Linking Pain and Motor Control: Conceptualization of Movement Deficits in Patients With Painful Conditions

Individuals with chronic low back pain show impaired adaptations of lumbar extensor muscle reflex amplitude during unexpected perturbations

PURPOSE

This study investigated the adaptability of trunk muscle responses to a series of unexpected external perturbations in patients with chronic low back pain (LBP).

METHODS

Thirty-seven adult participants, including 19 without LBP (control group) and 18 with chronic LBP, were submitted to 15 repetitions of trunk perturbations applied in a posterior-to-anterior direction, inducing trunk flexion. High-density surface electromyography (HDsEMG) was used to analyze lumbar muscle reflex amplitude. A two-way repeated measures ANOVA (2 × 2) was conducted to compare group differences and the effect of trial repetition over time (first five trials vs. last five trials of perturbations).

RESULTS

Significant interaction effects were found on both sides (Left: p = 0.038; Right: p = 0.007). Post hoc comparisons revealed a decrease in response amplitude only in the control group between the first and last five perturbations, with reductions of 5.0% on the left side (p = 0.026, Bonferroni corrected) and 5.7% on the right side (p = 0.030, Bonferroni corrected). In contrast, individuals with chronic LBP showed no significant adaptation through repetition in the reflex response amplitude of the lumbar extensor muscles (post hoc both sides: p > 0.05).

CONCLUSION

Individuals with chronic LBP fail to adapt reflex amplitudes to repeated perturbations, possibly due to impaired proprioception, reduced motor variability and neuroplastic changes observed in individuals with chronic LBP. These changes might limit their ability to optimize responses to repeated perturbations, potentially compromising spinal stability and increasing functional cost.

Quantifying Impairments in the Subacute Phase of Whiplash Associated Disorders-A Cross-Sectional Study

Whiplash-Associated Disorders (WADs) often result from traffic accidents, leading to persistent symptoms, including neck pain, disability, dizziness, and central sensitization (CS). A key concern is cervical range of motion (cROM) impairment and sensorimotor dysfunction, which contribute to prolonged disability. This study assessed functional performance in individuals with subacute (>1, <3 months) WADs (n = 122) compared to healthy controls (n = 45). Clinical measures included cROM, movement control (Butterfly test), and position sense (Head-Neck Relocation Test, HNRT). Patient-reported outcomes included neck disability, pain intensity, central sensitization, and dizziness. Mixed and linear models evaluated group differences and the influence of demographic and symptom-related factors. WAD patients had significantly reduced cROM and impaired movement control (p < 0.001). Neck disability (p < 0.001) and pain intensity (p = 0.015) affected cROM within the WAD group. Interaction effects revealed greater amplitude accuracy (AA) impairments at greater difficulty levels (p = 0.043), while time on target (TOT) differences decreased (p < 0.001). Dizziness was associated with increased undershoot (p < 0.001), while pain negatively impacted both AA (p = 0.003) and TOT (p = 0.037). Position sense did not differentiate WAD patients from controls. Findings suggest task-dependent sensorimotor deficits, highlighting the need for multimodal assessment. Early CS screening may optimize rehabilitation and prevent chronic disability.

Motor Control Exercises and Their Design for Short-Term Pain Modulation in Patients with Pelvic Girdle Pain: A Narrative Review

Background: Pelvic girdle pain (PGP) is described in the literature as a subgroup of low back pain (LBP), characterized by pain localized between the posterior iliac crest and the gluteal fold, particularly near the sacroiliac joints. This condition can manifest in different forms non-specific PGP, occurring during pregnancy or postpartum (pregnancy-related PGP), which represents the most prevalent form and non-pregnancy-related PGP, resulting from mechanical alterations caused by trauma or microtrauma. Specific PGP, associated with identifiable causes such as fractures, infections, or arthritis. Over the years, research has focused on identifying the most effective approaches for managing this condition and addressing its associated biopsychosocial impairments. The aim of this narrative review is to determine the types of motor control exercises (MCEs) used to reduce short-term pain in patients with PGP and to assess whether these exercises are designed in accordance with the principles of motor control (MC) theories. Methods: A narrative review was conducted through searches in various medical and rehabilitation databases, including MEDLINE (via PubMed), PEDro, Scopus, and Web of Science. The inclusion criteria of the review encompassed case studies, case reports, editorials, original research articles, randomized controlled trials (RCTs), and systematic reviews (SRs). Results: Six articles met the eligibility criteria, comprising two SRs and four RCTs, all of which were included in the qualitative analysis. Among these, two studies examine MCEs for non-pregnancy-related PGP, while all the other studies focus on pregnancy-related PGP. The exercises described focused on lumbar-pelvic stabilization or deep spinal muscle activation. Among the six included studies, five did not report statistically significant changes in pain outcomes, while only one study demonstrated a statistically significant improvement. Conclusions: The analysis highlighted that the exercises currently employed are generally unspecific and not systematically structured according to the principles outlined in MC theories. The available evidence, combined with the incorrect design of these exercises, does not allow for definitive conclusions regarding the efficacy of MCEs in reducing short-term pain in patients with both pregnancy-related and non-pregnancy-related PGP.

