4. contraindications to SMT or mild-exertion exercise, as determined by the clinician through physical exam and x-rays (if indicated). Contraindications include but are not limited to: signs and symptoms associated with vertebrobasilar insufficiency (including facial numbness, diplopia, drop attacks, dysphagia, and ataxia which are not fatiguable or habituable with repeated provocative head positioning); unstable or severe medical condition; severe osteoporosis, fracture or other osseous abnormalities; "high cardiovascular risk", i.e. persons with known severe cardiovascular, pulmonary or metabolic disease, or one or more major signs/symptoms suggestive of cardiovascular and pulmonary disease