Coordination of hip and spine in individuals with acute low back pain during unstable sitting

BACKGROUND CONTEXT

Trunk postural control differs between individuals with and without chronic low back pain (LBP). Whether this corresponds to differences in hip/spine coordination during the early acute phase of LBP (ALBP) is unclear.

PURPOSE

To compare hip/spine coordination in relation to seat movements between individuals with and without ALBP when balancing on an unstable seat and to identify coordination strategies to maintain balance using cluster analysis.

STUDY DESIGN/SETTING

Cross-sectional observational study.

PATIENT SAMPLE

ALBP (n=130) and pain-free (n=72) individuals.

OUTCOME MEASURES

Frequency domain measures to evaluate hip/spine coordination (amplitude spectrum, phase angle, and coherence) and time-series measures to assess overall balance performance (center of pressure [CoP] reflecting the amount of seat movements, upper thorax motion as a surrogate for head motion).

METHODS

Participants maintained balance while sitting on a seat fixed to a hemisphere. Seat, hip, and spine (lower lumbar, lumbar, upper lumbar, and thoracic) angular motion and force plate data were recorded.

RESULTS

Overall, seat/CoP movements (amplitude spectrum and RMSdisplacement) were greater (in both planes) and sagittal coordination (coherence) between the hip or lower spine and seat movements was lower in ALBP than controls. Cluster analysis using coherence data revealed different coordination strategies to maintain balance. Separate clusters used a "lower lumbar strategy" and "hip strategy" in the sagittal plane, and a "lower and upper lumbar strategy" and "lower lumbar strategy" in the frontal plane. A cluster using a "low coherence strategy" in both planes was also identified.

CONCLUSIONS

Hip and lower spine coordination was less in individuals with ALBP in conjunction with a lower quality of overall balance performance. However, interpretation of the relationship between coherence and overall balance performance was not straightforward. Clusters in both the ALBP group and the control group adopted a low coherence strategy, and this was not consistently related to poor overall balance performance. This suggests overall balance performance cannot be inferred from coherence alone and requires consideration of interaction of other different features.

Targeted multifidus muscle activation reduces fibrosis of multifidus muscle following intervertebral disc injury

PURPOSE

Aerobic exercise produces beneficial outcomes in patients with low back pain and partially attenuates the fibrotic changes to the multifidus in a model of intervertebral disc (IVD) degeneration. More targeted exercise might be required to fully attenuate these fibrotic alterations. This study aimed to investigate whether activation of the multifidus induced by neurostimulation could reduce fibrosis of the multifidus in a model of IVD degeneration in sheep.

METHODS

IVD degeneration was induced in 18 merino sheep via a partial thickness unilateral annulus fibrosus lesion to the L1/2 and L3/4 IVDs. All sheep received an implantable neurostimulation device that provides stimulation of the L2 medial branch of the dorsal ramus. Three months after surgery, the animals were assigned to Injury or Activated groups. Activated animals received neurostimulation and the Injury group received no stimulation. Six months after surgery, the multifidus was harvested at L2 and L4. Van Gieson's, Sirius Red and immunofluorescence staining for Collagen-I and -III and quantitative PCR was used to examine fibrosis. Muscle harvested from a previous study without IVD injury was used as a control.

RESULTS

Neurostimulation of the multifidus attenuated IVD degeneration dependent increases in the connective tissue, including Collagen-I but not Collagen-III, compared to the Injury group at L4. No measures of the multifidus muscle at L2, which received no stimulation, differed between the Injury and Activated groups.

CONCLUSIONS

These data reveal that targeted activation of the multifidus muscle attenuates IVD degeneration dependent fibrotic alterations to the multifidus.

Nociceptive, neuropathic, or nociplastic low back pain? The low back pain phenotyping (BACPAP) consortium's international and multidisciplinary consensus recommendations

The potential to classify low back pain as being characterised by dominant nociceptive, neuropathic, or nociplastic mechanisms is a clinically relevant issue. Preliminary evidence suggests that these low back pain phenotypes might respond differently to treatments; however, more research must be done before making specific recommendations. Accordingly, the low back pain phenotyping (BACPAP) consortium was established as a group of 36 clinicians and researchers from 13 countries (five continents) and 29 institutions, to apply a modified Nominal Group Technique methodology to develop international and multidisciplinary consensus recommendations to provide guidance for identifying the dominant pain phenotype in patients with low back pain, and potentially adapt pain management strategies. The BACPAP consortium's recommendations are also intended to provide direction for future clinical research by building on the established clinical criteria for neuropathic and nociplastic pain. The BACPAP consortium's consensus recommendations are a necessary early step in the process to determine if personalised pain medicine based on pain phenotypes is feasible for low back pain management. Therefore, these recommendations are not ready to be implemented in clinical practice until additional evidence is generated that is specific to these low back pain phenotypes.

Potential role of physical labor and cultural views of menstruation in high incidence of pelvic organ prolapse in Nepalese women: a comparative study across the menstrual cycle

Introduction

Pelvic organ prolapse (POP) is a significant health concern for young Nepali women, with potential risk factors including pelvic floor trauma from vaginal delivery and heavy lifting. The prevalence of symptomatic POP (SPOP) among nulliparous women in Nepal is 6%, while the general population of Nepali women aged 15-49 years reports a prevalence of 7%. Surprisingly, the average age of SPOP onset in Nepal is 27 years, challenging the assumption that postmenopausal age and vaginal delivery are the sole risk factors. This study aims to investigate the influence of increased intra-abdominal pressure (IAP) during lifting tasks on pelvic organ descent in Nepali women across different menstrual cycle stages.

Methods

The study included 22 asymptomatic Nepali women aged 18-30 years who regularly engage in heavy lifting. Intra-abdominal pressure was measured intra-vaginally during typical and simulated lifting tasks, which encompassed various scenarios such as ballistic lifting, ramped lifting, and pre-contraction of pelvic floor muscles, as well as coughing, Valsalva maneuver, and pelvic floor contractions. Pelvic floor displacement was recorded using transperineal ultrasound during menstruation, ovulation, and the mid-luteal phase.

Results

Results indicated that pelvic floor displacement was greater during menstruation than ovulation when performing a simulated ballistic lifting task (6.0 ± 1.6 mm vs. 5.1 ± 1.5 mm, p = 0.03, d = 0.6). However, there was no significant difference in pelvic floor displacement during lifting when the pelvic muscles were pre-contracted.

Conclusion

These findings suggest that lifting heavy loads during menstruation may increase the risk of stretching and injuring pelvic floor supportive tissues, potentially contributing to SPOP in young Nepali women. Pre-contracting pelvic floor muscles during lifting tasks may offer a protective effect. Understanding these factors could aid in developing targeted preventive measures and raising awareness about the impact of heavy lifting on pelvic floor health among Nepali women.

Poor sleep versus exercise: A duel to decide whether pain resolves or persists after injury

Poor sleep is thought to enhance pain via increasing peripheral and/or central sensitization. Aerobic exercise, conversely, relives pain via reducing sensitization, among other mechanisms. This raises two clinical questions: (1) does poor sleep contribute to the transition from acute-to-persistent pain, and (2) can exercise protect against this transition? This study tested these questions and explored underlying mechanisms in a controlled injury model. Twenty-nine adult female Sprague-Dawley rats performed an intensive lever-pulling task for 4 weeks to induce symptoms consistent with clinical acute-onset overuse injury. Rats were then divided into three groups and exposed for 4 weeks to either: voluntary exercise via access to a running wheel, sleep disturbance, or both. Pain-related behaviours (forepaw mechanical sensitivity, reflexive grip strength), systemic levels of brain derived neurotrophic factor (BDNF), estradiol and corticosterone, and white blood cells (WBC) were assessed pre-injury, post-injury and post-intervention. Mechanical sensitivity increased post-injury and remained elevated with sleep disturbance alone, but decreased to pre-injury levels with exercise both with and without sleep disturbance. Reflexive grip strength decreased post-injury but recovered post-intervention-more with exercise than sleep disturbance. BDNF increased with sleep disturbance alone, remained at pre-injury levels with exercise regardless of sleep, and correlated with mechanical sensitivity. WBCs and estradiol increased with exercise alone and together with sleep disturbance, respectively. Corticosterone was not impacted by injury/intervention. Findings provide preliminary evidence for a role of poor sleep in the transition from acute-to-persistent pain, and the potential for aerobic exercise to counter these effects. BDNF might have a role in these relationships.

