Trunk control during repetitive sagittal movements following a real-time tracking task in people with chronic low back pain

The association of fear of movement and postural sway in people with low back pain

BACKGROUND

Fear of movement is thought to interfere with the recovery from low back pain (LBP). To date, the relationship between fear of movement and postural balance has not been adequately elucidated. Recent findings suggest that more specific fears need to be assessed and put in relation to a specific movement task. We propose that the fear to bend the trunk in a certain direction is distinctly related to the amount of postural sway in different directions. Therefore, our aim was to investigate whether fear of movement in general and fear of bending the trunk in a certain plane is related to postural sway.

METHODS

Data was collected from participants with LBP during two assessments ~3 weeks apart. Postural sway was measured with a force-platform during quiet standing with the eyes closed. Fear of movement was assessed with an abbreviated version of the Tampa Scale of Kinesiophobia (TSK-11) and custom items referring to fear of bending the trunk in the sagittal and the frontal plane.

RESULTS

Based on data from 25 participants, fear of bending the trunk in the frontal plane was positively related to displacement in the sagittal and frontal plane and to velocity in the frontal plane (χ 2 = 4.35, p = 0.04; χ 2 = 8.15, p = 0.004; χ 2 = 9.79, p = 0.002). Fear of bending the trunk in the sagittal plane was not associated with any direction specific measure of sway. A positive relation of the TSK-11 with velocity of the frontal plane (χ 2 = 7.14, p = 0.008) was found, but no association with undirected measures of sway.

DISCUSSION

Fear of bending the trunk in the frontal plane may be especially relevant to postural sway under the investigated stance conditions. It is possible that fear of bending the trunk in the frontal plane could interfere with balance control at the hip, shifting the weight from side to side to control balance.

CONCLUSION

For the first time the directional relationship of fear of movement and postural sway was studied. Fear of bending the trunk in the frontal plane was positively associated with several measures of postural sway.

People with chronic low back pain display spatial alterations in high-density surface EMG-torque oscillations

We quantified the relationship between spatial oscillations in surface electromyographic (sEMG) activity and trunk-extension torque in individuals with and without chronic low back pain (CLBP), during two submaximal isometric lumbar extension tasks at 20% and 50% of their maximal voluntary torque. High-density sEMG (HDsEMG) signals were recorded from the lumbar erector spinae (ES) with a 64-electrode grid, and torque signals were recorded with an isokinetic dynamometer. Coherence and cross-correlation analyses were applied between the filtered interference HDsEMG and torque signals for each submaximal contraction. Principal component analysis was used to reduce dimensionality of HDsEMG data and improve the HDsEMG-based torque estimation. sEMG-torque coherence was quantified in the δ(0–5 Hz) frequency bandwidth. Regional differences in sEMG-torque coherence were also evaluated by creating topographical coherence maps. sEMG-torque coherence in the δ band and sEMG-torque cross-correlation increased with the increase in torque in the controls but not in the CLBP group (p = 0.018, p = 0.030 respectively). As torque increased, the CLBP group increased sEMG-torque coherence in more cranial ES regions, while the opposite was observed for the controls (p = 0.043). Individuals with CLBP show reductions in sEMG-torque relationships possibly due to the use of compensatory strategies and regional adjustments of ES-sEMG oscillatory activity.

Feedback on Trunk Movements From an Electronic Game to Improve Postural Balance in People With Nonspecific Low Back Pain: Pilot Randomized Controlled Trial

Background

Postural balance is compromised in people with low back pain, possibly by changes in motor control of the trunk. Augmenting exercising interventions with sensor-based feedback on trunk posture and movements might improve postural balance in people with low back pain.

Objective

We hypothesized that exercising with feedback on trunk movements reduces sway in anterior-posterior direction during quiet standing in people with low back pain. Secondary outcomes were lumbar spine and hip movement assessed during box lift and waiter bow tasks, as well as participant-reported outcomes. Adherence to the exercising intervention was also examined.

