Differences in the organization of the primary motor cortex in people with and without low back pain and associations with motor control and sensory tests.

Differences in organization of the primary motor cortex and altered trunk motor control (sensing, processing and motor output) have been reported in people with low back pain (LBP). Little is known to what extent these differences are related. We investigated differences in 1) organization of the primary motor cortex and 2) motor and sensory tests between people with and without LBP, and 3) investigated associations between the organization of the primary motor cortex and motor and sensory tests. We conducted a case-control study in people with (N=25) and without (N=25) LBP. The organization of the primary motor cortex (Center of Gravity (CoG) and Area of the cortical representation of trunk muscles) was assessed using neuronavigated transcranial magnetic stimulation, based on individual MRIs. Sensory tests (quantitative sensory testing, graphaesthesia, two-point discrimination threshold) and a motor test (spiral-tracking test) were assessed. Participants with LBP had a more lateral and lower location of the CoG and a higher temporal summation of pain. For all participants combined, better vibration test scores were associated with a more anterior, lateral, and lower CoG and a better two-point discrimination threshold was associated with a lower CoG. A small subset of variables showed significance. Although this aligns with the concept of altered organization of the primary motor cortex in LBP, there is no strong evidence of the association between altered organization of the primary motor cortex and motor and sensory test performance in LBP. Focusing on subgroup analyses regarding pain duration can be a topic for future research.

Evidence of splinting in low back pain? A systematic review of perturbation studies.

PURPOSE: The purpose of this systematic review was to assess whether LBP patients demonstrate signs of splinting by evaluating the reactions to unexpected mechanical perturbations in terms of (1) trunk muscle activity, (2) kinetic and (3) kinematic trunk responses and (4) estimated mechanical properties of the trunk. METHODS: The literature was systematically reviewed to identify studies that compared responses to mechanical trunk perturbations between LBP patients and healthy controls in terms of muscle activation, kinematics, kinetics, and/or mechanical properties. If more than four studies reported an outcome, the results of these studies were pooled. RESULTS: Nineteen studies were included, of which sixteen reported muscle activation, five kinematic responses, two kinetic responses, and two estimated mechanical trunk properties. We found evidence of a longer response time of muscle activation, which would be in line with splinting behaviour in LBP. No signs of splinting behaviour were found in any of the other outcome measures. CONCLUSIONS: We conclude that there is currently no convincing evidence for the presence of splinting behaviour in LBP patients, because we found no indications for splinting in terms of kinetic and kinematic responses to perturbation and derived mechanical properties of the trunk. Consistent evidence on delayed onsets of muscle activation in response to perturbations was found, but this may have other causes than splinting behaviour.

Is There a Relationship Between Lumbar Proprioception and Low Back Pain? A Systematic Review With Meta-Analysis.

OBJECTIVE: To systematically review the relationship between lumbar proprioception and low back pain (LBP). DATA SOURCES: Four electronic databases (PubMed, EMBASE, CINAHL, SPORTDiscus) and reference lists of relevant articles were searched from inception to March-April 2014. STUDY SELECTION: Studies compared lumbar proprioception in patients with LBP with controls or prospectively evaluated the relationship between proprioception and LBP. Two reviewers independently screened articles and determined inclusion through consensus. DATA EXTRACTION: Data extraction and methodologic quality assessment were independently performed using standardized checklists. DATA SYNTHESIS: Twenty-two studies (1203 participants) were included. Studies measured lumbar proprioception via active or passive joint repositioning sense (JRS) or threshold to detection of passive motion (TTDPM). Data from 17 studies were pooled for meta-analyses to compare patients with controls. Otherwise, descriptive syntheses were performed. Data were analyzed according to measurement method and LBP subgroup. Active JRS was worse in patients compared with controls when measured in sitting (standard mean difference, .97; 95% confidence interval [CI], .31-1.64). There were no differences between groups measured via active JRS in standing (standard mean difference, .41; 95% CI, -.07 to .89) or passive JRS in sitting (standard mean difference, .38; 95% CI, -.83 to 1.58). Patients in the O'Sullivan flexion impairment subgroup had worse proprioception than the total LBP cohort. The TTDPM was significantly worse in patients than controls. One prospective study found no link between lumbar proprioception and LBP. CONCLUSIONS: Patients with LBP have impaired lumbar proprioception compared with controls when measured actively in sitting positions (particularly those in the O'Sullivan flexion impairment subgroup) or via TTDPM. Clinicians should consider the relationship between sitting and proprioception in LBP and subgroup patients to guide management. Further studies focusing on subgroups, longitudinal assessment, and improving proprioception measurement are needed.

