 Neck pain is a second the most common problems in musculoskeletal problems the low back pain in general population.The prevalence of neck pain at the some point in their lifetime in general population had been reported to be between 43 to 66.7 percent.the neck problems could be involved physical function, psychological function and social function. The economic burden for neck pain is very high.Recent studies indicate that the patients with chronic neck pain present decreased activation and weak of neck muscles, especially deep flexor and extensor muscles. Alterations of deep are associated with pain and impairment of neck function in chronic neck pain.Recently, many studies have focused on specific training on deep cervical muscles, especially deep cervical flexor and deep cervical extensor muscles. The specific training on deep cervical muscles aims to improve control strategy, improve activation of deep cervical flexor muscles to optimize movement control of segmental motion of the cervical spine. Numerous studies using cranio-cervical flexor exercise as a treatment have revealed reduction on pain, neck disability, changing in activation of deep and superficial cervical flexor muscles. Further, the cervical extensor muscles are believed to be equally important for the rehabilitation of patients with neck pain. So, the activation of the deep cervical extensors should be emphasized for the management in people with neck pain. Schomacher et al 2012 suggested that isometric resisted exercise at the second cervical vertebra can improve semispinalis cervicis muscle activity in neck pain patients. However, the retention effect of semispinalis cervicis exercise is unknown. Therefore, the semispinalis cervicis exercise still need more evidence to support clinically effects. The current study will be conducted to fill the gap of the previous study in immediately, short, and long term effects of semispinalis cervicis exercise in chronic neck pain. 