Disability, kinesiophobia, perceived stress, and pain are not associated with trunk muscle strength or aerobic capacity in chronic nonspecific low back pain

Objectives: To investigate to which extent disability, psychological and pain-related factors are associated with the outcomes of an isometric trunk muscle strength test and a cardiopulmonary exercise test in persons with chronic nonspecific low back pain (CNSLBP). Design: Cross-sectional study. Setting: REVAL Rehabilitation Research Center (Hasselt, Belgium). Participants: Persons with CNSLBP. Main outcome measures: Questionnaires concerning disability, patient specific functioning, kinesiophobia, perceived stress, pain intensity, and central sensitization were recorded. Outcomes of an isometric trunk strength test (maximum back and abdominal torque) and cardiopulmonary exercise test (VO(2)max) were assessed. Multivariate linear regression models determined factors explaining outcome variance. Results: Data of 101 persons (39 males, mean age: 44.2y (SD = 9.6)) was assessed. Neither disability, nor psychological, nor pain-related factors were associated with the assessments. Variance in back muscle strength (R-2 = 0.44, F = p < 0.01), abdominal muscle strength (R-2 = 0.68, F = p < 0.01), and aerobic capacity (R-2 = 0.76, F = p < 0.01) could only be explained through the included demographics covariates (age, gender, weight). Conclusion: This study highlighted the lack of biopsychosocial factors in explaining variance in outcomes of abdominal and back strength, and aerobic capacity in persons with CNSLBP with characteristics as depicted in the current sample. This information supports the valid interpretation of the outcomes of these assessments. (C) 2020 Published by Elsevier Ltd.