Measures of complexity during walking in chronic non-specific low back pain patients

Risk of unfavorable pain prognosis impacts walking physiomechanical parameters and psychophysiological workload in sufferers of chronic low back pain

BACKGROUND

Tolerating physical tasks depends not only on task-specific characteristics but also on an individual's psychophysiological capacity to respond to the imposed load. People suffering from chronic low back pain (CLBP) may experience reduced psychophysiological capacity and are at risk for poor pain prognosis, which could lead to an increased walking workload.

AIM

To investigate how the risk of unfavorable pain prognosis in CLBP can impact walking physiomechanical parameters and psychophysiological workload.

METHODS

A cross-sectional observational study. The study classified 74 volunteers into four groups based on their prognosis for pain: pain-free control (CG/n = 20), low (LrG/n = 21), medium (MrG/n = 22), and high (HrG/n = 11) risk of poor prognosis for CLBP. The ground assessments identified the self-selected (SSW) and optimal (OWS) walking speeds, as well as the locomotor rehabilitation index (LRI). Treadmill assessments were conducted at two different speeds (0.83 and 1.11 m s-1, SSW and OWS) to record physiomechanical parameters. Psychophysiological workloads during walking were measured via workload impulse for the session (TRIMP), determined by variations in heart rate.

RESULTS

CLBP groups exhibited slower SSW and lower LRI compared to the CG. The TRIMP was lower in the LrG. However, both MrG and HrG exhibited a comparable overload to the CG, even while walking at a lower intensity with a psychophysical demand. SSW and OWS displayed an increased TRIMP compared to fixed speeds.

CONCLUSION

Psychosocial factors may affect SSW in people with CLBP but not among the risk strata. An unfavorable prognosis for pain could jeopardize the psychophysiological capacity to withstand walking demands.

Limited evidence of altered gait parameters in people with chronic nonspecific low back pain

BACKGROUND

Differences in gait parameters have been shown between people with and without low back pain (LBP). However, previous studies did not well control factors such as sex, age, height and walking speed known to influence gait parameters.

RESEARCH QUESTION

Is gait altered in people with LBP when sex, age, height and walking speed are controlled?

METHODS

A series of gait parameters were measured in 16 participants with LBP and 16 age, sex and height matched healthy controls while walking on an instrumented treadmill. LBP group walked at a comfortable speed whilst control group walked at their own comfortable speed and at the comfortable speed of their matched participants with LBP. Pain and disability were measured for the LBP group. The between-group differences in mean, standard deviation (SD) and coefficient of variation (CV) of gait parameters were tested using paired samples t-test, Wilcoxon signed-rank test or two-factor repeated measures analyses of variance.

RESULTS

The median (interquartile range) of pain intensity was 2 (1, 3.5). From 102 tests of between-group difference in mean, SD and CV of 17 gait parameters at both comfortable speed and matched speed walking, only the mean of stride length (p = 0.037) during matched speed walking and SD of single support phase (p = 0.040) during comfortable speed walking showed significant between-group differences. There was no significant between-group difference in the rest means (comfortable walking: p ≥ 0.116; matched speed walking: p ≥ 0.069), SDs (comfortable walking: p ≥ 0.066; matched speed walking: p ≥ 0.098) and CVs of gait parameters (comfortable walking: p ≥ 0.110; matched speed walking: p ≥ 0.121).

SIGNIFICANCE

The lack of significant between-group difference in gait parameters may suggest that the gait of people with low level of LBP were not altered when sex, age and height were controlled.

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.

Relationship between gait complexity and pain attention in chronic low back pain

ABSTRACT

Clinical models of chronic low back pain (cLBP) highlight the role of excessive attention to pain and kinesiophobia on the origin of disability. At the motor control level, various mechanisms are involved in the impairments observed in patients with cLBP. We aimed to assess the role of maladaptative attentional behaviors by using a complex systems approach and a visual display as a distraction during walking. Sixteen patients with cLBP with no previous surgery or significant leg pain and 16 healthy matched controls were included. Patients walked on a treadmill at preferred walking speed with and without distraction. Stride time (ST) fractal complexity was assessed using detrended fluctuation analysis. A two-way analysis of variance with repeated measures on distraction was performed on fractal exponents. We found a significant group × distraction interaction effect on fractal complexity of ST series (F(1,30) = 9.972, P = 0.004). Post hoc analysis showed that, without distraction, patients with cLBP had significantly lower ST complexity than controls, but when distracted, they regained gait complexity, recovering the level of controls. Our results suggest that excessive attention to pain causes loss of complexity and adaptability in cLBP and explain alterations of motor control with pain. Fractal analysis seems to be a promising method to explore movement variability and individual adaptability in musculoskeletal disorders.

Revisiting the lumbosacral orthosis from the perspective of dynamical systems theory: a preliminary randomized clinical trial on patients with chronic low back pain

BACKGROUND

The prevalent method for investigating the effect of therapeutic interventions on walking in the individuals with chronic low back pain (CLBP) is component-level approach in which all measurements focus on the spine component alone. However, this approach cannot disclose information about the overall function of the movement system such as complex walking patterns, which, in turn, reveal the underlying movement control.

OBJECTIVES

To compare the effect of 3-week wearing of lumbosacral orthosis (LSO) along with routine physical therapy with routine physical therapy alone on walking complexity in the individuals with nonspecific CLBP on the basis of the systems approach.

STUDY DESIGN

Preliminary randomized clinical trial.

METHODS

Twenty-four subjects were randomly allocated to two groups. The control group received the routine physical therapy for 3 weeks. The intervention group received the same program plus an LSO. Nonlinear analysis was used to quantify walking complexity, as behavior of the entire movement system, before and after the intervention and at 1-month follow-up.