Trunk postural control during unstable sitting among individuals with and without low back pain: A systematic review with an individual participant data meta-analysis

INTRODUCTION

Sitting on an unstable surface is a common paradigm to investigate trunk postural control among individuals with low back pain (LBP), by minimizing the influence lower extremities on balance control. Outcomes of many small studies are inconsistent (e.g., some find differences between groups while others do not), potentially due to confounding factors such as age, sex, body mass index [BMI], or clinical presentations. We conducted a systematic review with an individual participant data (IPD) meta-analysis to investigate whether trunk postural control differs between those with and without LBP, and whether the difference between groups is impacted by vision and potential confounding factors.

METHODS

We completed this review according to PRISMA-IPD guidelines. The literature was screened (up to 7th September 2023) from five electronic databases: MEDLINE, CINAHL, Embase, Scopus, and Web of Science Core Collection. Outcome measures were extracted that describe unstable seat movements, specifically centre of pressure or seat angle. Our main analyses included: 1) a two-stage IPD meta-analysis to assess the difference between groups and their interaction with age, sex, BMI, and vision on trunk postural control; 2) and a two-stage IPD meta-regression to determine the effects of LBP clinical features (pain intensity, disability, pain catastrophizing, and fear-avoidance beliefs) on trunk postural control.

RESULTS

Forty studies (1,821 participants) were included for the descriptive analysis and 24 studies (1,050 participants) were included for the IPD analysis. IPD meta-analyses revealed three main findings: (a) trunk postural control was worse (higher root mean square displacement [RMSdispl], range, and long-term diffusion; lower mean power frequency) among individuals with than without LBP; (b) trunk postural control deteriorated more (higher RMSdispl, short- and long-term diffusion) among individuals with than without LBP when vision was removed; and (c) older age and higher BMI had greater adverse impacts on trunk postural control (higher short-term diffusion; longer time and distance coordinates of the critical point) among individuals with than without LBP. IPD meta-regressions indicated no associations between the limited LBP clinical features that could be considered and trunk postural control.

CONCLUSION

Trunk postural control appears to be inferior among individuals with LBP, which was indicated by increased seat movements and some evidence of trunk stiffening. These findings are likely explained by delayed or less accurate corrective responses.

SYSTEMATIC REVIEW REGISTRATION

This review has been registered in PROSPERO (registration number: CRD42021124658).

Fostering equitable change in health services: Using critical reflexivity to challenge dominant discourses in low back pain care in Australia

OBJECTIVES

Justice and equity-focused practices in health services play a critical but overlooked role in low back pain (LBP) care. Critical reflexivity - the ability to examine and challenge power relations, and broader social issues embedded in everyday life - can be a useful tool to foster practices that are more socially just. No research has yet explored this approach in back pain health services. This study sought to understand how clinicians construct LBP in relation to broader socio-cultural-political aspects of care and explore if those constructions changed when clinicians engaged with critically reflexive dialogues with researchers.

METHODS

Using critical discourse analysis methods, this qualitative study explored institutionalised patterns of knowledge in the construction of LBP care. We conducted 22 critically reflexive dialogues with 29 clinicians from two health services in Australia - a private physiotherapy clinic and a public multidisciplinary pain clinic.

RESULTS

Our analyses suggested that clinicians and services often constructed LBP care at an individual level. This dominant individualistic discourse constrained consideration of justice-oriented practices in the care of people with LBP. Through dialogues, discursive constructions of LBP care expanded to incorporate systems and health service workplace practices. This expansion fostered more equitable clinical and service practices - such as assisting patients to navigate health care systems, considering patients' socioeconomic circumstances when developing treatment plans, encouraging staff discussion of possible systemic changes to enhance justice, and fostering a more inclusive workplace culture. Although such expansions faced challenges, incorporating broader discourses enabled recommendations to address LBP care inequities.

CONCLUSIONS

Critical reflexivity can be a tool to foster greater social justice within health services. By expanding constructions of LBP care beyond individuals, critical reflexive dialogues can foster discussion and actions towards more equitable workplace cultures, services and systems.

'Engaging on a slightly more human level': A qualitative study exploring the care of individuals with back pain in a multidisciplinary pain clinic

Chronic low back pain is characterised by multiple and overlapping biological, psychological, social and broader dimensions, affecting individuals' lives. Multidisciplinary pain services have been considered optimal settings to account for the multidimensionality of chronic low back pain but have largely focused on cognitive and behavioural aspects of individuals' pain. Social dimensions are usually underexplored, considered outside or beyond healthcare professionals' scope of practice. Employing Actor Network Theorist Mol's concept multiplicity, our aim in this paper is to explore how a pain service's practices bring to the fore the social dimensions of individuals living with low back pain. Drawing on 32 ethnographic observations and four group exchanges with the service's clinicians, findings suggest that practices produced multiple enactments of an individual with low back pain. Although individuals' social context was present and manifested during consultations at the pain service (first enactment: 'the person'), it was often disconnected from care and overlooked in 'treatment/management' (second enactment: 'the patient'). In contrast, certain practices at the pain service not only provided acknowledgement of, but actions towards enhancing, individuals' social contexts by adapting rules and habits, providing assistance outside the service and shifting power relations during consultations (third enactment: 'the patient-person'). We therefore argue that different practices enact different versions of an individual with low back pain in pain services, and that engagement with individuals' social contexts can be part of a service's agenda.

Lessons learnt from a nationally funded training and mentoring programme for early-mid career musculoskeletal researchers in Australia

INTRODUCTION

Quality training and mentoring are crucial components of successful career development for early mid career researchers (EMCRs). This paper describes the overarching framework of novel ongoing national Training and Mentoring Programme Melbourne University Sydney Queensland:Impact (MUSQ:Impact) for musculoskeletal researchers, including a description of how it was set up and established, and lessons learned from its implementation.

RESULTS

The MUSQ:Impact programme spans four multidisciplinary musculoskeletal research teams across three universities in Australia, comprising 40-60 EMCR members. It was established to provide EMCRs with a unique learning environment and opportunities to gain exposure to, and network with, other national musculoskeletal research teams. Specific goals are to focus on core research competencies (e.g. writing skills, managing grant budgets, public speaking and media engagement, research translation), provide career mentoring, fund development activities (e.g. conference attendance, laboratory visits, skill development courses), and share training resources (e.g. data dictionaries, project summaries). A Steering Committee of 10-12 EMCR members, co-chaired by a senior researcher and one EMCR, is responsible for overseeing MUSQ:Impact and organising regular activities, including a monthly webinar series, a mentor/mentee scheme, annual group research retreats, annual infographic competition, and funding awards. An evaluation survey found that most participants perceived each activity to be beneficial and of value to their research career and development.

CONCLUSION

This paper presents the structure of national training and mentoring programme that serves as a potential template for other research teams to adapt within their own contexts.

Pelvic floor muscle length changes with breathing in males: A preliminary report

The study aimed to identify whether pelvic floor muscles modulate length with breathing, and if any length changes induced by breathing relate to abdominal cavity displacement and intra-abdominal pressure. To investigate these relationships, displacement of pelvic landmarks that related to pelvic floor muscle length using transperineal ultrasound imaging, breath volume, intra-abdominal pressure, abdominal and ribcage displacement, and abdominal and anal sphincter muscle electromyography were measured during quiet breathing and breathing with increased dead-space in ten healthy men. Pelvic floor muscle landmark displacement modulated with ribcage motion during breathing. This relationship was stronger for: i) motion of the urethrovesical junction (puborectalis muscle length change) than the mid-urethra landmark (striated urethral sphincter muscle length change), and ii) dead-space breathing in standing than dead-space breathing in supine or quiet breathing in standing. In most (but not all) participants, the urethrovesical junction descended during inspiration and elevated during expiration. Striated urethral sphincter length changes during the respiratory cycle was independent of intra-abdominal pressure. In summary, breathing involves pelvic floor muscle length changes and is consistent with the role of these muscles during respiration to aid maintenance of continence, lung ventilation and/or provision of support to the abdominal cavity. Clinicians who train pelvic floor muscles need to be aware that length change of pelvic floor muscles is expected with breathing.

