Diaphragm Therapy for Chronic Neck Pain: What RCTs Show

Chronic neck pain may respond better when treatment includes the diaphragm as well as the cervical spine. That does not mean neck pain is secretly a breathing disorder. It means a small group of recent trials found that treating breathing-related dysfunction alongside cervical manual therapy improved neck movement and forward-head posture more than cervical treatment alone.

The signal is worth discussing with a physiotherapist, especially if standard care has helped but left you with persistent symptoms. It is not strong enough to justify diagnosing yourself by watching your belly rise in a mirror.

The best direct trial tested a combined treatment

In a 2025 three-arm randomized controlled trial, Tatsios et al. assigned 90 adults aged 25 to 65 with non-specific chronic neck pain to 10 sessions over one month. One group received cervical Mulligan manual therapy—NAGs, SNAGs, and traction—plus diaphragm doming and release techniques and breathing re-education. A second group received the same cervical Mulligan treatment plus sham diaphragm ultrasound delivered at 0 W/cm². The control group received TENS, microwave diathermy, and conventional physiotherapy.

The combined-treatment group improved more than both comparison groups in active cervical range of motion across six planes and craniovertebral angle, a measure of forward-head posture. Those advantages remained at the three-month follow-up. The publication does not provide a confidence interval or effect estimate in the evidence summarized here, so the size and precision of the between-group difference cannot be judged from these findings alone.

The comparison with the Mulligan-only group carries the most weight. Both groups received the same cervical treatment, while only one received active diaphragm therapy and breathing re-education. That design supports an incremental benefit from the added component. It does not tell us whether diaphragm release, breathing instruction, additional therapist contact, or some combination drove the result.

The trial also had an important weakness: assessors were blinded, but participants and therapists were not. Expectations can affect posture, effort during range-of-motion testing, and reported symptoms. The investigators recruited volunteers rather than a probability sample, and no independent team has yet replicated the protocol.

Why researchers think the diaphragm could matter

The proposed explanation is plausible but unsettled. The sternocleidomastoid and scalenes help stabilize the neck and can also assist breathing. If the diaphragm contributes less to breathing, these neck muscles may work harder as accessory respiratory muscles. Researchers hypothesize that this extra load could reinforce upper-chest breathing, forward-head posture, and restricted cervical motion.

A 2025 pilot randomized trial by Cheng et al. adds a useful measurement that the combined-treatment trial lacked: it assessed diaphragm excursion by ultrasound and maximal inspiratory pressure, alongside pain and disability, in people with chronic neck pain. Manual diaphragm release produced preliminary improvements in both clinical outcomes and measured diaphragm-function parameters. Because this was a pilot trial, it was not designed to settle efficacy. Its main contribution is showing that diaphragm function can be measured in this population and may change during treatment.

That still does not prove that diaphragm dysfunction caused the neck pain, or that improving diaphragm measurements caused the clinical improvement. Ultrasound excursion and inspiratory pressure are physiological measures, not a verdict on the origin of someone's symptoms.

A separate placebo-controlled trial by Czępińska et al. found that one session of manual diaphragmatic relaxation improved cervical mobility and pain-pressure threshold immediately afterward in smartphone users with non-specific cervical pain, compared with a sham procedure. The sham comparator makes the acute result more persuasive than an uncontrolled before-and-after test. But the population was narrow, and the study measured only immediate effects. A better range of motion after one session is not evidence of durable pain relief.

The cervical-treatment evidence is encouraging, but low-certainty

The diaphragm protocol did not replace cervical care; it added to it. That matters because the cervical component has evidence of its own, although the quality of that evidence limits confidence.

A 2025 systematic review and meta-analysis by Barbosa-Silva et al. included 33 studies of Mulligan techniques for non-specific neck pain. In chronic non-specific neck pain, SNAGs combined with other therapies showed statistically significant effects on pain intensity, disability, and cervical range of motion compared with other treatments. The authors rated the certainty of most outcomes as very low using GRADE.

That rating came from high risk of bias, small trials, differences in technique and treatment dose, and substantial statistical heterogeneity. Several pooled analyses had I² values above 80%, which means the individual study results varied enough that a single pooled effect may conceal important differences. Very low certainty does not establish that Mulligan techniques fail. It means future well-designed studies could substantially change the estimate.

A 2021 systematic review by Fernández-López et al. also found that manual therapy applied to the diaphragm affected pain, mobility, and muscle function in musculoskeletal conditions beyond respiratory outcomes. This supports the rationale for studying diaphragm treatment in neck pain. It does not establish a specific neck-to-diaphragm anatomical pathway, and none of these studies directly tested a fascial mechanism.

The causal story remains contested

The most restrained interpretation is also the most useful: neck and breathing-related dysfunction can coexist, and combined treatment may improve some neck outcomes. The direction of influence remains uncertain.

In a 2025 randomized trial of neural mobilization in chronic neck pain, Tunç et al. measured respiratory parameters as secondary outcomes and argued that chronic neck pain does not directly affect breathing. The authors instead described indirect routes: kyphosis, forward-head posture, and restricted movement may mechanically limit chest expansion and diaphragm descent.

This account conflicts with stronger claims that cervical dysfunction directly inhibits diaphragm function through phrenic-nerve neurodynamics or a reciprocal neuromuscular loop. The studies differ in intervention, measured outcomes, and mechanistic focus, so they cannot settle that disagreement by themselves. More importantly, the Tatsios trial's clinical result does not depend on knowing the exact pathway. A treatment can help before science explains every gear in the machine.

What to do with this evidence

If you have chronic non-specific neck pain, especially pain that has only partly improved with conventional physiotherapy, ask whether your clinician assesses breathing pattern and respiratory muscle contribution along with neck movement, posture, strength, and daily-load factors. A physiotherapist trained in Mulligan cervical techniques and diaphragm manual therapy can decide whether the combined approach fits your presentation.

The evidence-supported model is clinician-supervised care: in the Tatsios trial, participants received 10 sessions over one month, combining cervical Mulligan techniques, diaphragm treatment, and structured breathing re-education. No trial in this evidence base validates a self-test for diaphragm dysfunction or a do-it-yourself breathing protocol for chronic neck pain outcomes. Diaphragm ultrasound and maximal inspiratory-pressure testing, used in the Cheng pilot trial, also require equipment and clinical expertise.

Verdict: Combined cervical and diaphragm therapy has a promising early clinical signal for chronic non-specific neck pain. One unreplicated three-arm RCT found better cervical range of motion and forward-head posture than cervical Mulligan therapy alone, while a pilot trial and a single-session placebo-controlled study provide supporting but limited evidence. Treat it as a reason to broaden a clinical assessment, not as proof that breathing dysfunction caused your neck pain.

Seek medical evaluation promptly for neck pain after major trauma, progressive weakness or numbness, loss of coordination, fever, unexplained weight loss, severe headache, or changes in bowel or bladder function. Manual therapy is not a substitute for sorting out those red flags.