Psychophysical capacity in non-specific chronic low back pain

In the rehabilitation of non-specific chronic low back pain (CLBP) patients the emphasis has shifted from biomedical to bio-psychosocial rehabilitation. In the bio-psychsocial rehabilitation biomedical tests like maximal or sub maximal capacity tests as well as assessment of perceived effort are thought to be important to obtain a comprehensive picture of the patient’s limitations and treatment goals and to evaluate effects of the rehabilitation program. Consequently, there is a need for tests that include both physical capacity and perceived effort in non-specific CLBP patients. Until now it was not clear which determinants could explain the beneficial effect of bio-psychosocial rehabilitation. This thesis focuses on the psychometric properties of the new developed outcome measures that included physical capacity as well as perceived effort and the determinants of the reduction in perceived disability of bio-psychosocial rehabilitation. This thesis shows that the psychophysical lifting capacity calculated as the ratio between physical effort expressed in Newton (N) and perceived effort expressed in Borg score(B) is a reliable outcome measure in non-specific CLBP patients. The beneficial effects of the reduction of perceived disability by biopsychosocial rehabilitation can partly be explained by an improvement of the psychophysical lifting capacity. Clinically, the thesis indicate that rehabilitation of non-specific CLBP patients should focus on psychophysical capacity and perceived disability of activities of daily living.