The influence of low back pain on muscle activity and coordination during gait: a clinical and experimental study

Comparing spinal loads in individuals with unilateral transtibial amputation with and without chronic low back pain: An EMG-informed approach

Chronic low back pain (cLBP) is highly prevalent after lower limb amputation (LLA), likely due in part to biomechanical factors. Here, three-dimensional full-body kinematics and kinetics during level-ground walking, at a self-selected and three controlled speeds (1.0, 1.3, and 1.6 m/s), were collected from twenty-one persons with unilateral transtibial LLA, with (n = 9) and without cLBP (n = 12). Peak compressive, mediolateral, and anteroposterior L5-S1 spinal loads were estimated from a full-body, transtibial amputation-specific OpenSim model and compared between groups. Predicted lumbar joint torques from muscle activations were compared to inverse dynamics and predicted and measured electromyographic muscle activations were compared for model evaluation and verification. There were no group differences in compressive or anterior shear forces (p > 0.466). During intact stance, peak ipsilateral loads increased with speed to a greater extent in the cLBP group vs. no cLBP group (p=0.023), while during prosthetic stance, peak contralateral loads were larger in the no cLBP group (p=0.047) and increased to a greater extent with walking speed compared to the cLBP group (p=0.008). During intact stance, intact side external obliques had higher activations in the no cLBP group (p=0.039), and internal obliques had higher activations in the cLBP group at faster walking speeds compared to the no cLBP group. Predicted muscle activations demonstrated similar activation patterns to electromyographic-measured activations (r = 0.56-0.96), and error between inverse dynamics and simulated spinal moments was low (0.08 Nm RMS error). Persons with transtibial LLA and cLBP may adopt movement strategies during walking to reduce mediolateral shear forces at the L5-S1 joint, particularly as walking speed increases. However, future work is needed to understand the time course from pain onset to chronification and the cumulative influence of increased spinal loads over time.

Stab lesion of the L4/L5 intervertebral disc in the rat causes acute changes in disc bending mechanics

Low-back pain often coincides with altered neuromuscular control, possibly due to changes in spine stability resulting from injury or degeneration, or due to effects of nociception. The relative importance of these mechanisms, and their possible interaction, are unknown. In spine bending, the bulk of the load is borne by the IVD, yet the acute effects of intervertebral disc (IVD) injury on bending mechanics have not been investigated. In the present study, we aimed to quantify the acute effects of a stab lesion of the disc on its mechanical properties, because such changes can be expected to elicit compensatory changes in neuromuscular control. L4/L5 spinal segments were collected from 27 Wistar rats within two hours after sacrifice and stored at -20℃. Following thawing, bending tests were performed to assess the intersegmental angle-moment characteristics. Specimens were loaded in right bending, left bending and flexion, before and after a stab lesion of the IVD fully penetrating the nucleus pulposus. In the angle-moment curves, we found reduced moments at equal bending angles after IVD lesion in left bending, right bending and flexion. Peak stiffness, peak moment, and hysteresis were significantly decreased (by 7.8-27.7 %) after IVD lesion in all directions. In conclusion, L4/L5 IVD lesion in the rat caused small to moderate acute changes in IVD mechanical properties. Our next steps will be to evaluate the longer term effects of IVD lesion on spine mechanics and the neural control of trunk muscles.

Intra- and interindividual reliability of muscle pain induced by an intramuscular injection of hypertonic saline injection into the quadriceps

BACKGROUND

Intramuscular injections of hypertonic saline are commonly used to induce experimental muscle pain, but reliability data on this technique are lacking. This study investigated the intra- and interindividual reliability of pain measures from a hypertonic saline injection into the vastus lateralis.

METHODS

Fourteen healthy participants (6 female) attended three laboratory visits where they received an intramuscular injection of 1 mL hypertonic saline into the vastus lateralis. Changes in pain intensity were recorded on an electronic visual analogue scale, and pain quality was assessed after pain had resolved. Reliability was assessed with the coefficient of variation (CV), minimum detectable change (MDC) and intraclass correlation coefficient (ICC) with 95% CIs.

RESULTS

Mean pain intensity displayed high levels of intraindividual variability (CV = 16.3 [10.5-22.0]%) and 'poor' to 'very good' relative reliability (ICC = 0.71 [0.45-0.88]) but had a MDC of 11 [8-16] au (out of 100). Peak pain intensity exhibited high levels of intraindividual variability (CV = 14.8 [8.8-20.8]%) with 'moderate' to 'excellent' levels of relative reliability (ICC = 0.81 [0.62-0.92]), whereas the MDC was 18 [14-26] au. Measures of pain quality exhibited good reliability. Interindividual variability in pain measures was high (CV > 37%).

CONCLUSIONS

Intramuscular injections of 1 mL of hypertonic saline into the vastus lateralis display substantial levels of interindividual variability, but MDC is below the clinically important changes in pain. This model of experimental pain is suitable for studies involving repeated exposures.

SIGNIFICANCE

Many pain research studies have performed intramuscular injections of hypertonic saline to investigate responses to muscle pain. However, the reliability of this technique is not well established. We examined the pain response over three repeated sessions of a hypertonic saline injection. The pain induced by hypertonic saline has considerable interindividual variability but has largely acceptable intraindividual reliability. Therefore, the injections of hypertonic saline to induce muscle pain are a reliable model of experimental muscle pain.

Erector Spinae Muscle Activation During Forward Movement in Individuals With or Without Chronic Lower Back Pain: A Systematic Review and Meta-analysis

Objective

To investigate the differences between erector spinae muscle activation in healthy individuals and patients with Chronic Lower Back Pain (CLBP) by conducting (a) systematic review and (b) meta-analysis.

Data Sources

PubMed, ScienceDirect, SPORTDiscus, and Google Scholar were used to conduct the searches, which included studies up to the 31st of March 2023 with no start date specified.

Study Selection

Any study otherwise meeting eligibility criteria was included if it reported either (1) a standard mean difference effect size; or (2) the means, SDs, and sample sizes for both the patient group and the comparator group.

Data Extraction

A total of 7 case control trials were used for the systematic review and meta-analysis.

Data Synthesis

The systematic review and meta-analysis revealed that total standardized mean difference in erector spinae muscle activation between healthy individuals vs patients with CLBP expressed in % maximum voluntary isometric contraction was 0.48 (95% confidence interval=0.21-0.74; P<.001) with the heterogeneity being I2=0% (P=.890). The electromyography (EMG) outputs showed significant differences in activation levels between the healthy and CLBP cohorts (P<.001).

Conclusions

A small effect size was found in the meta-analysis. The muscle activation levels of the erector spinae during forward propulsion were higher in CLBP individuals compared with healthy cohorts. The findings provide more clarity about the muscles that were the focus of previous research, what procedures were used to evaluate muscular contributions and what speeds the participants were moving at during the test sessions. Given the limited methodological quality of the included studies, the findings should be interpreted with caution. Future research should evaluate the effect of other factors such as walking distance and any changes in walking surfaces and gradients (ie, non-flat surfaces).

The Role of Back Muscle Dysfunctions in Chronic Low Back Pain: State-of-the-Art and Clinical Implications

Changes in back muscle function and structure are highly prevalent in patients with chronic low back pain (CLBP). Since large heterogeneity in clinical presentation and back muscle dysfunctions exists within this population, the potential role of back muscle dysfunctions in the persistence of low back pain differs between individuals. Consequently, interventions should be tailored to the individual patient and be based on a thorough clinical examination taking into account the multidimensional nature of CLBP. Considering the complexity of this process, we will provide a state-of-the-art update on back muscle dysfunctions in patients with CLBP and their implications for treatment. To this end, we will first give an overview of (1) dysfunctions in back muscle structure and function, (2) the potential of exercise therapy to address these dysfunctions, and (3) the relationship between changes in back muscle dysfunctions and clinical parameters. In a second part, we will describe a framework for an individualised approach for back muscle training in patients with CLBP.

Neuromuscular adaptations to experimentally induced pain in the lumbar region: systematic review and meta-analysis

ABSTRACT

Experimental pain models are frequently used to understand the influence of pain on the control of human movement. In this systematic review, we assessed the effects of experimentally induced pain in the lumbar region of healthy individuals on trunk muscle activity and spine kinematics. Databases were searched from inception up to January 31, 2022. In total, 26 studies using either hypertonic saline injection (n = 19), heat thermal stimulation (n = 3), nociceptive electrical stimulation (n = 3), or capsaicin (n = 1) were included. The identified adaptations were task dependent, and their heterogeneity was partially explained by the experimental pain model adopted. Meta-analyses revealed an increase of erector spinae activity (standardized mean difference = 0.71, 95% confidence interval [CI] = 0.22-1.19) during full trunk flexion and delayed onset of transversus abdominis to postural perturbation tasks (mean difference = 25.2 ms, 95% CI = 4.09-46.30) in the presence of pain. Low quality of evidence supported an increase in the activity of the superficial lumbar muscles during locomotion and during voluntary trunk movements during painful conditions. By contrast, activity of erector spinae, deep multifidus, and transversus abdominis was reduced during postural perturbation tasks. Reduced range of motion of the lumbar spine in the presence of pain was supported by low quality of evidence. Given the agreement between our findings and the adaptations observed in clinical populations, the use of experimental pain models may help to better understand the mechanisms underlying motor adaptations to low back pain.

