Differences in the organization of the primary motor cortex in people with and without low back pain and associations with motor control and sensory tests.

Differences in organization of the primary motor cortex and altered trunk motor control (sensing, processing and motor output) have been reported in people with low back pain (LBP). Little is known to what extent these differences are related. We investigated differences in 1) organization of the primary motor cortex and 2) motor and sensory tests between people with and without LBP, and 3) investigated associations between the organization of the primary motor cortex and motor and sensory tests. We conducted a case-control study in people with (N=25) and without (N=25) LBP. The organization of the primary motor cortex (Center of Gravity (CoG) and Area of the cortical representation of trunk muscles) was assessed using neuronavigated transcranial magnetic stimulation, based on individual MRIs. Sensory tests (quantitative sensory testing, graphaesthesia, two-point discrimination threshold) and a motor test (spiral-tracking test) were assessed. Participants with LBP had a more lateral and lower location of the CoG and a higher temporal summation of pain. For all participants combined, better vibration test scores were associated with a more anterior, lateral, and lower CoG and a better two-point discrimination threshold was associated with a lower CoG. A small subset of variables showed significance. Although this aligns with the concept of altered organization of the primary motor cortex in LBP, there is no strong evidence of the association between altered organization of the primary motor cortex and motor and sensory test performance in LBP. Focusing on subgroup analyses regarding pain duration can be a topic for future research.

Does having an external focus in immersive virtual reality increase range of motion in people with neck pain?

BACKGROUND: When instructing exercises to improve Range of Motion (ROM), clinicians often create an internal focus of attention, while motor performance may improve more when using an external focus. OBJECTIVES: Using Virtual Reality (VR), we investigated the effect of tasks with an internal and external focus on maximal ROM in people with neck pain and explored whether this effect was associated with fear of movement. METHOD: In this cross-over experimental design study, the cervical ROM of 54 participants was measured while performing a target-seeking exercise in a VR-environment (external focus task) and during three maximal rotation and flexion-extension movements with the VR-headset on, without signal (internal focus task). The main statistical analysis included two dependent T-tests. Pearson correlation coefficients were calculated to investigate whether the differences in ROM in both conditions were correlated to fear of movement. RESULTS: Maximal neck rotation was larger in the external focus condition than in the internal focus condition (mean difference: 26.4°, 95% CI [20.6, 32.3]; p < 0.001, d = 1.24). However, there was a difference favouring the internal focus condition for flexion-extension (mean difference: 8.2°, 95% CI [-14.9, -1.5]; p = 0.018, d = 0.33). The variability in ROM was not explained by variability in fear of movement (for all correlations p ≥ 0.197). CONCLUSION: An external focus resulted in a larger range of rotation, but our flexion-extension findings suggest that the task has to be specific to elicit such an effect. Further research, using a task that sufficiently elicits movement in all directions, is needed to determine the value of an external focus during exercise.

Mild untreated hypercholesterolaemia affects mechanical properties of the Achilles tendon but not gastrocnemius muscle.

Tendon xanthoma and altered mechanical properties have been demonstrated in people with familial hypercholesterolaemia. However, it is unclear whether mild, untreated hypercholesterolaemia alters musculotendinous mechanical properties and muscle architecture. We conducted a case-control study of adults aged 50 years and over, without lower limb injury or history of statin medication. Based on fasting low-density lipoprotein (LDL) cholesterol levels, 6 participants had borderline high LDL (>3.33 mmol/L) and 6 had optimal LDL cholesterol (<2.56 mmol/L). Using shear wave elastography, shear wave velocity (SWV) of the Achilles tendon and gastrocnemius medialis muscle (a proxy for stiffness), along with muscle fascicle length and pennation angle were measured under four passive tensile loads (0, 0.5, 1.0, 1.5 kg) applied via a pulley system. Differences between groups were found for tendon SWV but not muscle SWV, fascicle length or pennation angle. Participants with hypercholesterolaemia showed greater SWV (mean difference, 95 % CI: 2.4 m/s, 0.9 to 4.0, P = 0.024) compared to the control group across all loads. These findings suggest that adults with mild hypercholesterolaemia have increased tendon stiffness under low passive loads, while muscle was not affected. Future research is needed to confirm findings in a larger cohort and explore the impact of hypercholesterolaemia on tendon fatigue injury and tendinopathy.