Towards a better understanding of our patients. A qualitative study about how patients and their physiotherapists perceive the recovery of shoulder problems.

OBJECTIVE: To investigate how people with shoulder problems and their physiotherapists perceive the recovery of shoulder problems. METHOD: We performed a qualitative study using semi-structured interviews with patients and their physiotherapists. Nine pairs of patients and physiotherapists (n = 18) were recruited. The transcribed interviews were analyzed in a consecutive multistep iterative process using a conventional content analysis. RESULTS: Analysis of the interviews resulted in three major themes: 'What do I expect from my recovery?', 'Am I recovering?' and 'When do I consider myself recovered?' The patients and physiotherapists talked similarly about the importance of and interdependency between these themes. Central to these three themes are the analysis of the cause of shoulder problems and the experience of uncertainty. Our analyses suggest that there are conceptual differences in how patients and physiotherapists formulate their expectations about recovery, observe the recovering process, and conceptualize when someone may be considered recovered. Different interpretations by the patients of the information provided by the physical therapists appeared to fuel these differences. CONCLUSION: Our results show that the concept of recovery is defined by patients and physiotherapists in three distinct themes. Within these themes the patients and physiotherapists differ substantially in their conceptualization of the recovery. IMPACT STATEMENT: This insight in the concept of recovery can help patients and physiotherapists better understand each other, enhance the alignment of ideas about the care process, and support making decisions together. Physiotherapists should be aware that patients might interpret their words, explanations, and expectations substantially different.

Exploring health and illness perceptions to identify the perceived cause of pregnancy-related pelvic girdle pain. A mixed-methods study among primiparous women in The Netherlands.

BACKGROUND: Pregnancy-related pelvic girdle pain (PPGP) is common and considered a multifactorial condition with biomechanical and psychosocial contributions. The patient's perceived cause is an important aspect of illness perceptions, and a strong predictor of self-management and healthcare utilization. It is unknown what causal beliefs primiparae hold regarding PPGP. OBJECTIVE: To explore and describe health and illness perceptions among primiparae towards PPGP and its cause. DESIGN: Exploratory, convergent parallel mixed-methods. SETTING: At the participants' homes. PARTICIPANTS: Sixteen primiparae with and without PPGP. FINDINGS: Primiparae with and without PPGP held comparable causal beliefs about PPGP. PPGP was described as the result of hormonal softening and loosening of the pelvis, and failure of the muscular system to compensate for that. Women who experienced similar physical symptoms attributed them differently, leading to different coping strategies. Interestingly, maternal healthcare providers reinforced the unidimensional- and predominantly biomechanical view when women sought healthcare. CONCLUSION: The causal mechanism of PPGP held by the women was not determined by their lived experience. It was primarily based on the concept of inevitable hormonal softening of the pelvis. This biomechanical belief is based on theories that are not in line with current knowledge of PPGP and contemporary pain science, yet they were reinforced by maternity healthcare providers. IMPLICATIONS FOR PRACTICE: Healthcare seeking behavior is influenced by illness beliefs. Maternity healthcare providers may play a key role in providing reassurance and addressing the multifactorial nature of PPGP when providing care and support to pregnant women.

