Neck pain (NP) is one of the most common and costly musculoskeletal complaints in today's societies. Cervical muscles endurance has been commonly associated with the development of NP. Real-time ultrasound imaging is a reliable and valid technique recently used by physical therapists to evaluate muscle structure, function and activation patterns. The aim of this study is if change in muscle thickness can correlate with the results of the endurance testing.

Inclusion Criteria:

• Subjects with neck pain: experiencing pain for at least 3 months in the last year, having pain score of 3 or more on visual analogue scale.
• Healthy subjects: no history of neck pain

Exclusion Criteria:

• History of cervical discopathy
• Any surgery on neck
• Traumatic neck injury
• Any congenital disorders

Subjects with and without neck pain