Neck muscle activation in response to eye movement depends on sitting posture and is modified in whiplash associated disorders: Cross-sectional study

BACKGROUND

Activity of specific neck muscles is modulated by eye movement. This activity modulation is exaggerated in people with whiplash associated disorders (WAD), but it is unknown whether it is impacted by sitting posture.

OBJECTIVE

This study investigated; (i) whether activity of cervical muscles differs with spinal posture; (ii) whether the effect of eye gaze direction (horizontal/vertical) on neck muscle activity differs between postures, and (iii) whether these effects differ between individuals with and without WAD.

METHODS

In three seated postures (normal relaxed, head forward, sit tall) electromyography (EMG) was recorded right obliquus capitis inferior (OI), multifidus (MF), splenius capitis (SP) and left sternocleidomastoid (SCM) with fine-wire and surface electrodes in ten healthy controls and nine with WAD. Electro-oculography recorded eye movements.

RESULTS

In controls, EMG was less for extensor muscles in Sit Tall than Head Forward, but higher in SCM. Only SC EMG modulated with eye movement. When WAD participants adopted similar sitting postures several responses were different; compared to Normal Relaxed posture OI EMG was less in Head Forward; MF EMG was less in Sit Tall; and SC was less in Head Forward and Sit Tall. Neck muscles in WAD were generally more sensitive to eye movement, except SC which did not modulate.

CONCLUSIONS

These finding support the hypothesis that neck muscle activity is influenced by spinal posture and eye movement. In WAD, this relationship is distorted and the response to eye movement is increased.

SIGNIFICANCE

These observations have potential implications for clinical management of individuals with WAD.

Adaptability of the load sharing between the longissimus and components of the multifidus muscle during isometric trunk extension in healthy individuals

PURPOSE

Redundancy of the musculoskeletal system implies multiple strategies are theoretically available to coordinate back extensor muscles. This study investigated whether coordination between back muscles during a tightly constrained isometric trunk extension task varies within and between individuals, and whether this changes following brief exposure to activation feedback of a muscle.

METHODS

Nine healthy participants performed three blocks of two repetitions of ramped isometric trunk extension in side-lying against resistance from 0-30% of maximum voluntary contraction over 30 s (force feedback). Between blocks, participants repeated contractions with visual feedback of electromyography (EMG) from either superficial (SM) or deep multifidus (DM), in two conditions; 'After SM' and 'After DM'. Intramuscular EMG was recorded from SM, DM, and longissimus (LG) simultaneously with shear wave elastography (SWE) from SM or DM.

RESULTS

In the 'Natural' condition (force feedback only), group data showed incremental increases in EMG with force, with minor changes in distribution of activation between muscles as force increased. SM was the most active muscle during the 'Natural' condition, but with DM most active in some participants. Individual data showed that coordination between muscles differed substantially between repetitions and individuals. Brief exposure to EMG feedback altered coordination. SWE showed individual variation, but findings differed from EMG.

CONCLUSION

This study revealed substantial variation in coordination between back extensor muscles within and between participants, and after exposure to feedback, in a tightly constrained task. Shear modulus revealed similar variation, but with an inconsistent relationship to EMG. These data highlight highly flexible control of back muscles.

Nociceptive withdrawal reflexes of the trunk muscles in chronic low back pain

Individuals with chronic low back pain (CLBP) move their spine differently. Changes in brain motor areas have been observed and suggested as a mechanism underlying spine movement alteration. Nociceptive withdrawal reflex (NWR) might be used to test spinal networks involved in trunk protection and to highlight reorganization. This study aimed to determine whether the organization and excitability of the trunk NWR are modified in CLBP. We hypothesized that individuals with CLBP would have modified NWR patterns and lower NWR thresholds. Noxious electrical stimuli were delivered over S1, L3 and T12, and the 8th Rib to elicit NWR in 12 individuals with and 13 individuals without CLBP. EMG amplitude and occurrence of lumbar multifidus (LM), thoracic erector spinae, rectus abdominus, obliquus internus and obliquus externus motor responses were recorded using surface electrodes. Two different patterns of responses to noxious stimuli were identified in CLBP compared to controls: (i) abdominal muscle NWR responses were generally more frequent following 8th rib stimulation and (ii) occurrence of erector spinae NWR was less frequent. In addition, we observed a subgroup of participants with very high NWR threshold in conjunction with the larger abdominal muscle responses. These results suggest sensitization of NWR is not present in all individuals with CLBP, and a modified organization in the spinal networks controlling the trunk muscles that might explain some changes in spine motor control observed in CLBP.

The effect of skilled motor training on corticomotor control of back muscles in different presentations of low back pain

Transcranial magnetic stimulation (TMS) has revealed differences in the motor cortex (M1) between people with and without low back pain (LBP). There is potential to reverse these changes using motor skill training, but it remains unclear whether changes can be induced in people with LBP or whether this differs between LBP presentations. This study (1) compared TMS measures of M1 (single and paired-pulse) and performance of a motor task (lumbopelvic tilting) between individuals with LBP of predominant nociceptive (n = 9) or nociplastic presentation (n = 9) and pain-free individuals (n = 16); (2) compared these measures pre- and post-training; and (3) explored correlations between TMS measures, motor performance, and clinical features. TMS measures did not differ between groups at baseline. The nociplastic group undershot the target in the motor task. Despite improved motor performance for all groups, only MEP amplitudes increased across the recruitment curve and only for the pain-free and nociplastic groups. TMS measures did not correlate with motor performance or clinical features. Some elements of motor task performance and changes in corticomotor excitability differed between LBP groups. Absence of changes in intra-cortical TMS measures suggests regions other than M1 are likely to be involved in skill learning of back muscles.

Uncertainty in low back pain care - insights from an ethnographic study

PURPOSE

To explore how uncertainty plays out in low back pain (LBP) care and investigate how clinicians manage accompanying emotions/tensions.

MATERIALS AND METHODS

We conducted ethnographic observations of clinical encounters in a private physiotherapy practice and a public multidisciplinary pain clinic. Our qualitative reflexive thematic analysis involved abductive thematic principles informed by Fox and Katz (medical uncertainty) and Ahmed (emotions).

RESULTS

We identified three themes. (1) Sources of uncertainty: both patients and clinicians expressed uncertainty during clinical encounters (e.g., causes of LBP, mismatch between imaging findings and presentation). Such uncertainty was often accompanied by emotions - anger, tiredness, frustration. (2) Neglecting complexity: clinicians often attempted to decrease uncertainty and associated emotions by providing narrow answers to questions about LBP. At times, clinicians' denial of uncertainty also appeared to deny patients the right to make informed decisions about treatments. (3) Attending to uncertainty?: clinicians attended to uncertainty through logical reasoning, reassurance, acknowledgement, personalising care, shifting power, adjusting language and disclosing risks.

CONCLUSIONS

Uncertainty pervades LBP care and is often accompanied by emotions, emphasising the need for a healthcare culture that recognises the emotional dimensions of patient-clinician interactions and prepares clinicians and patients to be more accepting of, and clearly communicate about, uncertainty.IMPLICATIONS FOR REHABILITATIONUncertainty pervades LBP care and is often accompanied by emotions.Neglecting complexity in LBP care may compromise person-centred care.Acknowledging uncertainty can enhance communication, balance patient-clinician relationships and address human aspects of care.

Consensus for experimental design in electromyography (CEDE) project: Single motor unit matrix

The analysis of single motor unit (SMU) activity provides the foundation from which information about the neural strategies underlying the control of muscle force can be identified, due to the one-to-one association between the action potentials generated by an alpha motor neuron and those received by the innervated muscle fibers. Such a powerful assessment has been conventionally performed with invasive electrodes (i.e., intramuscular electromyography (EMG)), however, recent advances in signal processing techniques have enabled the identification of single motor unit (SMU) activity in high-density surface electromyography (HDsEMG) recordings. This matrix, developed by the Consensus for Experimental Design in Electromyography (CEDE) project, provides recommendations for the recording and analysis of SMU activity with both invasive (needle and fine-wire EMG) and non-invasive (HDsEMG) SMU identification methods, summarizing their advantages and disadvantages when used during different testing conditions. Recommendations for the analysis and reporting of discharge rate and peripheral (i.e., muscle fiber conduction velocity) SMU properties are also provided. The results of the Delphi process to reach consensus are contained in an appendix. This matrix is intended to help researchers to collect, report, and interpret SMU data in the context of both research and clinical applications.

