently demonstrate that they fail a substantial proportion of patients. If this is our primary clinical tool, the profession should be alarmed at this finding. A study in Musculoskeletal Science and Practice found non-adherence to home exercise programs as high as 70% in patients with neck pain, with adherent patients showing significantly superior functional outcomes-a finding that underscores both the importance of adherence and the fact that, for most patients, current prescription models fail to achieve it (ScienceDirect, 2023). A 2024 cross-sectional study of 300 patients at an academic outpatient pain clinic found that fewer than half fully adhered to their home programs, with pain experience during exercise and insufficient patient education emerging as primary barriers (Petrosyan et al., 2024).

The deeper problem is that the profession’s response to poor adherence has largely been to add complexity-more exercises, more repetitions, more instructional materials, more follow-up calls-when the evidence suggests the solution is structural simplification and load prioritization. If the signal is mechanical load, then a patient who performs two exercises with appropriate resistance and consistency has received more therapeutic input than a patient who irregularly completes a 12-exercise protocol prescribed to target specific muscle activation sequences based on movement analysis. Let’s just think about patients still doing their McKenzie protocol from 20 years ago. Is the spine effectively loaded (yes, pain modulation, directional preference, etc, I get it, but still).

The noise around exercise specificity is just as worth naming. The clinical culture around therapeutic exercise has, over the past two decades, developed a strong affinity for precision movement prescriptions: specific activation of specific muscle groups at specific points in a range of motion, with specific cues and specific feedback mechanisms. Trust me, holding the director position for the last decade, the complexity of digital exercise customization in mind boggling. This level of specificity has intuitive appeal and value in certain clinical contexts-post-surgical rehabilitation, elite athletic performance, and in some level of neurological care. But as a general model for musculoskeletal pain management, it is unsupported by evidence and creates clinical environments in which exercise prescription becomes so burdensome that it fails on both adherence and efficiency grounds.

A patient who performs two simple loaded exercises three times per week, consistently, for twelve weeks has almost certainly received more therapeutic mechanotransduction than the patient who was given sixteen exercises, understood half of them, and completed 30% of their program. Load progression is the key, not exercise specificity.

For health systems and payers, the signal is clear: outcomes in therapeutic exercise are driven by load dosing and adherence, not by program complexity. Quality metrics and utilization review frameworks that reward prescriptive complexity are rewarding noise. Frameworks that prioritize load documentation, functional outcome tracking, and adherence support are chasing signal. If you are documenting loads and justifying it in your documentation, the payers will support it.

NEUROMUSCULAR CONTROL: THE SIGNAL IS THE NERVOUS SYSTEM, THE NOISE IS THE MODEL

What the Evidence Actually Says

Neuromuscular control is, of the three domains addressed in this post, the one with the most intellectually exciting contemporary evidence-and also the one where the gap between the research literature and clinical practice is perhaps most striking. The science of how the nervous system controls movement, adapts to pain, and learns new motor patterns has advanced substantially over the past decade. The clinical frameworks through which physical therapists commonly address these phenomena have not kept pace.

A 2022 paper in Physical Therapy reviewing the current state of motor learning science documented that there are now at least four distinguishable mechanisms through which motor learning occurs-use-dependent, instructive, reinforcement, and sensorimotor adaptation-based learning-each governed by distinct neural substrates and each responsive to different clinical inputs. The implications for physical therapy practice are significant: movement rehabilitation is not a single process, but a family of processes, and the interventions that optimize one do not necessarily optimize others. Critically, the authors noted that passive or overly guided movement practice-a staple of traditional neuromuscular facilitation protocols-does not reliably produce the neuroplastic changes associated with durable motor behavior change.