Post-injury pain and behaviour: a control theory perspective

Injuries of various types occur commonly in the lives of humans and other animals and lead to a pattern of persistent pain and recuperative behaviour that allows safe and effective recovery. In this Perspective, we propose a control-theoretic framework to explain the adaptive processes in the brain that drive physiological post-injury behaviour. We set out an evolutionary and ethological view on how animals respond to injury, illustrating how the behavioural state associated with persistent pain and recuperation may be just as important as phasic pain in ensuring survival. Adopting a normative approach, we suggest that the brain implements a continuous optimal inference of the current state of injury from diverse sensory and physiological signals. This drives the various effector control mechanisms of behavioural homeostasis, which span the modulation of ongoing motivation and perception to drive rest and hyper-protective behaviours. However, an inherent problem with this is that these protective behaviours may partially obscure information about whether injury has resolved. Such information restriction may seed a tendency to aberrantly or persistently infer injury, and may thus promote the transition to pathological chronic pain states.

The immediate effects of iTBS on the muscle activation pattern under challenging balance conditions in the patients with chronic low back pain: A preliminary study

Background

The patients with chronic low back pain (CLBP) showed impaired postural control, especially in challenging postural task. The dorsolateral prefrontal cortex (DLPFC) is reported to involve in the complex balance task, which required considerable attentional control. The effect of intermittent theta burst stimulation (iTBS) over the DLPFC to the capacity of postural control of CLBP patients is still unknown.

Methods

Participants diagnosed with CLBP received a single-session iTBS over the left DLPFC. All the participants completed the postural control tasks of single-leg (left/right) standing before and after iTBS. The activation changes of the DLPFC and M1 before and after iTBS were recorded by functional near-infrared spectroscopy (fNIRS). The activation pattern of the trunk [transversus abdominis (TrA), superficial lumbar multifidus (SLM)] and leg [tibialis anterior (TA), gastrocnemius medialis (GM)] muscles including root mean square (RMS) and co-contraction index (CCI) during single-leg standing were measured by surface electromyography (sEMG) before and after the intervention. The paired t-test was used to test the difference before and after iTBS. Pearson correlation analyses were performed to test the relationship between the oxyhemoglobin concentration and sEMG outcome variables (RMS and CCI).

Results

Overall, 20 participants were recruited. In the right-leg standing condition, compared with before iTBS, the CCI of the right TrA/SLM was significantly decreased (t = −2.172, p = 0.043), and the RMS of the right GM was significantly increased (t = 4.024, p = 0.001) after iTBS. The activation of the left DLPFC (t = 2.783, p = 0.012) and left M1 (t = 2.752, p = 0.013) were significantly decreased and the relationship between the left DLPFC and M1 was significant after iTBS (r = 0.575, p = 0.014). Correlation analysis showed the hemoglobin concentration of M1 was negatively correlated with the RMS of the right GM (r = −0.659, p = 0.03) and positively correlated between CCI of the right TrA/SLM (r = 0.503, p = 0.047) after iTBS. There was no significant difference in the brain or muscle activation change in the left leg-standing condition between before and after iTBS.

Conclusion

Intermittent theta burst stimulation over the left DLPFC seems to be able to improve the muscle activation pattern during postural control ability in challenging postural task, which would provide a new approach to the treatment of CLBP.

The temporal expression of circulating microRNAs after acute experimental pain in humans

BACKGROUND

MicroRNAs (miRNAs) can modulate several biological systems, including the pain system. This study aimed to evaluate the temporal expression of circulating miRNAs in the plasma of healthy volunteers as a marker for epigenetic changes before and after an acute, experimental, pain provocation by intramuscular hypertonic saline injection.

METHODS

Twenty volunteers were randomly allocated into two groups and received either hypertonic (pain) or isotonic (control) saline injection in the first dorsal interosseous muscle of their dominant hand. Pain intensity was continuously recorded for 20 minutes after injection on a VAS scale from 0 to 100 (0 indicates no pain and 100 the worst imaginable pain). Blood samples were taken at baseline, 30 minutes, 3 hours, and 24 hours post-injection, and plasma was separated. MiRNA extracts were used for RNA sequencing with the Illumina NextSeq platform. MiRNA transcripts were compared between the pain and the no-pain, control group at every time point. Significant differences were considered when folds were >2 and the False Discovery Rate was p < 0.05.

RESULTS

After 30 minutes, 4 miRNAs were significantly altered in the pain group compared to controls, which increased to 24 after 3 hours and to 42 after 24 hours from baseline (p < 0.0001). Two miRNAs were consistently upregulated throughout the experiment. Enrichment analysis showed significant miRNAs involved in brain perception of pain, brain signalling and response to stimuli.

CONCLUSIONS

This exploratory study is the first to report on the temporal expression of circulating miRNAs after an acute, human experimental muscle pain model.

SIGNIFICANCE

This exploratory study evaluated the temporal profile of circulating miRNAs in the plasma of healthy subjects after acute experimental pain. Several miRNAs were altered in subjects at the times of follow-up after the acute pain model when compared to controls. MiRNAs previously associated with pain processes were altered in the pain group. Our results, by showing the fast and prolonged modifications of miRNA elicited by the acute experimental pain model, add new perspectives to the topic of epigenetics and pain.

Motion analysis in patients with postpartum sacroiliac joint dysfunction: A cross-sectional case-control study

BACKGROUND

Patients with sacroiliac joint dysfunction are limited in daily life activities such as gait, climbing stairs and rising from a chair. It is well known that individuals with chronic low back pain have impaired balance compared to healthy individuals. This cross-sectional case-control study aims to investigate spatiotemporal parameters, center of pressure and mass, pelvic angles and other joint angles in patients with sacroiliac joint dysfunction in comparison with healthy controls.

METHODS

Motion analysis existed of three tasks: (1) normal gait, (2) single-leg-stance, and (3) sit-to-stance. Spatiotemporal parameters, center of pressure, pelvic angles and other joint angles were measured using a twelve-camera, three-dimensional motion capture system and ground reaction force platforms.

FINDINGS

Thirty subjects were recruited for this study; ten patients, ten matched controls and ten healthy student controls. For gait, patients had a lower cadence, longer double support phase, shorter step length and slower walking speed than controls. For single-leg-stance, patients had a smaller hip angle of the risen leg than controls. Also, variability in center of pressure was larger in patients. For sit-to-stance, the total time to perform the task was almost doubled for patients compared to controls.

INTERPRETATION

This study demonstrates that patients with sacroiliac joint dysfunction have an impaired gait, more balance problems during standing and standing up compared to healthy controls. This novel information assists to further comprehend the pathology and disease burden of sacroiliac joint dysfunction, in addition, it may allow us to evaluate the effect of current therapies.

Exercise Selection and Common Injuries in Fitness Centers: A Systematic Integrative Review and Practical Recommendations

Weight resistance training (RT) is an essential component of physical conditioning programs to improve the quality of life and physical fitness in different ages and populations. This integrative review aimed to analyze the scientific evidence on the relationship between exercise selection and the appearance of musculoskeletal injuries in physical fitness centers (PFC). The PubMed or Medline, EMBASE or Science Direct, Google Scholar and PEDro databases were selected to examine the available literature using a Boolean algorithm with search terms. The review process was performed using the five-stage approach for an integrative review and it was reported according to the PRISMA in Exercise, Rehabilitation, Sport Medicine and Sports Science (PERSiST) guidelines. A total of 39 peer-reviewed articles (Price index = 71.7%) met the inclusion criteria and evaluated the link between exercise selection and the incidence of injuries in exercisers who regularly attend PFC. Most injuries occur to the shoulders, elbows, vertebrae of the spine, and knees. Although the injury etiologies are multifactorial, the findings of the reviewed articles include the impacts of overuse, short post-exercise recovery periods, poor conditioning in the exercised body areas, frequent use of heavy loads, improper technique in certain exercises, and the abuse of performance- and image-enhancing drugs. Practical recommendations addressed to clinical exercise physiologists, exercise professionals, and health professionals are given in this paper. The exercise selection in RT programs requires professional supervision and adhering to proper lifting techniques and training habits that consider the anatomical and biomechanical patterns of the musculoskeletal structures, as well as genetic, pedagogical, and methodological aspects directly related to the stimulus-response process to mitigate the occurrence of RT-related injuries in PFC.

