Young individuals with a more ankle-steered proprioceptive control strategy may develop mild non-specific low back pain

Poor lumbar spine coordination in acute low back pain predicts persistent long-term pain and disability

PURPOSE

Sitting balance on an unstable surface requires coordinated out-of-phase lumbar spine and provides sufficient challenge to expose quality of spine control. We investigated whether the quality of spine coordination to maintain balance in acute low back pain (LBP) predicts recovery at 6 months.

METHODS

Participants in an acute LBP episode (n = 94) underwent assessment of sitting balance on an unstable surface. Seat, hip and spine (lower lumbar, lumbar, upper lumbar, thoracic) angular motion and force plate data were recorded. Coordination between the seat and hip/spine segments to maintain balance was quantified in the frequency domain to evaluate coordination (coherence) and relative timing (phase angle: in-phase [segments move together]; out-of-phase [segments move opposite]). Center of pressure (CoP) and upper thorax motion assessed overall balance performance. Hip and spine coordination with the seat were compared between those who did not recover (increased/unchanged pain/disability), partially recovered (reduced pain/disability) or recovered (no pain and disability) at 6 months.

RESULTS

In both planes, coherence between the seat and lower lumbar spine was lower (and in-phase-unhelpful for balance) at baseline in those who did not recover than those who recovered. Coherence between the seat and hip was higher in partially recovered in both planes, suggesting compensation by the hip. LBP groups had equal overall balance performance (CoP, upper thorax motion), but non-recovery groups used a less optimal strategy that might have consequences for long-term spine health.

CONCLUSION

These longitudinal data revealed that individuals with compromised contribution of the lumbar spine to the balance during unstable sitting during acute LBP are less likely to recover.

Lower Limb Proprioception in Low Back Pain and Its Relationship With Voluntary Postural Control

This study aimed to investigate whether patients with low back pain (LBP) had impaired lower limb proprioception and its association with somatosensory acuity. Thirty patients with LBP and 30 asymptomatic people volunteered, using Sway Discrimination Apparatus tests to assess somatosensory acuity during voluntary anteroposterior and mediolateral postural sway. Results showed significantly reduced somatosensory acuity in mediolateral sway in LBP patients (p = 0.005) with ankle, knee, and hip proprioception showing significantly impairment compared to asymptomatic controls (all p ≤ 0.012). Regression analysis showed that ankle and hip proprioception were significantly associated with somatosensory perception (0.001 ≤ p ≤ 0.026, 0.067 ≤ R2≤ 0.235). Overall, findings suggested a global deterioration of lower limb proprioception in LBP patients, with ankle and hip proprioception playing crucial role in somatosensory perception.

Lack of Proprioceptive Strategy Modulation Leads to At-Risk Biomechanics for Anterior Cruciate Ligament in Healthy Athletes

INTRODUCTION

Anterior cruciate ligament (ACL) injuries are frequent in handball, and altered sensory integration may contribute to increased injury risk. Recent evidence showed that proprioceptive postural control strategies differ among athletes. The aim of this study was to evaluate the relationship between proprioceptive strategy and biomechanics during side-cutting maneuvers.

METHODS

A total of 47 handball players performed anticipated and unanticipated cutting tasks. Their postural proprioceptive strategy was then characterized according to the perturbation of the center of pressure displacement generated by the muscle vibration on a firm and foam surface. Individuals able to reweight proprioception from ankle to lumbar signals according to the stability of the support were defined as flexible. Conversely, athletes maintaining an ankle-steered strategy on foam surface were characterized as rigid. Statistical parametric mapping analysis was used to compare pelvic and lower limb side-cutting kinematics, kinetics, and EMG activity from seven muscles 200 ms before and after initial contact (IC) using a two-way ANOVA (group-condition).

RESULTS

Twenty athletes (11 females and 9 males, 18.5 yr) were characterized as flexible and 20 athletes (12 females and 8 males, 18.9 yr) as rigid. No interaction between condition and proprioceptive profile was observed. More ipsilateral pelvic tilt before IC and lower vastus lateralis (VL) activity immediately after IC was observed during CUT ant . When comparing proprioceptive strategy, rigid individuals exhibited less preactivity of the semitendinosus ( P < 0.001) and higher VL activity ( P = 0.032). Conversely, rigid showed higher gluteus medius preactivity ( P < 0.05) and higher VL activity 100 ms after IC ( P < 0.001). Ankle was also more internally rotated before and during the stance phase ( P < 0.05) among rigid athletes.

CONCLUSIONS

Rigid handball players exhibited at-risk determinants for anterior cruciate ligament injuries during side-cutting maneuvers.

The association between pain-related psychological variables and postural control in low back pain: A systematic review and meta-analysis

BACKGROUND

Alterations in postural control have been found in individuals with low back pain (LBP), particularly during challenging postural tasks. Moreover, higher levels of negative pain-related psychological variables are associated with increased trunk muscle activity, reduced spinal movement, and worse maximal physical performance in individuals with LBP.

RESEARCH QUESTION

Are pain-related psychological variables associated with postural control during static bipedal standing tasks in individuals with LBP?

METHODS

A systematic review and meta-analysis were conducted. Pubmed, Web of Science, and PsycINFO were searched until March 2023. Studies were included if they evaluated postural control during static bipedal standing in individuals with LBP by measuring center of pressure (CoP) variables, and reported at least one pain-related psychological variable. Correlation coefficients between pain-related psychological variables and CoP variables were extracted. Study quality was assessed with the "Quality In Prognosis Studies" tool (QUIPS). Random-effect models were used to calculate pooled correlation coefficients for different postural tasks. Sub-analyses were performed for positional or dynamic CoP variables. Certainty of evidence was assessed with an adjusted "Grading of Recommendations, Assessment, Development, and Evaluations" tool (GRADE). The protocol was registered on PROSPERO (CRD42021241739).

RESULTS

Sixteen studies (n = 723 participants) were included. Pain-related fear (16 studies) and pain catastrophizing (three studies) were the only reported pain-related psychological variables. Both pain-related fear (-0.04 < pooled r < 0.14) and pain catastrophizing (0.28 < pooled r < 0.29) were weakly associated with CoP variables during different postural tasks. For all associations, the certainty of evidence was very low.

SIGNIFICANCE

Pain-related fear and pain catastrophizing are only weakly associated with postural control during static bipedal standing in individuals with LBP, regardless of postural task difficulty. Certainty of evidence is very low thus it is conceivable that future studies accounting for current study limitations might reveal different findings.

Sedentary lifestyle of university students is detrimental to the thoracic spine in men and to the lumbar spine in women

BACKGROUND

Sitting for long periods of time and lack of physical activity in young adults can cause postural deterioration leading to rapid onset of fatigue and increase the risk of back pain. We were interested in whether there are gender differences in spinal curvature among university students with a predominantly sedentary lifestyle.

METHODS

20 sedentary female (age 20 ± 0.73 years) and 39 sedentary male university students (age 20 ± 1.08 years) participated in this study. Their thoracic and lumbar curvatures were assessed while standing and sitting using a Spinal Mouse.

RESULTS

In standing, 80.0% of the females and 69.2% of the males had a neutral position of the thoracic spine (33.25° and 35.33°, respectively). However, more males, 30.8%, than females, 10.0%, had hyperkyphosis (54.27° and 47.0°, respectively). Hypokyphosis was found in 10.0% of the females (18.50°) and none in the males. Similarly, 90.0% of the females and 97.4% of the males had neutral position of the lumbar spine (-33.11° and -29.76°, respectively). Increased hyperlordosis was found in 10.0% of the females and 2.6% of the males (-41.0° and -50.0°, respectively). Hypolordosis was not detected in either females or males. In sitting, on the other hand, 70.0% of the females and only 33.3% of the males had a neutral position of the thoracic spine (30.20° and 30.62°, respectively). Increased hyperkyphosis was found in 46.2% of the males (59.76°) and none of the females. 30.0% of the females and 23.1% of the males had light hypokyphosis (47.50° and 46.67°, respectively). Similarly, 70.0% of the females and only 38.5% of the males had a neutral position of the lumbar spine (7.0° and 6.6°, respectively). 35.9% of the males and only 5.0% of the females had a light hypokyphosis (16.14° and 16.0°, respectively). Slightly increased hyperkyphosis was identified in 25.6% of the males and 25.0% of the females (23.9° and 22.5°, respectively).

