Effects of warming up on reliability of anthropometric techniques in ankylosing spondylitis.

To determine the effect of warm-up on anthropometric measures, 10 patients with ankylosing spondylitis and 10 normal control subjects were measured over a 1-hour period by one therapist. A series of 4 measures--a modified Schober's test, finger-to-floor with the subject standing on a 23-cm stool, chest expansion, and cervical rotation using an arthrodial protractor--were repeated completely 4 times. Subjects exercised between each series (except between the third and fourth series). Intra-rater reliability was determined by comparing measurement 3 with measurement 4, and the warm-up effect was determined by comparing measurement 1 with measurement 3. The Schober's test and chest expansion are stable measures and are not affected by warm-up. However, the finger-to-floor and cervical rotation exercises require warm-up to ensure stable values for clinical or research followup of spondylitis.