Do people with low back pain walk differently? A systematic review and meta-analysis

BACKGROUND

The biomechanics of the trunk and lower limbs during walking and running gait are frequently assessed in individuals with low back pain (LBP). Despite substantial research, it is still unclear whether consistent and generalizable changes in walking or running gait occur in association with LBP. The purpose of this systematic review was to identify whether there are differences in biomechanics during walking and running gait in individuals with acute and persistent LBP compared with back-healthy controls.

METHODS

A search was conducted in PubMed, CINAHL, SPORTDiscus, and PsycINFO in June 2019 and was repeated in December 2020. Studies were included if they reported biomechanical characteristics of individuals with and without LBP during steady-state or perturbed walking and running. Biomechanical data included spatiotemporal, kinematic, kinetic, and electromyography variables. The reporting quality and potential for bias of each study was assessed. Data were pooled where possible to compare the standardized mean differences (SMD) between back pain and back-healthy control groups.

RESULTS

Ninety-seven studies were included and reviewed. Two studies investigated acute pain and the rest investigated persistent pain. Nine studies investigated running gait. Of the studies, 20% had high reporting quality/low risk of bias. In comparison with back-healthy controls, individuals with persistent LBP walked slower (SMD = -0.59, 95% confidence interval (95%CI): -0.77 to -0.42)) and with shorter stride length (SMD = -0.38, 95%CI: -0.60 to -0.16). There were no differences in the amplitude of motion in the thoracic or lumbar spine, pelvis, or hips in individuals with LBP. During walking, coordination of motion between the thorax and the lumbar spine/pelvis was significantly more in-phase in the persistent LBP groups (SMD = -0.60, 95%CI: -0.90 to -0.30), and individuals with persistent LBP exhibited greater amplitude of activation in the paraspinal muscles (SMD = 0.52, 95%CI: 0.23-0.80). There were no consistent differences in running biomechanics between groups.

CONCLUSION

There is moderate-to-strong evidence that individuals with persistent LBP demonstrate differences in walking gait compared to back-healthy controls.

Assessing Pain Research: A Narrative Review of Emerging Pain Methods, Their Technosocial Implications, and Opportunities for Multidisciplinary Approaches

Pain research traverses many disciplines and methodologies. Yet, despite our understanding and field-wide acceptance of the multifactorial essence of pain as a sensory perception, emotional experience, and biopsychosocial condition, pain scientists and practitioners often remain siloed within their domain expertise and associated techniques. The context in which the field finds itself today-with increasing reliance on digital technologies, an on-going pandemic, and continued disparities in pain care-requires new collaborations and different approaches to measuring pain. Here, we review the state-of-the-art in human pain research, summarizing emerging practices and cutting-edge techniques across multiple methods and technologies. For each, we outline foreseeable technosocial considerations, reflecting on implications for standards of care, pain management, research, and societal impact. Through overviewing alternative data sources and varied ways of measuring pain and by reflecting on the concerns, limitations, and challenges facing the field, we hope to create critical dialogues, inspire more collaborations, and foster new ideas for future pain research methods.

Comparison of the effects of conventional physiotherapy and proprioception exercises on pain and ankle proprioception in patients with lumbar radiculopathy

BACKGROUND

Lumbar radiculopathy is characterized by a significant amount of backache causing loss of workforce and is a significant health problem frequently seen in the general population.

OBJECTIVE

The purpose of this study was to compare the effects of conventional physiotherapy (CT) and proprioception exercises (PE) on ankle proprioception and lumbar pain between patients with lumbar radiculopathy and a healthy control group.

METHODS

In this randomized clinical trial, 89 patients referred to the Physical Medicine and Rehabilitation outpatient clinic were selected through convenience sampling. They were randomly assigned to three groups: CT (n= 27), PE (n= 31), CT&PE (n= 31). Thirty healthy volunteers were included in the study as the control group. Proprioception measurements were made with an isokinetic dynamometer at 10∘ dorsiflexion (DF), 11∘, and 25∘ plantarflexion (PF) angles. Lumbar pain was assessed by using the Numerical Pain Rating Scale (NPRS). The data were analyzed by IBM SPSS Statistics version 22.0 via the Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

There was a statistically significant difference between the groups in terms of ankle proprioception and NPRS measurements in post-treatment evaluations (p< 0.05). Statistically significant differences were found between CT and PE groups and CT&PE and control groups. There was no statistically significant difference in comparing CT and PE groups and CT&PE and control groups within themselves (p> 0.05).

CONCLUSION

The combined use of CT and PE is an effective method that can be used in the clinic to reduce angular differences in ankle proprioception which is one of the primary factors of balance and coordination and lumbar pain.

Vibrating Exercise Equipment in Middle-Age and Older Women with Chronic Low Back Pain and Effects on Bioelectrical Activity, Range of Motion and Pain Intensity: A Randomized, Single-Blinded Sham Intervention Study

Simple Summary

Physical activity is often recommended as part of the management of chronic low back pain, which is one of the most common musculoskeletal disorders. Vibrating exercise equipment is used despite little scientific evidence to support its effectiveness in the prevention and treatment of musculoskeletal problems. The aim of this study was to evaluate the efficiency of using vibrating exercise equipment in women with chronic low back pain. Here, 92 women aged 49–80 years were assigned to one of two groups: the experimental and the control group. The intervention consisted of aerobic exercises with specific handheld equipment. Both groups performed physical activity twice weekly for 10 weeks. The erector spinae muscles’ bioelectrical activity, the lumbar range of motion and pain intensity were measured in all participants at baseline and after 10 weeks. Compared with baseline measures, there was a significant decrease in the bioelectrical activity of the erector spinae muscles during flexion movement, rest at maximum flexion, extension movement and rest in a prone position; an increase in the lumbar range of motion and a decrease in pain intensity following a program of physical activity with vibrating exercise equipment. No significant changes were found in intergroup comparisons; however, physical activity with vibrating exercise equipment could be a prospective strategy for increasing lumbar range of motion and decreasing pain and erector spinae muscle activity in people with chronic low back pain.

Abstract

Background: Chronic low back pain (CLBP) is one of the most common musculoskeletal disorders. Physical activity (PA) is often recommended as part of the management of CLBP, but to date, no one particular exercise has been shown to be superior. Vibrating exercise equipment (VEE) is widely available and used despite little scientific evidence to support its effectiveness in the prevention and treatment of musculoskeletal problems. The aim of this study was to evaluate the efficiency of using VEE compared with sham-VEE in women with CLBP. Methods: A randomized (1:1 randomization scheme) single-blinded sham-controlled intervention study was conducted. Through simple randomization, 92 women aged 49–80 years were assigned to one of two groups: VEE (the experimental group) and sham-VEE (the control group). The VEE and sham-VEE intervention consisted of aerobic exercises with specific handheld equipment. Both groups performed physical activity twice weekly for 10 weeks. The erector spinae muscles’ bioelectrical activity (using an eight-channel electromyograph MyoSystem 1400L), lumbar range of motion (Schober’s test) and pain intensity (visual analog scale) were measured in all participants at baseline and after 10 weeks. Results: There was a significant decrease in the bioelectrical activity of the erector spinae muscles during flexion movement (left: Me = 18.2 before; Me = 14.1 after; p = 0.045; right: Me = 15.4 before; Me = 12.6 after; p = 0.010), rest at maximum flexion (left: Me = 18.1 before; Me = 12.5 after; p = 0.038), extension movement (right: Me = 21.8 before; Me = 20.2 after; p = 0.031) and rest in a prone position (right: Me = 3.5 before; Me = 3.2 after; 0.049); an increase in lumbar range of motion (Me = 17.0 before; Me = 18.0 after; p = 0.0017) and a decrease in pain intensity (Me = 4.0 before; Me = 1.0 after; p = 0.001) following a program of PA in the VEE group. Conclusions: No significant changes were found in intergroup comparisons. The beneficial changes regarding decreased subjective pain sensation in the VEE and sham-VEE groups may be due to participation in systematic physical activity. However, PA with vibrating exercise equipment could be a prospective strategy for increasing lumbar range of motion and for decreasing pain and erector spinae muscle activity in people with CLBP.

