Physical Profile of Cervicogenic Headache: Comparison With Neck Pain and Healthy Controls

The goal of this observational study is to compare physical findings across three adult groups. Cervicogenic headache (CGH) is a headache linked to a problem in the neck. Neck pain may affect posture, muscle function, grip strength, and sensitivity to pressure. Researchers do not know whether CGH has a distinct pattern of these findings. The main questions are: * Do posture, grip strength, muscle stiffness, elasticity, and pressure sensitivity differ among the groups? * Are any differences more closely associated with CGH than with neck pain? Researchers will compare adults ages 25 through 60. One group will include people with CGH lasting at least three months. Another group will include people with neck pain lasting at least six months. People in the neck pain group will have no headaches. Healthy participants will have no neck pain or headaches. Researchers will not provide treatment or change participants' usual care. Each participant will complete one study visit lasting about 15 minutes. Participants will: * Answer short questions about their health and pain * Stand while researchers measure their head and neck posture * Squeeze a device that measures grip strength * Complete brief tests of neck muscle stiffness and elasticity * Tell researchers when applied pressure first becomes painful Researchers will compare results across the three groups. The findings may guide future CGH assessment and treatment research.