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The most common cause of neck soreness and stiffness in otherwise healthy individuals is muscle strain. This is because the neck muscles have to hold up the head all day, and the head is quite heavy (about the weight of a bowling ball). Tasks that require a lot of bending of the head downward (neck flexion) put a lot of strain on these muscles. In addition, the muscles along the scapula are there to stablize the scapulae so that you can generate power with your arms, so even keyboarding and mousing put strain there. I would suggest you ask your doctor for a cervical spine series (xrays) to rule out arthritis or other risk factors for neck pain and see if you can get a referral to a physical therapist. He or she can work with you on posture and mechanics and even evaluate your workstation and other work related requirements to make sure none of them are contributing to your condition.
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