Correlation between change in pain, disability, and surface electromyography topographic parameters after interferential current treatment in patients with chronic low back pain

[Purpose] Surface electromyography (SEMG) topography is used to objectively assess patients with low back pain (LBP). This study aimed to investigate the correlation between SEMG topographic variables, pain, and disability in patients with chronic LBP (CLBP) after interferential current (IFC) treatment, and to evaluate IFC treatment efficacy using SEMG topography. [Participants and Methods] Twenty nine patients with CLBP were recruited for a 6-week IFC treatment. Pain and disability scores, and the root-mean-square difference (RMSD) of SEMG topographic variables (relative areas [RAs] at flexion and extension) were compared before and after the intervention by repeated measures ANOVA; the correlation between variables was also explored and p-value was set at 0.001. [Results] Significant positive correlations between changes in pain score and the RMSD of RA at flexion (r(29)=0.593), and between changes in pain and disability scores (r(29)=0.426) were observed. All participants showed statistically significant improvements in the RMSD of RA at flexion, pain score, and disability score after IFC treatment. [Conclusion] SEMG topographic variables are closely associated with changes in pain score in patients with CLBP after IFC treatment. The RMSD of RA at flexion can be used as an objective marker in IFC treatment efficacy evaluation.

Classification and Automated Interpretation of Spinal Posture Data Using a Pathology-Independent Classifier and Explainable Artificial Intelligence (XAI)

Clinical classification models are mostly pathology-dependent and, thus, are only able to detect pathologies they have been trained for. Research is needed regarding pathology-independent classifiers and their interpretation. Hence, our aim is to develop a pathology-independent classifier that provides prediction probabilities and explanations of the classification decisions. Spinal posture data of healthy subjects and various pathologies (back pain, spinal fusion, osteoarthritis), as well as synthetic data, were used for modeling. A one-class support vector machine was used as a pathology-independent classifier. The outputs were transformed into a probability distribution according to Platt's method. Interpretation was performed using the explainable artificial intelligence tool Local Interpretable Model-Agnostic Explanations. The results were compared with those obtained by commonly used binary classification approaches. The best classification results were obtained for subjects with a spinal fusion. Subjects with back pain were especially challenging to distinguish from the healthy reference group. The proposed method proved useful for the interpretation of the predictions. No clear inferiority of the proposed approach compared to commonly used binary classifiers was demonstrated. The application of dynamic spinal data seems important for future works. The proposed approach could be useful to provide an objective orientation and to individually adapt and monitor therapy measures pre- and post-operatively.

Flexible Electrodes for In Vivo and In Vitro Electrophysiological Signal Recording

A variety of electrophysiological signals (electrocardiography, electromyography, electroencephalography, etc.) are generated during the physiological activities of human bodies, which can be collected by electrodes and thus provide critical insights into health status or facilitate fundamental scientific research. The long-term stable and high-quality recording of electrophysiological signals is the premise for their further applications, leading to demands for flexible electrodes with similar mechanical modulus and minimized irritation to human bodies. This review summarizes the latest advances in flexible electrodes for the acquisition of various electrophysiological signals. First, the concept of electrophysiological signals and the characteristics of different subcategory signals are introduced. Second, the invasive and noninvasive methods are reviewed for electrophysiological signal recording with a highlight on the design of flexible electrodes, followed by a discussion on their material selection. Subsequently, the applications of the electrophysiological signal acquisition in pathological diagnosis and restoration of body functions are discussed, showing the advantages of flexible electrodes. Finally, the main challenges and opportunities in this field are discussed. It is believed that the further exploration of materials for flexible electrodes and the combination of multidisciplinary technologies will boost the applications of flexible electrodes for medical diagnosis and human-machine interface.

Gait Kinetic and Kinematic Changes in Chronic Low Back Pain Patients and the Effect of Manual Therapy: A Randomized Controlled Trial

Patients with chronic back pain as a result of degenerated disc disease, besides pain, also present with impaired gait. The purpose of the article was to evaluate kinetic and kinematic characteristics during gait analysis in patients with chronic low back pain as a result of degenerated disc disease, before and after the application of physiotherapy, including manual therapy techniques. Seventy-five patients suffering from chronic low back pain were randomly divided into 3 groups of 25 each. Each group received five sessions (one per week) of interventions with the first group receiving manual therapy treatment, the second a sham treatment and the third, classic physiotherapy (stretching exercises, TENS and massage). The effectiveness of each treatment was evaluated using an optoelectronic system for recording and analysis of gait (kinetic and kinematic data). Patients overall showed an impaired gait pattern with a difference in kinetic and kinematic data between the left and the right side. Following the application of the above-named interventions, only the group that received manual therapy showed a tendency towards symmetry between the right and left side. In patients suffering from chronic low back pain as a result of degenerated disc disease, the application of five manual therapy sessions seems to produce a tendency towards symmetry in gait.

Empirically derived back pain subgroups differentiated walking performance, pain, and disability

ABSTRACT

Low back pain (LBP) is a leading cause of disability. However, the processes contributing to disability are not well understood. Therefore, this study (1) empirically derived LBP subgroups and (2) validated these subgroups using walking performance, pain, and disability measures. Seventy adults with LBP underwent testing for a priori determined sensory (temporal summation; conditioned pain modulation), psychological (positive affect/coping; negative coping), and motor (trunk extensor muscle activation during forward bending and walking) measures. A hierarchical cluster analysis determined subgroups that were then validated using walking (walking speed; Timed Up and Go [TUG]; TUG-Cognitive [TUG-Cog]; obstacle negotiation) and clinical (Brief Pain Inventory; Oswestry Disability Index; low back pressure pain threshold) measures. Two subgroups were derived: (1) a "Maladaptive" subgroup (n = 21) characterized by low positive affect/coping, high negative coping, low pain modulation, and atypical trunk extensor activation and (2) an "Adaptive" subgroup (n = 49) characterized by high positive affect/coping, low negative coping, high pain modulation, and typical trunk extensor activation. There were subgroup differences on 7 of 12 validation measures. The Maladaptive subgroup had reduced walking performance (slower self-selected walking speed, TUG completion, and obstacle approach and crossing speed) and worse clinical presentation (higher pain intensity, pain interference, and disability) (moderate to large effect sizes; P's < 0.05). Findings support the construct validity of this multidimensional subgrouping approach. Longitudinal studies are needed to determine whether the Maladaptive subgroup is predictive of poor outcomes, such as pain chronicity or persistent disability.

Non-uniform Effects of Nociceptive Stimulation to Motoneurones during Experimental Muscle Pain

Nociceptive stimulation is predicted to uniformly inhibit motoneurone pools of painful muscles and those producing painful movements. Although reduced motoneurone discharge rate during pain provides some evidence, recent data show evidence of increased excitability of some motoneurones. These observations suggest non-uniform effects of nociception on motoneurone excitability. More direct measures are required, but this is difficult to assess as few measures enable in vivo evaluation of motoneurone excitability in humans. We investigated changes in motoneurone excitability during experimental pain using two methods in separate experiments: (i) estimation of the time-course of motoneurone afterhyperpolarization (AHP) from interval death rate analysis of interspike intervals of single motor unit discharge; and (ii) probability of early motoneurone discharge to a descending volley excited using transcranial magnetic stimulation (TMS). Tibialis anterior motor units were recorded with fine-wire electrodes before, during and after painful infusion of 5% hypertonic saline into the muscle. Activation of 17 units (16 participants) could be used for AHP analysis. Data show shortened (n = 11) and lengthened (n = 6) AHP time-course. Increased (n = 6) and decreased (n = 6) probability of early motoneurone discharge were observed in the TMS experiment. These convergent observations suggest non-uniform effects of nociceptive stimulation on motoneurone pools. This does not support the hypothesis that nociceptive input induces uniform inhibition of painful muscle. Instead, interpretation of results implies redistribution of activity between motor units, with possible benefit for unloading painful tissues. This finding supports an interpretation that differs from the generally accepted view in pain physiology regarding adaptation to motor function in pain.

A new hypertonic saline assay for analgesic screening in mice: effects of animal strain, sex, and diurnal phase

PURPOSE

There exists a pressing need for the identification of novel analgesics. We recently reported on a new preclinical assay for rapid analgesic screening based on intraplantar (i.pl.) injection of 10% hypertonic saline (HS) in female outbred (CD-1) mice. Herein, we characterized the HS assay's performance in inbred (C57BL/6) mice, sensitivity to sex differences, and effects of diurnal rhythm phase.

METHODS

In randomized, controlled, blinded in vivo animal experiments, we studied nociceptive responses induced by i.pl. HS in C57BL/6 (vs CD-1) mice of both sexes (n = 240) and determined diurnal rhythm phase effects in female animals. We established the HS assay's sensitivity to morphine by constructing dose-response curves and calculating half-maximal inhibitory doses (ID₅₀s).