The link between neuromuscular control, behavioral adaptation, and psychological state is now equally well established. Central sensitization-the upregulation of pain processing in the spinal cord and brain that transforms local tissue signals into a persistent, distributed pain experience-is a neurological phenomenon, not a psychological one, though psychological factors profoundly modulate its expression. A study protocol published in PLOS ONE in 2024 investigating PNE combined with neuromuscular exercise for chronic low back pain articulated a model in which addressing the nervous system’s altered processing state alongside targeted loading produces superior outcomes to either intervention alone-a finding consistent with a broader meta-analytic literature showing that cognitive-behavioral elements combined with neuromuscular training outperform exercise alone for persistent spinal pain.

Active > Passive

Passive or overly guided movement practice does not produce the neuroplastic changes required for durable motor behavior change-a finding with direct implications for facilitation-based physical therapy protocols.

The Noise: Bobath, Specificity Dogma, and the Refusal to Update

The noise in the neuromuscular domain is the persistence of frameworks whose theoretical foundations have been substantially revised or abandoned by the research community. The Bobath concept, developed in the 1940s and still taught and practiced in neurological rehabilitation settings internationally, rests on assumptions about motor control, reflex inhibition, and tone normalization that are inconsistent with contemporary neuroscience. This permeated pediatric and neurological rehab flow. A 2024 article in the Journal of Neurological Disorders and Stroke reviewing motor learning in the context of PNF-based neurorehabilitation found that evidence for specific facilitation techniques producing distinct neurological effects remains limited, while the general principle of active, task-oriented practice with feedback has robust empirical support across neuroplasticity research.

The motor control specificity debate within musculoskeletal physical therapy is equally sounded. A widely cited viewpoint in the Journal of Orthopedic and Sports Physical Therapy traced the rise of motor control exercise-particularly transversus abdominis activation protocols and spinal stabilization programs-to biomechanical models of spinal instability that subsequent research has not supported as clinically meaningful frameworks. The theoretical architecture linking specific deep muscle activation to spinal stability was built on Panjabi’s stabilization model and Bergmark’s biomechanical theory-a combination that gave rise to decades of lumbar stabilization protocols that, when examined rigorously, the research supports only modestly and non-specifically.

The conclusion from this body of work is through the effects that are mediated by nervous system conditioning, behavioral adaptation, and context-dependent motor learning-not by the specific muscle activation sequences or facilitation techniques that many protocols nominally target. The signal is the nervous system’s plasticity, its responsiveness to meaningful, challenging, active practice. The noise is the theoretical superstructure that claims to explain exactly which neurons we are training and precisely how.

The nervous system does not care about your model. It responds to challenge, context, repetition, and meaning. Physical therapy’s task is to create those conditions-not to impose a theoretical framework that the evidence cannot support.

PHYSICAL THERAPY AS A SYSTEM: THE SIGNAL IS VALUE, THE NOISE IS THE STATUS QUO

The Organizational Case for Signal Clarity

The three clinical domains examined above come to a common organizational problem: a profession that generates clinical value through specific, neurobiologically grounded mechanisms but delivers that value through systems, explanatory frameworks, and practice cultures misaligned with the evidence. For health system executives, payers, and clinical leaders, the signal-to-noise distinction has direct implications for resource allocation, quality infrastructure, and strategic positioning in a market moving rapidly toward value-based accountability.

Early, guideline-concordant physical therapy for low back pain is associated with reduced imaging utilization, reduced opioid exposure, and reduced downstream surgical rates. A 2025 retrospective matched-cohort analysis found that participation in a structured digital care program combining exercise, education, and behavioral support was associated with a 58% relative reduction in surgical risk at twelve months compared to patients initiating standard in-person physical therapy-a finding that speaks not to the superiority of digital over in-person care per se, but to the importance of structural, evidence-based delivery over variable, convention-driven practice.

Guideline concordance data support this picture. A 2025 scoping review in the Journal of Evaluation in Clinical Practice documented that physiotherapy delivered according to current evidence-based guidelines produces improved pain and function outcomes, reduced medical service utilization, and lower healthcare costs-but also found substantial and persistent gaps between guideline recommendations and routine clinical practice, particularly for low back pain and osteoarthritis. The gap is not between what physical therapy can do and what it does do. It is between what we know works and what we actually deliver.