CONCLUSION

There are significant gender differences in spinal curvature. While in the thoracic spine it was to the detriment of the males when both standing and sitting, in the lumbar spine it is related to the females only when standing. It is therefore necessary to eliminate these spinal deviations in young adults induced by prolonged sitting during university courses by appropriate recovery modalities.

The effect of chronic low back pain on postural control during quiet standing: A meta-analysis

Low back pain (LBP) has been associated with altered body sway during quiet standing, but the pattern of results is inconsistent. The purpose of this meta-analysis is to examine the effects of vision (eyes open, eyes closed) and changing the support surface (foam surface, firm surface) on postural sway during quiet standing in individuals with chronic LBP (cLBP). Five electronic databases were searched on March 27th, 2022. Of 2,856, 16 studies (n = 663) were included. Across all conditions, we found a positive and medium effect size (g = 0.77 [0.50, 1.04]) that represented greater body sway in individuals with cLBP. Subgroup analyses revealed medium effects during eyes open conditions (firm surface: g = 0.60 [0.33, 0.87]; foam surface: g = 0.68 [0.38, 0.97]), and large effects during eyes closed conditions (firm surface: g = 0.97 [0.60, 1.35]; foam surface: g = 0.89 [0.28, 1.51]). We quantified effects of self-reported pain and found a moderate effect during eyes closed plus firm surface conditions (Q = 3.28; p = 0.070). We conclude that cLBP is associated with increased postural sway, with largest effect sizes evident when vision is removed and when self-reported pain intensity is higher.

Amplitude of Electromyographic Activity of Trunk and Lower Extremity Muscles during Oscillatory Forces of Flexi-Bar on Stable and Unstable Surfaces in People with Nonspecific Low Back Pain

BACKGROUND

Recently, the oscillatory bar has been proposed as a new and effective rehabilitation tool in people with nonspecific low back pain (NSLBP), although its effects on muscular control in this population have not been well documented, especially in lower extremity muscles and different support surface conditions.

OBJECTIVE

This study aimed to evaluate and compare the effects of flexi-bar use on stable and unstable surfaces on electromyographic activity of trunk and lower extremity muscles in healthy persons and those with NSLBP.

MATERIAL AND METHODS

18 healthy men and 18 men with NSLBP participated in this cross-sectional study. The root mean square value of electromyographic activity was calculated in the trunk and lower extremity muscles during 4 different task conditions: quiet standing (QS) or flexi-bar use on a rigid or foam support surface. A repeated measures test was used for statistical analysis.

RESULTS

The results showed that the amplitude activity of almost all muscles was significantly greater during flexi-bar use than in the QS condition (P<0.05). The rectus femoris, tibialis anterior, and gastrocnemius demands were significantly greater on the foam than the rigid surface (P<0.05).

CONCLUSION

This study showed that oscillatory forces caused by flexi-bar use can increase muscle activation in multiple segments (hip and ankle in addition to trunk muscles) that are crucial for postural stability. Furthermore, the foam surface appeared to target the rectus femoris in addition to the ankle muscles. Using a flexi-bar may be helpful in NSLBP rehabilitation, and exercising on a foam surface may enhance additive hip muscle activity in people with NSLBP.

Ankle reaction times with tray usage following a slip perturbation between subjects with and without chronic low back pain

BACKGROUND

Abnormal stepping strategies have been associated with handheld tasks in subjects with chronic low back pain (LBP). However, the dominant ankle reactions of subjects with LBP remain unclear following a perturbation during handheld tasks.

RESEARCH QUESTION

Are there differences in the reaction times of the ankle muscles during handheld tasks between subjects with and without LBP following a treadmill-induced slip perturbation?

METHODS

Thirty-seven right limb dominant subjects with LBP and 37 subjects without LBP participated in the study. Each subject was introduced to a slip perturbation (1.37 m/sec velocity for 8.22 cm) with and without a handheld tray in random order. Subjects were allowed to recover by stepping forward for a 0.12 s duration while bilateral tibialis anterior (TA) and gastrocnemius (GA) muscle reaction times were measured by electromyography (EMG).

RESULTS

The EMG results indicated that the groups demonstrated significant interactions on the limb sides and muscles (F = 4.86, p = 0.03). The dominant TA reaction time was significantly faster in the LBP group (t = 2.14, p = 0.03) while holding a tray.

SIGNIFICANCE

The LBP group demonstrated faster reaction times on the dominant TA muscles during perturbations. Clinicians need to consider dominance-dependent compensatory ankle dorsiflexion strategies in LBP patients to help enhance dynamic balance and control.

The sensorimotor theory of pathological pain revisited

Harris (1999) proposed that pain can arise in the absence of tissue damage because changes in the cortical representation of the painful body part lead to incongruences between motor intention and sensory feedback. This idea, subsequently termed the sensorimotor theory of pain, has formed the basis for novel treatments for pathological pain. Here we review the evidence that people with pathological pain have changes to processes contributing to sensorimotor function: motor function, sensory feedback, cognitive representations of the body and its surrounding space, multisensory processing, and sensorimotor integration. Changes to sensorimotor processing are most evident in the form of motor deficits, sensory changes, and body representations distortions, and for Complex Regional Pain Syndrome (CRPS), fibromyalgia, and low back pain. Many sensorimotor changes are related to cortical processing, pain, and other clinical characteristics. However, there is very limited evidence that changes in sensorimotor processing actually lead to pain. We therefore propose that the theory is more appropriate for understanding why pain persists rather than how it arises.

Cross-cultural adaptation and validation of the simplified chinese version of the fremantle back awareness questionnaire in patients with low back Pain

PURPOSE

The Fremantle back awareness questionnaire (FreBAQ) was recently developed as simple and quick tool to assess back-specific body perception in Low back pain (LBP) patients. The aim of the present study was to translate and cross-culturally adapt the Fremantle back awareness questionnaire (FreBAQ) into a Simplified Chinese version (FreBAQ-C), and evaluate the reliability and validity of the FreBAQ-C in patients with non-specific Chronic Low back pain (CLBP).

METHODS

The FreBAQ was translated into Chinese according to established methods. Internal consistency was assessed according to Cronbach's alpha. Test-retest reliability was estimated by Intraclass correlation coefficient (ICC). Construct validity was evaluated by correlations between the FreBAQ-C and Visual analogue scale (VAS), Roland-Morris disability questionnaire (RDQ), Pain catastrophizing scale (PCS), Tampa scale for kinesiophobia (TSK) as well as Hospital anxiety and depression scale (HADS).

RESULTS

A total of 105 participants (38 males and 67 females) were included in this study with the mean age of 54.1 ± 15.6 years, mean duration of LBP of 6.8 ± 4.6 years. The FreBAQ-C total scores were well distributed, with no floor or ceiling effects. Internal consistency was excellent (Cronbach's alpha = 0.833). ICC of test-retest reliability was good (0.897, 95% confidence interval: 0.852-0.929). The limits of agreement (LOA) ranged from - 5.8 to 6.3. The Standard error of measurement (SEM) and Minimum detectable change (MDC) were 2.16 and 5.99. Construct validity was confirmed by significant correlation of The FreBAQ-C and VAS during motion (r = 0.274, p = 0.005) and rest (r = 0.243, p = 0.012), RDQ (r = 0.377, p < 0.001), PCS (r = 0.439, p < 0.001), and TSK(r = 0.311, p = 0.001).