RESULTS

The injection of i.pl. HS produced nociceptive (licking and biting) responses in all C57BL/6 mice tested. In both C57BL/6 and CD-1 mice, the mean (95% confidence interval [CI]) response magnitudes were greater in females vs males (C57BL/6: 87 sec [64 to 110] vs 45 sec [29 to 61]; difference in means, 42 sec; 95% CI, 17 to 68; P < 0.001; n = 10/group; CD-1: 110 sec [95 to 126] vs 53 sec [32 to 74]; difference in means, 57 sec; 95% CI, 34 to 79; P < 0.001; n = 10/group). The mean (95% CI) nociceptive responses were greater at 24:00 hr than at 12:00 hr in C57BL/6 mice (64 sec [40 to 88] vs 37 sec [24 to 51]; difference in means, 27 sec; 95% CI, 7 to 47; P = 0.007; n = 10/group), but not in CD-1 mice (P = 0.97). Intravenous morphine dose-dependently attenuated nociceptive responses of both C57BL/6 and CD-1 mice (ID₅₀, 0.6 and 2.5 mg·kg^-1, respectively; P = 0.41).

CONCLUSION

These findings in inbred and outbred mice solidify the utility of the HS assay as an effective, rapid, robust, and versatile preclinical tool for analgesic screening.

Application of accelerometer-based gait recognition to adjuvant clinical gait analysis

BACKGROUND

Gait recognition is an emerging biometric technology applied to the mobile environment. With built-in accelerometers, wearable devices are used to recognize user identity according to gait periodic pattern, which shows strong stability and uniqueness property.

OBJECTIVE

The purpose of this study is to build analyzing models to find the change of gait normal and pathological function based on gait features.

METHODS

This work relies on gait recognition methods. In this paper, the performance of different hybrid filter methods is compared by combining four classical filtering methods. The influence of the abnormal pattern of gait cycle is estimated by standard deviation. The effectiveness of feature matching methods is evaluated by six classical distance discrimination function.

RESULTS

The results highlight the stability and invariance of gait periodic pattern. For analyzing models, the best recognition rate is 96.67% with the combination of MF hybrid filter and Correlation distance function in the small sample, and minimal time consumption is 0.038 s. The effectiveness of analyzing models is further analyzed for different practical applications.

CONCLUSIONS

This study provides evidence for future scientific teams to make decisions on selecting filter methods and discrimination functions which can more efficiently extract gait features and suggest ways to analyze clinical gait pattern.

Classification-Specific Treatment Improves Pain, Disability, Fear-Avoidance Beliefs, and Erector Spinae Muscle Activity During Walking in Patients With Low Back Pain Exhibiting Lumbar Extension-Rotation Pattern: A Randomized Controlled Trial

OBJECTIVE

Low back pain (LBP) has commonly been managed via classification-specific interventions in homogeneous groups. However, it is largely unknown whether treatment tailored to specific classifications is more effective than generic treatment. The purpose of this study was to evaluate the effects of classification-specific treatment on the self-reported responses and erector spinae (ES) activity of patients with LBP exhibiting a lumbar extension-rotation (ExtRot) pattern.

METHODS

In total, 39 patients exhibiting the lumbar ExtRot pattern were randomized to an experimental (n = 19) group and a control (n = 20) group. Participants in the experimental group received classification-specific treatment, which included exercise to control or prevent lumbopelvic motion during lower-extremity movement. Participants in the control group were encouraged to perform general exercises and were educated about LBP. Patient-reported pain intensity, disability, and fear-avoidance belief and ES muscle activity during walking were assessed prior to and after the intervention. Two-way analysis of covariance was used to examine the effects of classification-specific treatment.

RESULTS

After 6-week intervention, significant time-by-group interaction effects were demonstrated on pain intensity, disability, fear-avoidance beliefs-physical activity score, and ES muscle activity during walking. There were significant effects of group on pain, disability, and fear-avoidance beliefs-physical activity score after intervention. After the 6-week intervention, the ES muscle activity significantly decreased in the experimental group during walking, but does not represent an all-events decrease.

CONCLUSION

Classification-specific treatment may be effective in patients with LBP exhibiting the lumbar ExtRot pattern, reducing pain intensity, disability, fear-avoidance beliefs, and ES muscle activity during walking.

Soft Tissue: A Possible Source of Pain Pre and Post Minimally Invasive Spine Surgery

STUDY DESIGN

Case studies.

OBJECTIVES

To demonstrate that muscle generated pain (MGP) may be a cause of pain in patients who have undergone minimally invasive spine surgery (MISS).

METHODS

A physical examination including electrical stimulation of putative pain generating muscles to identify the presence of lowered thresholds for depolarization of muscle nociceptors, and an examination of strength and flexibility of key muscles in the upper and lower body, may identify multiple etiologies of MGP. Treatment of identified muscles consisted of muscle/tendon injections to identified sensitized muscles followed by exercises incorporating relaxation limbering and stretching.

RESULTS

Postsurgical pain was eliminated and mobility restored in both presented cases replicating success in prior published studies.

CONCLUSIONS

Understanding the pathophysiological mechanisms of muscle pain may facilitate the evaluation and treatment of MGP in MISS patients diagnosed with failed back surgery syndrome.

Is the Pelvis-Thorax Coordination a Valuable Outcome Instrument to Assess Patients With Hip Osteoarthritis?

Objective: The evaluation of the disease severity in hip osteoarthritis (OA) patients being currently based on subjective instruments. It would be of interest to develop more objective instruments, for example based on gait analysis. The aims of this study were to explore if pelvis-thorax coordination parameters could be valuable instrument outcomes to achieve this evaluation by assessing their reliability, discriminant capacity and responsiveness.

Methods: Three groups of subjects; healthy, hip OA patients with severe disease (defined as indication to surgery), hip OA patients with less severe disease (no indication to surgery) were included. Hip OA patients with severe disease were evaluated before and 6 months after surgery. Subjects had to perform a gait analysis at comfortable speed, and pelvis-thorax coordination was evaluated. The correlations with clinical and structural parameters, as well as reliability, discriminant capacities and responsiveness, were assessed.

Results: The pelvis-thorax coordination in the coronal plane during walking was correlated to clinical and to structural severity in hip OA patients (R² = 0.13). The coronal plane coordination allowed to discriminate healthy subjects from all hip OA patients (sensibility = 0.86; specificity = 0.59). Moreover, when comparing OA patients only, coronal plane coordination allows to discriminate patients with indication of surgery from those with no indication of surgery (sensibility = 0.72; specificity = 0.72). Moreover, the pelvis-thorax coordination demonstrated an excellent reliability and a good responsiveness.

Conclusion: Changes in the pelvis-thorax coordination might refer to different mechanisms, from analgesia to motor control plasticity, and might be a possible explanation for the weak correlation between structure and symptoms in hip OA patients. Moreover, such parameter might be used as an objective outcome in hip OA clinical trials.

Clinical Trials Registration:www.ClinicalTrials.gov, identifier: NCT02042586 and NCT01907503.

The interaction between pain and movement

STUDY DESIGN

Clinical commentary.

INTRODUCTION/PURPOSE

Pain and movement are universally relevant phenomena that influence human experiences in readily observable ways. Improved understanding of pain-movement relationships can guide medical and rehabilitative approaches to recovery and decrease risk of dysfunctional long-term consequences of otherwise normal neuromuscular responses. Therefore, the overall intent of this article is to elucidate the relationships between pain and movement as they relate to clinical decision making.

CONCLUSIONS

Motor output is highly adaptable, can be influenced by multiple mechanisms at various levels along the nervous system, and may vary between individuals despite similar diagnoses. Therefore, interventions need to be individualized and consider both the types of motor response observed (ie, whether the response is protective or maladaptive), and the patient's acute physical activity tolerance when prescribing exercise/movement.

Changing the Narrative in Diagnosis and Management of Pain in the Sacroiliac Joint Area

The sacroiliac joint (SIJ) is often considered to be involved when people present for care with low back pain where SIJ is located. However, determining why the pain has arisen can be challenging, especially in the absence of a specific cause such as pregnancy, disease, or trauma, when the SIJ might be identified as a source of symptoms with the help of manual clinical tests. Nonspecific SIJ-related pain is commonly suggested to be causally associated with movement problems in the SIJ(s)-a diagnosis traditionally derived from manual assessment of movements of the SIJ complex. Management choices often consist of patient education, manual treatment, and exercise. Although some elements of management are consistent with guidelines, this Perspective article argues that the assumptions on which these diagnoses and treatments are based are problematic, particularly if they reinforce unhelpful, pathoanatomical beliefs. This article reviews the evidence regarding the clinical detection and diagnosis of SIJ movement dysfunction. In particular, it questions the continued use of assessing movement dysfunction despite mounting evidence undermining the biological plausibility and subsequent treatment paradigms based on such diagnoses. Clinicians are encouraged to align their assessment methods and explanatory models with contemporary science to reduce the risk of their diagnoses and choice of intervention negatively affecting clinical outcomes.