The relationship between pre- and postprostatectomy measures of pelvic floor muscle function and development of early incontinence after surgery

AIMS

The aim of this study is to investigate (i) whether pelvic floor muscle (PFM) shortening can be enhanced by provision of training focused on striated urethral sphincter (SUS) with feedback before prostatectomy, (ii) whether PFM shortening during voluntary efforts and coughing before and after prostatectomy differs between men who do and do not report symptoms of urinary incontinence 1 month after prostatectomy, and (iii) the relationship between severity of incontinence after prostatectomy and features of pelvic floor function (muscle shortening) and urethral length before and after prostatectomy.

METHODS

Sixty men referred for preoperative PFM training before radical prostatectomy participated. The International Continence Society Male Short Form questionnaire was used to quantify continence status. Transperineal ultrasound (US) imaging was used to record pelvic displacements related to activation of striated urethral sphincter, bulbocavernosus (BC) and puborectalis muscles during cough, "natural" voluntary contraction following pamphlet instruction, and trained voluntary contraction after formal physiotherapist instruction including US feedback.

RESULTS

Pelvic floor displacements following training differed between continent and incontinent men; continent participants demonstrated increased SUS shortening after training (compared with "natural"), but no difference was observed between trained and "natural" contractions for incontinent participants. Motion at ano-rectal junction during cough was reduced following surgery, but voluntary and involuntary activation of SUS or BC was not consistently affected by surgery.

CONCLUSIONS

Participants' capacity to improve function of the SUS with training appears related to postprostatectomy continence outcome.

Features and methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system: a Delphi expert consensus study

ABSTRACT

Classification of musculoskeletal pain based on underlying pain mechanisms (nociceptive, neuropathic, and nociplastic pain) is challenging. In the absence of a gold standard, verification of features that could aid in discrimination between these mechanisms in clinical practice and research depends on expert consensus. This Delphi expert consensus study aimed to: (1) identify features and assessment findings that are unique to a pain mechanism category or shared between no more than 2 categories and (2) develop a ranked list of candidate features that could potentially discriminate between pain mechanisms. A group of international experts were recruited based on their expertise in the field of pain. The Delphi process involved 2 rounds: round 1 assessed expert opinion on features that are unique to a pain mechanism category or shared between 2 (based on a 40% agreement threshold); and round 2 reviewed features that failed to reach consensus, evaluated additional features, and considered wording changes. Forty-nine international experts representing a wide range of disciplines participated. Consensus was reached for 196 of 292 features presented to the panel (clinical examination-134 features, quantitative sensory testing-34, imaging and diagnostic testing-14, and pain-type questionnaires-14). From the 196 features, consensus was reached for 76 features as unique to nociceptive (17), neuropathic (37), or nociplastic (22) pain mechanisms and 120 features as shared between pairs of pain mechanism categories (78 for neuropathic and nociplastic pain). This consensus study generated a list of potential candidate features that are likely to aid in discrimination between types of musculoskeletal pain.

What messages predict intention to self-manage low back pain? A study of attitudes towards patient education

ABSTRACT

This observational study evaluated people's attitudes towards educational statements and tested whether this predicted intention to self-manage low back pain (LBP). People with or without LBP who were older than 18 years and fluent in written English were recruited. Participants completed an online survey asking demographic questions and questions on the presence or absence of LBP, its duration, and intensity. We assessed attitude toward educational statements and conducted linear regression analyses to investigate the relationship between attitude toward each statement and intention to self-manage. We recruited 656 participants, n = 345 (53.6%), with LBP of varying duration. On average, participants had a positive attitude toward all statements except one; participants with chronic LBP had a negative attitude toward a statement relating to the cause of LBP. The effect of attitude on intention to self-manage was dependent on whether someone had LBP and for how long. For example, increased intention to self-manage was predicted by a positive attitude toward educational statements related to staying active (β = 0.22 [CI 0.11-0.33]) in participants without pain, statements about reassurance (β = 0.33 [CI 0.16-0.49]) for participants with acute or subacute LBP, and statements about the severity of back pain (β = 0.25 [CI 0.18-0.33]) for participants with chronic LBP. We noted differences in attitude toward educational messages and individuals' intention to self-manage LBP depending on pain duration. Self-management could be encouraged with specific reassurance in people with acute or subacute LBP and education about severity in people with chronic LBP.

Validation of shear wave elastography as a noninvasive measure of pelvic floor muscle stiffness

OBJECTIVES

To investigate the validity of shear wave elastography (SWE) as a measure of stiffness of the puborectalis muscle by examining: (1) the relationship between puborectalis muscle stiffness and pelvic floor muscle (PFM) activation at different intensities; and (2) the relationship between puborectalis stiffness and pelvic floor morphometry during contractions at different intensities.

METHODS

Fifteen healthy asymptomatic women performed 6-s isometric PFM contractions at different intensities (0, 10%, 20%, 30%, 50%, 75%, and 100% of maximal voluntary contraction) guided by intravaginal electromyography (EMG). Stiffness of the puborectalis muscle was measured using SWE by calculating the average shear modulus in regions of interest that contained puborectalis muscle fibers parallel to the transducer. Pelvic floor morphometry was assessed in the mid-sagittal plane using transperineal B-mode ultrasound imaging. Shear modulus, EMG (root mean square amplitude) and pelvic floor morphometry parameters were normalized to the value recorded during maximal voluntary contraction. To assess the relationship between stiffness and pelvic floor activation/morphometry, coefficient of determination (r² ) was calculated for each participant and a group average was computed.

RESULTS

Shear modulus and EMG were highly correlated (average r² ; left 0.90 ± 0.08, right 0.87 ± 0.15). Shear modulus also strongly correlated with bladder neck position (x-axis horizontal coordinates relative to the pubic symphysis), anorectal rectal angle and position, levator plate angle, and antero-posterior diameter of the levator hiatus (average r² : range 0.62-0.78).

CONCLUSIONS

These findings support the validity of SWE to assess puborectalis muscle stiffness in females. Stiffness measures were strongly associated with PFM EMG and pelvic floor morphometry and may be used to indirectly assess the level of activation of the puborectalis muscle without the use of more invasive techniques. By overcoming limitations of current assessment tools, this promising noninvasive and real-time technique could enable important breakthrough in the pathophysiology and management of pelvic floor disorders.

The Effects of Reconditioning Exercises Following Prolonged Bed Rest on Lumbopelvic Muscle Volume and Accumulation of Paraspinal Muscle Fat

Reduced muscle size and accumulation of paraspinal muscle fat content (PFC) have been reported in lumbopelvic muscles after spaceflights and head-down tilt (HDT) bed rest. While some information is available regarding reconditioning programs on muscle atrophy recovery, the effects on the accumulation of PFC are unknown. Recently, a device (the Functional Re-adaptive Exercise Device—FRED) has been developed which aims to specifically recruit lumbopelvic muscles. This study aimed to investigate the effects of a standard reconditioning (SR) program and SR program supplemented by FRED (SR + FRED) on the recovery of the lumbopelvic muscles following 60-day HDT bed rest. Twenty-four healthy participants arrived at the facility for baseline data collection (BDC) before the bed rest period. They remained in the facility for 13-day post-HDT bed rest and were randomly allocated to one of two reconditioning programs: SR or SR + FRED. Muscle volumes of the lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles were measured from axial T1-weighted magnetic resonance imaging (MRI) at all lumbar intervertebral disc levels. PFC was determined using a chemical shift-based lipid/water Dixon sequence. Each lumbopelvic muscle was segmented into four equal quartiles (from medial to lateral). MRI of the lumbopelvic region was conducted at BDC, Day-59 of bed rest (HDT59), and Day-13 after reconditioning (R13). Comparing R13 with BDC, the volumes of the LM muscle at L4/L5 and L5/S1, LES at L1/L2, and QL at L3/L4 had not recovered (all—p < 0.05), and the PM muscle remained larger at L1/L2 (p = 0.001). Accumulation of PFC in the LM muscle at the L4/L5 and L5/S1 levels remained higher in the centro-medial regions at R13 than BDC (all—p < 0.05). There was no difference between the two reconditioning programs. A 2-week reconditioning program was insufficient to fully restore all volumes of lumbopelvic muscles and reverse the accumulation of PFC in the muscles measured to BDC values, particularly in the LM muscle at the lower lumbar levels. These findings suggest that more extended reconditioning programs or alternative exercises may be necessary to fully restore the size and properties of the lumbopelvic muscles after prolonged bed rest.

