Preliminary development of a tool allowing to predict which patients with low back pain who would best benefit from a specific exercise program

1. Perceived disability is measured using the Oswestry disability questionnaire (OSW) at baseline, 4 weeks, 8 weeks and 6 months
2. Pain intensity, measured using an 11-point (0 to 10) numeric pain rating scale (NPRS) to assess the current, best and worst levels of pain intensity during the last week, so as to average the three ratings and obtain a more reliable composite score at baseline, 4 weeks, 8 weeks and 6 months
3. Patient satisfaction is measured using the Physical Therapy Patient Satisfaction (PTPS) questionnaire at 8 weeks

Clinical assessment:
Outcomes will be measured at baseline and 8 weeks
1. Posture (pelvic tilt, lordosis, kyphosis) and range of motion is measured using one or two inclinometers
2. Aberrant movements are measured using observations during flexion – extension
3. Lumbar instability is measured using the prone instability test
4. Ligamentous laxity is measured using the Beighton Scale
5. Lumbar instability is measured using painful arc in flexion
6. Lumbar instability is measured using painful arc in return from flexion
7. Posterior chain flexibility is measured using the passive straight leg rising test
8. Load transfer of lumbo-pelvic area is measured using the active straight leg rising test
9. Muscle testing is measured using three brief tests: side support, active set-up, extensor endurance
10. Physical performance is measured using repeated sit-to-stand, repeated trunk flexions, loaded reach and 360 degree rollover

Psychological assessment:
Outcomes will be measured at at baseline, 4 weeks, 8 weeks and 6 months, unless stated otherwise
1. Fear-avoidance beliefs are measured using the Fear-avoidance beliefs questionnaire (FABQ)
2. Pain catastrophizing is measured using the Pain Catastrophizing Scale (PCS)
3. Psychological distress is measured using the Psychological distress Inventory
4. Activity-related pain is measured by asking participant "Do you experience increased pain during general activity or exercise?"
5. The physical activity level is measured using the Baecke physical activity questionnaire (last month recall)
6. Self-efficacy for exercise is measured using the Self-efficacy for exercise Scale (SEES)
7. Barriers to exercise is measured using the Barriers Efficacy Scale (BES)
8. Social/Family support to exercise is measured using Exercise-specific Items (n = 12/50) of the Friend/Peer Support-Health Eating Physical Activity Scale – FPS-HEPAS
9. Illness perceptions are measured using the Brief Illness Perception Questionnaire (Brief-IPQ)
10. Risk of poor prognosis is measured using the StarT Back screening tool.
11. Expectations about exercise are measured using the Outcome expectation for exercise scale (OEES)
12. Treatment credibility is measured using the Credibility/Expectancy Questionnaire (CEQ). This outcome was measured at 1 week (instead of baseline) as well as mid-treatment (4 weeks) and end of treatment (8 weeks), to allow the patients understand the basic elements of the exercise program.
13. Quality of patient/therapist relationship is measured using the Short form of the Working Alliance Inventory (WAI). This outcome was measured at 1 week (instead of baseline) as well as mid-treatment (4 weeks) and end of treatment (8 weeks) because a minimum of three meetings are required before it is administered.
14. Readiness to exercise is measured using the Stages of Change Questionnaire
15. Home exercise adherence (HEA) is evaluated with two questions asked at the end of treatment (8 weeks) and six-month follow-up:
(1) How many times have you done your exercises as prescribed in the last week?
(2) On average during the last month, how many times a week did you do your exercises as prescribed?
These questions were developed for this study. The frequency is divided by the physiotherapist’s recommendation to obtain a ratio, in accordance with the most common definition of adherence. The ratio may vary between 0 and 1, 1 meaning that the frequency will be equal or higher than prescribed.

Neuromuscular assessment:
Outcomes will be measured at baseline and 8 weeks
1. Deep trunk muscle motor control of abdominal and lumbar multifidus muscles is measured using ultrasound imaging
2. Lumbar proprioception (motion perception threshold) is measured using a custom built motorized apparatus allowing to passively rotate the lumbar spine in the transverse plane (trunk rotation) by rotating the lower body (seat) at a very slow steady rate. As soon as motion is perceived, participants (eyes closed) stop the rotation by pressing a switch.
3. Trunk postural stability during unstable sitting is measured using a wobble chair and an inertial sensor measuring its angular position
4. Lumbar stiffness is measured using a custom built motorized apparatus generating series of pseudorandom position-controlled trunk perturbations and measuring forces and displacements at the harness surrounding the thorax, allowing to estimate the intrinsic and reflexive contributions to lumbar stiffness
5. Anticipatory postural adjustments to a rapid arm flexion movement is measured using surface electromyographic measures of 12 trunk muscles (6 abdominals + 6 back) and the angular kinematics of the lumbar spine
6. Trunk muscle coordination during maximal trunk flexion/extension movements is measured using surface electromyographic measures of 6 back muscles and the angular kinematics of the pelvis, lumbar spine and thoracic spine