Strength and mobility measurements in assessing the outcome of an intensive back rehabilitation program

The purpose of this study was to evaluate the practicability and advantages of isokinetic measurements compared to mobility and non-isokinetic strength measurements in the rehabilitation program of 88 chronic low back pain (LBP) patients. The outcomes of a 3-week rehabilitation program were measured and evaluated by means of changes in spinal mobility, trunk strength measured isokinetically and non-isokinetically, Oswestry Disability Index as well as subjective working capacity. Changes in these measurements during the follow-up period of 6 months were correlated with each other. The results showed high internal correlations (r = 0.72 to 0.84) between isokinetic measurements with different speeds (60 degrees/s and 120 degrees/s). The isokinetic trunk strength measurements showed high correlations with the ones of non-isokinetic strength measurements, but rather weak correlations with the spinal flexibility measurements. Crossectionally, Oswestry disability index and subjective working capacity did not correlate better with the isokinetic repetitive measurements and isokinetic measurements than with non-isokinetic measurements. The highest correlations between the change in Oswestry Disability index and the change in physical measurements were seen for side-bending (r = -0.30) and isometric lifting (r = -0.39). It was concluded that non-isokinetic tests are still useful in clinical practice in spite of the development of more accurate and sophisticated muscle strength evaluation methods.