How Individuals With Low Back Pain Conceptualize Their Condition: A Collaborative Modeling Approach

Low back pain (LBP) is complex. This study aimed to use collaborative modeling to evaluate conceptual models that individuals with LBP have of their condition, and to compare these models with those of researchers/clinicians. Twenty-eight individuals with LBP were facilitated to generate mental models, using "fuzzy cognitive maps," that represented conceptualization of their own LBP and LBP "in general." "Components" (ie, causes, outcomes and treatments) related to pain, disability and quality of life were proposed, along with the weighted "Connections" between Components. Components were classified into thematic categories. Weighting of Connections were summed for each Component to judge relative importance. Individual models were aggregated into a metamodel. When considering their own condition, participants' models included 19(SD = 6) Components and 43(18) Connections with greatest weight on "Biomechanical" components. When considering LBP in general, models changed slightly. Patient models contrasted the more complex models of researchers/clinicians (25(7) Components; 77(42) Connections), with most weight on "Psychological" components. This study provides unique insight into how individuals with LBP consider their condition, which is largely biomedical and narrower than clinician/researcher perspectives. Findings highlight challenges for changing public perception of LBP, and provide a method with potential utility to understand how individuals conceptualize their condition. PERSPECTIVE: Collaborative modeling was used to understand how individuals with low back pain conceptualize their own condition, the condition in general, and compare this with models of expert researchers/clinicians. Data revealed issues in how individuals with back pain conceptualize their condition, and the method's potential utility for clinical evaluation of patients.

Balance control in unstable sitting in individuals with an acute episode of low back pain

BACKGROUND

Low back pain (LBP) is associated with altered postural control, mostly observed at later stages in the LBP trajectory. It is unclear whether postural control differs in the acute phase of LBP.

RESEARCH QUESTION

Is postural control different in the acute phase of LBP (<2 weeks) and do differences depend on pain intensity, psychological features and/or availability of vision to control posture?

METHODS

Cross-sectional study design. An unstable sitting paradigm (to reduce the contribution of the legs) assessed postural control of participants with acute LBP (n = 133) and pain-free controls (n = 74). Centre of pressure (CoP) reflected seat movements. Participants balanced with eyes closed, open, or with visual feedback of the anteroposterior CoP position. Balance performance was expressed by CoP displacement and velocity, and stabilogram diffusion analysis. Generalised estimating equations (GEEs) including body mass index, sex, and safety bar touch, tested differences between groups and between balance conditions. Separate GEEs were used to model performance measures and bar touch (yes/no) including pain intensity, disability and psychological features.

RESULTS

CoP displacement and critical point coordinates (time and distance where CoP diffusion rate or spread slows) were larger in LBP than pain-free controls independent of balance condition. Long-term diffusion rate was greater in LBP than controls with eyes closed. CoP velocity measures (RMS, short term diffusion rate) were not different between groups. Pain intensity and psychological features were not linearly related to balance performance in participants with acute LBP. Higher pain catastrophizing was associated with touching the safety bar.

SIGNIFICANCE

Postural control differs in acute LBP than pain-free controls. Findings might be explained by altered sensory processing, lesser ability to reweight proprioceptive information and/or less accurate trunk muscle control. Although not linearly related to pain-intensity or psychological features in the acute stage, reduced balance performance could potentially have impact on LBP recovery.

Postural control of the trunk in individuals with and without low back pain during unstable sitting: A protocol for a systematic review with an individual participant data meta-analysis

Introduction

Postural control of the trunk is critical for performance of everyday activities and the health of spinal tissues. Although some studies report that individuals with low back pain (LBP) have poorer/compromised postural control than pain-free individuals when sitting on an unstable surface, others do not. Analyses commonly lack the statistical power to evaluate the relevance of features that could impact the performance of postural control, such as sex, age, anthropometrics, pain intensity or disability. This paper outlines a protocol for a systematic review with an individual participant data (IPD) meta-analysis that aims to synthesise the evidence and evaluate differences of postural control measures between individuals with and without LBP during unstable sitting.

Methods and analysis

A systematic review with IPD meta-analysis will be conducted according to PRISMA-IPD guidelines. To identify relevant studies, electronic databases and the reference lists of included articles will be screened. Unstable seat movements are derived from centre of pressure (CoP) data using a force plate or angle of the seat using motion systems/sensors. The comprehensiveness of reporting and methodological quality of included studies will be assessed. Analysis will involve a descriptive analysis to synthesise the findings of all included studies and a quantitative synthesis using two-stage IPD meta-analysis of studies that include both individuals with and without LBP for which IPD set can be obtained from authors. Analyses will include consideration of confounding variables.

Ethics

Exemption from ethical approval was obtained for this review (University of Queensland, ID: 2019003026).

Systematic review registration

PROSPERO ID: CRD42021124658.

Can training of a skilled pelvic movement change corticomotor control of back muscles? Comparison of single and paired-pulse transcranial magnetic stimulation

Evidence suggests excitability of the motor cortex (M1) changes in response to motor skill learning of the upper limb. Few studies have examined immediate changes in corticospinal excitability and intra‐cortical mechanisms following motor learning in the lower back. Further, it is unknown which transcranial magnetic stimulation (TMS) paradigms are likely to reveal changes in cortical function in this region. This study aimed to (1) compare corticospinal excitability and intra‐cortical mechanisms in the lower back region of M1 before and after a single session of lumbopelvic tilt motor learning task in healthy people and (2) compare these measures between two TMS coils and two methods of recruitment curve (RC) acquisition. Twenty‐eight young participants (23.6 ± 4.6 years) completed a lumbopelvic tilting task involving three 5‐min blocks. Single‐pulse (RC from 70% to 150% of active motor threshold) and paired‐pulse TMS measures (ICF, SICF and SICI) were undertaken before (using 2 coils: figure‐of‐8 and double cone) and after (using double cone coil only) training. RCs were also acquired using a traditional and rapid method. A significant increase in corticospinal excitability was found after training as measured by RC intensities, but this was not related to the RC slope. No significant differences were found for paired‐pulse measures after training. Finally, there was good agreement between RC parameters when measured with the two different TMS coils or different acquisition methods (traditional vs. rapid). Changes in corticospinal excitability after a single session of lumbopelvic motor learning task are seen, but these changes are not explained by changes in intra‐cortical mechanisms.

Physiotherapists Both Reproduce and Resist Biomedical Dominance when Working With People With Low Back Pain: A Qualitative Study Towards New Praxis

Despite recommendations to incorporate physical and psychosocial factors when providing care for people with back pain, research suggests that physiotherapists continue to focus on biological aspects. This study investigated how interpersonal and institutional norms influence this continued enactment of the biological aspects of management. We used theoretically-driven analysis, drawing from Foucauldian notions of power, to analyse 28 ethnographic observations of consultations and seven group discussions with physiotherapists. Analysis suggested that physiotherapy training established expectations of what a physiotherapist 'should' focus on, and institutional circumstances strongly drew the attention of physiotherapists towards biological aspects. Resistance to these forces was possible when, for example, physiotherapists reflected upon their practice, used silences and pauses during consultations, and actively collaborated with patients. These circumstances facilitated use of non-biomedical management approaches. Findings may assist physiotherapists to rework the enduring normative focus on biomedical aspects of care when providing care for patients with back pain.