CONCLUSIONS

The FreBAQ-C was demonstrated to have acceptable reliability and validity for patients with non-specific CLBP in Chinese mainland. It will allow evaluating body preception of the back in the Chinese population with CLBP.

Abnormal Anatomical and Functional Connectivity of the Thalamo-sensorimotor Circuit in Chronic Low Back Pain: Resting-state Functional Magnetic Resonance Imaging and Diffusion Tensor Imaging Study

Thalamocortical dysfunction is thought to underlie the pathophysiology of chronic pain revealed by electroencephalographic studies. The thalamus serves as a primary relay center to transmit sensory information and motor impulses via dense connections with the somatosensory and motor cortex. In this study, diffusion tensor imaging (DTI) (probabilistic tractography) and resting-state functional magnetic resonance imaging (functional connectivity) were used to characterize the anatomical and functional integrity of the thalamo-sensorimotor pathway in chronic low back pain (cLBP). Fifty-four patients with cLBP and 54 healthy controls were included. The results suggested significantly increased anatomical connectivity of the left thalamo-motor pathway characterized by probabilistic tractography in patients with cLBP. Moreover, there was significantly altered resting-state functional connectivity (rsFC) of bilateral thalamo-motor/somatosensory pathways in patients with cLBP as compared to healthy controls. We also detected a significant correlation between pain intensity during the MRI scan and rsFC of the right thalamo-somatosensory pathway in cLBP. Our findings highlight the involvement of the thalamo-sensorimotor circuit in the pathophysiology of cLBP.

Validity and reliability of video analysis to evaluate ankle proprioceptive reintegration during postural control

BACKGROUND

The ability to dynamically reintegrate proprioceptive signals after they have been perturbated is impaired in certain pathologies. Evaluation of proprioceptive reintegration is useful for clinical practice but currently requires expensive laboratory tools. We developed a simple method, accessible to clinicians.

RESEARCH QUESTION

Is two-dimensional (2D) video analysis of earlobe displacement a valid and reliable tool for the evaluation of ankle proprioceptive reintegration following muscle vibration?

METHODS

Thirty-eight healthy individuals underwent vibration of the triceps surae while standing on a force plate (FP). Anterior (sagittal plane) earlobe displacement ('overshoot') was recorded at vibration cessation using 2D video analysis and rated by 3 blind examiners. Correlation analysis was performed between earlobe and center of pressure displacement (dCoP, recorded with the FP) to determine validity. Intra and interrater reliability were determined by calculation of the intraclass correlation coefficient (ICC), change in the mean (CiM), standard error of measurement (SEM) and the minimal detectable change (MDC).

RESULTS AND SIGNIFICANCE

Strong positive correlations (r = 0.82-0.94, p < .001) were found between video and FP data. Intra- and interrater reliability were excellent (ICC from 0.99 to 1.00 and from 0.90 to 0.97 respectively). For intrarater analysis, the CiM was 0.01 cm, SEM were 0.27 cm (95% CI: 0.23-0.33) and 3.43% (95% CI: 2.92-4.20) and the MDC was 0.74 cm. For interrater reliability, the CiM ranged from - 0.81-0.55 cm, the SEM from 0.61 to 1.12 cm and the MDC from 1.69 to 3.10 cm. 2D video analysis of anterior (sagittal) earlobe displacement is therefore a valid and reliable method to assess postural recovery following muscle vibration. This simple method could be used by clinicians to evaluate the ability of the central nervous system to reintegrate proprioceptive signals from the ankle. Further studies are needed to assess its validity in individuals with proprioceptive impairment.

Proprioceptive postural control strategies differ among non-injured athletes

Postural control during complex tasks requires adequate sensory integration and somaesthetic reweighting: suboptimal postural strategies can lead to injury. We assessed the ability of healthy athletes to reweight somaesthetic signals during postural perturbations on different surfaces. Thirty-five young (16 ± 1 years), healthy, elite handball players participated in this cross-sectional study. Proprioceptive reweighting was evaluated via vibration of the triceps surae and lumbar muscles on firm and foam surfaces. Postural variables and the electromyographic activity of the gluteus medius (GM), semitendinosus (ST) and fibularis longus (FL) were recorded during the PRE (10 s), VIBRATION (20 s) and POST (20 s) periods. Ankle proprioception was predominantly used on the firm compared to foam support. However, two opposing behaviours were observed: a "rigid" strategy in which reliance on ankle proprioception increased on the foam, and a "plastic" strategy that involved a proximal shift of proprioceptive reliance (p < 0.001). The plastic strategy was associated with a more effective recovery of balance after vibration cessation (p < 0.05). ST activation was higher during POST in the rigid strategy and did not return to the PRE level (p < 0.05) whereas it did in the plastic strategy. Proprioceptive strategies for postural control are highly variable and future studies should evaluate their contribution to injury.

Impairment of Proprioception in Young Adult Nonradicular Patients with Lumbar Derangement Syndrome

Maintaining body balance is a complex function based on the information deriving from the vestibular, visual, and proprioceptive systems. The aim of the study was to evaluate quiet single stance stability in young adults with lumbar derangement syndrome (LDS) and in the control group of the healthy subjects. The second aim of this study was to determine whether pain intensity, degree of disability, and the level of physical activity can influence postural control in patients with LDS. It is important to underline that selecting a homogeneous group of LBP patients using, for example, mechanical diagnosis and therapy method and Quebec Task Force Classification, can result in an increased sensitivity of the study. The study included 126 subjects: 70 patients with LDS (37 women, 33 men) and the control group 56 healthy volunteers (36 women, 20 men). In case of multiple group comparisons for variables with normal distribution, ANOVA post hoc test was used or, as the nonparametric equivalent, Kruskal-Wallis test. In all these calculations, the statistical significance level was set to p < 0.05. The stability index eyes open for the study group was 88.34 and for the control group 89.86. There was no significant difference in the level of postural control between the study and control groups (p > 0.05). The level of stability index eyes closed (SI EC) for the study group was 71.44 and for the control group 77.1. SI EC results showed significant differences in proprioceptive control during single leg stance between the study and control groups (p < 0.05). The level of pain intensity, the degree of disability, and physical activity level did not influence postural control in the study group with LDS. In summary, patients with LDS showed significantly worse proprioceptive control.

The association of reactive balance control and spinal curvature under lumbar muscle fatigue

Background

Although low back fatigue is an important intervening factor for physical functioning among sedentary people, little is known about its possible significance in relation to the spinal posture and compensatory postural responses to unpredictable stimuli. This study investigates the effect of lumbar muscle fatigue on spinal curvature and reactive balance control in response to externally induced perturbations.

Methods

A group of 38 young sedentary individuals underwent a perturbation-based balance test by applying a 2 kg load release. Sagittal spinal curvature and pelvic tilt was measured in both a normal and Matthiass standing posture both with and without a hand-held 2 kg load, and before and after the Sørensen fatigue test.

Results

Both the peak anterior and peak posterior center of pressure (CoP) displacements and the corresponding time to peak anterior and peak posterior CoP displacements significantly increased after the Sørensen fatigue test (all at p < 0.001). A lumbar muscle fatigue led to a decrease of the lumbar lordosis in the Matthiass posture while holding a 2 kg load in front of the body when compared to pre-fatigue conditions both without a load (p = 0.011, d = 0.35) and with a 2 kg load (p = 0.000, d = 0.51). Also the sacral inclination in the Matthiass posture with a 2 kg additional load significantly decreased under fatigue when compared to all postures in pre-fatigue conditions (p = 0.01, d = 0.48). Contrary to pre-fatigue conditions, variables of the perturbation-based balance test were closely associated with those of lumbar curvature while standing in the Matthiass posture with a 2 kg additional load after the Sørensen fatigue test (r values in range from −0.520 to −0.631, all at p < 0.05).