Therapeutic validity and replicability of power training interventions in older adults: A review using the TIDieR checklist and CONTENT scale.

Background: Randomized controlled trials (RCTs) indicate that power training has the ability to improve muscle power and physical performance in older adults. However, power training definitions are broad and previously-established criteria are vague, making the validity and replicability of power training interventions used in RCTs uncertain. Objective: The aim of this review was to assess whether the power training interventions identified in a previous systematic review (el Hadouchi 2022) are fully described, therapeutically valid, and meet our proposed criteria for power training. Design: Review. Methods: Power training interventions used in older adults, previously-identified in a systematic review, were assessed. The completeness of intervention descriptions was evaluated using the Template for Intervention Description and Replication (TIDieR), and therapeutic validity was evaluated using the CONTENT scale in combination with a set of criteria specific for power training. Results: None of the power training interventions were fully described or met the CONTENT scale's criteria for therapeutic validity. Five out of 14 interventions (35.7 %) met all specific power training criteria. Conclusions: Power training interventions used in RCTs comparing power training to strength training are poor to moderately described, may not be therapeutically valid, and may not reflect the construct of power training. This makes it difficult for clinicians or researchers to apply or replicate power training interventions reported in RCTs, and begs the question whether the true effects of power training have been estimated.

Precision of trunk movement in people with chronic low back pain.

BACKGROUND: Motor control exercise is commonly applied in people with chronic low back pain (CLBP), but possibly not all people with CLBP have motor control impairments. We suggest movement precision as measure to identify motor control impairments. Movement precision has been operationalized as trunk movement variability (TMV) and as trunk tracking error(s) (TTE). OBJECTIVES: To compare the known-group validity and the responsiveness of TMV and TTE. DESIGN: We used a case-control comparison (Healthy controls (n = 30) vs CLBP (n = 60)) to assess the known-group validity. A cohort study, (measurements in week 3 and week 12 of treatment), was used to assess responsiveness. METHODS: TMV (temporal (CyclSD) and spatial (MeanSD)) was analyzed during standing, repetitive flexion and rotation tasks (35x). TTE was measured during movement target tracking tasks, again in flexion and rotation. Participants with CLBP followed a multidisciplinary intervention and both measures were assessed in week 3 and week 12 of treatment. 2-way MANOVA and 2-way ANOVA were used to assess the effect of Group (CLBP vs healthy controls) and direction (flexion vs rotation) on TMV and TTE. For responsiveness, 2-way MANOVA and 2-way ANOVA were used to assess the effect of treatment and direction on both measures. FINDINGS: At baseline, TMV was not different between groups, while TTE was higher in the people with CLBP (p = 0.005, np2 = 0.09). Treatment strongly decreased temporal TMV (p = 0.025, np2 = 0.33) and TTE (p < 0.001, np2 = 0.844). CONCLUSIONS: These results demonstrate that TTE is more sensitive to CLBP and more responsive to treatment than TMV.

Effect of postural threat on motor control in people with and without low back pain.

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<0.000, η2 = 0.26; CyclSD, p = 0.003, η2 = 0.14) and decreased stability (LDE, p = 0.004, η2 = 0.14), indicating large effects of postural threat. CONCLUSION: Postural threat increased variability and decreased stability of lumbar movements, regardless of group or EBS. These results suggest that perceived postural threat may underlie changes in motor behavior in patients with LBP. Since LBP is likely to impose such a threat, this could be a driver of changes in motor behavior in patients with LBP, as also supported by the higher spatial variability in the group with LBP and higher EBS in the reference condition.

Trunk resistance to mechanical perturbations, associations with low back pain, pain-related cognitions and movement precision.