Pain exacerbation following physical activity in adults with diabetic neuropathy: Ecological momentary assessment of foot symptoms.

BACKGROUND AND OBJECTIVES: People with diabetic peripheral neuropathy (DPN) report fluctuating foot symptoms. This study used ecological momentary assessment to: (1) compare foot symptoms between days, time points and periods with/without preceding physical activity or pain medication; and (2) determine relationships between symptoms and endogenous pain modulation. METHOD: Ten low-active Australian adults with probable DPN underwent temporal summation of pain (TSP) and conditioned pain modulation (CPM) then completed mobile phone surveys five times daily for seven days, where they recorded the intensity of six foot symptoms and whether they performed physical activity or consumed pain medication in the preceding three hours.  RESULTS: All foot symptoms except numbness were greater in periods following physical activity, whereas periods following pain medication showed greater shooting pain. TSP showed very large correlations with sensitivity to touch, burning pain, shooting pain and prickling/tingling.  DISCUSSION: General practitioners should be aware that physical activity might exacerbate symptoms of DPN when encouraging their patients to be active.

Illness perceptions in people with chronic and disabling non-specific neck pain seeking primary healthcare: a qualitative study.

BACKGROUND: Illness perceptions can affect the way people with musculoskeletal pain emotionally and behaviorally cope with their health condition. Understanding patients illness perceptions may help facilitate patient-centered care. The purpose of this study was to explore illness perceptions and the origin of those perceptions in people with chronic disabling non-specific neck pain seeking primary care. METHODS: A qualitative study using a deductive and inductive analytical approach was conducted in 20 people with persistent (> 3 months) and disabling (i.e., Neck Disability Index ≥ 15) neck pain. Using a semi-structured format, participants were interviewed about their illness perceptions according to Leventhal's Common Sense Model. Purposive sampling and member checking were used to secure validity of study results. RESULTS: Participants reported multiple symptoms, thoughts and emotions related to their neck pain, which continuously required attention and action. They felt trapped within a complex multifactorial problem. Although some participants had a broader biopsychosocial perspective to understand their symptoms, a biomedical perspective was dominant in the labelling of their condition and their way of coping (e.g., limiting load, building strength and resilience, regaining mobility, keep moving and being meaningful). Their perceptions were strongly influenced by information from clinicians. Several participants indicated that they felt uncertain, because the information they received was contradictory or did not match their own experiences. CONCLUSION: Most participants reported that understanding their pain was important to them and influenced how they coped with pain. Addressing this 'sense making process' is a prerequisite for providing patient-centered care.

Associations between facial expressions and observational pain in residents with dementia and chronic pain.

AIM: To identify specific facial expressions associated with pain behaviors using the PainChek application in residents with dementia. DESIGN: This is a secondary analysis from a study exploring the feasibility of PainChek to evaluate the effectiveness of a social robot (PARO) intervention on pain for residents with dementia from June to November 2021. METHODS: Participants experienced PARO individually five days per week for 15 min (once or twice) per day for three consecutive weeks. The PainChek app assessed each resident's pain levels before and after each session. The association between nine facial expressions and the adjusted PainChek scores was analyzed using a linear mixed model. RESULTS: A total of 1820 assessments were completed with 46 residents. Six facial expressions were significantly associated with a higher adjusted PainChek score. Horizontal mouth stretch showed the strongest association with the score, followed by brow lowering parting lips, wrinkling of the nose, raising of the upper lip and closing eyes. However, the presence of cheek raising, tightening of eyelids and pulling at the corner lip were not significantly associated with the score. Limitations of using the PainChek app were identified. CONCLUSION: Six specific facial expressions were associated with observational pain scores in residents with dementia. Results indicate that automated real-time facial analysis is a promising approach to assessing pain in people with dementia. However, it requires further validation by human observers before it can be used for decision-making in clinical practice. IMPACT: Pain is common in people with dementia, while assessing pain is challenging in this group. This study generated new evidence of facial expressions of pain in residents with dementia. Results will inform the development of valid artificial intelligence-based algorithms that will support healthcare professionals in identifying pain in people with dementia in clinical situations. REPORTING METHOD: The study adheres to the CONSORT reporting guidelines. PATIENT OR PUBLIC CONTRIBUTION: One resident with dementia and two family members of people with dementia were consulted and involved in the study design, where they provided advice on the protocol, information sheets and consent forms, and offered valuable insights to ensure research quality and relevance. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry number (ACTRN12621000837820).

