A Randomized Controlled Trial Comparing Thoracic Expansion Exercises and Dynamic Neuromuscular Stabilization on Respiratory Function and Bilateral Trapezius Muscle Activity in Individuals With Forward Head Posture

Forward head posture (FHP) is a common postural deviation characterized by reduced craniovertebral angle (CVA), altered cervicothoracic alignment, and compensatory activation of accessory respiratory muscles. Individuals with FHP frequently demonstrate limited thoracic mobility, decreased respiratory efficiency, and increased demand on superficial neck musculature. These biomechanical alterations may negatively influence pulmonary function parameters such as FEV1 and FVC, as well as contribute to elevated electromyographic (EMG) activity in the upper trapezius muscles.

Various therapeutic approaches have been developed to address posture-related respiratory dysfunction. Thoracic expansion breathing exercises aim to enhance chest wall mobility and improve lung expansion across upper, middle, and lower thoracic regions. Dynamic Neuromuscular Stabilization (DNS), based on developmental kinesiology principles, seeks to optimize diaphragmatic function, intra-abdominal pressure regulation, and coordinated activation of deep stabilizing musculature. Although both methods have theoretical benefits for improving respiratory mechanics and postural alignment, comparative evidence regarding their differential effects in individuals with FHP remains limited.

This randomized controlled trial will investigate the immediate and short-term effects of thoracic expansion breathing exercises versus DNS-based stabilization exercises on respiratory function, cervicothoracic posture, and muscle activation patterns. Thirty-two adults aged 18-40 years with a CVA of less than 53° will be enrolled and randomly assigned using an opaque envelope method to one of two intervention groups: the Thoracic Expansion Exercise Group or the Dynamic Neuromuscular Stabilization Group. Each intervention protocol will be implemented over a 6-week period, consisting of twice-weekly supervised sessions complemented by twice-daily home exercise routines.

Outcome assessments will be conducted at baseline and at the end of the 6-week intervention period. These assessments will include: CVA measured by standardized lateral photography and ImageJ analysis; bilateral upper trapezius muscle activity assessed using surface EMG biofeedback; pulmonary function tests (FEV1, FVC, FEV1/FVC) conducted with spirometry; thoracic expansion measured at three levels using a tape-measure chest mobility test; and health-related quality of life evaluated with the St. George's Respiratory Questionnaire (SGRQ). The study protocol was approved by the Istanbul Medipol University Non-Interventional Clinical Research Ethics Committee.

This trial is designed to provide a comparative analysis of two commonly used physiotherapy interventions for FHP, with a focus on their effects on posture-related respiratory mechanics, thoracic mobility, and neuromuscular activation. All findings will be reported separately in the Results section. The present description outlines the scientific rationale, study design, and intervention procedures without duplicating eligibility criteria or outcome measure definitions.