BACKGROUND: Pain-related cognitions are associated with motor control changes in people with chronic low-back pain (CLBP). The mechanism underlying this association is unclear. We propose that perceived threat increases muscle-spindle-reflex-gains, which reduces the effect of mechanical perturbations, and simultaneously decreases movement precision. AIM: To evaluate effects of CLBP and pain-related cognitions on the impact of mechanical perturbations on trunk movement, and associations between these perturbation effects and movement precision. METHODS: 30 participants with CLBP and 30 healthy controls, performed two consecutive trials of a seated repetitive reaching task. During both trials participants were warned for mechanical perturbations, which were only administered during the second trial. The perturbation effect was characterized by the deviation of the trajectory of the T8 vertebra relative to the sacrum. Trunk movement precision was expressed as tracking error during a trunk movement target tracking task. We assessed pain-related cognitions with the task-specific 'Expected Back Strain'-scale (EBS). We used a two-way-Anova to assess the effect of Group (CLBP vs back-healthy) and dichotomized EBS (higher vs lower) on the perturbation effect, and a Pearson's correlation to assess associations between perturbation effects and movement precision. FINDINGS: Higher EBS was associated with smaller perturbation effects (p ≤ 0.011). A negative correlation was found between the perturbation effect and the tracking error, in the higher EBS-group (r = -0.5, p = 0.013). INTERPRETATION: These results demonstrate that pain-related cognitions influence trunk movement control and support the idea that more negative pain-related cognitions lead to an increased resistance against perturbations, at the expense of movement precision.

Reliability of two lumbar motor control tests for people with low back pain that are feasible in clinical practice.

BACKGROUND: Clinically feasible and reliable methods to measure motor control in people with low back pain (LBP) are lacking. This reliability and measurement error study design (i.e. repeated measurements in stable patients) aimed to determine the intra- and interrater reliability, and measurement errors of several parameters for two clinical lumbar motor control tests. METHOD: Participants 18-65 years of age, with current or a history of LBP performed a spiral tracking task (n = 33; i.e., tracing a spiral on a computer monitor by making spinal movements) or a repositioning task (n = 34; i.e., returning the trunk to a predefined position). Accelerometers were used to measure trunk positions. To explore the potential of these tests, we evaluated a broad range of parameters. To assess intra- and interrater reliability, we calculated the intraclass correlation coefficient (ICC(2,1) for absolute agreement), standard error of measurement and smallest detectable change for each parameter. FINDINGS: Overall, the interrater reliability of the spiral tracking test was good (ICC>0.75). The reliability of the second and third trial revealed higher ICC values compared to the reliability of the first two trials. The intra- and interrater reliability of the repositioning test was overall poor (ICC <0.5, with the exception of trunk inclination: ICC: 0.5 to 0.75). CONCLUSION: The reliability and set-up of the spiral tracking test supports its feasibility for clinical use. Considering the poor reliability of the repositioning test, it is doubtful whether further development of this measurement protocol is indicated. Only for the direction trunk inclination further standardisation might be warranted.

Ankle proprioception is not targeted by exercises on an unstable surface.

Laboratory study using a repeated measures design. The aim of this study was to determine if ankle proprioception is targeted in exercises on unstable surfaces. Lateral ankle sprain (LAS) has recurrence rates over 70%, which are believed to be due to a reduced accuracy of proprioceptive signals from the ankle. Proprioceptive exercises in rehabilitation of LAS mostly consist of balancing activities on an unstable surface. The methods include 100 healthy adults stood barefoot on a solid surface and a foam pad over a force plate, with occluded vision. Mechanical vibration was used to stimulate proprioceptive output of muscle spindles of triceps surae and lumbar paraspinal musculature. Each trial lasted for 60 s; vibration was applied from the 15th till the 30th second. Changes in mean velocity and mean position of the center of pressure (CoP) as a result of muscle vibration were calculated. Results show that on foam, the effect of triceps surae vibration on mean CoP velocity was significantly smaller than on a solid surface, while for paraspinal musculature vibration the effect was bigger on foam than on solid surface. Similar effects were seen for mean CoP displacement as outcome. Exercises on unstable surfaces appear not to target peripheral ankle proprioception. Exercises on an unstable surface may challenge the capacity of the central nervous system to shift the weighting of sources of proprioceptive signals on balance.