Cervical proprioception, postural control, and pain: unraveling the interconnected challenges in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disease that impairs proprioception and postural control, increasing fall risk and reducing quality of life. This study evaluated cervical proprioception and postural control in RA patients versus asymptomatic individuals, examined their relationship within the RA group, and investigated pain's mediating effects on this association.

METHODS

In this cross-sectional study, 82 RA patients and 82 age- and gender-matched controls were recruited. Cervical proprioception was assessed using the Cervical Joint Position Error Test (CJPET), while postural control was evaluated via a stabilometric force platform measuring center-of-pressure length (L CoP), 95% confidence ellipse sway area (ESA 95%), and center-of-pressure velocity (V CoP). Statistical analyses included t-tests, correlation, regression, and mediation analysis to evaluate relationships and the role of pain in cervical proprioception and postural control.

RESULTS

RA patients demonstrated significantly impaired cervical proprioception and postural control compared to controls (p < 0.001). Significant differences were observed in cervical flexion, extension, rotation, and postural control measures (L CoP, ESA 95%, and V CoP; p < 0.001 for all parameters). Pearson's correlations revealed significant relationships between cervical proprioception and postural control parameters. Regression analysis indicated that cervical proprioception, particularly when combined with age and disease duration, significantly predicted postural control. Mediation analysis revealed that pain significantly mediated the relationship between cervical proprioception and postural control.

CONCLUSIONS

Cervical proprioception is significantly reduced in RA patients and strongly influences postural control. Pain serves as a key mediator in this relationship, emphasizing the need for effective pain management to enhance proprioceptive and postural functions in RA patients. These findings suggest that the insights from this cross-sectional study could inform future interventions aimed at enhancing proprioception and managing pain, which may significantly benefit RA patients' postural stability and overall quality of life.

An examination of ankle joint position sense, postural control and associated neuromuscular deficits in patients with plantar fasciitis: a cross-sectional analysis with advanced biomechanical and psychosocial correlates

BACKGROUND

Ankle joint position sense (AJPS) accuracy and postural control are crucial for maintaining balance and stability, particularly in individuals with plantar fasciitis who may experience proprioceptive and functional impairments. Understanding how psychosocial factors, such as pain catastrophizing, and biomechanical measures, like muscle strength and gait parameters related to proprioception and postural control, can inform more effective treatment approaches. This study aimed to (1) examine the relationship between AJPS accuracy and biomechanical factors-including postural stability, lower limb muscle strength, and gait parameters-in individuals with plantar fasciitis d (2) analyze the impact of psychosocial factors, including pain catastrophizing, physical activity level, and quality of life, on AJPS accuracy and postural control in this population.

METHODS

A total of 126 participants (63 with plantar fasciitis and 63 controls) were recruited. AJPS was assessed using a digital inclinometer across four movement directions (plantarflexion, dorsiflexion, inversion, eversion). Postural stability metrics (antero-posterior and medio-lateral sway) were measured using computerized posturography, while muscle strength in plantar flexors, dorsiflexors, inverters, and evertors was assessed with a hand-held dynamometer. Gait parameters (step length, cadence, stance time) were captured via 3D motion capture. Pain catastrophizing, physical activity, and quality of life were evaluated using validated questionnaires (PCS, IPAQ, FHSQ).

RESULTS

Significant differences were observed in AJPS accuracy between groups, with plantar fasciitis patients showing higher AJPS error in plantarflexion (mean difference = 1.22°, p < 0.001) and dorsiflexion (mean difference = 1.31°, p < 0.001). Pain catastrophizing was a significant predictor of AJPS in plantarflexion (β = -0.05, p = 0.001). Postural stability was negatively correlated with AJPS accuracy, particularly in mediolateral sway (r = -0.32, p = 0.037), while physical activity and quality of life had minimal effects.

CONCLUSION

This study highlights the impact of pain catastrophizing on proprioceptive deficits in plantar fasciitis, emphasizing the importance of addressing psychological as well as biomechanical factors in treatment. Integrating cognitive-behavioral strategies may enhance proprioceptive accuracy and stability outcomes in this population.