Effects of different modalities of afferent stimuli of the lumbo-sacral area on control of lumbar paravertebral muscles

Somatosensory feedback to the central nervous system is essential to plan, perform and refine spine motor control. However, the influence of somatosensory afferent input from the trunk on the motor output to trunk muscles has received little attention. The objective was to compare the effects of distinct modalities of afferent stimulation on the net motoneuron and corticomotor excitability of paravertebral muscles. Fourteen individuals were recruited. Modulation of corticospinal excitability (motor-evoked potential [MEP]) of paravertebral muscles was measured when afferent stimuli (cutaneous noxious and non-noxious, muscle contraction) were delivered to the trunk at 10 intervals prior to transcranial magnetic stimulation. Each peripheral stimulation was applied alone, and subsequent EMG modulation was measured to control for net motoneuron excitability. MEP modulation and MEP/EMG ratio were used as measures of corticospinal excitability with and without control of net motoneuron excitability, respectively. MEP and EMG modulation were smaller after evoked muscle contraction than after cutaneous noxious and non-noxious stimuli. MEP/EMG ratio was not different between stimulation types. Both MEP and EMG amplitudes were reduced after evoked muscle contraction, but not when expressed as MEP/EMG ratio. Noxious and non-noxious stimulation had limited impact on all variables. Distinct modalities of peripheral afferent stimulation of the lumbo-sacral area differently modulated responses of paravertebral muscles, but without an influence on corticospinal excitability with control of net motoneuron excitability. Muscle stimulation reduced paravertebral activity and was best explained by spinal mechanisms. The impact of afferent stimulation on back muscles differs from the effects reported for limb muscles.

The Flares of Low back pain with Activity Research Study (FLAReS): study protocol for a case-crossover study nested within a cohort study

BACKGROUND

Although it is generally accepted that physical activity and flares of low back pain (LBP) are related, evidence for the directionality of this association is mixed. The Flares of Low back pain with Activity Research Study (FLAReS) takes a novel approach to distinguish the short-term effects of specific physical activities on LBP flares from the cumulative effects of such activities, by conducting a longitudinal case-crossover study nested within a cohort study. The first aim is to estimate the short-term effects (≤ 24 h) of specific physical activities on LBP flares among Veterans in primary care in the Veterans Affairs healthcare system. The second aim is to estimate the cumulative effects of specific activities on LBP-related functional limitations at 1-year follow-up.

METHODS

Up to 550 adults of working age (18-65 years) seen for LBP in primary care complete up to 36 "Scheduled" surveys over 1-year follow-up, and also complete unscheduled "Flare Window" surveys after the onset of new flares. Each survey asks about current flares and other factors associated with LBP. Surveys also inquire about activity exposures over the 24 h, and 2 h, prior to the time of survey completion (during non-flare periods) or prior to the time of flare onset (during flares). Other questions evaluate the number, intensity, duration, and/or other characteristics of activity exposures. Other exposures include factors related to mood, lifestyle, exercise, concurrent treatments, and injuries. Some participants wear actigraphy devices for weeks 1-4 of the study. The first aim will examine associations between 10 specific activity categories and participant-reported flares over 1-year follow-up. The second aim will examine associations between the frequency of exposure to 10 activity categories over weeks 1-4 of follow-up and long-term functional limitations at 12 months. All analyses will use a biopsychosocial framework accounting for potential confounders and effect modifiers.

DISCUSSION

FLAReS will provide empirically derived estimates of both the short-term and cumulative effects of specific physical activities for Veterans with LBP, helping to better understand the role of physical activities in those with LBP.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04828330 , registered April 2, 2021.

Intramuscular lipid concentration increased in localized regions of the lumbar muscles following 60 day bedrest

BACKGROUND CONTEXT

Prolonged bedrest induces accumulation of intramuscular lipid concentration (ILC) in the lumbar musculature; however, spatial distribution of ILC has not been determined. Artificial gravity (AG) mitigates some adaptations induced by 60 day bedrest by creating a head-to-feet force while participants are in a supine position.

PURPOSE

To quantify the spatial distribution of accumulation of ILC in the lumbar musculature after 60 day bedrest, and whether this can be mitigated by AG exposure.

STUDY DESIGN

Prospective longitudinal study.

PATIENT SAMPLE

Twenty-four healthy individuals (8 females) participated in the study: Eight received 30 min continuous AG (cAG); Eight received 6 × 5 min AG (iAG), interspersed with rests; Eight were not exposed to AG (CRTL).

OUTCOME MEASURES

From 3T magnetic resonance imaging (MRI), axial images were selected to assess lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles from L1/L2 to L5/S1 intervertebral disc levels. Chemical shift-based 2-echo lipid and/or water Dixon sequence was used to measure tissue composition. Each lumbar muscle was segmented into four equal quartiles (from medial to lateral).

METHODS

Participants arrived at the facility for the baseline data collection before undergoing a 60 day strict 6° head-down tilt (HDT) bedrest period. MRI of the lumbopelvic region was conducted at baseline and Day-59 of bedrest. Participants performed all activities, including hygiene, in 6° HDT and were discouraged from moving excessively or unnecessarily.

RESULTS

At the L4/L5 and L5/S1 intervertebral disc levels, 60-day bedrest induced a greater increase in ILC in medial and lateral regions (∼+4%) of the LM than central regions (∼+2%; p<.05). A smaller increase in ILC was induced in the lateral region of LES (∼+1%) at L1/L2 and L2/L3 than at the centro-medial region (∼+2%; p<.05). There was no difference between CRTL and intervention groups.

CONCLUSIONS

Inhomogeneous spatial distribution of accumulation of ILC was found in the lumbar musculature after 60 day bedrest. These findings might reflect pathophysiological mechanisms related to muscle disuse and contribute to localized lumbar spine dysfunction. Altered spatial distribution of ILC may impair lumbar spine function after prolonged body unloading, which could increase injury risk to vulnerable soft tissues, such as the lumbar intervertebral discs. These novel results may represent a new biomarker of lumbar deconditioning for astronauts, bedridden, sedentary individuals, or those with chronic back pain. Changes are potentially modifiable but not by the AG protocols tested here.

A vision for the future of wearable sensors in spine care and its challenges: narrative review

OBJECTIVE

This review aimed to: (I) provide a brief overview of some topical areas of current literature regarding applications of wearable sensors in the management of low back pain (LBP); (II) present a vision for a future comprehensive system that integrates wearable sensors to measure multiple parameters in the real world that contributes data to guide treatment selection (aided by artificial intelligence), uses wearables to aid treatment support, adherence and outcome monitoring, and interrogates the response of the individual patient to the prescribed treatment to guide future decision support for other individuals who present with LBP; and (III) consider the challenges that will need to be overcome to make such a system a reality.

BACKGROUND

Advances in wearable sensor technologies are opening new opportunities for the assessment and management of spinal conditions. Although evidence of improvements in outcomes for individuals with LBP from the use of sensors is limited, there is enormous future potential.

METHODS

Narrative review and literature synthesis.

CONCLUSIONS

Substantial research is underway by groups internationally to develop and test elements of this system, to design innovative new sensors that enable recording of new data in new ways, and to fuse data from multiple sources to provide rich information about an individual's experience of LBP. Together this system, incorporating data from wearable sensors has potential to personalise care in ways that were hitherto thought impossible. The potential is high but will require concerted effort to develop and ultimately will need to be feasible and more effective than existing management.

Distinct displacement of the superficial and deep fascial layers of the iliotibial band during a weight shift task in runners: An exploratory study

Motion of the fascial layers of the iliotibial band (ITB), as a reinforcement of the deep fascia lata, is likely to be relevant for its function and mechanical behaviour. This exploratory study aimed to evaluate the ITB fascial layers displacement during a weight shift task. Thirteen pain-free runners performed a 6-second standing weight shift task. B-mode ultrasound imaging using an automated fascicle tracking algorithm was used to measure proximal and distal displacement of superficial and deep ITB layers at the middle region. To study the potential contributors to individual variation of fascial motion, we recorded the activity of five hip/thigh muscles with electromyography (EMG), thigh/pelvis/trunk position with accelerometers, and centre of pressure with a force plate. Linear regressions estimated the relationship between displacement of fascial layers and hip/trunk angles. Independent t-tests or Fisher's exact tests compared EMG and movement-related parameters between participants who demonstrated motion of the fascia in the proximal and distal directions. Thickness of the ITB and the loose connective tissue between its layers were calculated. Proximal displacement was observed in six (-4.1 ± 1.9 mm [superficial]) and two (-6.2 ± 2.0 mm [deep]) participants. Distal displacement was observed for seven participants for each layer (3.1 ± 1.1 mm [superficial]; 3.6 ± 1.3 mm [deep]). Four participants did not show displacement of the deep layer. Trunk lateral flexion and gluteus medius muscle activity were determinants of proximal motion of the superficial layer. Loose connective tissue was thinner in participants without displacement of the deep layer. Displacement of the ITB fascial layers varies between individuals. Variation related to differences in joint movements and muscle activity. This study highlights the complex interaction between fascia and movement.

