Effects of Cervical Spine Manipulation on Gait

Inclusion Criteria: 1. Volunteers may or may not have mechanical neck pain 2. Aged 18 to 70 years 3. If neck pain is present, must have Neck Disability Index score of at least 10 out of 50 points Exclusion Criteria: 1. 'Red flag' items indicated in Neck Medical Screening Questionnaire such as history of a tumor, bone fracture, metabolic diseases, Rheumatoid Arthritis, osteoporosis, severe atherosclerosis, prolonged history of steroid use, etc. 2. History of neck whiplash injury 3. Diagnosis from physician of cervical spinal stenosis (narrowing of spinal canal) or presence of symptoms (pain, pins and needles, numbness) down both arms 4. Presence of central nervous system involvement such as exaggerated reflexes, changes in sensation in the hands, muscle wasting in the hands, impaired sensation of the face, altered taste, and presence of abnormal reflexes 5. Evidence of neurological signs consistent with nerve root entrapment (pinched nerve in the neck) 6. Prior surgery to neck or upper back 7. A medical condition which may influence assessment of pain or pressure pain thresholds (i.e. taking analgesics, sedatives, history of substance abuse, or cognitive deficiency) 8. Diagnosis from your physician of fibromyalgia syndrome 9. Currently pregnant, or could be pregnant