Conclusion

These findings indicate that lumbar muscle fatigue causes changes in the lumbar spinal curvature and this is functionally relevant in explaining the impaired ability to maintain balance after externally induced perturbations. This emphasizes the importance for assessing both spinal posture and reactive balance control under fatigue in order to reveal their interrelations in young sedentary adults and predict any significant deterioration in later years.

Understanding the impact of lumbar disc degeneration and chronic low back pain: A cross-sectional electromyographic analysis of postural strategy during predicted and unpredicted postural perturbations

People with chronic low back pain (LBP) exhibit changes in postural control. Stereotypical muscle activations resulting from external perturbations include anticipatory (APAs) and compensatory (CPAs) postural adjustments. The aim and objective of this study was to determine differences in postural control strategies (peak amplitude, APAs and CPAs) between symptomatic and asymptomatic adults with and without Lumbar Disc Degeneration (LDD) using surface electromyography during forward postural perturbation. Ninety-seven subjects participated in the study (mean age 50 years (SD 12)). 3T MRI was used to acquire T2 weighted images (L1-S1). LDD was determined using Pfirrmann grading. A bespoke translational platform was designed to deliver horizontal perturbations in sagittal and frontal planes. Electromyographic activity was analysed bilaterally from 8 trunk and lower limb muscles during four established APA and CPA epochs. A Kruskal-Wallis H test with Bonferroni correction for multiple comparisons was conducted. Four groups were identified: no LDD no pain (n = 19), LDD no pain (n = 38), LDD pain (n = 35) and no LDD pain (n = 5). There were no significant differences in age or gender between groups. The most significant difference between groups was observed during forward perturbation. In the APA and CPA phases of predictable forward perturbation there were significant differences ankle strategy between groups (p = 0.007–0.008); lateral gastrocnemius and tibialis anterior activity was higher in the LDD pain than the LDD no pain group. There were no significant differences in the unpredictable condition (p>0.05). These findings were different from the remaining groups, where significant differences in hip strategy were observed during both perturbation conditions (p = 0.004–0.006). Symptomatic LDD patients exhibit different electromyographic strategies to asymptomatic LDD controls. Future LBP electromyographic research should benefit from considering assessment of both lower limbs in addition to the spine. This approach could prevent underestimation of postural control deficits and guide targeted rehabilitation.

Test-Retest Reliability of an iPhone® Inclinometer Application to Assess the Lumbar Joint Repositioning Error in Non-Specific Chronic Low Back Pain

Background: The joint position sense (JPS) has been used as an indirect marker of proprioception in subjects with non-specific chronic low back pain (NSCLBP), showing impairment in previous studies. It seems necessary to devise reliable tests to measure proprioceptive deficits in subjects with NSLBP. The objective of this study was to analyse the test-retest reliability and smallest real difference (SRD) of lumbar proprioception through the JPS indicator in a sample of patients with NSCLBP. Methods: Fifty participants with NSCLBP performed three repetitions of 30° lumbar flexion while standing and sitting using the iPhone^® inclinometer application to measure the lumbar joint repositioning error. For the reliability analysis, we performed an intra-session test-retest. Results: The total sample ICC values were excellent for standing (0.96) and sitting (0.93) 30° lumbar flexion. In addition, our results showed that, for the total sample, an SRD < 12% can be considered as a true change in proprioception concerning this procedure. On the other hand, men have better reliability than women in both standing and sitting positions. Additionally, the sitting position has better reliability than the standing position. The standard error of measurement (SEM) percentage was 4.2 for standing and 3.8 for sitting. The SRD percentage was 11.6 for standing and 10.4 for sitting. Conclusions: The iPhone^® inclinometer seems reliable for assessing proprioceptive ability through the lumbar joint repositioning error in subjects with NSCLBP in both standing (ICC = 0.96) and sitting (ICC = 0.93) positions. This technological device showed a lower measurement error for sitting position (SRD < 12%).

Differences in Proprioception Between Young and Middle-Aged Adults With and Without Chronic Low Back Pain

Introduction: While young adults with chronic low back pain (CLBP) exhibit impaired lumbar proprioception, it remains unclear if the same phenomenon is observed in middle-aged adults with CLBP. Objectives: This study aimed to investigate whether young or middle-aged adults with CLBP displayed different proprioception ability as compared to age-matched asymptomatic controls. Methods: Sixty-four young adults with [median age:34 [interquartile range (IQR): 29-37] years] and without [median age:29 (IQR; 23-34) years] CLBP, and 87 middle-aged adults with [median age:53 (IQR: 49-58) years] and without [median age: 54 (IQR: 45-64) years] CLBP underwent postural sway tests on a force-plate with (unstable surface) and without a foam (stable surface), while bilateral L5/S1 multifidi and triceps-surae were vibrated separately. An individual's proprioception reweighting ability was estimated by relative proprioceptive reweighting (RPW). Higher RPW values indicate less reliance on lumbar multifidus proprioceptive signals for balance. Participants also underwent lumbar repositioning tests in sitting to determine repositioning errors in reproducing target lumbar flexion/extension positions. Results: Young adults with CLBP demonstrated significantly higher median RPW values than age-matched asymptomatic controls for maintaining standing balance [stable surface: CLBP: 0.9 (IQR: 0.7-0.9), asymptomatic: 0.7 (IQR: 0.6-0.8), p < 0.05; unstable surface: CLBP: 0.6 (IQR: 0.4-0.8), asymptomatic: 0.5 (IQR: 0.3-0.7), p < 0.05]. No significant differences in repositioning error were noted between young or middle-aged adults with and without CLBP (p > 0.05). RPW values were unrelated to repositioning errors in all groups (p > 0.05). Conclusion: Young adults with CLBP, and middle-aged adults with and without CLBP had inferior proprioceptive reweighting capability. This finding may indicate potential age-related deterioration in central and peripheral processing of lumbar proprioceptive signals. Future studies should use advanced imaging and/or electroencephalogram to determine mechanisms underlying changes in proprioceptive reweighting in middle-aged adults.

Linear and Non-linear Dynamic Methods Toward Investigating Proprioception Impairment in Non-specific Low Back Pain Patients

Central nervous system (CNS) uses vision, vestibular, and somatosensory information to maintain body stability. Research has shown that there is more lumbar proprioception error among low back pain (LBP) individuals as compared to healthy people. In this study, two groups of 20 healthy people and 20 non-specific low back pain (NSLBP) participants took part in this investigation. This investigation focused on somatosensory sensors and in order to alter proprioception, a vibrator (frequency of 70 Hz, amplitude of 0.5 mm) was placed on the soleus muscle area of each leg and two vibrators were placed bilaterally across the lower back muscles. Individuals, whose vision was occluded, were placed on two surfaces (foam and rigid) on force plate, and trunk angles were recorded simultaneously. Tests were performed in eight separate trials; the independent variables were vibration (four levels) and surface (two levels) for within subjects and two groups (healthy and LBP) for between subjects (4 × 2 × 2). MANOVA and multi-factor ANOVA tests were done. Linear parameters for center of pressure (COP) [deviation of amplitude, deviation of velocity, phase plane portrait (PPP), and overall mean velocity] and non-linear parameters for COP and trunk angle [recurrence quantification analysis (RQA) and Lyapunov exponents] were chosen as dependent variables. Results indicated that NSLBP individuals relied more on ankle proprioception for postural stability. Similarly, RQA parameters for the COP on both sides and for the trunk sagittal angle indicated more repeated patterns of movement among the LBP cohort. Analysis of short and long Lyapunov exponents showed that people with LBP caused no use of all joints in their bodies (non-flexible), are less stable than healthy subjects.

