It has been suggested that the suboccipital muscles are a causative factor in both cervicogenic neck pain and headache. Hamstrings and sub-occipital muscles are connected by a neural system and sub-occipital muscles pass through the dura Mater. Increased tension and shortening of the hamstring's muscles can cause neck and shoulder pain. In addition, when the muscles around the neck are tensed, the muscles in the limbs are also tensed, so that if the tone of the hamstring muscles is decreased, SLR test score increased, and the tone of the sub-occipital muscles is reduced. Active release technique is found to have an effect on hamstring flexibility.

Cervicogenic Headache (CGH) is a secondary and often unilateral headache that is known by referring pain from soft or hard cervical structures to occipital, temporal and frontal regions. There are some fascial connections between suboccipital muscles with dura mater and C2 vertebra. Presumably, fascial restriction in one part of the body causes unusual stress in other parts of the body due to fascial continuity. It has demonstrated that increased tension and shortening of the hamstring's muscles can cause neck and shoulder pain. This occurs because the superficial fascial back line of the myofascial chain connects from the neck to the lower extremity, and the soft tissue in the cervical spine links the dura and suboccipital muscle fascia. Therefore, it is probable that if the tone of the hamstring muscles is decreased (passively, with a fascial treatment or with active movements), the tone of the knee flexors (hamstring muscles) is reduced and the amplitude of hip flexion is increased, thereby increasing the straight leg raise (SLR) test score. Active release technique (ART) is a type of manual therapy used for treating soft tissue injuries. Problems with muscles, tendons, ligaments, fascia and nerves are successfully treated with it and is found to have an effect on hamstring flexibility.

Inclusion Criteria:

• Unilateral headache (in the same side) related by pain, movement and sustaining position of neck started from the occiput spread to the tempro-frontal region for more than 3 months.
• Pain and tenderness at the upper cervical segment's palpation.
• Movement restriction in cervical region, especially in the upper cervical rotation.
• Positive SLR test for hamstring muscle less than 80◦.

Exclusion Criteria:

• Malignancy.
• Other types of headaches, including migraine, tension type, other serious headaches.
• History of head and neck trauma or surgery.
• Pregnancy.
• Physiotherapy for headache in the last 3 months.