Measurement of back movement.
D000293:Adolescent; D000328:Adult; D000368:Aged; D001827:Body Height; D001835:Body Weight; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology*; D008297:Male; D008722:Methods; D008875:Middle Aged; D009068:Movement; D011859:Radiography; D012737:Sex Factors; D013131:Spine / Q000000981:diagnostic imaging*; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging / Q000503:physiopathology*