Physical fitness, rather than self-reported physical activities, is more strongly associated with low back pain: evidence from a working population.

INTRODUCTION: Physical activity is suggested to be important for low back pain (LBP) but a major problem is the limited validity of the measurement of physical activities, which is usually based on questionnaires. Physical fitness can be viewed as a more objective measurement and our question was how physical activity based on self-reports and objective measured levels of physical fitness were associated with LBP. MATERIALS AND METHODS: We analyzed cross-sectional data of 1,723 police employees. Physical activity was assessed by questionnaire (SQUASH) measuring type of activity, intensity, and time spent on these activities. Physical fitness was based on muscular dynamic endurance capacity and peak oxygen uptake (VO(2) peak). Severe LBP, interfering with functioning, was defined by pain ratings ≥ 4 on a scale of 0-10. RESULTS: Higher levels of physical fitness, both muscular and aerobic, were associated with less LBP (OR: 0.54; 95% CI: 0.34-0.86, respectively, 0.59: 95%CI: 0.35-0.99). For self-reported physical activity, both a low and a high level of the total physical activity pattern were associated with an increase of LBP (OR: 1.52; 95%CI: 1.00-2.31, respectively, 1.60; 95%CI: 1.05-2.44). CONCLUSION: These findings suggest that physical activity of an intensity that improves physical fitness may be important in the prevention of LBP.

Associations of low-back pain and pain-related cognitions with lumbar movement patterns during repetitive seated reaching.

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 pain-related 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, lateral-bending, 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.

Effectiveness of power training compared to strength training in older adults: a systematic review and meta-analysis.

BACKGROUND: Research suggests that muscle power is a more critical determinant of physical functioning in older adults than muscle strength. The objective of this study was to systematically review the literature on the effect of power training compared to strength training in older adults on tests for muscle power, two groups of activity-based tests under controlled conditions: generic tests and tests with an emphasis on movement speed, and finally, physical activity level in daily life. METHODS: A systematic search for randomized controlled trials comparing effects of power training to strength training in older adults was performed in PubMed, Embase, Ebsco/CINAHL, Ebsco/SPORTDiscus, Wiley/Cochrane Library and Scopus. Risk of bias was assessed using the Cochrane Collaboration Tool, and quality of evidence was evaluated using GRADEpro Guideline Development Tool. Standardized mean differenences (SMD) and 95% confidence intervals (CI) were calculated for outcomes separately using a random effects model. RESULTS: Fifteen trials and 583 participants were included in the meta-analysis. Results indicated a statistically significant benefit of power training on all reported outcomes (muscle power SMD: 0.99, 95% CI: 0.54 to 1.44, p < 0.001; generic activity-based tests SMD: 0.37, 95% CI 0.06 to 0.68; p = 0.02, activity-based tests emphasizing movement speed SMD: 0.43, 95% CI 0.23 to 0.62, p < 0.001). None of the included studies used physical activity level in daily life as outcome. CONCLUSIONS: Power training offers more potential for improving muscle power and performance on activity tests in older adults compared to strength training. Future research should assess exercise parameters for power training in older adults. In addition, the validity and reliability of the tests used must be evaluated to establish a standardized test protocol. This protocol should also include measurements of physical activity in daily life.

Experiences of physiotherapists regarding a standard set of measurement instruments to improve quality of care for patients with chronic obstructive pulmonary disease: a mixed methods study.

