[Isokinetic strength of lumbar muscles in patients with chronic backache].

Lumbar isokinetic strength and the influence of age, bodyweight and testing velocity in patients with chronic low back pain in comparison with persons without pain. Lumbar isokinetic strength parameters of 80 patients with chronic low back pain and 70 persons without pain were compared and the influence of age, bodyweight and testing velocity was evaluated. The patients with chronic low back pain showed less strength than the persons without pain. All parameters of extension discriminated between the two groups whereas only some of the flexion parameters did. The isokinetic strength of the lumbal extension muscles was higher than the strength of the flexion muscles. In patients with chronic low back pain, isokinetic strength of lumbar extension muscles was more reduced than the strength of flexion muscles in comparison with persons without pain. At 90 degrees/sec in comparison to 60 degrees/sec, lower extension forces, higher flexion forces and changed ratios of flexion and extension muscles were measured. Age had an influence only on women. There were no changes in ratios of flexion and extension muscles with increasing age. Bodyweight showed weak correlations with isokinetic flexion forces. The influence of different factors on isokinetic force varies between patients with chronic low back patients and healthy subjects.