Systemic Inflammation, Sleep, and Psychological Factors Determine Recovery Trajectories for People With Neck Pain: An Exploratory Study.

We conducted an explorative prospective cohort study with 6 months follow-up to 1) identify different pain and disability trajectories following an episode of acute neck pain, and 2) assess whether neuroimmune/endocrine, psychological, behavioral, nociceptive processing, clinical outcome, demographic and management-related factors differ between these trajectories. Fifty people with acute neck pain (ie, within 2 weeks of onset) were included. At baseline, and at 2, 4, 6, 12, and 26 weeks follow-up, various neuroimmune/endocrine (eg, inflammatory cytokines and endocrine factors), psychological (eg, stress symptoms), behavioral (eg, sleep disturbances), nociceptive processing (eg, condition pain modulation), clinical outcome (eg, trauma), demographic factors (eg, age), and management-related factors (eg, treatment received) were assessed. Latent class models were performed to identify outcome trajectories for neck pain and disability. Linear mixed models or the Pearson chi-square test were used to evaluate differences in these factors between the trajectories at baseline and at each follow-up assessment and over the entire 6 months period. For pain, 3 trajectories were identified. The majority of patients were assigned to the "Moderate pain - Favourable recovery" trajectory (n = 25; 50%) with smaller proportions assigned to the "Severe pain - Favourable recovery" (n = 16; 32%) and the "Severe pain - Unfavourable recovery" (n = 9; 18%) trajectories. For disability, 2 trajectories were identified: "Mild disability - Favourable recovery" (n = 43; 82%) and "Severe disability - Unfavourable recovery" (n = 7; 18%). Ongoing systemic inflammation (increased high-sensitive C-reactive protein), sleep disturbances, and elevated psychological factors (such as depression, stress and anxiety symptoms) were mainly present in the unfavorable outcome trajectories compared to the favorable outcome trajectories. PERSPECTIVE: Using exploratory analyses, different recovery trajectories for acute neck pain were identified based on disability and pain intensity. These trajectories were influenced by systemic inflammation, sleep disturbances, and psychological factors.

Efficacy of Conservative Interventions for Musculoskeletal Conditions on Pain and Disability in Active Serving Military Personnel-A Systematic Review.