Influence of cervical muscle strength and pain severity on functional balance and limits of stability in elderly individuals with chronic nonspecific neck pain: a cross-sectional study

BACKGROUND

Chronic nonspecific neck pain (CNSNP) is a common musculoskeletal disorder, particularly in the elderly, leading to reduced cervical muscle strength, impaired functional balance, and decreased postural stability. This study investigated the correlation between cervical muscle strength, functional balance, and limits of stability (LOS) in elderly individuals with CNSNP. Additionally, it assessed the moderating effect of pain severity on the relationship between cervical muscle strength and these balance outcomes.

METHODS

A prospective study included a total of 186 participants, including 93 with CNSNP and 93 asymptomatic individuals, were recruited. Cervical flexor and extensor muscle strength were assessed using an ergoFET hand-held dynamometer. Functional balance was measured using the Berg Balance Scale (BBS) and Timed Up and Go (TUG) test, while LOS were evaluated using the Iso-Free machine.

RESULTS

Individuals with CNSNP exhibited significantly lower cervical flexor strength (32.45 ± 5.67 N vs. 40.75 ± 5.20 N, p < 0.001) and extensor strength (28.30 ± 6.05 N vs. 36.90 ± 5.90 N, p < 0.001) compared to asymptomatic individuals. Functional balance was also poorer in the CNSNP group, with lower BBS scores (47.85 ± 4.20 vs. 53.65 ± 3.85, p < 0.001) and slower TUG times (11.30 ± 2.05 s vs. 8.45 ± 1.80 s, p < 0.001). Cervical muscle strength showed moderate to strong positive correlations with LOS (r = 0.56 to 0.62, p < 0.001) and BBS (r = 0.48 to 0.53, p < 0.001). Pain severity significantly moderated the relationship between cervical muscle strength and functional balance (β = 0.20, p = 0.045) as well as LOS (β = 0.22, p = 0.038), suggesting that higher pain levels diminish the positive effects of muscle strength on balance.

CONCLUSION

Cervical muscle strength plays a crucial role in maintaining functional balance and postural stability in elderly individuals with CNSNP. Pain severity moderates the relationship between cervical muscle strength and balance outcomes, emphasizing the importance of integrating muscle strengthening and pain management in rehabilitation programs for elderly individuals with CNSNP to optimize postural control and minimize fall risk.

Impact of lumbar delayed-onset muscle soreness on postural stability in standing postures

BACKGROUND

Similar impact on proprioception has been observed in participants with lumbar delayed-onset muscle soreness (DOMS) and chronic low back pain (LBP), raising questions about the relevance of lumbar DOMS as a suitable pain model for LBP when assessing back pain-related postural stability changes.

RESEARCH QUESTION

Does lumbar DOMS impact postural stability?

METHODS

Twenty healthy adults participated in this experimental study and underwent a posturographic examination before and 24 to 36 h after a protocol designed to induce lumbar DOMS. Posturographic examination was assessed during quiet standing on both feet with eyes opened (EO), with eyes closed (EC), and on one-leg (OL) standing with eyes opened. Postural stability was assessed through center of pressure (COP) parameters (COP area, velocity, root mean square, mean power frequency) which were compared using repeated measure ANOVA. Moreover, pain, soreness and pressure pain threshold (PPT) on specific muscles were assessed.

RESULTS

There was a significant main effect of the postural condition on all COP variables investigated. More specifically, each COP variable reached a significantly higher value in the OL stance condition than in both EO and EC bipedal conditions (all with p < 0.001). In addition, the COP velocity and the mean power frequency along the anteroposterior direction both reached a significantly higher value in EC than in EO (p < 0.001). In contrast, there was no significant main effect of the DOMS nor significant DOMS X postural condition interaction on any of the COP variables. There was a significant decrease in the PPT value for both the left and right erector spinae muscles, as well as the left biceps femoris.

SIGNIFICANCE

Lumbar DOMS had no impact on postural stability, which contrasts findings in participants with clinical LBP. Although DOMS induces similar trunk sensorimotor adaptations to clinical LBP, it does not appear to trigger similar postural stability adaptations.

Kinesiophobia, limits of stability, and functional balance assessment in geriatric patients with chronic low back pain and osteoporosis: a comprehensive study

Background

The significance of studying Kinesiophobia, Limits of Stability (LOS), and functional balance in geriatric patients with CLBP and osteoporosis lies in their profound impact on rehabilitation outcomes and fall risk, ultimately affecting patients' quality of life. This study aimed to examine LOS and functional balance in the geriatric population concurrently experiencing Chronic Low Back Pain (CLBP) and osteoporosis, in comparison to age-matched healthy controls; to assess the correlations between Kinesiophobia, LOS, and functional balance assessments; and to evaluate the mediating influence of Kinesiophobia on the association between LOS and functional balance tests.