Trunk-Pelvis motions and spinal loads during upslope and downslope walking among persons with transfemoral amputation

Larger trunk and pelvic motions in persons with (vs. without) lower limb amputation during activities of daily living (ADLs) adversely affect the mechanical demands on the lower back. Building on evidence that such altered motions result in larger spinal loads during level-ground walking, here we characterize trunk-pelvic motions, trunk muscle forces, and resultant spinal loads among sixteen males with unilateral, transfemoral amputation (TFA) walking at a self-selected speed both up ("upslope"; 1.06 ± 0.14 m/s) and down ("downslope"; 0.98 ± 0.20 m/s) a 10-degree ramp. Tri-planar trunk and pelvic motions were obtained (and ranges-of-motion [ROM] computed) as inputs for a non-linear finite element model of the spine to estimate global and local muscle (i.e., trunk movers and stabilizers, respectively) forces, and resultant spinal loads. Sagittal- (p = 0.001), frontal- (p = 0.004), and transverse-plane (p < 0.001) trunk ROM, and peak mediolateral shear (p = 0.011) and local muscle forces (p = 0.010) were larger (respectively 45, 35, 98, 70, and 11%) in upslope vs. downslope walking. Peak anteroposterior shear (p = 0.33), compression (p = 0.28), and global muscle (p = 0.35) forces were similar between inclinations. Compared to previous reports of persons with TFA walking on level ground, 5-60% larger anteroposterior and mediolateral shear observed here (despite ∼0.25 m/s slower walking speeds) suggest greater mechanical demands on the low back in sloped walking, particularly upslope. Continued characterization of trunk motions and spinal loads during ADLs support the notion that repeated exposures to these larger-than-normal (i.e., vs. level-ground walking in TFA and uninjured cohorts) spinal loads contribute to an increased risk for low back injury following lower limb amputation.

A parametric study of effect of experimental tibialis posterior muscle pain on joint loading and muscle forces-Implications for patients with rheumatoid arthritis?

BACKGROUND

Foot pain and deformities are commonly encountered in patients with rheumatoid arthritis (RA). Likewise, Posterior tibial tendon dysfunction (PTTD) is commonly involved in development of foot and ankle abnormalities and has been reported with a prevalence in two-thirds of the RA patients.

RESEARCH QUESTION

Redundancy in the physiological function between different muscles provides the central nervous system multiple options to perform the same movement but which muscles compensate for the impairment of the tibialis posterior (TP) muscle? And how does these changes affect ankle joint loading?

METHODS

Experimental and computational disciplines were applied to investigate changes in muscle forces as result of induced pain in the right TP muscle. Twelve healthy subjects were enrolled in the study. Experimental pain was induced in the TP by a single ultrasound graphically guided injection of 1 mL hypertonic saline (5.0% Sodium Chloride). The participants' gait was assessed by skin marker-based motion capture and force plates. Musculoskeletal models were used to investigate compensation mechanisms systematically in the lower under extremity when TP muscle was recruited less as a consequence of the induced pain.

RESULTS

Experimental TP muscle pain and simulated reduced strength caused altered muscle recruitment and made the flexor digitorum longus and flexor hallucis longus muscles compensated for the impairment of the TP muscle. Further, the resultant ankle joint force was increased as the strength of the TP muscle was reduced.

SIGNIFICANCE

The compensation mechanism observed in the present study indicate that alterations in muscle recruitment and muscle force distribution as a result of the underlying disease inflammation itself may contribute to development of chronic foot pain and deformities in patients with RA. Further studies are required to understand the role of PTTD in occurrence of those late adverse musculoskeletal manifestations aiming at search for early preventive strategies.

Convergence and Divergence of Exercise-Based Approaches That Incorporate Motor Control for the Management of Low Back Pain

Many approaches for low back pain (LBP) management focus on modifying motor control, which refers to motor, sensory, and central processes for control of posture and movement. A common assumption across approaches is that the way an individual loads the spine by typical postures, movements, and muscle activation strategies contributes to LBP symptom onset, persistence, and recovery. However, there are also divergent features from one approach to another. This commentary presents key principles of 4 clinical physical therapy approaches, including how each incorporates motor control in LBP management, the convergence and divergence of these approaches, and how they interface with medical LBP management. The approaches considered are movement system impairment syndromes of the lumbar spine, Mechanical Diagnosis and Therapy, motor control training, and the integrated systems model. These were selected to represent the diversity of applications, including approaches using motor control as a central or an adjunct feature, and approaches that are evidence based or evidence informed. This identification of areas of convergence and divergence of approaches is designed to clarify the key aspects of each approach and thereby serve as a guide for the clinician and to provide a platform for considering a hybrid approach tailored to the individual patient. J Orthop Sports Phys Ther 2019;49(6):437-452. Epub 15 May 2019. doi:10.2519/jospt.2019.8451.

Changes in Structure and Function of the Back Muscles in Low Back Pain: Different Time Points, Observations, and Mechanisms

Spinal health depends on optimal back muscle performance, and this is determined by muscle structure and function. There has been substantial research evaluating the differences in structure and function of many back muscles, including the multifidus and erector spinae, but with considerable variation in results. Many studies have shown atrophy, fat infiltration, and connective tissue accumulation in back muscles, particularly deep fibers of the multifidus, but the results are not uniform. In terms of function, results are also somewhat inconsistent, often reporting lower multifidus activation and augmented recruitment of more superficial components of the multifidus and erector spinae, but, again, with variation between studies. A major recent observation has been the identification of time-dependent differences in features of back muscle adaptation, from acute to subacute/recurrent to chronic states of the condition. Further, these adaptations have been shown to be explained by different time-dependent mechanisms. This has substantial impact on the rationale for rehabilitation approaches. The aim of this commentary was to review and consolidate the breadth of research investigating adaptation in back muscle structure and function, to consider explanations for some of the variation between studies, and to propose how this model can be used to guide rehabilitation in a manner that is tailored to individual patients and to underlying mechanisms. J Orthop Sports Phys Ther 2019;49(6):464-476. doi:10.2519/jospt.2019.8827.

Visual and instrumental diagnostics using chromokinegraphics: Reliability and validity for low back pain stratification

BACKGROUND

Low back pain patients have been suggested to exhibit dysfunctional spinal movement patterns. However, there is a lack of clinically applicable but valid and reliable assessment tools, helping to discriminate normal and pathologically altered movement.

OBJECTIVE

We aimed to examine whether kinematic parameters determined with an ultrasound-based motion analysis and thereof derived chromokinegraphical angle-time matrices (CATMAs) are able to discriminate between non-symptomatic and symptomatic movement behaviour in individuals with non-specific chronic (CLBP), specific low back pain (SLBP), and controls.

METHODS

Thoracic and lumbar spine range of motion (ROM [∘]); angular velocity (V [∘/sec]) and side-to-side differences [%] during a lateral flexion movement were assessed in 17 healthy participants, 16 individuals with CLBP and 11 SLBP patients. CATMAs ratings of two investigators (6-item Likert scale) were dichotomised, classifying the observed movement as physiological or non-physiological. Intrarater and interrater reliability were estimated using kappa statistics and Cronbach's Alpha. T-tests and a ROC analysis to determine optimal cut-offs for the separation of the collectives as well as contingency tables for selectivity of the cut-offs (motor outcomes) were calculated.

RESULTS

CATMA ratings displayed partly moderate to good (rater B; i.e. CLBP vs. controls) and partly insufficient discriminant validity (rater A). Due to this, inter-rater reliability was poor (k= 0.061 to 0.135), while intra-rater-reliability was moderate to good for both raters (k= 0.329 to 0.625) except for SLBP vs. controls (rater A; k=-0.18). Regarding kinematics, group differences occurred neither in ROM nor in V (p> 0.05), but in terms of the relative side comparison between CLBP and controls (p<0.05). ROC analysis (CLBP vs. controls) revealed an optimal cut-off at side asymmetries of 16.9% (ROM) and 28.9% (V). Between SLBP patients and controls, no significant differences were observed neither in terms of the absolute values nor the relative side differences of both kinematic variables.

CONCLUSIONS

Side asymmetries of V and ROM may be used to differentiate between controls and individuals with CLBP. CATMAs appear to be of limited diagnostic value for the identification of pathological spine movement.