INTRODUCTION: Musculoskeletal (MSK) injuries and associated pain disorders are one of the leading causes for soldiers not being medically fit for deployment, impacting force capability and readiness. Musculoskeletal pain continues to be a leading cause of disability within military services and is associated with a substantial financial burden. A better understanding of the effectiveness of MSK pain management strategies is required. This review was designed to determine the efficacy of nonsurgical interventions, such as physiotherapy, exercise, pharmacology, and multidisciplinary programs, to manage MSK conditions in active serving military populations. MATERIALS AND METHODS: MEDLINE, Embase, CINAHL, and SPORTDiscus were searched to identify relevant randomized clinical trials. Recommended methods were used for article identification, selection, and data extraction. The Cochrane Risk of Bias tool and the Grade of Recommendation, Assessment, Development, and Evaluation were used to appraise the studies. Where possible, meta-analyses were performed. The review was conducted according to the PRISMA guidelines. RESULTS: Nineteen articles (1,408 participants) met the eligibility criteria. Low back pain (LBP) was the most frequently investigated condition, followed by knee pain, neck pain, and shoulder pain. Early physiotherapy, exercise and adjunct chiropractic manipulation (for LBP), and multidisciplinary pain programs (physiotherapy, occupational therapy, and psychology) (for chronic MSK pain) improved pain (standardized mean difference ranged from -0.39 to -1.34; low strength of evidence). Participation in multidisciplinary pain programs, adjunct chiropractic manipulation, and early physiotherapy improved disability (for LBP) (standardized mean difference ranged from -0.45 to -0.86; low to very low strength of evidence). No studies evaluated pain medication. Dietary supplements (glucosamine, chondroitin sulfate, and manganese ascorbate), electrotherapy, isolated lumbar muscle exercises, home cervical traction, or training in virtual reality showed no benefit. The studies had a high risk of bias, were typically underpowered, and demonstrated high clinical heterogeneity. CONCLUSIONS: Currently available randomized clinical trials do not provide sufficient evidence to guide military organizations or health care professionals in making appropriate treatment decisions to manage MSK pain in active serving military personnel. Future research is essential to enable evidence-based recommendations for the effective management of MSK pain conditions in this unique population.

Exploring health and illness perceptions to identify the perceived cause of pregnancy-related pelvic girdle pain. A mixed-methods study among primiparous women in The Netherlands.

BACKGROUND: Pregnancy-related pelvic girdle pain (PPGP) is common and considered a multifactorial condition with biomechanical and psychosocial contributions. The patient's perceived cause is an important aspect of illness perceptions, and a strong predictor of self-management and healthcare utilization. It is unknown what causal beliefs primiparae hold regarding PPGP. OBJECTIVE: To explore and describe health and illness perceptions among primiparae towards PPGP and its cause. DESIGN: Exploratory, convergent parallel mixed-methods. SETTING: At the participants' homes. PARTICIPANTS: Sixteen primiparae with and without PPGP. FINDINGS: Primiparae with and without PPGP held comparable causal beliefs about PPGP. PPGP was described as the result of hormonal softening and loosening of the pelvis, and failure of the muscular system to compensate for that. Women who experienced similar physical symptoms attributed them differently, leading to different coping strategies. Interestingly, maternal healthcare providers reinforced the unidimensional- and predominantly biomechanical view when women sought healthcare. CONCLUSION: The causal mechanism of PPGP held by the women was not determined by their lived experience. It was primarily based on the concept of inevitable hormonal softening of the pelvis. This biomechanical belief is based on theories that are not in line with current knowledge of PPGP and contemporary pain science, yet they were reinforced by maternity healthcare providers. IMPLICATIONS FOR PRACTICE: Healthcare seeking behavior is influenced by illness beliefs. Maternity healthcare providers may play a key role in providing reassurance and addressing the multifactorial nature of PPGP when providing care and support to pregnant women.

The impact of being overweight or obese on 12 month clinical recovery in patients following lumbar microdiscectomy for radiculopathy.

BACKGROUND CONTEXT: The proportion of patients who undergo lumbar microdiscectomy due to lumbar radiculopathy who are also overweight or obese is high. However, whether high body mass index (BMI) affects clinical outcomes is not well-studied. PURPOSE: To investigate the difference in the clinical course between normal weight, overweight, and obese patients with radiculopathy who underwent lumbar microdiscectomy followed by physical therapy and to evaluate whether high BMI is associated with poor recovery. STUDY DESIGN/SETTING: A prospective cohort study with a 12-month follow-up was conducted in a multidisciplinary clinic. PATIENT SAMPLE: We included 583 patients (median [IQR] age: 45 [35-52] years; 41% female) with clinical signs and symptoms of lumbar radiculopathy, consistent with magnetic resonance imaging findings, who underwent microdiscectomy followed by postoperative physical therapy. OUTCOME MEASURES: Outcomes were leg pain and back pain intensity measured with a visual analogue scale, disability measured with the Roland Morris Disability Questionnaire at 3 and 12-month follow-ups, and complications. METHODS: Patients were classified as being normal weight (46.9%), overweight (38.4%), or obese (14.7%). A linear mixed-effects model was used to assess the difference in the clinical course of pain and disability between the three BMI categories. The association between BMI and outcomes was evaluated using univariable and multivariable logistic regression analyses. RESULTS: All three patient groups experienced a significant improvement in leg pain, back pain, and disability over 3 and 12-month follow-up. Patients who were overweight, obese, or normal weight experienced comparable leg pain (p=.14) and disability (p=.06) over the clinical course (p=.14); however, obese patients experienced higher back pain (MD=-6.81 [95%CI: -13.50 to -0.14]; p=.03). The difference in back pain scores was not clinically relevant. CONCLUSIONS: In the first year following lumbar microdiscectomy, patients demonstrated clinical improvements and complications that were unrelated to their preoperative BMI.

