Are fear-avoidance beliefs in low back pain patients a risk factor for low physical activity or vice versa? A cross-lagged panel analysis.

Objective: The assumption that low back pain (LBP) patients suffer from "disuse" as a consequence of high fear-avoidance beliefs is currently under debate. A secondary analysis served to investigate whether fear-avoidance beliefs are associated cross-sectionally and longitudinally with the physical activity level (PAL) in LBP patients. Methods: A total of 787 individuals (57% acute and 43% chronic LBP) were followed up over a period of one year with measurements of fear-avoidance beliefs and physical activity level. Fear-avoidance beliefs concerning physical activity were measured by the physical-activity subscale of the FABQ (Fear-Avoidance Beliefs Questionnaire), the physical activity level was assessed in weighted metabolic equivalents (MET) hours/week with a German self-report questionnaire. Data were investigated by structural equation modelling in a cross-lagged panel design for the whole sample and separately for acute and chronic LBP.Results: The acute and chronic sub sample increased their total physical activity level significantly after one year. The structural equation modelling results did not support the disuse-aspect inherent in the fear-avoidance belief model. Cross-lagged path coefficients were low (.04 and .05 respectively) and, therefore, did not allow to predict final physical activity by initial fear-avoidance beliefs or vice versa. Discussion: Consequently, due to missing links between fear-avoidance beliefs and physical activity in a longitudinal design, the assumptions of the fear-avoidance belief model have to be questioned. These findings are in line with other investigations published recently. Most probably, "fear-avoidance belief" represents a cognitive scheme that does not limit activity per se, but only is directed to the avoidance of specific movements.