Relationship between systemic inflammation and recovery over 12 months after an acute episode of low back pain

BACKGROUND CONTEXT

Individual characteristics can influence outcomes after injury. Our previous work in individuals with early-acute low back pain (LBP) identified subgroups (clusters) with specific biopsychosocial features that recovered poorly or well by 6 months.

PURPOSE

This study extends on that work by revealing the short- and long-term trajectories of recovery and systemic inflammation of these participant clusters: (1) "inflammatory & poor sleep" (Cluster 1), "high TNF & depression" (Cluster 2), "high pain & high pain-related fear" (Cluster 3), and "low pain & low pain-related fear" (Cluster 4).

STUDY DESIGN/SETTING

Longitudinal cohort study.

PATIENT SAMPLE

Eighty-three individuals within 2 weeks of an acute episode of LBP - grouped into their a priori-defined cluster.

OUTCOME MEASURES

General participant characteristics (sex, age, body mass index, smoking history, previous LBP history); self-reported LBP (0-10 numerical rating scale, LBP-related disability (Roland-Morris Disability Questionnaire), depression (Center for Epidemiological Studies Depression Scale, pain catastrophizing (Pain Catastrophizing Scale), fear avoidance (Fear Avoidance Beliefs Questionnaire), pain self-efficacy (Pain Self-Efficacy Questionnaire), and sleep (Pittsburgh Sleep Quality Index); systemic inflammatory biomarkers (C-reactive protein [CRP], interleukin-6 [IL-6], interleukin-1β, tumor necrosis factor [TNF]).

METHODS

Participants provided blood for the measurement of CRP/cytokines, and completed questionnaires related to their pain/disability, psychological and sleep status. Blood measures were repeated 3-monthly for 9 months, and pain/disability were self-reported fortnightly for 12 months. Recovery (change in pain) and CRP/cytokines were longitudinally compared between clusters using mixed-models. Associations between baseline factors and follow-up CRP/cytokines levels were assessed with multiple regression.

RESULTS

Clusters 1 and 2 were associated, but oppositely, with recovery over the 12-months. Cluster 1 reported most recovery at every 3-monthly interval, whereas Cluster 2 reported least recovery. Cluster 1 had elevated CRP (and IL-6) at baseline that continued to decrease from 3 to 9 months. TNF was elevated early and persistently in Cluster 2. Baseline factors other than inflammation generally failed to predict follow-up inflammation.

CONCLUSIONS

Findings support the early role of CRP (and perhaps IL-6) in control of inflammation and recovery, and a pathological role of persistent TNF overexpression, which may be perpetuated by depressive-like behaviors.

Risk factors for low back pain outcome: Does it matter when they are measured?

BACKGROUND

The early identification of factors that increase risk of poor recovery from acute low back pain (LBP) is critical to prevent the transition to chronicity. Although most studies of risk factors for poor outcome in LBP tend to investigate the condition once it is already persistent, there is evidence to suggest that this differs from risk factors measured during the early-acute stage. This study aimed to identify early risk factors for poor outcome in the short- and long-term in individuals with acute LBP, and to compare this with factors identified at 3 months in the same cohort.

METHODS

One hundred and thirty-three individuals were recruited within 2 weeks of an acute LBP episode and completed questionnaires related to their sociodemographic, psychological, clinical and history/treatment status at baseline and 3 months later, and their pain-level fortnightly for 12 months.

RESULTS

Of the 133 participants recruited, follow-up data was provided by 120 at 3 months, 97 at 6 months, 85 at 9 months and 94 at 12 months. Linear regression identified various factors at baseline (acute phase) and 3 months later that predicted short- and long-term outcome (pain level, change in pain). Key findings were that: (1) depressive symptoms at baseline most consistently predicted worse outcome; (2) psychological factors in general at 3 months were more predictive of outcome than when measured at baseline; (3) early health care utilisation predicted better outcome, whereas use of pain medication later (3 months) predicted worse outcome; and (4) sex and BMI predicted outcome inconsistently over 12-months.

CONCLUSIONS

The results highlight the multidimensional nature of risk factors for poor outcome in LBP and the need to consider time variation in these factors.

Expert-Moderated Peer-to-Peer Online Support Group for People With Knee Osteoarthritis: Mixed Methods Randomized Controlled Pilot and Feasibility Study

Background

Osteoarthritis (OA) is a major problem globally. First-line management comprises education and self-management strategies. Online support groups may be a low-cost method of facilitating self-management.

Objective

The aim of this randomized controlled pilot study is to evaluate the feasibility of the study design and implementation of an evidence-informed, expert-moderated, peer-to-peer online support group (My Knee Community) for people with knee OA. The impacts on psychological determinants of self-management, selected self-management behaviors, and health outcomes were secondary investigations.

Methods

This mixed methods study evaluated study feasibility (participant recruitment, retention, and costs), experimental intervention feasibility (acceptability and fidelity to the proposed design, including perceived benefit, satisfaction, and member engagement), psychological determinants (eg, self-efficacy and social support), behavioral measures, health outcomes, and harms. Of a total of 186, 63 (33.9%) participants (41/63, 65% experimental and 22/63, 35% control) with self-reported knee OA were recruited from 186 volunteers. Experimental group participants were provided membership to My Knee Community, which already had existing nonstudy members, and were recommended a web-based education resource (My Joint Pain). The control group received the My Joint Pain website recommendation only. Participants were not blinded to their group allocation or the study interventions. Participant-reported data were collected remotely using web-based questionnaires. A total of 10 experimental group participants also participated in semistructured interviews. The transcribed interview data and all forum posts by the study participants were thematically analyzed.

Results

Study feasibility was supported by acceptable levels of retention; however, there were low levels of engagement with the support group by participants: 15% (6/41) of participants did not log in at all; the median number of times visited was 4 times per participant; only 29% (12/41) of participants posted, and there were relatively low levels of activity overall on the forum. This affected the results for satisfaction (overall mean 5.9/10, SD 2.7) and perceived benefit (17/31, 55%: yes). There were no differences among groups for quantitative outcomes. The themes discussed in the interviews were connections and support, information and advice, and barriers and facilitators. Qualitative data suggest that there is potential for people to derive benefit from connecting with others with knee OA by receiving support and assisting with unmet informational needs.

Conclusions

Although a large-scale study is feasible, the intervention implementation was considered unsatisfactory because of low levels of activity and engagement by members. We recommend that expectations about the support group need to be made clear from the outset. Additionally, the platform design needs to be more engaging and rewarding, and membership should only be offered to people willing to share their personal stories and who are interested in learning from the experiences of others.

Trial Registration

Australian New Zealand Clinical Trials Registry ACTRN12619001230145; http://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377958

How reliable is measurement of posture during sleep: real-world measurement of body posture and movement during sleep using accelerometers

Objective Understanding sleeping behaviours could improve prevention and treatment of sleep problems and associated health conditions. This study aimed to evaluate a method to assess body posture and movement during sleep using trunk-worn accelerometers for 28 days. Approach Participants (50 adults with low back pain (66% female); aged 32(±9) years) wore two activPAL-micro sensors (thigh, trunk) during their normal daily life for 28 consecutive days. Parameters related to body posture (e.g., time spent lying supine or prone) and movement (e.g., number of turns) during sleep were calculated for each night. Average values for each parameter were identified for different periods, the Spearman-Brown Prophecy Formula was used to estimate the minimum number of nights required to obtain a reliable estimate of each parameter, and repeatability of measures between different weeks was calculated. Main Results Participants spent 8.1(±0.8) hours asleep and most time (44%) was spent in a supine posture. The minimum number of nights required for reliable estimates varied between sleep parameters, range 4-21 nights. The most stable parameters (i.e., requiring less than seven nights) were "average activity", "no. of turns", "time spent prone", and "posture changes in the first hour". Some measures differed substantially between weeks. Significance Most sleep parameters related to body posture and movement require a week or more of monitoring to provide reliable estimates of behaviour over one month. Notably, one week may not reflect behaviour in another week, and the time varying nature of sleep needs to be considered.