Changes in the Organization of the Secondary Somatosensory Cortex While Processing Lumbar Proprioception and the Relationship With Sensorimotor Control in Low Back Pain

OBJECTIVES

Patients with nonspecific low back pain (NSLBP) rely more on the ankle compared with the lower back proprioception while standing, perform sit-to-stand-to-sit (STSTS) movements slower, and exhibit perceptual impairments at the lower back. However, no studies investigated whether these sensorimotor impairments relate to a reorganization of the primary and secondary somatosensory cortices (S1 and S2) and primary motor cortex (M1) during proprioceptive processing.

MATERIALS AND METHODS

Proprioceptive stimuli were applied at the lower back and ankle muscles during functional magnetic resonance imaging in 15 patients with NSLBP and 13 controls. The location of the activation peaks during the processing of proprioception within S1, S2, and M1 were determined and compared between groups. Proprioceptive use during postural control was evaluated, the duration to perform 5 STSTS movements was recorded, and participants completed the Fremantle Back Awareness Questionnaire (FreBAQ) to assess back-specific body perception.

RESULTS

The activation peak during the processing of lower back proprioception in the right S2 was shifted laterally in the NSLBP group compared with the healthy group (P=0.007). Moreover, patients with NSLSP performed STSTS movements slower (P=0.018), and reported more perceptual impairments at the lower back (P<0.001). Finally, a significant correlation between a more lateral location of the activation peak during back proprioceptive processing and a more disturbed body perception was found across the total group (ρ=0.42, P=0.025).

CONCLUSIONS

The results suggest that patients with NSLBP show a reorganization of the higher-order processing of lower back proprioception, which could negatively affect spinal control and body perception.

Non-specific chronic low back pain and physical activity: A comparison of postural control and hip muscle isometric strength: A cross-sectional study

Most research on sedentary lifestyle has focused on pain and disability, while neuromuscular outcomes (postural control and strength) have received less attention. The objective of the study was to determine whether low level of physical activity is negatively associated with measures of lower body muscular strength and postural control in individuals with and without non-specific chronic low back pain (NSCLBP).Twenty-four subjects with NSCLBP (28.8 ± 5.9 years) and 24 age, gender, and body mass index matched healthy controls participated in the study. Subjects were sub-classified into 4 subgroups based on their physical activity level: Non-active NSCLBP; Active NSCLBP; Non-active healthy control; and Active healthy control. Each subgroup consisted of 12 subjects. Peak force of hip muscles strength was assessed using a handheld dynamometer. Postural control was assessed using computerized posturography and the Y Balance Test.There was no significant group by physical activity interaction for strength and static and dynamic postural control, except for static control during left single leg stance with eyes closed (P = .029). However, there was a significant difference in strength and postural control by physical activity (P < .05). Postural control and peak force of hip muscles strength were significantly associated with physical activity (r ranged from 0.50 to 0.66, P < .001 and r ranged from 0.40 to 0.59, P < .05, respectively).Postural control and hip strength were independently related to physical activity behavior. A sedentary behavior may be an important risk factor for impaired postural control and hip muscles strength, and that physical fitness is vital to neuromuscular outcomes.

Low Back Pain: The Potential Contribution of Supraspinal Motor Control and Proprioception

Motor control, which relies on constant communication between motor and sensory systems, is crucial for spine posture, stability and movement. Adaptions of motor control occur in low back pain (LBP) while different motor adaption strategies exist across individuals, probably to reduce LBP and risk of injury. However, in some individuals with LBP, adapted motor control strategies might have long-term consequences, such as increased spinal loading that has been linked with degeneration of intervertebral discs and other tissues, potentially maintaining recurrent or chronic LBP. Factors contributing to motor control adaptations in LBP have been extensively studied on the motor output side, but less attention has been paid to changes in sensory input, specifically proprioception. Furthermore, motor cortex reorganization has been linked with chronic and recurrent LBP, but underlying factors are poorly understood. Here, we review current research on behavioral and neural effects of motor control adaptions in LBP. We conclude that back pain-induced disrupted or reduced proprioceptive signaling likely plays a pivotal role in driving long-term changes in the top-down control of the motor system via motor and sensory cortical reorganization. In the outlook of this review, we explore whether motor control adaptations are also important for other (musculoskeletal) pain conditions.

Reduction of postural sway in athletes with chronic low back pain through eight weeks of inspiratory muscle training: A randomized controlled trial

BACKGROUND

Postural control and respiratory function are mechanically and neuromuscularly dependent on each other. The present study was conducted to determine the effects of inspiratory muscle training on postural sway in athletes with chronic low back pain.

METHODS

Twenty-four patients were randomly selected as the experimental group and 23 patients as the control group. The experimental group underwent the inspiratory muscle training protocol for eight weeks, seven days per week and twice daily. The postural sway variables were recorded using a plantar pressure measurement device. The postural sway variables were recorded when performing overhead and single leg squat. Patient's perceived low back pain was assessed using Visual Analog Scale. Disability was assessed using the Athletes Disability Index questionnaire. Patient depression/anxiety was assessed using the Patient Health Questionnaire-4.

FINDINGS

The results of the two-way ANOVA in the overhead squat test showed that postural sway indices significantly decreased in the experimental group after 8-weeks intervention compared to the pre-test values. The results of the two-way ANOVA in single leg squat test showed significant differences between the pre- and post-test in the experimental group in the postural sway indices except for the factor of standard deviation Y, also compared to the pre-test value, pain was significantly decreased in the experimental group.

INTERPRETATION

The 8-weeks inspiratory muscle training decreased postural sway in athletes with chronic low back pain when performing the overhead and single leg squat. In addition, the pain index decreased after 8-weeks of inspiratory muscle training.

Effect of respiratory muscle training session on ankle muscle activity in athletes with chronic low back pain performing overhead squats: a randomized controlled trial

AIM

The current study was conducted to evaluate the effect of a respiratory muscle training session on ankle muscle activity in athletes with chronic low back pain performing overhead squats.

METHODS

The current double-blind, randomized, controlled trial was conducted on 24 patients randomly selected as the training group and 23 patients as the control group. The training group received the respiratory muscle training protocol. The electromyography activity of the tibialis anterior, peroneus longus, gastrocnemius medialis and gastrocnemius lateralis muscles of the dominant leg was recorded in the participants.

RESULTS

The findings showed that a session of respiratory muscle training reduced the activities of some ankle joint muscles when performing overhead squats, including tibialis anterior in the static and dynamic overhead squat tests and peroneus longus in the ascending phase. In the dynamic test, the angle to reach peak activity changed in tibialis anterior in the descending phase and also in tibialis anterior and peroneus longus in the ascending phase.

CONCLUSION

Effects of respiratory muscle training prevented excessive ankle joint muscle activity through stimulating local muscles while performing overhead squats, which had indicated an improved postural control and multisectional proprioception to maintain postural stability and stimulated the local muscles of the core area.

Risk factors for episodes of back pain in emerging adults. A systematic review

BACKGROUND AND OBJECTIVE

The transition from adolescence to adulthood is a sensitive period in life for health outcomes, including back pain. The objective was to synthesize evidence on risk factors for new episodes of back pain in emerging adults (18-29 years).

METHODS

The protocol was registered in PROSPERO (CRD42016046635). We searched Medline; EMBASE; AMED and other databases up to September 2018 for prospective cohort studies that estimated the association between risk factor(s) and self-reported back pain. Risk factors could be measured before or during the age range 18-29 years, and back pain could be measured during or after this age range, with at least 12 months between assessments. Risk factors assessed in ≥3 studies were summarized. Risk of bias was assessed using a 6-item checklist.

RESULTS

Forty-nine studies were included with more than 150 different risk factors studied. Nine studies had low risk of bias, 26 had moderate and 14 had high risk of bias. Age, sex, height, body mass index (BMI), smoking, physical activity level, a history of back pain, job satisfaction and structural imaging findings were investigated in three or more studies. History of back pain was the only risk factor consistently associated with back pain after adjustment (nine studies).

