Chronic low back pain is a worldwide burden that is not being abated with our current knowledge and treatment of the condition. The fear-avoidance model is used to explain the relationship between pain and disability in patients with chronic low back pain. However there are gaps in empirical support for pathways proposed within this model, and no evidence exists as to whether physical activity moderates these pathways. This was a cross-sectional study of 218 people with chronic low back pain. Multiple mediation analyses were conducted to determine the role of fear, catastrophizing, depression, and anxiety in the relationship between pain and disability. Separate analyses were performed with physical activity as the moderator. Individuals were classified as performing regular structured physical activity if they described on average once per week for > 30-minutes an activity classified at least moderate intensity (≥ 4–6 METs), activity prescribed by an allied health professional for their back pain, leisure time sport or recreation, or self-directed physical activity such as resistance exercise. Fear, catastrophizing, and depression significantly mediated the relationship between pain and disability (p<0.001). However the mediating effect of catastrophizing was conditional upon weekly physical activity. That is, the indirect effect for catastrophizing mediating the relationship between pain and disability was only significant for individuals reporting weekly physical activity (B = 1.31, 95% CI 0.44 to 2.23), compared to individuals reporting no weekly physical activity (B = 0.21, 95% CI -0.50 to 0.97). Catastrophizing also mediated the relationship between pain and fear (B = 0.37, 95% CI 0.15 to 0.62), with higher scores explaining 53% of the total effect of pain on fear. These results support previous findings about the importance of fear and depression as factors that should be targeted in low back pain patients to reduce back pain related disability. We have also extended understanding for the mediating effect of catastrophizing on back pain related disability. Back pain patients engaged with regular physical activity may require counselling with regards to negative pain perceptions.

The purpose of this pilot study was to use a multidimensional model to evaluate deficits in patients with low back pain (LBP) over the course of a 12-week rehabilitation program using the Swiss ball. A within-subjects, repeated-measures design based at the University exercise training clinic was used. Twenty patients with chronic nonspecific LBP (12 men, 8 women; symptom duration, 4.8 years; 38.8 +/- 12.1 years old; height, 1.76 +/- 0.06 m; weight, 76.15 +/- 7.21 kg) participated in this study. Self-report measures were the Oswestry Disability Index, Visual Analog Scale, Medical Outcomes 12-Item Short Form Health Survey, and Self-Efficacy For Exercise Scale. Physiologic measures were electromyography measurement of feedforward muscle activation, flexion relaxation phenomenon, myoelectric fatigue, endurance capacity measured by the Sorenson test, and a modified sit-up test. Individuals performed 12 weeks of progressive exercise periodized every 4 weeks using a Swiss ball. Outcome measures were assessed at baseline, 4 weeks, 8 weeks, 12 weeks, and at a 3-month follow-up. Repeated-measures analysis for variance for time differences and regression analysis for variance in Oswestry scores were performed. The Oswestry score for self-reported disability significantly decreased over the intervention (F(4,14) = 19.456, P < .001). Significant improvements in pain and disability maintained to the 3 months of follow-up. There were significant changes in perceptions of physical and mental well-being, erector spinae fatigue, and flexion relaxation measures. Change in flexion relaxation explained 38% of the improvement in Oswestry scores at the 12-week measurement. This study showed that the Swiss ball may be successfully used in a rehabilitation context for patients with LBP. This pilot study has used a novel approach to assess improvements during a rehabilitation program, which may be used in the future to explain differences between different treatment modalities.