This randomized controlled trial aims to compare the effects of Dynamic Neuromuscular Stabilization (DNS) exercises and thoracic stabilization exercises on thoracic erector spinae muscle strength, thoracic kyphosis angle, pain and trunk stabilization in individuals with thoracic kyphosis. Thirty participants aged 18-40 years with thoracic kyphosis will be randomly allocated to a DNS exercise group or a thoracic stabilization exercise group. Surface EMG biofeedback will be used to assess thoracic erector spinae muscle activation, while pain, thoracic kyphosis angle and trunk endurance will be evaluated using validated clinical tests. The interventions will be applied for 6 weeks, and outcomes will be assessed before and after the intervention period.

Thoracic kyphosis is a frequently observed postural deviation that affects the sagittal alignment of the spine and may lead to alterations in muscular balance, impaired trunk stability, and increased biomechanical stress on the vertebral column. Postural thoracic kyphosis typically results from prolonged sedentary behaviors-such as extended computer and smartphone use-and habitual forward-flexed postures adopted during work or daily activities. Over time, inadequate thoracic extension, weakness of the thoracic erector spinae musculature, and compensatory recruitment of accessory trunk muscles may further contribute to the progression of the deformity. Although postural kyphosis is considered flexible and reversible in early stages, insufficient management may allow gradual transition toward more structural changes.

Conservative physiotherapy interventions represent the primary approach to managing postural thoracic kyphosis. These interventions traditionally include thoracic mobility exercises, strengthening of the spinal extensors, scapular stabilization strategies, and postural retraining. In recent years, neuromuscular re-education methods and biofeedback-supported interventions have become increasingly prominent, reflecting a shift toward approaches that emphasize sensorimotor control and integration of respiratory-postural synergy.

Dynamic Neuromuscular Stabilization (DNS) is a rehabilitation method grounded in developmental kinesiology principles. DNS aims to restore optimal joint stabilization and postural alignment through coordinated activation of the diaphragm, deep spinal stabilizers, and global trunk musculature. By replicating developmental postures, DNS seeks to reintegrate diaphragmatic breathing patterns and promote central stabilization strategies that influence thoracic alignment and motor control.

Thoracic stabilization exercises represent another commonly applied approach and typically include targeted thoracic extension, scapular retraction, and segmental mobilization techniques. These exercises aim to improve local muscle function of the thoracic erector spinae, enhance thoracic mobility, and promote more efficient load transfer across the spine. While both DNS and thoracic stabilization approaches have theoretical and clinical justification, direct comparative evidence regarding their short-term effects on neuromuscular activation and postural correction in adults with thoracic kyphosis remains limited.

This single-center randomized controlled trial will be conducted at Mudanya University and will include 30 adults aged 18 to 40 years with postural thoracic kyphosis confirmed through flexible ruler assessment. Participants will be randomly assigned in a 1:1 ratio to either a Dynamic Neuromuscular Stabilization intervention group or a Thoracic Stabilization Exercise group. Both intervention programs will extend over a 6-week period and will include two supervised sessions per week, complemented by home-based exercises performed twice daily. To ensure adherence, each participant will maintain an exercise diary, and individuals who fail to perform the prescribed exercises for three consecutive days will be withdrawn from the study in accordance with predefined adherence criteria.

Outcome measures will be collected at baseline and after the 6-week intervention. Surface electromyography (EMG) biofeedback will be used to assess thoracic erector spinae muscle activity. Pain intensity will be evaluated using the Visual Analog Scale (VAS). Trunk endurance and stabilization capacity will be measured using standardized plank tests and the Biering-Sørensen back endurance test. Thoracic curvature will be quantified using a flexible ruler, from which a kyphosis index will be calculated. Additional data-such as demographic characteristics, body mass index, and relevant medical history-will be recorded to contextualize findings and ensure appropriate characterization of the study population.

The primary aim of this trial is to compare the effects of DNS and thoracic stabilization exercises on thoracic erector spinae muscle activation measured via EMG. Secondary objectives include comparing the influence of both interventions on thoracic kyphosis angle, pain intensity, and trunk stabilization performance. The study is designed to provide a detailed evaluation of two physiotherapy approaches grounded in distinct theoretical frameworks, thereby offering insight into their mechanisms and potential applicability for individuals presenting with postural thoracic kyphosis. Findings will be reported separately in the Results section once data collection and analysis are completed. The present description outlines the scientific rationale and methodological approach without including results or interpretations.

Inclusion Criteria:

• Age between 18 and 40 years.
• Presence of thoracic kyphosis based on clinical and flexible ruler assessment.
• Able to perform exercise-based interventions.
• Voluntarily agrees to participate and signs the informed consent form.
• No neurological, systemic, cardiac or orthopedic condition that would prevent safe participation in the exercise program.

Exclusion Criteria:

• Age outside the range of 18-40 years.
• Pregnancy.
• Malignancy.
• History of spinal surgery within the last year.
• Currently performing spinal or intensive core stabilization exercises.
• Visual, auditory or cognitive impairment that would interfere with cooperation during the intervention.
• Contraindications to exercise participation.
• Non-adherence to the exercise program (not performing exercises for three consecutive days).

Randomization will be done by the sealed envelope method.