RATIONALE: The quality of physiotherapy care for patients with chronic obstructive pulmonary disease (COPD) can be improved by comparing outcomes of care in practice. AIM: To evaluate the experiences of physiotherapists implementing a standard set of measurement instruments to measure outcomes and improve the quality of care for patients with COPD. METHODS: This sequential explanatory mixed methods study was performed in two parts. In the quantitative part, a survey of 199 physiotherapists was conducted to evaluate their attitudes and knowledge, as well as the influence of contextual factors (i.e., practice policy and support from colleagues), in the implementation of the standard measurement set. In the qualitative part, 11 physiotherapists participated in individual interviews to elucidate their experiences using a thematical framework. RESULTS: The survey showed that, on average, 68.4% of the physiotherapists reported having a positive attitude about using the standard set, 85.0% felt they had sufficient knowledge of the measurement instruments, and 84.7% felt supported by practice policy and colleagues. In total, 80.3% of physiotherapists thought the standard set had added value in clinical practice, and 90.3% indicated that the measurement instruments can be valuable for evaluating treatment outcomes. The physiotherapists mentioned several barriers, such as lack of time and the unavailability of the entire standard set of measurement instruments in their practice. Moreover, the physiotherapists indicated that the measurement instruments have added value in providing transparency to policymakers through the anonymized publication of outcomes. CONCLUSION: Physiotherapists support the use of the standard set of measurement instruments to improve the quality of physiotherapy treatment for patients with COPD.

A practice test and selection of a core set of outcome-based quality indicators in Dutch primary care physical therapy for patients with COPD: a cohort study.

Aim: To estimate the comparability and discriminability of outcome-based quality indicators by performing a practice test in Dutch physical therapy primary care, and to select a core set of outcome-based quality indicators that are well accepted by physical therapists based on their perceived added value as a quality improvement tool. Methods: First, a list of potential quality indicators was defined, followed by determination of the comparability (case-mix adjusted multilevel analysis) and discriminability (intraclass correlation coefficient (ICC)). Second, focus group meetings were conducted with stakeholders (physical therapists and senior researchers) to select a core set of quality indicators. Results: Overall, 229 physical therapists from 137 practices provided 2651 treatment episodes. Comparability: in 10 of the 11 case-mix adjusted models, the ICC increased compared with the intercept-only model. Discriminability: the ICC ranged between 0.01 and 0.34, with five of the 11 ICCs being >0.10. The majority of physical therapists in each focus group preferred the inclusion of seven quality indicators in the core set, including three process and four outcome indicators based upon the 6-min walk test (6MWT), the Clinical COPD Questionnaire (CCQ), and the determination of quadriceps strength using a hand-held dynamometer. Conclusion: This is the first study to describe the comparability and discriminability of the outcome-based quality indicators selected for patients with COPD treated in primary care physical therapy practices. Future research should focus on increasing data collection in daily practice and on the development of tangible methods to use as the core set of a quality improvement tool.

Associations between primary motor cortex organization, motor control and sensory tests during the clinical course of low back pain. A protocol for a cross-sectional and longitudinal case-control study.

Background: In people with low back pain (LBP), altered motor control has been related to reorganization of the primary motor cortex (M1). Sensory impairments in LBP have also been suggested to be associated with reorganization of M1. Little is known about reorganization of M1 over time in people with LBP, and whether it relates to changes in motor control and sensory impairments and recovery. This study aims to investigate 1) differences in organization of M1 of trunk muscles between people with and without LBP, and whether the organization of M1 relates to motor control and sensory impairments (cross-sectional component) and 2) reorganization of M1 over time and its relation with changes in motor control and sensory impairments and experienced recovery (longitudinal component). Methods: A case-control study with a cross-sectional and five-week longitudinal component is conducted in participants with LBP (N = 25) and participants without LBP (N = 25). Participants with LBP received usual care physiotherapy. Various tests were administered at baseline and follow-up. Following an anatomical MRI, organization of M1 (Center of Gravity and Area of the cortical representation of trunk muscles) was determined using transcranial magnetic stimulation. Quantitative sensory testing, a spiral-tracking motor control test, graphesthesia, two-point discrimination threshold and various self-reported questionnaires were also assessed. Multivariate multilevel analysis will be used for statistical analysis. Conclusion: We will address the gaps in knowledge about the association between reorganization of M1 and motor control and sensory tests during the clinical course of LBP. This study is registered at DOI 10.17605/OSF.IO/5C8ZG.

