Whole-Body Vibration vs. Exercises for Chronic Neck Pain in Young Adults

For the evaluation of cervical Joint Position Sense (JPS), the CROM device was preferred as it is an effective, simple, and cost-efficient measurement tool, similar to its use in Range of Motion (ROM) assessment. This ensured consistency across the evaluation environment, preparation phase, standardized measurement posture, device placement, and calibration. The participants' cervical ROM in three planes was measured three times, and the arithmetic mean of these measurements served as the baseline for JPS assessment. The target angle for the JPS test was then calculated as 65% of the average ROM for the respective cervical movement.

Active cervical flexion, extension, right-left rotation, and right-left lateral flexion were evaluated using the Baseline CROM Deluxe device. The CROM device consists of two gravity-dependent goniometers and a head-mounted compass dial, allowing for range of motion (ROM) measurements across three anatomical planes. During the assessments, participants were instructed to sit with their feet flat on the floor, hands resting on their thighs, and the pelvis in a neutral position. For active movements, they were asked to move the head at a constant speed while keeping the back and shoulders stationary, followed by a 5-10 second rest in the neutral position after each movement.

To assess gaze stability, the Head-Eye Movement Control Test was conducted. For participant safety, the testing area was positioned in a corner of the room. A camera was mounted on a tripod at eye level at the center of a 1-meter equilateral triangle marked on the floor. Participants were seated in a neutral position and instructed to rotate their head as rapidly as possible to the right and left while maintaining visual fixation on the camera lens. Performance was scored using a 3-point scale:

• 0 (negative): Stable gaze with smooth, well-coordinated, and rapid head movements.
• 1 (mild positive): Stable gaze but with slightly uncontrolled head movements.
• 2 (strong positive): Repeatedly unstable gaze with slow and uncontrolled head movements.

Static balance was assessed using the Single-Leg Stance (SLS) test, performed separately for the right and left lower extremities under both eyes-open and eyes-closed conditions. Three trials were conducted for each condition, and the mean duration was recorded. The test was terminated if the weight-bearing foot shifted from its original position, the non-weight-bearing foot touched the floor, the participant sought external support, or the maximum duration of 60 seconds was reached.

Dynamic postural was assessed using the Y-Balance Test (YBT). Reach distances were measured in three directions: anterior (ANT), posterolateral (PL), and posteromedial (PM). To allow for data normalization, participants' leg length was measured from the anterior superior iliac spine (ASIS) to the medial malleolus. Following six practice trials to minimize learning effects, the maximum reach of three successful trials in each direction was recorded and normalized to leg length to calculate a composite balance score.

To evaluate the alignment of the cervical spine, participants' head posture was assessed by measuring the craniovertebral angle (CVA). The CVA is defined as the angle formed between the horizontal plane and a line connecting the midpoint of the tragus of the ear to the C7 spinous process. Measurements were conducted using the photogrammetry technique while participants were in a standing position. For this purpose, a digital camera was positioned at a fixed point 1.5 meters from the participant at shoulder level. After placing an anatomical marker on the C7 spinous process, participants were instructed to bring their heads into a neutral position through small flexion and extension movements and to look at a fixed point directly in front of them. CVA values were calculated from photographs taken from the left lateral projection. A decrease in the CVA value was recorded as an indicator of increased anterior head posture (forward head displacement).

Neck-specific body perception and awareness were evaluated using the Fremantle Neck Awareness Questionnaire (FreNAQ). This 9-item scale assesses body image, proprioception, and perceptual distortions of the neck region. Each item is scored on a 5-point Likert scale (0 = never, 4 = always), with higher total scores indicating greater body image distortion. The Turkish version of the FreNAQ has been previously validated and demonstrated high reliability for individuals with neck pain.

For a detailed evaluation of neck pain and its multidimensional impacts, the seven-item Bournemouth Neck Pain Questionnaire (BNPQ) was utilized to assess participants' pain intensity, as well as kinesiophobia, anxiety, depression, and coping abilities. This scale provides a biopsychosocial assessment by covering four of the five components of the International Classification of Functioning, Disability and Health (ICF), as it assesses pain intensity over the past week, disability in daily and social activities, levels of anxiety and depression, kinesiophobia, and pain control abilities. The BNPQ was selected for its ability to determine the comprehensive effects of neck pain, and its Turkish version has demonstrated validity and reliability (Cronbach's alpha = 0.865; ICC = 0.963).