CONCLUSION

There is moderate quality evidence that a history of back pain is a risk factor for back pain. There are inconsistent associations for age, sex, height, BMI, smoking and activity level. No associations were found between job satisfaction and structural imaging findings and back pain.

SIGNIFICANCE

Emerging adulthood is a transitional period of life with changes in life style, potentially influencing future musculoskeletal health. This systematic review included 49 articles evaluating more than 150 potential risk factors for back pain, one of the most prevalent musculoskeletal disorders. No consistent results were found for life style factors such as physical activity level or BMI, both highlighted as important risk factors in previous literature. Importantly, a previous episode of back pain was a consistent risk factor for a new episode of back pain across several studies, and further investigation of risk factors for the first back pain episode is needed.

Factors Associated With the Ultrasound Characteristics of the Lumbar Multifidus: A Systematic Review

OBJECTIVE

The first aim of this review was to investigate the association between age, sex, height, weight, physical activity level, posture, lumbar level and body side, and structural characteristics (cross-sectional area [CSA], thickness, linear dimensions, and echo intensity) of the lumbar multifidus (LM) measured by ultrasound. Second, differences between healthy individuals and patients with chronic low back pain (CLBP) were investigated. TYPE: Systematic review.

LITERATURE SURVEY

PubMed, Embase and Web of Science were searched until September 2018.

METHODOLOGY

Studies were included if (a) full text was available in English, Dutch, or French; (b) participants were older than 18 years of age and were asymptomatic or had nonspecific CLBP; and (c) the relation between structural characteristics of the LM, measured by ultrasound, and at least one of the above-mentioned factors was described, and/or a comparison between a CLBP and control group was made. Data were extracted independently by two reviewers. Quality of studies was assessed using an adapted version of the Downs and Black checklist.

SYNTHESIS

Twenty-seven studies were included. Thickness and CSA of the LM do not correlate with age. Males have a larger LM size than females. Thickness and CSA of left and right LM are highly correlated in healthy subjects. More significant side-to-side differences are present in subjects with CLBP than in those without. Muscle size increases from proximal to caudal lumbar levels. The presence of CLBP is associated with muscle size and function.

CONCLUSIONS

The association between the factors age, sex, height, weight, physical activity level, posture, lumbar level, body side, and presence of CLBP, and the ultrasound characteristics of the LM is discussed. These factors should be taken into account in future research on structural muscle characteristics, or when correlating with functional behavior or investigating the effect of a targeted intervention.

LEVEL OF EVIDENCE

I.

Neuroplasticity of Sensorimotor Control in Low Back Pain

Low back pain (LBP) is an important medical and socioeconomic problem. Impaired sensorimotor control has been suggested to be a likely mechanism underlying development and/or maintenance of pain. Although early work focused on the structural and functional abnormalities within the musculoskeletal system, in the past 20 years there has been an increasing realization that patients with LBP might also have extensive neuroplastic changes within the central nervous system. These include changes related to both the structure (eg, gray matter changes) and function (eg, organization of the sensory and motor cortices) of the nervous system as related to processing of pain and nociception and to motor and somatosensory systems. Moreover, clinical interventions increasingly aim to drive neuroplasticity with treatments to improve pain and sensorimotor function. This commentary provides a contemporary overview of neuroplasticity of the pain/nociceptive and sensorimotor systems in LBP. This paper addresses (1) defining neuroplasticity in relation to control of the spine and LBP, (2) structural and functional nervous system changes as they relate to nonspecific LBP and sensorimotor function, and (3) related clinical implications. Individuals with recurrent and persistent LBP differ from those without LBP in several markers of the nervous system's function and structure. Neuroplastic changes may be addressed by top-down cognitive-based interventions and bottom-up physical interventions. An integrated clinical approach that combines contemporary pain neuroscience education, cognition-targeted sensorimotor control, and physical or function-based treatments may lead to better outcomes in patients with recurrent and persistent LBP. This approach will need to consider variation among individuals, as no single finding/mechanism is present in all individuals, and no single treatment that targets neuroplastic changes in the sensorimotor system is likely to be effective for all patients with LBP. J Orthop Sports Phys Ther 2019;49(6):402-414. doi:10.2519/jospt.2019.8489.

Differences in brain processing of proprioception related to postural control in patients with recurrent non-specific low back pain and healthy controls

Patients with non-specific low back pain (NSLBP) show an impaired postural control during standing and a slower performance of sit-to-stand-to-sit (STSTS) movements. Research suggests that these impairments could be due to an altered use of ankle compared to back proprioception. However, the neural correlates of these postural control impairments in NSLBP remain unclear. Therefore, we investigated brain activity during ankle and back proprioceptive processing by applying local muscle vibration during functional magnetic resonance imaging in 20 patients with NSLBP and 20 controls. Correlations between brain activity during proprioceptive processing and (Airaksinen et al., 2006) proprioceptive use during postural control, evaluated by using muscle vibration tasks during standing, and (Altmann et al., 2007) STSTS performance were examined across and between groups. Moreover, fear of movement was assessed. Results revealed that the NSLBP group performed worse on the STSTS task, and reported more fear compared to healthy controls. Unexpectedly, no group differences in proprioceptive use during postural control were found. However, the relationship between brain activity during proprioceptive processing and behavioral indices of proprioceptive use differed significantly between NSLBP and healthy control groups. Activity in the right amygdala during ankle proprioceptive processing correlated with an impaired proprioceptive use in the patients with NSLBP, but not in healthy controls. Moreover, while activity in the left superior parietal lobule, a sensory processing region, during back proprioceptive processing correlated with a better use of proprioception in the NSLBP group, it was associated with a less optimal use of proprioception in the control group. These findings suggest that functional brain changes during proprioceptive processing in patients with NSLBP may contribute to their postural control impairments.

Non-specific Low Back Pain and Postural Control During Quiet Standing-A Systematic Review

Background: There is a great number of people who require treatment for non-specific low back pain (LBP) yet the causes are still unclear. One proposed cause for LBP is impaired motor control and more specific an impaired postural control.

Objective: The purpose of this review is to provide an overview of postural control parameter differences in persons with and without non-specific LBP during quite standing.

Methods: A literature search in five databases from January 2000 until January 2018 was performed and was followed by a hand search. Twenty-one articles comparing healthy adults and adults with non-specific LBP in neuromuscular and/or biomechanical parameters during bipedal stance without external perturbation in lab studies were examined. Data extraction and quality assessment were independently performed by two persons. Factors such as study population, outcome measures, and results were extracted from the articles and included in this analysis.

Results: The results show that persons with and without non-specific LBP differed in several parameters of postural control such as the center of pressure displacement, postural control strategy, and muscle activation patterns.

Conclusion: While the results show that none of the parameters alone lead to significant effects, the combination of neuromuscular and biomechanical parameters was associated with the impairment of postural control in individuals with LBP during standing. Since the studies included in this analysis used different methodological procedures a replication of these studies with standardized procedures is imperative for the acquisition of more conclusive evidence on the differences in postural control during standing.

Association Between Sensorimotor Impairments and Functional Brain Changes in Patients With Low Back Pain: A Critical Review

Low back pain (LBP) coincides with sensorimotor impairments, for example, reduced lumbosacral tactile and proprioceptive acuity and postural control deficits. Recent functional magnetic resonance imaging studies suggest that sensorimotor impairments in LBP may be associated with brain changes. However, no consensus exists regarding the relationship between functional brain changes and sensorimotor behavior in LBP. Therefore, this review critically discusses the available functional magnetic resonance imaging studies on brain activation related to nonnociceptive somatosensory stimulation and motor performance in individuals with LBP. Four electronic databases were searched, yielding nine relevant studies. Patients with LBP showed reduced sensorimotor-related brain activation and a reorganized lumbar spine representation in higher-order (multi)sensory processing and motor regions, including primary and secondary somatosensory cortices, supplementary motor area, and superior temporal gyrus. These results may support behavioral findings of sensorimotor impairments in LBP. In addition, patients with LBP displayed widespread increased sensorimotor-evoked brain activation in regions often associated with abnormal pain processing. Overactivation in these regions could indicate an overresponsiveness to sensory inputs that signal potential harm to the spine, thereby inducing overgeneralized protective responses. Hence, functional brain changes could contribute to the development and recurrence of LBP. However, future studies investigating the causality between sensorimotor-related brain function and LBP are imperative.

