Towards an understanding of physical activity in people with chronic low back pain

Physical activity (PA) is well recognised as an essential component of a healthy lifestyle and is commonly recommended as part of a multimodal management approach for people with chronic low back pain (CLBP). However, to date there is limited evidence of how best to promote PA in people with CLBP. Knowledge of the correlates and determinants of PA in this patient group is necessary to facilitate and promote PA in patients’ everyday lives. The main aim of this thesis was to determine the physical and psychological correlates of objectively measured PA in people with CLBP. This doctoral thesis examined the correlates of PA and sedentary activity in people with CLBP using a mixed methods approach. Initially, a systematic review was undertaken to examine the common assumption that patients with CLBP are less active than healthy individuals. There was no consistent evidence supporting this hypothesis for adults or adolescents. For older adults, there was evidence that they are less active than healthy control based on self-reported levels of PA. The ActivPAL™ activity monitor has previously been validated as a measure of postural PA in people with CLBP. To further examine this monitor, a study was designed to determine if the ActivPAL™ can also accurately measure the intensity of PA in this patient group. The findings were positive and suggest that the ActivPAL™ “counts” function may be useful, from which one can accurately determine PA intensity especially during locomotor activity. A study designed to examine the correlates of free-living PA and sedentary activity in people with CLBP revealed an important role of depression and elevated body mass index (BMI) respectively. Moreover, given the heterogeneity of people with CLBP, the comparative PA and sedentary activity profile of patients with and without a neuropathic pain (NeuP) component was examined. The findings are in line with previous findings which suggest that patients with a NeuP component are more disabled and have poorer psychological functioning. However, there was no significant difference in the level of PA or sedentary activity between the groups. Finally, to add perspective and aid in the interpretation of the quantitative findings of this thesis, a qualitative study was undertaken to explore the perceptions and attitudes towards PA among patients with CLBP. The results, while highlighting a number of important barriers and motivations for PA, support recent experimental evidence which suggests that a decision to engage in or avoid activity is partly dependent on the motivational context of the activity. When patients are intrinsically motivated by non-pain goals, they are more likely to persist with an activity. In summary, only depression and BMI were associated with objectively measured free-living PA and sedentary activity respectively. From a qualitative perspective, a number of potential barriers and motivations for PA were indentified although it was clear from the results that choosing to engage in or avoid activity was highly task- and context-specific.