Personal Activity Intelligence eHealth intervention in people with diabetic peripheral neuropathy: A feasibility study.

BACKGROUND AND OBJECTIVES: People with diabetic peripheral neuropathy (DPN) report difficulty exercising. This study tested an innovative intervention to promote physical activity self-management and its impact on foot symptoms. METHOD: Ten adults with DPN not meeting exercise guidelines consented to four weekly sessions involving exercise tasters, behaviour change counselling and Physical Activity Intelligence (PAI) self-monitoring, with a goal to maintain daily PAI scores ≥100. Foot symptoms were assessed using repeated mobile phone surveys at 0 and 12 weeks. RESULTS: Participants attended a mean 3.5 sessions and achieved 100 PAI on 53% and 15% of days during Weeks 2-4 and 5-12, respectively. No major adverse events and large reductions in aching (P=0.02) and burning pain (P=0.03) in the feet were recorded. DISCUSSION: The PAI eHealth intervention was feasible and safe and might reduce foot symptoms. More work is needed to support self-directed exercise maintenance.

The potential protective effects of pre-injury exercise on neuroimmune responses following experimentally-induced traumatic neuropathy: a systematic review with meta-analysis.

Pre-clinical evidence shows that neuropathy is associated with complex neuroimmune responses, which in turn are associated with increased intensity and persistence of neuropathic pain. Routine exercise has the potential to mitigate complications of future nerve damage and persistence of pain through neuroimmune regulation. This systematic review aimed to explore the effect of pre-injury exercise on neuroimmune responses, and other physiological and behavioural reactions following peripheral neuropathy in animals. Three electronic databases were searched from inception to July 2022. All controlled animal studies assessing the influence of an active exercise program prior to experimentally-induced traumatic peripheral neuropathy compared to a non-exercise control group on neuroimmune, physiological and behavioural outcomes were selected. The search identified 17,431 records. After screening, 11 articles were included. Meta-analyses showed that pre-injury exercise significantly reduced levels of IL-1ß (SMD: -1.06, 95% CI: -1.99 to -0.13, n=40), but not iNOS (SMD: -0.71 95% CI: -1.66 to 0.25, n=82). From 72 comparisons of different neuroimmune outcomes at different anatomical locations, vote counting revealed reductions in 23 pro-inflammatory and increases in 6 anti-inflammatory neuroimmune outcomes. For physiological outcomes, meta-analyses revealed that pre-injury exercise improved one out of six nerve morphometric related outcomes (G-ratio; SMD: 1.95, 95%CI: 0.77 to 3.12, n=20) and one out of two muscle morphometric outcomes (muscle fibre cross-sectional area; SMD: 0.91, 95%CI: 0.27 to 1.54, n=48). For behavioural outcomes, mechanical allodynia was significantly less in the pre-injury exercise group (SMD -1.24, 95%CI: -1.87 to -0.61) whereas no overall effect was seen for sciatic function index. Post hoc subgroup analysis suggests that timing of outcome measurement may influence the effect of pre-injury exercise on mechanical allodynia. Risk of bias was unclear in most studies, as the design and conduct of the included experiments were poorly reported. Preventative exercise may have potential neuroprotective and immunoregulatory effects limiting the sequalae of nerve injury, but more research in this field is urgently needed.

