Trapezius, Sternocleidomastoid (SCM), Scalene, pectoral muscles will be targeted for stretching exercises and deep neck flexors, Trapezius, Levator Scapula, Rhomboids will be targeted for strengthening exercises. The intensity of the exercises will be increased according to the weeks. Stretching exercises will be performed as a single set at the pain limit, maintaining the position of the muscle groups in the longest tolerable position for 30 seconds. In strengthening exercises, participants will hold the position for 5-10 seconds at the end of the movement. Moderate resistance elastic bands and free weights will be used for resistance exercises. In the following weeks, progression will be made in all exercises according to the patient's condition.

Craniovertebral angle will be measured in a standing position using photogrammetry technique. A digital camera will be placed at a distance of 1.5 meters on a stable base, the height of the camera will be adjusted to shoulder level and individuals will be asked to look at a point in front of them to ensure correct posture. A marker will be attached to the C7 spinous process and the targa of the ear of the participants and the craniovertebral angle will be determined from the photographs taken.

Neck Disability Index is a valid and reliable scale used to determine activity limitations due to neck pain. It assesses the level of neck disability in 10 different situations and functions, including pain intensity, self-care, lifting, reading, headache, concentration, work, driving, sleep and leisure activities. Each item is scored from 0 (activity limitation/no disability) to 5 (significant activity limitation/severe disability). The total score ranges from 0-50. In the categorical classification of the total score, 0- 4 indicates no disability, 5-14 indicates mild disability, 15-24 indicates moderate disability, 25-34 indicates severe disability and ≥35 indicates complete disability. A Turkish version and cultural adaptation have been made and its validity and reliability have been demonstrated in individuals with neck pain.

Maximal isometric muscle strength of cervical region flexor and extensor muscles will be measured with a hand-held dynamometer. Cervical flexor muscle strength will be measured with the participants in supine position, head and neck in neutral position, knee flexion and arms at the side of the body. Cervical extensor muscle strength will be measured with the participants in the prone position with arms at the side of the body. During the measurements, participants will be asked to generate maximum force against the dynamometer device throughout the test (3-5 seconds). In flexor and extensor muscle strength measurements, three measurements will be made with a one-minute rest period between each measurement and their averages will be recorded. It has been reported that measuring maximal isometric muscle forces of flexor and extensor muscles in the cervical region with a hand-held dynamometer is a reliable and easy-to-apply method.

Normal range of motion of the cervical joints was measured using a 360-degree universal goniometer. Normal range of motion of the cervical joints will be measured in the flexion, extension, rotation and lateral flexion directions with the participants in a sitting position, head and trunk held upright.

The physical activity levels of the participants will be assessed using the 'International Physical Activity Index short form' whose validity and reliability studies were conducted by Craig et al. In this questionnaire, the time spent in sitting, walking, moderately vigorous and vigorous activities during the last seven days is questioned. Turkish validity and reliability of the questionnaire was performed.

The stress perception level of the participants will be assessed with the 'Perceived Stress Scale'. The questionnaire, which consists of 14 items in total, evaluates the level of stress perception in certain situations in one's life. Participants evaluate each item on a 5-point Likert-type scale ranging from "Never (0)" to "Very often (4)". Survey scores range from 0 to 56. A high score indicates a high level of stress perception (Cohen et al., 1983). Turkish validity and reliability study of the questionnaire was conducted (Eskin et al., 2013).

The fatigue level of the participants will be assessed using the 'Fatigue multidimensional assessment scale' (Piper et al., 1989). Turkish validity and reliability study of the scale in chronic musculoskeletal diseases has been conducted (Yildirim & Ergin, 2013).

Participants' work performance will be assessed with the Health and Work Performance Scale. The short version of the scale developed by the World Health Organization consists of 11 items answered in two different types. The scale assesses employees' work productivity with two subscales (Kessler et al., 2003). The absenteeism part consists of 8 items and measures the time spent on work and lost time as numerical values. The absenteeism part consists of 3 items and evaluates the quality of the work done during the work process. This section is measured by scoring between 0 (worst) and 10 (best). In the scale, the evaluation process can be done for a seven-day period and for a four-week period. The scale has been shown to be valid and reliable for white-collar employees in Turkey (Kuru, 2019).

The level of satisfaction of all study participants with the treatment they received at the end of the study will be assessed with the Global Change Scale. It is a scale in which patients determine the amount of improvement or deterioration in their health status over time from their own perspectives. Global change scales are widely used in clinical research, especially in the musculoskeletal system. There are different rating scales. In this study, an 11-unit scale will be used (-5: much worse, 0: same, +5: completely improved).

Endurance of the deep cervical flexor muscles will be assessed using the Cranio-Cervical Flexion Test. A pressure biofeedback device (Stabilizer™, Chattanooga, USA) will be used while participants lie in a supine hook-lying position. After instruction, the pressure sensor will be set to 20 mmHg, and participants will be asked to increase and hold the pressure for 10 seconds. The performance score will be calculated by multiplying the pressure increase by the number of repetitions. Higher scores will indicate better muscle endurance, whereas lower scores will reflect reduced endurance capacity.