Methods

A randomized controlled trial was conducted with the intervention group receiving unsupervised home exercises with visual feedback using the Valedo Home, an exergame based on 2 inertial measurement units. The control group received no intervention. Outcomes were recorded by blinded staff during 4 visits (T1-T4) at University Hospital Zurich. The intervention group performed 9 sessions of 20 minutes in the 3 weeks between T2 and T3 and were instructed to exercise at their own convenience between T3 and T4. Postural balance was assessed on a force platform. Lumbar spine and hip angles were obtained from 3 inertial measurement units. The assessments included pain intensity, disability, quality of life, and fear of movement questionnaires.

Results

A total of 32 participants with nonspecific low back pain completed the first assessment T1, and 27 (84%) participants were randomized at T2 (n=14, 52% control and n=13, 48% intervention). Intention-to-treat analysis revealed no significant difference in change in anterior-posterior sway direction during the intervention period with a specified schedule (T2-T3) between the groups (W=99; P=.36; r=0.07). None of the outcomes showed significant change in accordance with our hypotheses. The intervention group completed a median of 61% (55/90; range 2%-99%) of the exercises in the predefined training program. Adherence was higher in the first intervention period with a specified schedule.

Conclusions

The intervention had no significant effect on postural balance or other outcomes, but the wide range of adherence and a limited sample size challenged the robustness of these conclusions. Future work should increase focus on improving adherence to digital interventions.

Trial Registration

ClinicalTrials.gov NCT04364243; https://clinicaltrials.gov/ct2/show/NCT04364243

International Registered Report Identifier (IRRID)

RR2-10.2196/26982

Review of Real-Time Biomechanical Feedback Systems in Sport and Rehabilitation

Real-time biomechanical feedback (BMF) is a relatively new area of research. The potential of using advanced technology to improve motion skills in sport and accelerate physical rehabilitation has been demonstrated in a number of studies. This paper provides a literature review of BMF systems in sports and rehabilitation. Our motivation was to examine the history of the field to capture its evolution over time, particularly how technologies are used and implemented in BMF systems, and to identify the most recent studies showing novel solutions and remarkable implementations. We searched for papers in three research databases: Scopus, Web of Science, and PubMed. The initial search yielded 1167 unique papers. After a rigorous and challenging exclusion process, 144 papers were eventually included in this report. We focused on papers describing applications and systems that implement a complete real-time feedback loop, which must include the use of sensors, real-time processing, and concurrent feedback. A number of research questions were raised, and the papers were studied and evaluated accordingly. We identified different types of physical activities, sensors, modalities, actuators, communications, settings and end users. A subset of the included papers, showing the most perspectives, was reviewed in depth to highlight and present their innovative research approaches and techniques. Real-time BMF has great potential in many areas. In recent years, sensors have been the main focus of these studies, but new types of processing devices, methods, and algorithms, actuators, and communication technologies and protocols will be explored in more depth in the future. This paper presents a broad insight into the field of BMF.

The Relationship Between Pain-Related Threat and Motor Behavior in Nonspecific Low Back Pain: A Systematic Review and Meta-Analysis

OBJECTIVE

Although pain-related fear and catastrophizing are predictors of disability in low back pain (LBP), their relationship with guarded motor behavior is unclear. The aim of this meta-analysis was to determine the relationship between pain-related threat (via pain-related fear and catastrophizing) and motor behavior during functional tasks in adults with LBP.

METHODS

This review followed PRISMA guidelines. MEDLINE, Embase, PsychINFO, and CINAHL databases were searched to April 2021. Included studies measured the association between pain-related fear or pain catastrophizing and motor behavior (spinal range of motion, trunk coordination and variability, muscle activity) during movement in adults with nonspecific LBP. Studies were excluded if participants were postsurgery or diagnosed with specific LBP. Two independent reviewers extracted all data. The Newcastle-Ottawa Scale was used to assess for risk of bias. Correlation coefficients were pooled using the random-effects model.