Risk assessment of vascular complications following manual therapy and exercise for the cervical region: diagnostic accuracy of the International Federation of Orthopaedic Manipulative Physical Therapists framework (The Go4Safe project).

QUESTION: What is the diagnostic accuracy of the International Federation of Orthopaedic Manipulative Physical Therapists (IFOMPT) framework to assess the risk of vascular complications in patients seeking physiotherapy care for neck pain and/or headache? DESIGN: Cross-sectional diagnostic accuracy study. PARTICIPANTS: One hundred and fifty patients seeking physiotherapy for neck pain and/or headache in primary care. METHODS: Nineteen physiotherapists performed the index test according to the IFOMPT framework. Patients were classified as having a high, intermediate or low risk of vascular complications, following manual therapy and/or exercise, derived from the estimated risk of the presence of vascular pathology. The reference test was a consensus medical decision reached by a vascular neurologist and an interventional neurologist, with input from a neuroradiologist. The neurologists had access to clinical data and magnetic resonance imaging of the cervical spine, including an angiogram of the cervical arteries. OUTCOME MEASURES: Diagnostic accuracy measures were calculated for 'no contraindication' (ie, the low-risk category) and 'contraindication' (ie, the high-risk and intermediate-risk categories) for manual therapy and/or exercise. Sensitivity, specificity, predictive values, likelihood ratios and the area under the curve were calculated. RESULTS: Manual therapy and/or exercise were contraindicated in 54.7% of the patients. The sensitivity of the IFOMPT framework was low (0.50, 95% CI 0.39 to 0.61) and its specificity was moderate (0.63, 95% CI 0.51 to 0.75). The positive and negative likelihood ratios were weak at 1.36 (95% CI 0.93 to 1.99) and 0.79 (95% CI 0.60 to 1.05), respectively. The area under the curve was poor (0.57, 95% CI 0.49 to 0.65). CONCLUSION: The IFOMPT framework has poor diagnostic accuracy when compared with a reference standard consisting of a consensus medical decision.

Immediate systemic neuroimmune responses following spinal mobilisation and manipulation in people with non-specific neck pain: a randomised placebo-controlled trial.

Spinal mobilisation/manipulation is a common intervention for spinal pain, yet the working mechanisms are largely unknown. A randomised placebo-controlled trial was conducted to (1) compare the immediate neuroimmune responses following spinal mobilisation/manipulation and placebo spinal mobilisation/manipulation; (2) compare the immediate neuroimmune responses of those with a good outcome with those of a poor outcome following spinal mobilisation/manipulation; and (3) explore the association between neuroimmune responses and pain reduction. One hundred patients were randomly allocated to spinal mobilisation/manipulation or a placebo mobilisation/manipulation. Primary outcomes were whole blood in-vitro evoked released concentrations of IL-1ß and TNF-α measured 10 min and 2 h after the intervention. Immediate effects were studied because successful mobilisation/manipulation is often associated with immediate pain reduction, and immediate neuroimmune responses are less affected by potential confounders than long-term responses. Secondary outcomes included multiple systemic inflammatory marker concentrations, phenotypic analysis of white blood cells and clinical outcomes. Outcomes were compared between the experimental and placebo group, and between people with a good and poor outcome in the experimental group. Estimates of intervention effects were based on intention-to-treat analyses, by using linear mixed-effect models. Although there was a substantial difference in pain reduction between groups (mean (SD) difference visual analogue scale: 30 (21) mm at 10 min and 32 (21) mm at 2 h (p < 0.001) in favour of mobilisation/manipulation, there were no differences in primary outcomes between groups or between people with a good and poor outcome (p ≥ 0.10). In conclusion, possible neuroimmune responses following spinal mobilisations/manipulation cannot be identified at a systemic level. Future research may focus on longer treatment duration and more localised neuroimmune responses.

Visual feedback manipulation in virtual reality to influence pain-free range of motion. Are people with non-specific neck pain who are fearful of movement more susceptible?