Do different sitting postures affect spinal biomechanics of asymptomatic individuals?

BACKGROUND

Static sitting is thought to be related to low back pain. Of various common seated postures, slouched sitting has been suggested to cause viscoelastic creep. This, in turn, may compromise trunk muscle activity and proprioception, and heightening the risk of low back pain. To date, no research has evaluated immediate and short-term effects of brief exposures to different sitting postures on spinal biomechanics and trunk proprioception.

RESEARCH QUESTION

This study aimed to compare the impacts of 20 min of static slouched, upright and supported sitting with a backrest on trunk range of motion, muscle activity, and proprioception immediately after and 30 min after the sitting tasks.

METHODS

Thirty-seven adults were randomly assigned to the three sitting posture groups. Surface electromyography of six trunk muscles during maximum voluntary contractions were measured at baseline for normalization. Pain intensity, lumbar range of motion, and proprioceptive postural control strategy were assessed at baseline, 20 min (immediately post-test) and at 50 min (recovery). Trunk muscle activity during sitting was continuously monitored by surface electromyography.

RESULTS

While the slouched sitting group demonstrated the lowest bilateral obliquus internus/transversus abdominis activity as compared to other sitting postures (F = 4.87, p < 0.05), no significant temporal changes in pain intensity, lumbar range of motion nor proprioceptive strategy were noted in any of the groups.

SIGNIFICANCE

Sitting for 20 min of duration appears to have no adverse effects on symptoms or spinal biomechanics regardless of the posture adopted. Future research should determine if there is a point at which does slouched sitting cause significant changes in pain/spinal biomechanics in people both with and without low back pain.

Anticipatory and compensatory postural adjustments in people with low back pain: a systematic review and meta-analysis

BACKGROUND CONTEXT

Despite altered anticipatory (APAs) and compensatory postural adjustments (CPAs) being hypothesized to contribute to the onset and persistence of low back pain (LBP), results from studies comparing people with and without LBP are conflicting.

PURPOSE

This systematic review aimed to determine whether APAs or CPAs are altered in the presence of acute and chronic LBP.

STUDY DESIGN

A systematic review of studies was carried out.

PATIENT SAMPLE

No patient sample was required.

OUTCOME MEASURES

Between group standardized mean differences and 95% confidence intervals for APAs ad CPAs METHODS: A comprehensive search was conducted for articles comparing people with LBP (acute or chronic) to healthy controls for the onset or amplitude of muscle activity, center of pressure (COP), or kinematic responses to expected or unexpected perturbations. Two independent reviewers extracted data and assessed the methodological quality of relevant studies. Differences between people with and without LBP were calculated as standardized mean differences, and included in a meta-analysis if outcomes were homogeneous. Otherwise, a narrative synthesis was conducted.

RESULTS

Twenty-seven studies were included, of which the majority examined muscle onsets in response to expected and unexpected perturbations. Only two studies compared people with and without acute LBP, and results for these studies were conflicting. The results show delayed muscle onsets in response to expected and unexpected perturbations for people with chronic LBP when compared with healthy controls. No conclusive evidence for differences between people with and without chronic LBP for COP or kinematic responses.

CONCLUSIONS

There is currently no convincing evidence of differences between people with and without acute LBP for APAs or CPAs. Conversely, delayed muscle onsets in people with chronic LBP suggest APAs and CPAs are altered in this population. However, the functional relevance of these delayed muscle onsets (eg, COP and kinematics) is unknown.

Dynamic multi-segmental postural control in patients with chronic non-specific low back pain compared to pain-free controls: A cross-sectional study

Reduced postural control is thought to contribute to the development and persistence of chronic non-specific low back pain (CNLBP). It is therefore frequently assessed in affected patients and commonly reported as the average amount of postural sway while standing upright under a variety of sensory conditions. These averaged linear outcomes, such as mean centre of pressure (CP) displacement or mean CP surface areas, may not reflect the true postural status. Adding nonlinear outcomes and multi-segmental kinematic analysis has been reported to better reflect the complexity of postural control and may detect subtler postural differences. In this cross-sectional study, a combination of linear and nonlinear postural parameters were assessed in patients with CNLBP (n = 24, 24-75 years, 9 females) and compared to symptom-free controls (CG, n = 34, 22-67 years, 11 females). Primary outcome was postural control measured by variance of joint configurations (uncontrolled manifold index, UI), confidence ellipse surface areas (CEA) and approximate entropy (ApEn) of CP dispersion during the response phase of a perturbed postural control task on a swaying platform. Secondary outcomes were segment excursions and clinical outcome correlates for pain and function. Non-parametric tests for group comparison with P-adjustment for multiple comparisons were conducted. Principal component analysis was applied to identify patterns of segmental contribution in both groups. CNLBP and CG performed similarly with respect to the primary outcomes. Comparison of joint kinematics revealed significant differences of hip (P < .001) and neck (P < .025) angular excursion, representing medium to large group effects (r′s = .36 − .51). Significant (P′s < .05), but moderate correlations of ApEn (r = -.42) and UI (r = -.46) with the health-related outcomes were observed. These findings lend further support to the notion that averaged linear outcomes do not suffice to describe subtle postural differences in CNLBP patients with low to moderate pain status.

Postural sensorimotor training versus sham exercise in physiotherapy of patients with chronic non-specific low back pain: An exploratory randomised controlled trial

Sensorimotor training (SMT) is popularly applied as exercise in rehabilitation settings, particularly for musculoskeletal pain. With insufficient evidence on its effect on pain and function, this exploratory randomised controlled trial investigated the potential effects of SMT in rehabilitation of chronic non-specific low back pain. Two arms received 9x30 minutes physiotherapy with added interventions: The experimental arm received 15 minutes of postural SMT while the comparator arm performed 15 minutes of added sub-effective low-intensity training. A treatment blinded tester assessed outcomes at baseline 2-4 days prior to intervention, pre- and post-intervention, and at 4-week follow-up. Main outcomes were pain and functional status assessed with a 0-100mm visual analogue scale and the Oswestry Disability Questionnaire. Additionally, postural control was analysed using a video-based tracking system and a pressure plate during perturbed stance. Robust, nonparametric multivariate hypothesis testing was performed. 22 patients (11 females, aged 32 to 75 years) with mild to moderate chronic pain and functional limitations were included for analysis (11 per arm). At post-intervention, average values of primary outcomes improved slightly, but not to a clinically relevant or statistically significant extent. At 4-week follow-up, there was a significant improvement by 12 percentage points (pp) on the functional status questionnaire in the SMT-group (95% confidence intervall (CI) = 5.3pp to 17.7pp, p < 0.001) but not in the control group (4 pp improvement, CI = 11.8pp to 19.2pp). However, group-by-time interaction effects for functional status (Q = 3.3, 19 p = 0.07) and pain (Q = 0.84, p = 0.51) were non-significant. Secondary kinematic outcomes did not change over time in either of the groups. Despite significant improvement of functional status after SMT, overall findings of this exploratory study suggest that SMT provides no added benefit for pain reduction or functional improvement in patients with moderate chronic non-specific low back pain.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02304120 and related study protocol, DOI: 10.1186/1471-2474-15-382.

A systematic review on quantifiable physical risk factors for non-specific adolescent low back pain

PURPOSE

The aim of this systematic review was to analyze the results of studies on quantifiable physical risk factors (beyond questionnaires) for adolescent low back pain (LBP).

