Physical capacity tasks in chronic low back pain: what is the contributing role of cardiovascular capacity, pain and psychological factors?

Abstract

To explore the association of personal and body functions with physical capacity tasks used in the evaluation of chronic low back pain (CLBP) treatment. Cross-sectional study in which 221 patients with non-specific CLBP participated. Physical capacity was assessed by six capacity tasks, and several personal and body functions were assessed by questionnaires (age, gender, pain intensity, duration of pain, radiating pain to leg, fear of injury/movement, depression, pain catastrophizing and internal control of pain). Cardiovascular capacity was measured by a modified Astrand submaximal bicycle test. The association of these hypothetically influential personal and body function factors with capacity tasks was examined with multiple linear regression analyses. The total explained variance was low to moderate (9 - 19%), except for stair climbing for which the variance just reached 30%. Many putative factors did not contribute significantly to the level of outcome of several different tasks. Cardiovascular capacity, pain intensity, fear of injury/movement, cognitions, and depression had statistically significant but clinically minor effects on several, but not all capacity tasks. Radiating pain, age and duration of complaints had no significant influence at all. Due to anthropometric differences men outperformed women on most tasks. Apparently the influence of many personal, physical but especially psychological factors on the selected capacity tasks is not high at all. This might indicate that these tasks are more objectively measuring physical capacity than expected.