Decreased variability in postural control strategies in young people with non-specific low back pain is associated with altered proprioceptive reweighting.

Optimal postural control is an essential capacity in daily life and can be highly variable. The purpose of this study was to investigate if young people have the ability to choose the optimal postural control strategy according to the postural condition and to investigate if non-specific low back pain (NSLBP) influences the variability in proprioceptive postural control strategies. Young individuals with NSLBP (n = 106) and healthy controls (n = 50) were tested on a force plate in different postural conditions (i.e., sitting, stable support standing and unstable support standing). The role of proprioception in postural control was directly examined by means of muscle vibration on triceps surae and lumbar multifidus muscles. Root mean square and mean displacements of the center of pressure were recorded during the different trials. To appraise the proprioceptive postural control strategy, the relative proprioceptive weighting (RPW, ratio of ankle muscles proprioceptive inputs vs. back muscles proprioceptive inputs) was calculated. Postural robustness was significantly less in individuals with NSLBP during the more complex postural conditions (p < 0.05). Significantly higher RPW values were observed in the NSLBP group in all postural conditions (p < 0.05), suggesting less ability to rely on back muscle proprioceptive inputs for postural control. Therefore, healthy controls seem to have the ability to choose a more optimal postural control strategy according to the postural condition. In contrast, young people with NSLBP showed a reduced capacity to switch to a more multi-segmental postural control strategy during complex postural conditions, which leads to decreased postural robustness.

Randomised controlled study comparing comfort-related outcomes between two rigid gas permeable (RGP) lenses with different sessile drop contact angles.

PURPOSE: To compare comfort-related outcomes when wearing rigid gas permeable (RGP) contact lenses made of two different materials and using two cleaning regimes. METHODS: In a double-masked lens material cross-over study, subjects (n = 28 who completed the study) were refitted with new lenses made from (A) Boston XO material in one eye and made from (B) ONSI-56 material in the other eye. The lenses made from materials A and B were worn on the right eye and the left eye following the pattern AB-BA-AB (or vice versa) during the first, second, and third 5 week trial periods respectively. Miraflow cleaner (1st and 2nd period) was replaced by Boston Advance cleaner in the 3rd period. Comfort-related outcomes were assessed by a numerical rating scale (NRS) after each period. Subjects rated six comfort-related factors: satisfaction, sharpness of vision, end of day comfort, maximum comfortable wearing time, maximum wearing time and foreign body feeling. Additionally we obtained subjects' preferences for type of lens and lens cleaner during an exit interview. The sessile drop method was used to measure static contact angles. RESULTS: The mean of the contact angle measured for the Boston XO material was 93.3° and for the ONSI-56 material was 75.8 °. Mean 'end of the day comfort', 'satisfaction' and 'lens feeling' scores reached statistical significance (anova periods 1, 2 and 3, p's: 0.005, 0.028, 0.046, n = 23) with marginal differences in favour of those eyes that had worn lenses made of the ONSI-56 material (differences in mean scores on a 1-10 NRS never exceeded 0.7, 0.5 and 0.2 points in periods 1, 2, 3 respectively). At the exit interview 60% of the subjects (n = 17) were not able to express a preference for wearing either of the lenses, while 29% reported some preference for lenses made of the ONSI-56 material (n = 8) and 11% for wearing lenses made of the Boston XO material (n = 3) within one or more periods. CONCLUSIONS: The differences in comfort-related outcomes between contact lenses made from two different materials, with sessile contact angles that differed by 17.5°, were small. Although some observed comfort differences reached statistical significance, none of these differences were sufficiently large to support a clinically significant difference in comfort between the two materials. We recommend that both the sessile drop and the captive bubble contact angles, measured according to current standards, are made available to practitioners.

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.

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.