METHODS

A systematic search was conducted in Medline (OvidSP), Premedline (PubMed), EMBASE, Cochrane, CINAHL, PEDro and PsycINFO. Cross-sectional, prospective and retrospective English language studies on LBP in adolescents aged 10 to 18 years were included.

RESULTS

Twenty-two mostly cross-sectional studies were included. Trunk muscle endurance in particular seemed to be associated with adolescent LBP, while a possible association of trunk muscle strength and spinal flexibility was less clear.

CONCLUSION

There is a need for prospective studies on quantifiable physical risk factors for adolescent LBP. Such studies should focus on back and abdominal muscle endurance, possibly in combination with sagittal spinal mobility, sagittal postural alignment and neurodynamics as possible modifiable risk factors for LBP.

The development of the Dutch version of the Fremantle Back Awareness Questionnaire

BACKGROUND

Disturbed body perception may play a role in the aetiology of chronic low back pain (LBP). The Fremantle Back Awareness Questionnaire (FreBAQ) is currently the only self-report questionnaire to assess back-specific body perception in individuals with LBP.

OBJECTIVES

To perform a cross-cultural adaptation of the FreBAQ into Dutch.

DESIGN

Psychometric study.

METHODS

A Dutch version of the FreBAQ was generated through forward-backward translation, and was completed by 73 patients with LBP and 73 controls to assess discriminant validity. Structural validity was assessed by principal component analysis. Internal consistency was assessed by the Cronbach's alpha coefficient. Construct validity was assessed by examining the relationship with clinical measures (Numerical Rating Scale pain, Oswestry Disability Index (ODI), Tampa Scale for Kinesiophobia). Test-retest reliability was assessed in a subgroup (n = 48 with LBP and 48 controls) using intraclass correlation coefficients (ICC), standard error of measurement (SEM) and minimal detectable change (MDC 95%) RESULTS: The Dutch FreBAQ showed one component with eigenvalue >2. Cronbach's alpha values were respectively 0.82 and 0.73 for the LBP and control group. ICC values were respectively 0.69 and 0.70 for the LBP and control group. In the LBP group, the SEM was 3.9 and the MDC (95%) was 10.8. The LBP group (ODI 22 ± 21%) scored significantly higher on the Dutch FreBAQ than the control group (ODI 0%) (11 ± 7 vs. 3 ± 9, p < 0.001). Within the LBP group, higher Dutch FreBAQ scores correlated significantly with higher ODI scores (rho = 0.30, p = 0.010), although not with pain (rho = 0.10, p = 0.419) or kinesiophobia (r = 0.14, p = 0.226).

CONCLUSIONS

The Dutch version of the FreBAQ can be considered as unidimensional and showed adequate internal consistency, sufficient test-retest reliability and adequate discriminant and construct validity in individuals with and without LBP. It can improve our understanding on back-specific perception in the Dutch-speaking population with LBP.

Immediate effects of Pilates based therapeutic exercise on postural control of young individuals with non-specific low back pain: A randomized controlled trial

OBJECTIVES

Low back pain affects the person's ability to keep balance, especially in challenging conditions. The purpose of this study was to determine the immediate effects of Pilates exercises on postural sway and dynamic balance of young individuals with non-specific low back pain.

DESIGN

Controlled laboratory design.

SETTINGS AND MAIN OUTCOME MEASURES

Forty-six participants with non-specific low back pain were randomized to a Pilates (n=23, 10 males; age: 21.8±3.2years) and a control group (n=23, 9 males; age: 22.8±3.6years). Postural sway was assessed with a force platform and dynamic balance with the Star Excursion Balance Test, before and after the intervention or rest period. To assess postural sway, participants stood still on an unstable surface set on the force plate for 90s, with eyes closed.

INTERVENTION

The intervention lasted 20min and consisted on four Pilates exercises: single leg stretch (level 1), pelvic press (level 1), swimming (level 1) and kneeling opposite arm and leg reach.

RESULTS

At baseline, no differences were found between groups. The Pilates group improved in all the postural sway values (area of CoP: 11.5±3.4 to 9.7±2.7cm², p=0.002 and CoP velocity: 2.8±0.6 to 2.3±0.5cm/s, p<0.001) and in the Star Excursion Balance Test. Control group only improved in CoP velocity, however, this improvement was significantly inferior compared to the Pilates group.

CONCLUSIONS

Pilates exercises immediately improved postural sway and dynamic balance in young adults with non-specific low back pain.

The presence of respiratory disorders in individuals with low back pain: A systematic review

BACKGROUND

Inspiratory muscles, such as the diaphragm, play a key role in both respiration and spinal control. Therefore, diaphragm dysfunctions are often related to low back pain (LBP). However, few is known on the association between the presence of LBP and the presence of respiratory disorders (RD).

OBJECTIVES

To perform a systematic review on the relation between RD and LBP.

STUDY DESIGN

Systematic review.

METHODS

Two reviewers searched on PubMed/MEDLINE for studies concerning LBP and RD, from 1950 up to January 2016. The search string consisted of the following key words: low back pain, dyspnea, respiratory problems, lung diseases, comorbidity, pulmonary disease, chronic obstructive, smoking, asthma, allergy, sinusitis, respiratory tract infection and hyperventilation. The aim was to evaluate a potential correlation, co-occurrence or causality between RD and LBP.

RESULTS

A total of 16 articles were included. A significant correlation between the presence of LBP and the presence of RD such as dyspnea, asthma, different forms of allergy, and respiratory infections was found. No correlation was found between Chronic Obstructive Pulmonary Disease (COPD) and LBP, and no articles were found on the correlation between hyperventilation and LBP.

CONCLUSIONS

This is the first study providing an overview of the literature on the relation between LBP and RD. Immunological, biomechanical, psychosocial and socio-economic factors might explain this correlation. Smoking is likely to contribute. Future studies must reveal the causative relationship.

LEVEL OF EVIDENCE

Therapy, level 2a.

Proprioceptive use and sit-to-stand-to-sit after lumbar microdiscectomy: The effect of surgical approach and early physiotherapy

BACKGROUND

Individuals with non-specific low back pain show decreased reliance on lumbosacral proprioceptive signals and slower sit-to-stand-to-sit performance. However, little is known in patients after lumbar microdiscectomy.

METHODS

Patients were randomly assigned into transmuscular (n=12) or paramedian lumbar surgery (n=13). After surgery, the same patients were randomly assigned into individualized active physiotherapy starting 2 weeks after surgery (n=12) or usual care (n=13). Primary outcomes were center of pressure displacement during ankle and back muscles vibration (to evaluate proprioceptive use), and the duration of five sit-to-stand-to-sit movements, evaluated at 2 (baseline), 8 and 24 weeks after surgery.

FINDINGS

Two weeks after surgery, all patients showed smaller responses to back compared to ankle muscles vibration (P<0.05). Patients that underwent a transmuscular surgical procedure and patients that received physiotherapy switched to larger responses to back muscles vibration at 24 weeks, compared to 2 weeks after surgery (P<0.005), although not seen in the paramedian group and usual care group (P>0.05). Already 8 weeks after surgery, the physiotherapy group needed significantly less time to perform five sit-to-stand-to-sit movements compared to the usual care group (P<0.05).

INTERPRETATION

Shortly after lumbar microdiscectomy, patients favor reliance on ankle proprioceptive signals over lumbosacral proprioceptive reliance to maintain posture, which resembles the behavior of patients with non-specific low back pain. However, early active physiotherapy after lumbar microdiscectomy facilitated higher reliance on lumbosacral proprioceptive signals and early improvement of sit-to-stand-to-sit performance. Transmuscular lumbar surgery favoured recovery of lumbosacral proprioception 6 months after surgery.

CLINICAL TRIAL NUMBER

NCT01505595.