Tibialis posterior muscle pain effects on hip, knee and ankle gait mechanics

BACKGROUND

Tibialis posterior (TP) dysfunction is a common painful complication in patients with rheumatoid arthritis (RA), which can lead to the collapse of the medial longitudinal arch. Different theories have been developed to explain the causality of tibialis posterior dysfunction. In all these theories, pain is a central factor, and yet, it is uncertain to what extent pain causes the observed biomechanical alterations in the patients. The aim of this study was to investigate the effect of experimental tibialis posterior muscle pain on gait mechanics in healthy subjects.

METHODS

Twelve healthy subjects were recruited for this randomized crossover study. Experimental pain was induced by ultrasound-guided injection of 1 mL hypertonic saline into the upper part of the right tibialis posterior muscle with the use of isotonic saline as non-pain-inducing control. Subsequently, kinematic data during three self-paced over ground walking for each condition were collected. Ground reaction forces and external moments were measured from force plates installed in the floor. Painful areas were evaluated using body charts and pain intensity scoring via a verbal numerical rating scale.

FINDINGS

Decreased hip internal rotation was observed during the pain condition at the end of the stance phase. There were no changes in gait velocity and duration of stand phase between the pain and no pain conditions. Reduced external joint moment was found for external knee rotation and for external hip rotation.

INTERPRETATION

The study has demonstrated that induced pain in the TP muscle evokes kinematic alteration in the hip and the knee joints, but not in the ankle, which suggest an underlying early stage joint compensatory mechanism. These findings suggest the need to include those joints in current physical evaluations of tibialis posterior dysfunction.

Postural cueing increases multifidus activation during stabilization exercise in participants with chronic and recurrent low back pain: An electromyographic study

Persons with low back pain (LBP) have demonstrated altered morphology and function of the deep multifidus (DM). This study examined the effects of postural cueing for increased lumbar lordosis on DM and longissimus thoracis (LT) activation during lumbar stabilization exercises (LSE) performed by persons with LBP. Nine adults with a history of chronic or recurrent LBP were recruited. Fine-wire EMG data was collected while participants performed 10 LSE's in neutral posture and with postural cueing. Percent maximum voluntary isometric contraction of L5 DM and T12 LT, and ratios of activation (DM/LT) were analyzed. There was a significant main effect for posture on DM activation (p < 0.001), indicating greater activation levels during exercises performed with postural cueing vs. neutral posture. LT activation did not increase significantly with postural cueing. Following a significant 1-way repeated measures ANOVA (p = 0.034) for the postural cueing condition, pairwise comparisons demonstrated significantly higher DM/LT activation ratios for prone leg lift, variable-angle Roman chair at 15°, bridging, and bilateral arm and leg lift. These results suggest postural cueing can be used across a range of LSE intensities to increase DM activation without a significant increase in LT activation in patients with chronic or recurrent LBP.

Lumbar Muscle Activation Pattern During Forward and Backward Walking in Participants With and Without Chronic Low Back Pain: An Electromyographic Study

Objective

The purpose of this study was to investigate the electromyographic activity of lumbar multifidus (MF) and erector spinae (ES) muscle during forward walking (FW) and backward walking (BW) in participants with and without chronic low back pain (CLBP).

Methods

Twenty-one patients with CLBP were recruited from outpatient department of Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia. Twenty-one age-matched healthy controls without CLBP were recruited from community. Maximum voluntary isometric contraction (MVIC) was quantified for MF and ES using standard guidelines. Electromyographic activity of MF and ES was recorded using surface electrodes during FW and BW on a motorized treadmill, which was later normalized by respective MVIC's of each muscle.

Results

Muscle activity (in percentage MVIC) was determined to be higher for both the muscles during BW. Activity of MF muscle was significantly higher in CLBP patients compared with healthy controls (P < .04). Electromyographic activity of MF and ES was significantly increased during BW (MF: P < .001; ES: P < .001) compared with FW in both healthy and CLBP groups.

Conclusion

BW leads to greater activation of the paraspinal muscles. Along with global extensor (ES), activity of core extensor (MF) is also higher during BW than FW in both healthy participants and CLBP patients. BW is a more favorable aerobic activity to enhance lumbar paraspinal recruitment. These findings may have important clinical implications in the rehabilitation of CLBP.

Age- and low back pain-related differences in trunk muscle activation during one-legged stance balance task

BACKGROUND

Postural control declines with age and can be affected by low back pain. Poor balance has been reported in people with chronic low back pain (CLBP), which in turn could be explained by the changes in trunk muscle activation.

RESEARCH QUESTION

Are there differences between younger and older adults with and without chronic low back pain (CLBP) on trunk muscle activity during one-legged stance task?

METHODS

Twenty (20) with, and 20 subjects without nonspecific CLBP participated in the study. Each group was comprised of 10 younger (50% males; mean age: 31 years) and 10 older adults (50% males; mean age: 71 years). Subjects performed 3 × 30-second trials of one-legged stance, with eyes open, on a force platform, while surface electromyography (EMG) measurements were obtained bilaterally on the multifidus at L5, iliocostalis lumborum at L3, rectus abdominis and biceps femoris muscles.EMG amplitude analysis was processed by the Root Mean Square (250 ms window epochs) and normalized by the peak of activation during the balance tasks, to determine the muscular activity of each muscle.

RESULTS

Participants with CLBP presented 15% lower lumbar muscle activation (p <  0.05), and 23% higher co-activation (ratio between rectus adominis by multifidus) than participants without CLBP, regardless of age. Significant differences (p <  0.05) between older and young groups were observed only for lower lumbar muscles (mean 24% lower in older than younger adults) and rectus adominis muscles (mean 17% lower in older than younger adults).

SIGNIFICANCE

CLBP individuals have different trunk muscle activity than those without CLBP, and older adults exhibit lower trunk activation during one-legged stance balance task. The use of the EMG in evaluation of trunk neuromuscular function during one-legged stance may thus be a valuable tool when assessing balance in CLBP and older people.

Effect of acute experimental hand pain on left-right discrimination response latency for hand recognition

Background: Recent work has indicated that acute experimental pain affects left-right discrimination latency. This phenomenon highlights an effect of pain on the cortex that may have significant clinical importance in the form of pain state assessment. However, to date only limited study has further qualified this effect. A more thorough understanding of the magnitude and characteristics of this phenomenon is needed to determine its potential clinical utility. Objective: This study aimed to closely replicate previous studies investigating response latency changes for left-right discrimination judgements as a result of acute experimental pain. Methods: Twenty-two right-handed participants (n = 11 female, n = 11 male) free from pain, analgesia use, pain-related conditions, upper limb trauma/conditions, visual impairment, and dyslexia took part in this study. Participants completed a hand left-right discrimination judgement task before, during, and after an experimental pain stimulus was delivered to each hand separately. Experimental pain was achieved using an intramuscular injection of hypertonic (5%) saline into the thenar eminence of the left and right hands. Mean response times for the left-right discrimination task were determined and compared for pain location (right, left), pain condition (before, during, after), and image laterality (right, left). Pain intensity was rated at 20 s intervals during each left-right discrimination task. Results: A main effect of pain condition (p = 0.028) confirmed that pain intensity was significantly higher in the "during pain" condition compared to the "before pain" and "after pain" conditions. A main effect of image laterality (p = 0.002) further showed that response latency for right-hand pain was significantly shorter compared to left-hand pain. No significant interaction between the factors pain location and image laterality (p = 0.086) was found. For right-hand pain, response latencies for the unaffected hand were, however, descriptively greater compared to the affected hand, and this was not the case for left-hand pain. Furthermore, no main effect of pain stimulus or of pain location on response times was found (p = 1.00 and p = 0.202, respectively). Conclusion: Our results were not consistent with previous hand left-right discrimination response latency results and may cast doubt on the attentional bias hypothesis that is currently considered to underpin response latency changes during acute experimental hand pain. Individual responses to pain, subsets of participants, and differing mental rotation strategies during the left-right discrimination task may have influenced the results.

The relationship between functionality and erector spinae activity in patients with specific low back pain during dynamic and static movements

BACKGROUND

Alterations in the activity of the lumbar erector spinae (LES) muscles on both sides of the spine have been inconsistently reported in patients with specific low back pain (sLBP) after measuring the muscular activity with surface electromyography (sEMG). It also remains unclear whether these alterations in LES activity can be related to the functional level of patients with sLBP.

RESEARCH QUESTION

This study investigated the LES activity in patients with sLBP during activities of daily living (ADL) which included dynamic and static movement tasks. Moreover, the alterations in LES activity were correlated with the first seven questions of the Zurich Claudication Questionnaire (ZCQ-SS).