Evidence Gap

Guideline-concordant physiotherapy is associated with improved pain and function, reduced healthcare utilization, and lower costs-but significant evidence-to-practice gaps persist across common MSK conditions.

The Structural Noise That Undermines the Signal

The noise at the system level is multifaceted. It includes philosophical dogma-entrenched practitioner identities organized around specific techniques or schools of thought that resist updating in the face of contradictory evidence. CEU providers have a financial incentive to continue to build certificate culture, regardless of the empirical evidence behind the classes. It includes fragmented care delivery-siloed outpatient clinics, disconnected referral patterns, absence of longitudinal outcome tracking, and payment structures that reward visit volume over clinical value. And it includes a technology adoption curve that is, by healthcare standards, strikingly slow.

The profession’s relationship with evidence-based updating is complicated. Physical therapists receive rigorous doctoral-level training; the literature is substantial and growing. But clinical culture can be slow to integrate findings that disrupt established practice patterns, particularly when those practice patterns are tied to professional identity, certification, and revenue generation. A clinician who has invested years in a specific manual therapy certification has strong motivational and economic reasons to maintain the theoretical framework that justifies that certification, even as the basic science evolves away from it. We are a rigid profession.

For health system leaders, this raises a governance question: how do you build a physical therapy service line in which clinical culture is oriented toward evidence rather than tradition? The answers are structural: outcome measurement with feedback loops, continuing education requirements tied to evidence quality, utilization review that distinguishes guideline-concordant from convention-driven care, and clinical leadership that models intellectual humility and willingness to update.

A physical therapy department where clinicians cannot articulate the neurophysiological basis for the manual therapy they perform, the load rationale behind the exercises they prescribe, and the neuroscience that informs their motor learning approach is a department delivering care on philosophical credit, not scientific currency.

The Noise of Fractured Delivery

Beyond clinical culture, the structural fragmentation of physical therapy delivery is a source of noise that drowns out whatever clinical signal individual clinicians might generate. In most US health systems, physical therapy operates as a downstream referral service-patients arrive after diagnostic imaging, specialist consultation, and often failed pharmacological management. Primary care and PT as entry point into the health system is the key. Episodes of care are defined by authorization limits, not clinical logic. Outcomes are measured inconsistently, if at all. The patient’s experience across the episode is frequently discontinuous: different clinicians at different visits, inconsistent application of the treatment approach, no systematic mechanism for assessing whether the intervention is working. This is where digital MSK comes to support the continuity of care.

This fragmentation is not an accident. It is a structural feature of how physical therapy has been reimbursed and organized, and it actively undermines the conditions under which the signals in manual therapy, therapeutic exercise, and neuromuscular control can operate. Neurological effects from manual therapy require repetition and context. Mechanotransduction from therapeutic exercise requires consistent load dosing over time. Neuroplastic change from neuromuscular training requires active, meaningful practice with appropriate challenge and feedback. None of these mechanisms is well served by episodic, fragmented care delivery without longitudinal outcome tracking.

STRATEGIC TAKEAWAY: A FRAMEWORK FOR SYSTEM-LEVEL SIGNAL CLARITY

The signal-to-noise framework translates directly into organizational action. For health system executives and clinical leaders ready to operationalize these distinctions, the strategic priorities are concrete:

Manual Therapy: Audit the explanatory models your clinicians use. Clinical competence in manual therapy, exercise prescription, and neuromuscular training is necessary but insufficient. The theoretical frameworks clinicians use to explain their interventions shape their clinical reasoning, their patient communication, and their treatment design. Systems in which clinicians explain manual therapy through structural biomechanics, exercise through movement-pattern specificity, and neuromuscular control through outdated facilitation models are delivering noise alongside whatever signal those techniques produce. Regular clinical education reviews, case conference requirements, and peer learning structures that normalize evidence-based model updating are the organizational tools that address this.