RESULTS

Reduced spinal range of motion during flexion tasks was weakly related to pain-related fear (15 studies, r = -0.21, 95% CI = -0.31 to -0.11) and pain catastrophizing (7 studies, r = -0.24, 95% CI = -0.38 to -0.087). Pain-related fear was unrelated to spinal extension (3 studies, r = -0.16, 95% CI = -0.33 to 0.026). Greater trunk extensor muscle activity during bending was moderately related to pain-related fear (2 studies, r = -0.40, 95% CI = -0.55 to -0.23). Pain catastrophizing, but not fear, was related to higher trunk activity during gait (2 studies, r = 0.25, 95% CI = 0.063 to 0.42). Methodological differences and missing data limited robust syntheses of studies examining muscle activity, so these findings should be interpreted carefully.

CONCLUSION

This study found a weak to moderate relationship between pain-related threat and guarded motor behavior during flexion-based tasks, but not consistently during other movements.

IMPACT

These findings provide a jumping-off point for future clinical research to explore the advantages of integrated treatment strategies that target both psychological and motor behavior processes compared with traditional approaches.

Machine learning approaches applied in spinal pain research

The purpose of this narrative review is to provide a critical reflection of how analytical machine learning approaches could provide the platform to harness variability of patient presentation to enhance clinical prediction. The review includes a summary of current knowledge on the physiological adaptations present in people with spinal pain. We discuss how contemporary evidence highlights the importance of not relying on single features when characterizing patients given the variability of physiological adaptations present in people with spinal pain. The advantages and disadvantages of current analytical strategies in contemporary basic science and epidemiological research are reviewed and we consider how analytical machine learning approaches could provide the platform to harness the variability of patient presentations to enhance clinical prediction of pain persistence or recurrence. We propose that machine learning techniques can be leveraged to translate a potentially heterogeneous set of variables into clinically useful information with the potential to enhance patient management.

Trunk muscle activation patterns during active hip abduction test during remission from recurrent low back pain: an observational study

Background

The active hip abduction test (AHAbd) is widely used to evaluate lumbopelvic stability, but the onset of trunk muscle activation during the test in individuals with recurrent low back pain (rLBP) has not been investigated so far. It is important to investigate the pattern of trunk muscle activation during the AHAbd test to provide insight into the interpretation of observation-based assessment results; this may help to create exercise therapy interventions, from a movement control perspective, for people seeking treatment for rLBP. The purpose of this study was to compare the timing of trunk muscle activation between individuals with and without rLBP and to assess potential differences.

Methods

Seventeen subjects in remission from rLBP and 17 subjects without rLBP were recruited. We performed surface electromyography of the transversus abdominis/internal abdominal oblique, external oblique, erector spinae, and gluteus medius muscles during the AHAbd test on both sides. The onset of trunk muscle activation was calculated relative to the prime mover gluteus medius. The independent-samples t- and Mann-Whitney U tests were used to compare the onset of trunk muscle activation between the two groups.

Results

The onset of transversus abdominis/internal abdominal oblique activation on the ipsilateral (right AHAbd: −3.0 ± 16.2 vs. 36.3 ± 20.0 msec, left AHAbd: −7.2 ± 18.6 vs. 29.6 ± 44.3 ms) and contralateral sides (right AHAbd: −11.5 ± 13.9 vs. 24.4 ± 32.3 ms, left AHAbd: −10.1 ± 12.5 vs. 23.3 ± 17.2 ms) and erector spinae on the contralateral side (right AHAbd: 76.1 ± 84.9 vs. 183.9 ± 114.6 ms, left AHAbd: 60.7 ± 70.5 vs. 133.9 ± 98.6 ms) occurred significantly later in individuals with rLBP than in individuals without rLBP (p < 0.01). During the left AHAbd test, the ipsilateral erector spinae was also activated significantly later in individuals with rLBP than in individuals without rLBP (71.1 ± 80.1 vs. 163.8 ± 120.1 ms, p < 0.05). No significant difference was observed in the onset of the external oblique activation on the right and left AHAbd tests (p > 0.05).

Conclusions

Our results suggest that individuals with rLBP possess a trunk muscle activation pattern that is different from that of individuals without rLBP. These findings provide an insight into the underlying muscle activation patterns during the AHAbd test for people with rLBP and may support aggressive early intervention for neuromuscular control.