METHODS

Thirty patients with specific LBP and twenty healthy subjects were recruited to perform five ADLs including 'static waist flexion', 'sit to stand',' 30-seconds standing', '6-minutes walking' and 'climbing stairs'. sEMG sensors were mounted on the left and right LES muscles. The integrated EMG (IEMG) was calculated from the preprocessed sEMG data as statistical comparison criteria.

RESULTS

LES activity was significantly higher in patients during 'sit to stand',' 30-seconds standing' and 'climbing stairs' and significantly lower during 'static waist flexion' compared to healthy controls. All tasks showed a significant correlation with the ZCQ-SS score except for '6-minutes walking', whereby LES activity and ZCQ-SS score correspondingly increased during 'sit to stand' and 'climbing stairs' and the LES activity decreased with an increasing ZCQ-SS score during 'static waist flexion' and' 30-seconds standing'.

SIGNIFICANCE

There was a high correlation between alterations in LES activity and the level of functionality in LBP patients. However, the LES activity showed an opposite behavior during static and dynamic movement tasks. The methodology presented can be a useful tool for quantifying improvements in functionality after rehabilitation processes.

Individuals with sacroiliac joint dysfunction display asymmetrical gait and a depressed synergy between muscles providing sacroiliac joint force closure when walking

Walking is often compromised in individuals with low back and hip disorders, such as sacroiliac joint dysfunction (SIJD). The disorder involves reduced coactivation of the gluteus maximus and contralateral latissimus dorsi, which together provide joint stability during walking. The purpose of our study was to compare the kinematics and contributions of selected muscles to identified synergies during walking between healthy individuals and those with SIJD. Six women with unilateral SIJD and six age-matched healthy controls walked on a force-measuring treadmill at 1 m/s while we recorded kinematics and the activity of 16 muscles with surface EMG. Non-negative matrix factorization was used to identify patterns of EMG activity (muscle synergies). Individuals with SIJD exhibited less hip extension and lower peak vertical ground reaction forces on the affected side than the unaffected side. In contrast to controls, the SIJD group also displayed a depressed muscle synergy between gluteus maximus on the affected side and the contralateral latissimus dorsi. The results indicate that individuals with SIJD exhibited both reduced activation of gluteus maximus during a loading synergy present in walking and greater asymmetry between legs when walking compared with age-matched controls.

Delayed muscle onset soreness in the gastrocnemius muscle attenuates the spinal contribution to interlimb communication

PURPOSE

Delayed onset muscle soreness (DOMS) has been shown to induce changes in muscle activity during walking. The aim of this study was to elucidate whether DOMS also affects interlimb communication during walking by investigating its effect on short-latency crossed responses (SLCRs).

METHODS

SLCRs were elicited in two recording sessions by electrically stimulating the tibial nerve of the ipsilateral leg, and quantified in the contralateral gastrocnemius muscle. The second recording session occurred 24-36 h after the participants (n = 11) performed eccentric exercises with the ipsilateral calf.

RESULTS

DOMS caused a decreased magnitude of the spinally mediated component of the SLCR in the contralateral gastrocnemius medialis.

CONCLUSIONS

The results of the current study provide insight on the relationship between pain and motor control. Muscle pain affects the spinal pathway mediating interlimb communication, which might result in a reduced ability to maintain dynamical stability during walking.

Patients with sacroiliac joint dysfunction exhibit altered movement strategies when performing a sit-to-stand task

OF BACKGROUND DATA

The ability to rise from a chair is a basic functional task that is frequently compromised in individuals diagnosed with orthopedic disorders in the low back and hip. There is no published literature that describes how this task is altered by sacroiliac joint dysfunction (SIJD).

PURPOSE

The objective of this study was to compare lower extremity biomechanics and the onset of muscle activity when rising from a chair in subjects with SIJD and in healthy persons.

STUDY DESIGN

Six women with unilateral SIJD and six age-matched healthy controls performed a sit-to-stand task while we measured kinematics, kinetics, and muscle activity.

MATERIALS AND METHODS

Subjects stood up at a preferred speed from a seated position on an armless and backless adjustable stool. We measured kinematics with a 10-camera motion capture system, ground reaction forces for each leg with force plates, and muscle activity with surface electromyography. Joint angles and torques were calculated using inverse dynamics. Leg-loading rate was quantified as the average slope of vertical ground reaction (VGRF) force during the 500-millisecond interval preceding maximal knee extension.

RESULTS

Between-leg differences in loading rates and peak VGRFs were significantly greater for the SIJD group than for the control group. Maximal hip angles were significantly less for the SIJD group (p=.001). Peak hip moment in the SIJD group was significantly greater in the unaffected leg (0.75±0.22 N⋅m/kg) than in the affected leg (0.47±0.29 N⋅m/kg, p=.005). There were no between-leg or between-group differences for peak knee or ankle moments. The onset of activity in the latissimus dorsi muscle on the affected side was delayed and the erector spinae muscles were activated earlier in the SIJD group than in the control group.

CONCLUSIONS

Subjects with SIJD have a greater VGRF on the unaffected leg, generate a greater peak hip moment in the unaffected leg, use a smaller range of motion at the hip joint of the affected leg, and delay the onset of a key muscle on the affected side when rising from a seated position.

Correlation between Trunk-Pelvis Inter-Segmental Coordination Parameters during Walking and Disability Level in Chronic Low Back Pain Patients

BACKGROUND

Chronic low back pain (CLBP) disability has been particularly frustrating because its treatment has been a great therapeutic challenge. Disability has been suggested to depend on different factors that should be found and considered in the medical management. The inter-segmental coordination is often impaired in CLBP subjects; however, to the best of our knowledge, there is no evidence about the relationship between the existence of coordination problems and disability in CLBP patients.

OBJECTIVE

To evaluate the correlation between sagittal plane trunk-pelvis inter-segmental coordination parameters during walking and disability level in CLBP patients.

METHODS

Kinematic data were collected from 16 non-specific CLBP (18-40 years) volunteers during walking. Sagittal plane time-normalized segmental angles and velocities were used to calculate continuous relative phase for each data point. Coordination parameters, mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify the trunk-pelvis coordination pattern and variability during gait cycles, respectively. The disability level was quantified through Oswestry Disability Index (ODI) questionnaire. Pearson correlation coefficient was used to find the probable correlation between coordination parameters and disability level.

RESULTS

The analysis demonstrated a significant correlation between sagittal plane MARP or DP and disability level (%ODI) in CLBP subjects during walking (r= -0.806 P<0.001 and r= -0.856, P<0.001, respectively).

CONCLUSION

This study demonstrated that the lower the MARP (more in-phase pattern) and DP (less variable pattern) in the CLBP subjects, the more disability existing in such patients. The results suggest that clinicians should look beyond pain management when prescribing rehabilitation for CLBP and consider interventions that target segmental coordination improvement to manage CLBP induced disability.

Postural awareness and its relation to pain: validation of an innovative instrument measuring awareness of body posture in patients with chronic pain

Background

Habitual postural patterns are associated with musculoskeletal pain, and improving a maladaptive posture requires postural awareness in order to lead to clinical improvements. This study aimed to develop and evaluate the psychometric properties of an innovative postural awareness scale.

Methods

A 12-item Postural Awareness Scale (PAS) was developed and administered to 512 chronic pain patients (50.3 ± 11.4 years, 91.6% female, 37.1% spinal/shoulder pain) to assess its factor structure and reliability. To determine convergent validity, measures of body awareness, body responsiveness, body image, and mindfulness were correlated with the PAS, as were clinical measures of pain intensity, disability, and mental health. Sensitivity to change was assessed in 202 outpatients participating in a 10-week multimodal mind-body program.

Results

Factor analysis revealed two factors (Ease/Familiarity with Postural Awareness and Need for Attention Regulation with Postural Awareness) that explained 50.8% of the variance. Cronbach’s alpha for the complete scale was 0.80; Spearman-Brown coefficient of split-half reliability was 0.67; and intra-class correlation was ICC_2,1 = 0.75 (95% confidence interval = 0.71, 0.78). Significant positive correlations were found for body awareness (r = 0.23), body responsiveness (r = 0.41), body image (r = 0.22–0.32), and mindfulness (r = 0.38); negative correlations for pain intensity (r = − 0.14), disability (r = − 0.12), depression (r = − 0.23), and stress (r = − 0.29). Postural awareness scores increased with a mind-body program (p < 0.001); changes in the PAS were negatively correlated with changes in pain intensity (r = − 0.35) in patients with spinal/shoulder pain.

Conclusion

Self-reported postural awareness is associated with clinical symptoms in chronic pain patients; improvements in postural awareness are longitudinally associated with reduced pain in patients with spinal/shoulder pain.