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Introduction Negative pain-related cognitions are associated with persistence of low-back pain (LBP), but the mechanism underlying this association is not well understood. We propose that negative pain-related cognitions determine how threatening a motor task will be perceived, which in turn will affect how lumbar movements are performed, possibly with negative long-term effects on pain. Objective To assess the effect of postural threat on lumbar movement patterns in people with and without LBP, and to investigate whether this effect is associated with task-specific pain-related cognitions. Methods 30 back-healthy participants and 30 participants with LBP performed consecutive two trials of a seated repetitive reaching movement (45 times). During the first trial participants were threatened with mechanical perturbations, during the second trial participants were informed that the trial would be unperturbed. Movement patterns were characterized by temporal variability (CyclSD), local dynamic stability (LDE) and spatial variability (meanSD) of the relative lumbar Euler angles. Pain-related cognition was assessed with the task-specific ‘Expected Back Strain’-scale (EBS). A three-way mixed Manova was used to assess the effect of Threat, Group (LBP vs control) and EBS (above vs below median) on lumbar movement patterns. Results We found a main effect of threat on lumbar movement patterns. In the threat-condition, participants showed increased variability (MeanSDflexion-extension, p

In this study, we describe a protocol to assess relations between organization of the primary motor cortex of several trunk muscles with motor and sensory tests during the clinical course of low back pain. We used a cross-sectional and five-week longitudinal case-control design.

Additional file 1: Overview of the standard set of measurement instruments [13].

Additional file 5. Funnel plot comparing power training to strength training in older adults using muscle power.

Additional file 3. Forrest plot comparing power training to non-training control group using generic tests. Legend: Forest plot showing standardized mean difference between power training and non-training control group in older adults according to the 400 m walk test, 6 minute walk test, chair rise (reps), sit to stand transfer, and balance. The sit to stand transfer and the chair rise in Cadore et al. is, in fact, the same performance test but interpreted in two different manners. Sit to stand is considered to be a performance while chair rise is considered to be a physical function. PT = power training; SD = standard deviation; IV = intravitreal; CI = confidence interval.

Additional file 8. PEDro score for the studies included in the meta-analyses.

Additional file 6. Funnel plot comparing power training to strength training in older adults using generic tests.

Background: Development of more effective interventions for nonspecific chronic low back pain (LBP), requires a robust theoretical framework regarding mechanisms underlying the persistence of LBP. Altered movement patterns, possibly driven by pain-related cognitions, are assumed to drive pain persistence, but cogent evidence is missing. Aim: To assess variability and stability of lumbar movement patterns, during repetitive seated reaching, in people with and without LBP, and to investigate whether these movement characteristics are associated with painrelated cognitions. Methods: 60 participants were recruited, matched by age and sex (30 back-healthy and 30 with LBP). Mean age was 32.1 years (SD13.4). Mean Oswestry Disability Index-score in LBP-group was 15.7 (SD12.7). Pain-related cognitions were assessed by the ‘Pain Catastrophizing Scale’ (PCS), ‘Pain Anxiety Symptoms Scale’ (PASS) and the task-specific ‘Expected Back Strain’ scale(EBS). Participants performed a seated repetitive reaching movement (45 times), at self-selected speed. Lumbar movement patterns were assessed by an optical motion capture system recording positions of cluster markers, located on the spinous processes of S1 and T8. Movement patterns were characterized by the spatial variability (meanSD) of the lumbar Euler angles: flexion-extension, lateralbending, axial-rotation, temporal variability (CyclSD) and local dynamic stability (LDE). Differences in movement patterns, between people with and without LBP and with high and low levels of pain-related cognitions, were assessed with factorial MANOVA. Results: We found no main effect of LBP on variability and stability, but there was a significant interaction effect of group and EBS. In the LBP-group, participants with high levels of EBS, showed increased MeanSDlateral-bending (p = 0.004, η2 = 0.14), indicating a large effect. MeanSDaxial-rotation approached significance (p = 0.06). Significance: In people with LBP, spatial variability was predicted by the task-specific EBS, but not by the general measures of pain-related cognitions. These results suggest that a high level of EBS is a driver of increased spatial variability, in participants with LBP.

Additional file 2. Forest plot comparing power training to non-training control group using muscle power.Legend: Forest plot showing standardized mean difference between power training and non-training control group in older adults according to chest press and leg press. PT = power training; SD = standard deviation; IV = intravitreal; CI = confidence interval.

Additional file 3: Characteristics of the physiotherapists participating in the individual interviews.

Additional file 2: Interview guide.

Additional file 4. Forest plot comparing power training to non-training control group using tests with emphasis on movement speed. Legend: Forest plot showing standardized mean difference between power training and non-training control group in older adults according to the countermovement jump, chair rise, walking speed, short physical performance battery, timed up and go, stair climb, and floor rise to stand. PT = power training; SD = standard deviation; IV = intravitreal; CI = confidence interval.

