Performance capacity of trunk muscles in ankylosing spondylitis.

The comparative results of four tests (a dynamometer, a single and a repetitive dynamic and a static test) to determine the performance capacity of trunk muscles in ankylosing spondylitis are reported. Seventeen men and four women, aged 31 to 35 yrs, were examined. Trunk muscle performance was compared with the flexion mobility of the spine and ESR. The best correlation between muscle capacity of trunk extensors and spinal mobility was seen in the static trunk extensor test. The best correlation between muscle capacity of trunk flexors and spinal mobility was seen in the single dynamic test. Because the comprehensive exercise therapy including muscle strengthening is supported by our results and there is no generally recommended test for evaluating the performance capacity of trunk muscles, it seems reasonable to develop such tests of trunk muscles for clinical assessment of ankylosing spondylitis. Clinical trials to ensure the positive effect of well trained trunk muscles in ankylosing spondylitis are still lacking.