Not all steps in the process were part of each coaching session. The anticipated length of each coaching session was approximately 30 minutes, with the actual duration of each coaching session dependent on the rate of progress through the protocol. The coach did not offer any treatment advice or comment on the treatment provided by the treating physiotherapist GPCR Compound Library clinical trial or any other treating health practitioner. If the participant had specific questions

regarding their treatment, the coach encouraged the participant to discuss the concerns with the relevant practitioner. Coaching was applied via telephone once per week for 4 weeks after baseline, and once more 3 weeks later. In order to provide support throughout return to usual activity, coaching continued for a total of 5 sessions even if the participant reported returning to full activities. Coaching also continued for 5 sessions if the participant reported being discharged from physiotherapy or decided to pursue alternative forms of treatment. Coaching was applied independently to physiotherapy and there was no correspondence between the treating therapist and the coach. The treating physiotherapists were blind to group allocation in order to ensure knowledge of the coaching intervention did not influence their

management of the patient. Primary outcome: The primary outcome was activity limitation measured by the Patient Specific Functional Scale ( Stratford et al 1995). For this scale, participants Screening Library identified their primary non-leisure activity and two other activities they were unable to perform to the same level as they could before the problem. The item ratings were averaged to yield a total score between 0 and 10 where a higher score

indicates better functioning. The score for the single-item primary non-leisure activity was also analysed separately. The Patient Specific Functional Scale also has high test-retest reliability (ICC = 0.97) ( Stratford et al 1995), concurrent validity with other measures of back-specific activity limitation (r = 0.55 to 0.74) ( Donnelly and Carswell, 2002), and responsiveness to change in low back pain populations ( Pengel et al 2004). The minimum clinically important difference established in previous studies was 2 points on the average Patient Specific Functional Scale score ( Maughan and Lewis, 2010), and 3 points on the primary non-leisure activity ( Stratford et al 1995). Secondary outcomes: The modified Oswestry Disability Index ( Fritz and Irrgang, 2001) was also used as a region-specific measure of activity limitation. The Oswestry Index is scored as a percentage, with a higher percentage indicating a higher level of back-related disability. It has demonstrated evidence of reliability and validity ( Davidson and Keating, 2002, Jolles et al 2005, Ostelo and de Vet, 2005, Roland and Fairbank, 2000).