This study aims to investigate the relationship between cervical position sense, core stabilization, and postural balance in university students aged 18-30 years with Upper Crossed Syndrome (UCS). Upper Crossed Syndrome is a common musculoskeletal disorder characterized by muscle imbalance, including weakness of the deep cervical flexors, middle and lower trapezius, rhomboids, and serratus anterior, along with tightness of the upper trapezius, levator scapulae, sternocleidomastoid, and pectoralis major and minor. This condition frequently affects university students due to prolonged sitting, extensive computer use, and poor posture. While previous research has focused on discrete components of UCS such as posture correction or pain management, the combined effects of cervical proprioception, core stability, and postural balance remain poorly understood. A total of 48 participants will be enrolled and divided into two equal groups: 24 students diagnosed with Upper Crossed Syndrome and 24 healthy students as a control group. Assessments include cervical joint position error testing, core stabilization endurance tests (Unilateral Hip Bridge Endurance Test and Sahrmann Five-Level Core Stability Test), static balance evaluation using the Balance Error Scoring System (BESS), and dynamic balance assessment using the Y-Balance Test. Pain intensity will be measured using the Visual Analog Scale (VAS). This study will help identify neuromuscular and sensory mechanisms underlying these parameters and support evidence-based rehabilitation techniques to improve postural alignment, reduce musculoskeletal dysfunction, and enhance overall functional performance in this population.

This study is a cross-sectional intervational study designed to compare university students with Upper Crossed Syndrome (UCS) to healthy controls. The study will be conducted at the Physiotherapy and Rehabilitation Laboratory at Istinye University. All assessments will be carried out in a single session per participant under standardized conditions by a single trained physiotherapist.

STUDY POPULATION:

A total of 48 university students aged 18-30 years will be recruited. Participants will be divided into two equal groups: 24 students diagnosed with Upper Crossed Syndrome (UCS Group) and 24 healthy students (Control Group). Recruitment will be conducted through flyers posted across campus buildings, advertisements on student social media platforms, mass emails to all university departments, direct screening in common areas, and an online screening survey for volunteers.

INCLUSION CRITERIA FOR UCS GROUP:

• University students aged 18-30 years
• Diagnosis of Upper Crossed Syndrome
• Forward Head Posture (Craniovertebral Angle < 49°)
• Rounded Shoulder Posture (> 2.5 cm)
• Presence of chronic neck pain
• Impaired cervical position sense

EXCLUSION CRITERIA (both groups):

• History of cervical surgery
• Neurological disorders
• Acute musculoskeletal injury within the past 3 months
• Previous traumatic injuries to the neck or back

SCREENING AND ASSESSMENT PROTOCOL:

Phase 1 - Screening for Upper Crossed Syndrome:

Participants will be screened for UCS through postural assessment in both standing and sitting positions. Observational criteria include forward head posture, rounded shoulders, increased thoracic kyphosis, and scapular winging. UCS diagnosis will be confirmed using goniometric measurements and clinical observation.

Phase 2 - Pain Assessment:

Neck and upper thoracic pain intensity will be assessed using the Visual Analog Scale (VAS), a 10-cm horizontal line where 0 indicates no pain and 10 indicates the worst imaginable pain. Participants will mark their current pain level, and the distance from zero will be measured in centimeters.

Phase 3 - Cervical Proprioception Assessment:

Cervical joint position error (JPE) will be evaluated using the JPE test. Participants will be seated with feet flat on the floor and trunk supported. A laser pointer mounted on a headband will be aligned with a target at eye level on the wall. Participants will perform cervical extension and right/left rotation movements, then reposition the head to neutral with eyes closed. The distance between the original target and repositioned point will be measured in centimeters. Three trials will be performed in each movement direction, and the mean repositioning error will be calculated. Larger errors indicate impaired cervical position sense.

Phase 4 - Core Stabilization Assessment:

Core muscle endurance and stability will be evaluated using two tests:

1. Unilateral Hip Bridge Endurance (UHBE) Test: Participants lie supine with knees bent, extend one leg, and raise the hips into a bridge position using the other leg. The time maintained without hip sag or body misalignment is recorded for both sides.
2. Sahrmann Five-Level Core Stability Test: Performed in supine position with hips and knees flexed. A Pressure Biofeedback Unit (PBU) is placed under the lumbar spine (inflated to 40 mmHg). Participants must maintain pressure at 40 mmHg (±10 mmHg) while performing progressively challenging leg movements across five levels. The test is terminated when target pressure cannot be maintained, indicating loss of core motor control.

Phase 5 - Static Postural Balance Assessment:

Static balance will be evaluated using the Balance Error Scoring System (BESS). Participants maintain stability in six stances (double-leg, single-leg, and tandem) performed on firm and foam surfaces while keeping eyes closed. Postural deviations or "errors" are counted, with higher error scores indicating poorer balance performance.

Phase 6 - Dynamic Postural Balance Assessment:

Dynamic balance will be assessed using the Y-Balance Test. Participants stand on one limb while reaching with the contralateral limb in three directions: anterior, posteromedial, and posterolateral. Reach distances are measured in centimeters, normalized to limb length, and averaged across three trials for each direction. This test provides quantitative data on reach asymmetries and limb stability, reflecting functional mobility and proprioceptive control.

ETHICAL CONSIDERATIONS:

This study has been approved by the Istinye University Ethics Committee. All participants will provide written informed consent prior to participation. The study will be conducted in accordance with the Declaration of Helsinki.

STATISTICAL ANALYSIS:

Data analysis will be performed using IBM SPSS. Pearson's correlation will be used for normally distributed data and Spearman's rho for non-parametric data. Additionally, multiple linear regression analysis will be conducted to determine whether cervical position sense and core stability can significantly predict postural balance performance. Sample size (N=48) was determined using G*Power software (version 3.1.9.7) to achieve a statistical power of 0.80 with a significance level of 0.05 and an assumed large effect size (d = 0.82) for primary outcomes.

STUDY DURATION:

The study is expected to last approximately one year, including participant recruitment, data collection, and analysis

Inclusion Criteria:

• University students aged 18-30 years.
• Diagnosis of Upper Crossed Syndrome (UCS) confirmed by postural assessment.
• Forward Head Posture with Craniovertebral Angle (CVA) less than 49 degrees.
• Rounded Shoulder Posture greater than 2.5 cm.
• Presence of chronic neck pain.
• Impaired cervical position sense.

Exclusion Criteria:

• History of cervical spine surgery.
• Neurological disorders (e.g., stroke, multiple sclerosis, Parkinson's disease).
• Acute musculoskeletal injury to the neck, back, or upper extremities within the past 3 months.
• Previous traumatic injuries to the neck or back.
• Any diagnosed vestibular or balance disorder.
• Visual impairment that affects balance.
• Pregnancy.
• Participation in another interventional clinical trial within the past 30 days.

The study population consists of university students aged 18-30 years from Istinye University and other universities in Istanbul. Participants will be recruited from various academic disciplines. The target population includes students with Upper Crossed Syndrome (UCS) for the case group and healthy students without UCS for the control group. Recruitment will be conducted through flyers posted across campus buildings, advertisements on student social media platforms, mass emails to all university departments, direct screening in common areas, and an online screening survey for volunteers.