RESULTS

An average of 496 strides during ten minutes of walking was used for analysis. There was no significant difference (p > 0.05) in degree of walking complexity between two groups during all evaluation periods.

CONCLUSIONS

The administered orthotic intervention did not alter walking complexity. This suggests that therapeutic goal of current LSOs, which is not based on the systems approach, cannot recover the emergent behavior of the movement system. This may be a potential source of controversies.

CLINICAL RELEVANCE

To achieve an effective treatment, orthotists should focus on the individuals themselves, not only on their CLBP symptoms. Although the component-level approach aims to decrease the symptoms, the systems approach focuses on the whole context that fosters LBP symptoms.

Comparison of conservative treatment with and without neural mobilization for patients with low back pain: A prospective, randomized clinical trial

BACKGROUND

Low back pain (LBP) is a common problem that causes pain, disability, and gait and balance problems. Neurodynamic techniques are used in the treatment of LBP.

OBJECTIVE

The aim of this study was to compare the effects of electrotherapy and neural mobilization on pain, functionality, gait, and balance in patients with LBP.

MATERIALS AND METHODS

A total of 41 patients were randomly assigned to either the neural mobilization group (NMG, n= 20) or electrotherapy group (ETG, n= 21). Assessment tools used were Visual Analogue Scale (VAS) for pain, Oswestry Disability Index (ODI) for functionality, straight leg raise test (SLRT) for neural involvement, and baropedographic platform (Zebris FDM-2TM) for gait and static balance measurements.

RESULTS

Both groups showed a significant decrease in pain and functional disability, while only the NMG group showed a significant increase in SLRT scores (p< 0.05). However, there were no statistically significant pre- to post-treatment changes in gait or static balance parameters in either group (p< 0.05).

CONCLUSION

Neural mobilization was effective in reducing pain and improving functionality and SLRT performance in patients with LBP, but induced no change in gait and static balance parameters. Neural mobilization may be used as self-practice to supplement standard treatment programs.

Chronic Non-specific Low Back Pain and Motor Control During Gait

Background: Chronic non-specific low back pain (LBP) poses a major socioeconomic problem, although the mechanisms are not yet clear. Impaired motor control is one of the mechanisms being discussed. Objectives: The purpose of this review is to provide an overview of motor control parameter differences between individuals with and without non-specific LBP during gait. Methods: A literature search on Medline, SportDiscus, PsychInfo, PsychArticels, EMBASE, and Scopus was performed. Twenty-nine articles comparing healthy adults and adults with chronic non-specific LBP in neuromuscular and/or biomechanical parameters during walking or running were examined. Data extraction and quality assessment were independently performed by two persons. Among others, we extracted population, conditions, outcome measures, and results. Results: The results showed that persons with and without non-specific LBP differed in several parameters of motor control, which was indicated by a lower movement amplitude of the pelvis, more in-phase coordination, lower ground reaction forces, higher stride-to-stride variability and a higher activity in ES in the LBP group. Conclusion: Despite no strong evidence for any of the parameters, a combination of biomechanical and neuromuscular parameters provides a conclusive explanation. Impaired motor control during walking is reflected in higher activity of the erector spinae, which leads to a stiffened lumbar-pelvic region. Different acquisition and processing of data renders making comparisons difficult, whereby standards for future research are necessary.

[Possible changes in energy-minimizer mechanisms of locomotion due to chronic low back pain - a literature review]

One goal of the locomotion is to move the body in the space at the most economical way possible. However, little is known about the mechanical and energetic aspects of locomotion that are affected by low back pain. And in case of occurring some damage, little is known about how the mechanical and energetic characteristics of the locomotion are manifested in functional activities, especially with respect to the energy-minimizer mechanisms during locomotion. This study aimed: a) to describe the main energy-minimizer mechanisms of locomotion; b) to check if there are signs of damage on the mechanical and energetic characteristics of the locomotion due to chronic low back pain (CLBP) which may endanger the energy-minimizer mechanisms. This study is characterized as a narrative literature review. The main theory that explains the minimization of energy expenditure during the locomotion is the inverted pendulum mechanism, by which the energy-minimizer mechanism converts kinetic energy into potential energy of the center of mass and vice-versa during the step. This mechanism is strongly influenced by spatio-temporal gait (locomotion) parameters such as step length and preferred walking speed, which, in turn, may be severely altered in patients with chronic low back pain. However, much remains to be understood about the effects of chronic low back pain on the individual's ability to practice an economic locomotion, because functional impairment may compromise the mechanical and energetic characteristics of this type of gait, making it more costly. Thus, there are indications that such changes may compromise the functional energy-minimizer mechanisms.

iGAIT: an interactive accelerometer based gait analysis system

This paper presents a software program (iGAIT) developed in MATLAB, for the analysis of gait patterns extracted from accelerometer recordings. iGAIT provides a user-friendly graphical interface to display and analyse gait acceleration data recorded by an accelerometer attached to the lower back of subjects. The core function of iGAIT is gait feature extraction, which can be used to derive 31 features from acceleration data, including 6 spatio-temporal features, 7 regularity and symmetry features, and 18 spectral features. Features extracted are summarised and displayed on screen, as well as an option to be stored in text files for further review or analysis if required. Another unique feature of iGAIT is that it provides interactive functionality allowing users to manually adjust the analysis process according to their requirements. The system has been tested under Window XP, Vista and Window 7 using three different types of accelerometer data. It is designed for analysis of accelerometer data recorded with sample frequencies ranging from 5 Hz to 200 Hz.