Chronic obstructive pulmonary disease (COPD) is a heterogeneous lung condition characterised by chronic respiratory symptoms and persistent, often progressive, airflow obstruction.¹ It is a leading cause of morbidity and mortality worldwide.¹ The original project identified tobacco smoking, household biomass fuel exposure and occupational dusts as the principal risk factors.

 

The burden of COPD extends beyond the airways. Muscle dysfunction may involve both respiratory and peripheral muscles, and hyperinflation with increased work of breathing appears to be the main contributor to respiratory muscle dysfunction.² Chest-wall mobility is reduced in COPD and correlates with lung function.³ These changes contribute to dyspnoea and exercise intolerance.

 

Pulmonary rehabilitation (PR) is the established non-pharmacological treatment. The American Thoracic Society recommends PR for adults with stable COPD as a strong recommendation based on moderate-quality evidence.⁴ PR relieves dyspnoea and fatigue and improves emotional function.⁵ Exercise training is its core component.⁶ Interventions directed at chest-wall stiffness and shortened accessory muscles are less well established.

Proprioceptive neuromuscular facilitation (PNF) uses proprioceptive input, resisted contraction and stretch to modify neuromuscular responses. Autogenic inhibition, reciprocal inhibition, stress relaxation and gate control have been proposed to explain its effect on range of motion (ROM),⁷ although their relative contribution is debated.⁸ In respiratory care, PNF has been applied as hold–relax stretching of accessory and chest muscles and as facilitatory manual stimuli to the thorax.

 

Several studies have examined PNF-type interventions in COPD,^9-14 and a systematic review was published in 2025.¹⁵ Techniques, doses and comparators differ widely, and within-group improvement is frequently reported as efficacy. An updated critical synthesis is therefore warranted.

 

2. Rationale and objective

The original project asked “to determine the effect of different PNF technique in COPD individuals” and concluded that PNF was beneficial. This review updates that work. It incorporates recent clinical trials and systematic-review evidence and emphasises the distinction between within-group improvement and comparative treatment effect.

 

The objective was to critically synthesise published evidence on respiratory PNF in adults with COPD for pulmonary function, exercise capacity, dyspnoea, thoracic mobility, respiratory mechanics and health status, and to identify clinical implications and research gaps.

3.1 Review design This is a critical narrative literature review. It is not a systematic review, was not registered, and does not follow PRISMA methodology. 3.2 Literature search Original project. The project searched PubMed and Google Scholar. The search date was not reported in the original project. Targeted literature update. A targeted update was performed on 2 October 2026 by online searching of PubMed-indexed records, PEDro records, Cochrane records, ClinicalTrials.gov and publisher websites. Scopus and Web of Science were not searched directly. Publications from 2021 to 2026 were prioritised. 3.3 Search strategy The original project used the terms PNF, proprioception neuromuscular facilitation, repeated stretching, hold relax, COPD and chronic obstructive pulmonary diseases, combined with AND and OR. It reported 60,729 retrieved records. That figure exceeds one of its component searches (2,166 records) and is internally inconsistent; it is reported here as stated and is not relied upon. No screening counts were reported. The update combined intervention terms (proprioceptive neuromuscular facilitation, PNF, respiratory PNF, chest PNF, PNF stretching, respiratory muscle stretching, chest mobility) with COPD terms and outcome terms. Record counts were not logged and are not reported. 3.4 Eligibility considerations The original project included studies of people with COPD that used PNF as part of the intervention, published from 2015, with English full text. The update retained the population and intervention criteria, removed the lower date limit, and added quasi-experimental designs. One further criterion was applied: study details had to be verifiable against the published report or its indexed abstract. 3.5 Study selection A. Original project (four studies). Wada et al.10 and Liu et al.11 were retained. Singh et al.16 and Siva Jyothi et al.17 were not carried forward, because their full texts could not be accessed and their details could not be verified. Singh et al. also studied chronic bronchitis without confirmed spirometric staging, and Siva Jyothi et al. appears under the same title in two journals. B. Targeted update (four studies). Putt et al.,9 Mistry and Kamble,12 Kumaresan et al.13 and Zakaria et al.14 C. Contextual evidence. One systematic review,15 one trial of chest wall mobilisation20 and current guidelines.1,4 Six primary studies were synthesised (Figure 1). Selection was performed by a single reviewer. 3.6 Data extraction Design, sample, severity, intervention, comparator, duration, outcomes and findings were extracted. Four reports were read in full.10-13 Putt et al. was extracted from its indexed abstract.9 Zakaria et al. was extracted from its abstract and trial-registry record.14 3.7 Critical appraisal Randomisation, allocation concealment, blinding, attrition, sample size, comparator, co-interventions and follow-up were considered qualitatively. No formal risk-of-bias score was assigned. The PEDro scores in the original project were not carried forward.