BACKGROUND: Movement-evoked pain may have a protective or learned component, influenced by visual cues which suggest that the person is moving towards a position that may be perceived as threatening. We investigated whether visual feedback manipulation in virtual reality (VR) had a different effect on cervical pain-free range of motion (ROM) in people with fear of movement. METHOD: In this cross-sectional study, seventy-five people with non-specific neck pain (i.e., neck pain without a specific underlying pathology) rotated their head until the onset of pain, while wearing a VR-headset. Visual feedback about the amount of movement was equal, 30% smaller or 30% larger than their actual rotation. ROM was measured using the VR-headset sensors. The effect of VR manipulation in fearful (N = 19 using the Tampa Scale for Kinesiophobia (TSK) and N = 18 using the Fear Avoidance Beliefs Questionnaire-physical activity (FABQpa)) and non-fearful (N = 46; non-fearful on both scales) people was compared using mixed-design ANOVAs. RESULTS: Fear of movement, influenced the effect of visual feedback manipulation on cervical pain-free ROM (TSK: p = 0.036, Õ²p2 = 0.060; FABQpa: p = 0.020, Õ²p2 = 0.077); a greater amplitude of pain-free movement was found when visual feedback reduced the perceived rotation angle compared to the control condition (TSK: p = 0.090, Õ²p2 = 0.104; FABQpa: p = 0.030, Õ²p2 = 0.073). Independent of the presence of fear, visual feedback manipulation reduced the cervical pain-free ROM in the overstated condition (TSK: p< 0.001, Õ²p2 = 0.195; FABQpa: p<0.001, Õ²p2 = 0.329). DISCUSSION: Cervical pain-free ROM can be influenced by visual perception of the amount of rotation and people with fear of movement seem to be more susceptible to this effect. Further research in people with moderate/severe fear is needed to determine whether manipulating visual feedback may have clinical applicability to make patients aware that ROM may be influenced more by fear than tissue pathology.

Immediate and short-term effects of eccentric muscle contractions on structural, morphological, mechanical, functional and physiological properties of peripheral nerves: A protocol for a systematic review and meta-analysis.

BACKGROUND: It is widely acknowledged that eccentric muscle contractions may cause skeletal muscle damage. However, there is little knowledge about the impact of eccentric contractions on non-muscular structures. Animal and human studies revealed that eccentric contractions can also induce immediate and short-term nerve dysfunction. The purpose of this review is to examine whether eccentric muscle contractions induce immediate and short-term effects on structural, morphological, mechanical, functional and physiological properties of peripheral nerves, from both animal and human studies. METHODS AND ANALYSIS: A systematic review of randomised (RCTs) and non-randomised controlled trials will be conducted. Four electronic databases (i.e., Medline/Pubmed, Science Direct, PEDro and Cochrane) will be searched using predefined search terms to identify relevant studies. Eligible studies have to comprise any type of eccentric contraction of upper or lower limb muscles. Primary outcomes will include measures related to structure, morphology, mechanical, functional and physiological properties of peripheral nerves. Two independent reviewers will assess eligibility, evaluate risk of bias, and extract relevant data. In human studies, the risk of bias will be assessed by the Cochrane Collaboration risk of bias tool (RoB 2.0 tool) for RCTs and by risk of bias in non-randomised studies of interventions (ROBINS-I) for non-randomised controlled trials; while for animal studies, the risk of bias will be assessed using the SYRCLE's RoB tool. A narrative synthesis will be conducted for all included studies. Also, if appropriate, a meta-analysis will be performed, where the effect size of each outcome will be determined by the standardized mean difference as well as the 95% confidence intervals. I2 statistics will be used to assess heterogeneity. ETHICS AND DISSEMINATION: For this study, no ethical approval is required. Findings will be disseminated widely through peer-reviewed publication and conference presentations. SYSTEMATIC REVIEW REGISTRATION: The protocol has been registered at the International Prospective Register of Systematic Reviews (PROSPERO). Registration number: CRD42021285767.