Therapeutic Exercise: Restructure therapeutic exercise quality metrics around load and adherence, not prescription complexity. Home exercise program adherence data are clear and consistent: most patients do not complete the prescribed exercises. Volume-based prescription complexity is not a solution. Outcome measurement frameworks that track load dosing, functional progress, and patient-reported adherence-and that flag programs where complexity may be driving non-adherence-orient the clinical culture toward the variables that actually drive tissue repair.

Neuromuscular Control: Invest in neuroscience-literate clinical leadership. The neuromuscular domain is where the science is moving fastest and where clinical culture is most at risk of operating from outdated frameworks. Clinical leaders who understand the distinction between nervous system conditioning and technique-specific facilitation, who can evaluate motor learning research with appropriate critical literacy, and who can mentor clinicians through the discomfort of updating established practice patterns are the most valuable infrastructure investment a physical therapy service line can make.

Choice Architecture: Build longitudinal outcome infrastructure. Fragmented care delivery cannot be fixed at the clinician level. It requires system-level investment in outcome measurement, episode continuity, and care coordination. Patient-reported outcome measures at intake and discharge, episode-level outcome tracking by condition and clinician, and integration of physical therapy outcome data into population health dashboards are the minimum infrastructure requirements for a service line that can demonstrate its value in a value-based care environment.

The signal in physical therapy is real, scientifically grounded, and clinically meaningful. The nervous system responds to skilled manual contact. Tissue responds to mechanical load. The motor system adapts through active, challenging, meaningful practice. These mechanisms work. The evidence supporting them is extensive, growing, and increasingly precise.

The noise is real too-and in a profession under pressure to demonstrate outcomes in an increasingly accountable healthcare environment, tolerating it is no longer a neutral choice. Health systems that build the clinical culture, quality infrastructure, and delivery architecture to amplify the signal and eliminate the noise will be better positioned to deliver the value that physical therapy, at its evidence-based best, is genuinely capable of producing.

The question for every executive, clinical director, and payer reading this is not whether physical therapy works. It is whether the physical therapy your health system delivers is working through the mechanisms supported by science-or through the comfortable persistence of frameworks the science has moved past. That distinction is not academic. It is the difference between a high-value clinical asset and an expensive maintenance of tradition.

Let’s build a better future for our profession.

REFERENCES

1. Alanez, M. S., Degenhardt, B., & Kelley-Franklin, G. (2025). The mechanisms of manual therapy: A living review of systematic, narrative, and scoping reviews. PLOS ONE. https://doi.org/10.1371/journal.pone.0319586
2. Gögele, C., Stelling-Ferez, J., & Schulze-Tanzil, G. (2024). Tendon cell biology: Effect of mechanical loading. Cell Physiology and Biochemistry, 58, 549–573. https://doi.org/10.33594/000000743
3. Jupin, C., Beltran Aibar, V., & Sarhan, F.-R. (2025). Short-term effects of spinal manual therapy on the nervous system in managing musculoskeletal pain: A systematic review. Journal of Clinical Medicine, 14(11), 3830. https://doi.org/10.3390/jcm14113830
4. Leech, K. A., Roemmich, R. T., Gordon, J., Reisman, D. S., & Cherry-Allen, K. M. (2022). Updates in motor learning: Implications for physical therapist practice and education. Physical Therapy, 102(1), pzab250. https://doi.org/10.1093/ptj/pzab250
5. Petrosyan, H., Leonardi, C., Thakral, A., Roth, J., Russoniello, N., Goldin, Y., & Parikh, S. (2024). Barriers and factors associated with adherence to a home exercise program of adults with musculoskeletal pain. Journal of Back and Musculoskeletal Rehabilitation, 37(4). https://doi.org/10.3233/BMR-230178
6. Soriano-Segarra, M. L., Saura-Garro, M. J., Núñez-Cortés, R., et al. (2024). Effects of pain neuroscience education combined with neuromuscular exercises on pain, functional disability and psychological factors in chronic low back pain: A study protocol for a single-blind randomized controlled trial. PLOS ONE. https://doi.org/10.1371/journal.pone.0309679
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