Methods

This cross-sectional study included a total of 86 participants in each group. Kinesiophobia was assessed using the Tampa Scale of Kinesiophobia (TSK). LOS variables were evaluated with a computerized Iso-free platform in eight different directions. Functional balance was measured using the Timed Up and Go (TUG) test and the Berg Balance Scale (BBS).

Results

Patients with CLBP and osteoporosis showed significantly lower LOS percentages (45.78 ± 6.92) and impaired Functional Balance, reflected in a TUG Score (10.45 ± 2.23), compared to asymptomatic controls (LOS: 76.95 ± 8.21; TUG: 8.73 ± 1.90). Kinesiophobia showed a significant moderate negative correlation with LOS, indicated by r = -0.362 (p < 0.01). Additionally, Kinesiophobia was found to correlate with functional balance tests. Specifically, there was a moderate positive correlation with the TUG Score (r = 0.322, p < 0.01), indicating that higher Kinesiophobia is associated with slower TUG performance. Conversely, a stronger moderate negative correlation was observed with the Berg Balance Scale (BBS) Score (r = -0.436, p < 0.001), suggesting that increased Kinesiophobia is associated with lower BBS scores, indicating poorer balance performance. Mediation analysis revealed that Kinesiophobia significantly influences LOS and Functional Balance. For LOS and the TUG score, Kinesiophobia showed a direct effect (B = 0.24), an indirect effect (B = 0.09), and a total effect (B = 0.13). Similarly, for LOS and the BBS score, the direct effect of Kinesiophobia was B = 0.38, with an indirect effect of B = 0.10 and a total effect of B = 0.20.

Conclusion

This study underscores the substantial impact of Kinesiophobia on both stability and functional balance in individuals coping with CLBP and osteoporosis. The findings emphasize the clinical relevance of addressing Kinesiophobia as a potential target for interventions aimed at improving LOS and functional balance in this specific patient population.

Role of Immersive Virtual Reality in Motor Behaviour Decision-Making in Chronic Pain Patients

Primary chronic pain is a major contributor to disability worldwide, with an estimated prevalence of 20-33% of the world's population. The high socio-economic impact of musculoskeletal pain justifies seeking an appropriate therapeutic strategy. Immersive virtual reality (VR) has been proposed as a first-line intervention for chronic musculoskeletal pain. However, the growing literature has not been accompanied by substantial progress in understanding how VR exerts its impact on the pain experience and what neurophysiological mechanisms might be involved in the clinical effectiveness of virtual reality interventions in chronic pain patients. The aim of this review is: (i) to establish the state of the art on the effects of VR on patients with chronic pain; (ii) to identify neuroplastic changes associated with chronic pain that may be targeted by VR intervention; and (iii) to propose a hypothesis on how immersive virtual reality could modify motor behavioral decision-making through an interactive experience in patients with chronic pain.

Task-specific fear rather than general kinesiophobia assessment is associated with kinematic differences in chronic low back pain during lumbar flexion: a preliminary investigation

Introduction

Kinematic data obtained during a movement task by individuals with chronic low back pain seem to be related to pain-related fear. General kinesiophobia assessments, such as Tampa Scale for Kinesiophobia, are often used to assess pain-related fear. However, these questionnaires could suffer from a lack of sensitivity and do not measure the fear of specific movements.

Objectives

The purpose of this study was to investigate whether the task-specific assessment of pain-related fear exhibits a closer association with trunk kinematics during lumbar flexion compared with the general kinesiophobia in individuals with chronic low back pain.

Methods

We assessed pain-related factors, task-specific fear, and Tampa Scale for Kinesiophobia-11 scores of 51 company employees. The lumbar angle during a lumbar flexion task was recorded by 2 wireless Axivity Ax3 accelerometers attached to the subject's spinous process (L3) and sacral spine (S2). Only task-specific fear was evaluated after the lumbar flexion task. We calculated the maximum lumbar flexion angle (°) and the peak angular velocity of lumbar flexion/return from flexion (°/s2). We conducted a hierarchical multiple linear regression analysis to determine variance explained in lumbar flexion task performance by task-specific fear after controlling for demographic, pain, and general kinesiophobia.

Results

The results showed that task-specific fear was associated with the peak angular velocity of lumbar return from flexion (R 2 adj. = 0.36, P < 0.01) and lumbar flexion (R 2 adj. = 0.3, P = 0.01).

Discussion

Our results suggest that clinicians should consider the potential added value of task-specific fear assessment over the sole use of conventional kinesiophobia assessment.