Data of trial 1 contains position data of movement patterns of 30 people with and 30 people without LBP, during a repetitive seated reaching task (45 times) in a context of postural threat. Data of trial 3 contains position data of movement patterns of 30 people with and 30 people without LBP, during a steady state and familiar task: repetitive seated reaching 45 times. Pelvis, trunk or arm movement were not constrained, nor was the pace of moving. We aimed to study movement adaptations in LBP and thus needed to allow adaptations either in timing or in distribution of movement over joints involved. For more information about methods: See Wildenbeest MH, Kiers H, Tuijt M, van Dieën JH (2023) Effect of postural threat on motor control in people with and without low back pain. PLoS ONE 18(3): e0280607. https://doi.org/10.1371/journal.pone.0280607 M.H. Wildenbeest; H. Kiers; M.Tuijt; J.H.van Dieën; Associations of low-back pain and pain-related cognitions with lumbar movement patterns during repetitive seated reaching; Gait&Posture (2021) https://doi.org/10.1016/j.gaitpost.2021.10.032 M.H. Wildenbeest; H. Kiers; M.Tuijt; J.H.van Dieën; Reliability of measures to characterize lumbar movement patterns, in repeated seated reaching, in a mixed group of participants with and without low-back pain: A test-retest, within- and between session; Journal of Biomechanics (2021); https://www.sciencedirect.com/science/article/pii/S0021929021002153?via%3Dihub

Literature highlights the need for research on changes in lumbar movement patterns, as potential mechanisms underlying the persistence of low-back pain. Variability and local dynamic stability are frequently used to characterize movement patterns. In view of a lack of information on reliability of these measures, we determined their within- and between-session reliability in repeated seated reaching. Thirty-six participants (21 healthy, 15 LBP) executed three trials of repeated seated reaching on two days. An optical motion capture system recorded positions of cluster markers, located on the spinous processes of S1 and T8. Movement patterns were characterized by the spatial variability (meanSD) of the lumbar Euler angles: flexion–extension, lateral bending, axial rotation, temporal variability (CyclSD) and local dynamic stability (LDE). Reliability was evaluated using intraclass correlation coefficients (ICC), coefficients of variation (CV) and Bland-Altman plots. Sufficient reliability was defined as an ICC ≥ 0.5 and a CV < 20%. To determine the effect of number of repetitions on reliability, analyses were performed for the first 10, 20, 30, and 40 repetitions of each time series. MeanSD, CyclSD, and the LDE had moderate within-session reliability; meanSD: ICC = 0.60–0.73 (CV = 14–17%); CyclSD: ICC = 0.68 (CV = 17%); LDE: ICC = 0.62 (CV = 5%). Between-session reliability was somewhat lower; meanSD: ICC = 0.44–0.73 (CV = 17–19%); CyclSD: ICC = 0.45–0.56 (CV = 19–22%); LDE: ICC = 0.25–0.54 (CV = 5–6%). MeanSD, CyclSD and the LDE are sufficiently reliable to assess lumbar movement patterns in single-session experiments, and at best sufficiently reliable in multi-session experiments. Within-session, a plateau in reliability appears to be reached at 40 repetitions for meanSD (flexion–extension), meanSD (axial-rotation) and CyclSD.

Objective: To determine the construct validity, criterion validity, and responsiveness of measurement instruments evaluating scapular function. Design: Systematic review of measurement properties. Literature Search: The MEDLINE, Embase, CINAHL, and SPORTDiscus databases were systematically searched from inception until March 2019. Study Selection Criteria: Studies published in Dutch, English, or German were included when they evaluated at least 1 of the measurement properties of interest. No restrictions were made regarding participants' health status. Data Synthesis: Two reviewers independently evaluated study quality using the COSMIN checklist and extracted and analyzed data. Quality of evidence was graded by measurement property for each distinctive type of measurement. Results: Thirty-one measurement instruments in 14 studies were categorized into instruments to measure scapular posture and movement, and to assess scapular dyskinesis. Quality of evidence was at most moderate for 4 instruments with respect to criterion validity. Of these, criterion validity for instruments measuring scapular protraction/retraction posture and rotation angles up to 120° of thoracohumeral elevation was sufficient. Criterion validity for instruments measuring asymmetrical scapular posture, range of motion, and the lateral scapular slide test was insufficient. Quality of evidence for measurement properties of all other instruments was graded lower. Conclusion: There is currently insufficient evidence to recommend any instrument for the clinical examination of scapular function. Measurement instruments to assess scapular dyskinesis are prone to misinterpretation and should therefore not be used as such.