"Taking action" to reduce pain-Has interpretation of the motor adaptation to pain been too simplistic?

Movement adapts during acute pain. This is assumed to reduce nociceptive input, but the interpretation may not be straightforward. We investigated whether movement adaptation during pain reflects a purposeful search for a less painful solution. Three groups of participants performed two blocks (Baseline, Experimental) of wrist movements in the radial-ulnar direction. For the Control group (n = 10) both blocks were painfree. In two groups, painful electrical stimulation was applied at the elbow in Experimental conditions when the wrist crossed radial-ulnar neutral. Different stimulus intensities were given for specific wrist angles in a secondary direction (flexion-extension) as the wrist passed radial-ulnar neutral (Pain 5–1 group:painful stimulation at ~5 or ~1/10—n = 21; Pain 5–0 group:~5 or 0(no stimulation)/10—n = 6)). Participants were not informed about the less painful alternative and could use any strategy. We recorded the percentage of movements using the wrist flexion/extension alignment that evoked the lower intensity noxious stimulus, movement variability, and change in wrist/forearm alignment during pain. Participants adapted their strategy of wrist movement during pain provocation and reported less pain over time. Three adaptations of wrist movement were observed; (i) greater use of the wrist alignment with no/less noxious input (Pain 5–1, n = 8/21; Pain 5–0, n = 2/6); (ii) small (n = 9/21; n = 3/6) or (iii) large (n = 4/21; n = 1/6) change of wrist/forearm alignment to a region that was not allocated to provide an actual reduction in noxious stimulus. Pain reduction was achieved with “taking action” to relieve pain and did not depend on reduced noxious stimulus.

Multifidus Muscle Fiber Type Distribution is Changed in Mouse Models of Chronic Intervertebral Disc Degeneration, but is not Attenuated by Whole Body Physical Activity

STUDY DESIGN

Case-controlled animal study.

OBJECTIVE

The aim of this study was to investigate whether multifidus muscle fiber type distribution changes in models of interverbal disc (IVD) degeneration and whether this is resolved by physical activity (PA).

SUMMARY OF BACKGROUND DATA

The loss of slow type I muscle fibers in the multifidus muscle in people with low back pain is contentious. Data from animal models of IVD degeneration suggest some discrepancies in human studies might be explained by the dependence of slow muscle fiber changes and their underlying mechanisms, on the time since injury and progression of IVD degeneration. It is not yet resolved what changes are apparent once the chronic phase is established. It is also not known whether muscle fiber changes can be resolved by whole body PA. This study aimed to examine slow fiber distribution in the multifidus muscle in models of IVD injury or spontaneous degeneration in animals with or without exposure to PA.

METHODS

Two models of IVD degeneration were used. The first model used a genetically modified mouse (SPARC-null) that spontaneously develops IVD degeneration. The second model involved a surgically induced IVD lesion to induce degeneration. Mice in each study were allocated to housing with or without a running wheel for PA. At 12 months of age, the multifidus muscle was harvested. Slow muscle fiber distribution and the mRNA expression of genes associated with muscle fiber type transformation were examined.

RESULTS

The proportion and cross-sectional area of slow muscle fibers were reduced in both models of IVD degeneration compared to controls, without evidence of ongoing fiber transformation. Whole-body PA did not attenuate these alterations.

CONCLUSION

Results confirmed slow muscle fiber loss in the multifidus in the chronic phase of IVD degeneration induced spontaneously and by injury. Whole-body PA did not attenuate changes to muscle fiber distribution. More specific approaches to muscle activation might be required to achieve more complete reversal of muscle fiber changes, with potential implications for therapy in humans.Level of Evidence: N/A.

Paraspinal muscle imaging measurements for common spinal disorders: review and consensus-based recommendations from the ISSLS degenerative spinal phenotypes group

PURPOSE

Paraspinal muscle imaging is of growing interest related to improved phenotyping, prognosis, and treatment of common spinal disorders. We reviewed issues related to paraspinal muscle imaging measurement that contribute to inconsistent findings between studies and impede understanding.

METHODS

Three key contributors to inconsistencies among studies of paraspinal muscle imaging measurements were reviewed: failure to consider possible mechanisms underlying changes in paraspinal muscles, lack of control of confounding factors, and variations in spinal muscle imaging modalities and measurement protocols. Recommendations are provided to address these issues to improve the quality and coherence of future research.

RESULTS

Possible pathophysiological responses of paraspinal muscle to various common spinal disorders in acute or chronic phases are often overlooked, yet have important implications for the timing, distribution, and nature of changes in paraspinal muscle. These considerations, as well as adjustment for possible confounding factors, such as sex, age, and physical activity must be considered when planning and interpreting paraspinal muscle measurements in studies of spinal conditions. Adoption of standardised imaging measurement protocols for paraspinal muscle morphology and composition, considering the strengths and limitations of various imaging modalities, is critically important to interpretation and synthesis of research.

CONCLUSION

Study designs that consider physiological and pathophysiological responses of muscle, adjust for possible confounding factors, and use common, standardised measures are needed to advance knowledge of the determinants of variations or changes in paraspinal muscle and their influence on spinal health.

Gluteal Muscle Atrophy and Increased Intramuscular Lipid Concentration Are Not Mitigated by Daily Artificial Gravity Following 60-Day Head-Down Tilt Bed Rest

Exposure to spaceflight and head-down tilt (HDT) bed rest leads to decreases in the mass of the gluteal muscle. Preliminary results have suggested that interventions, such as artificial gravity (AG), can partially mitigate some of the physiological adaptations induced by HDT bed rest. However, its effect on the gluteal muscles is currently unknown. This study investigated the effects of daily AG on the gluteal muscles during 60-day HDT bed rest. Twenty-four healthy individuals participated in the study: eight received 30 min of continuous AG; eight received 6 × 5 min of AG, interspersed with rest periods; eight belonged to a control group. T1-weighted Dixon magnetic resonance imaging of the hip region was conducted at baseline and day 59 of HDT bed rest to establish changes in volumes and intramuscular lipid concentration (ILC). Results showed that, across groups, muscle volumes decreased by 9.2% for gluteus maximus (GMAX), 8.0% for gluteus medius (GMED), and 10.5% for gluteus minimus after 59-day HDT bed rest (all p < 0.005). The ILC increased by 1.3% for GMAX and 0.5% for GMED (both p < 0.05). Neither of the AG protocols mitigated deconditioning of the gluteal muscles. Whereas all gluteal muscles atrophied, the ratio of lipids to intramuscular water increased only in GMAX and GMED muscles. These changes could impair the function of the hip joint and increased the risk of falls. The deconditioning of the gluteal muscles in space may negatively impact the hip joint stability of astronauts when reexpose to terrestrial gravity.

Characterisation of motor cortex organisation in patients with different presentations of persistent low back pain

Persistence of low back pain is thought to be associated with different underlying pain mechanisms, including ongoing nociceptive input and central sensitisation. We hypothesised that primary motor cortex (M1) representations of back muscles (a measure of motor system adaptation) would differ between pain mechanisms, with more consistent observations in individuals presumed to have an ongoing contribution of nociceptive input consistently related to movement/posture. We tested 28 participants with low back pain sub-grouped by the presumed underlying pain mechanisms: nociceptive pain, nociplastic pain and a mixed group with features consistent with both. Transcranial magnetic stimulation was used to study M1 organisation of back muscles. M1 maps of multifidus (deep and superficial) and longissimus erector spinae were recorded with fine-wire electromyography and thoracic erector spinae with surface electromyography. The nociplastic pain group had greater variability in M1 map location (centre of gravity) than other groups (p < .01), which may suggest less consistency, and perhaps relevance, of motor cortex adaptation for that group. The mixed group had greater overlap of M1 representations between deep/superficial muscles than nociceptive pain (deep multifidus/longissimus: p = .001, deep multifidus/thoracic erector spinae: p = .008) and nociplastic pain (deep multifidus/longissimus: p = .02, deep multifidus/thoracic erector spinae: p = .02) groups. This study provides preliminary evidence of differences in M1 organisation in subgroups of low back pain classified by likely underlying pain mechanisms. Despite the sample size, differences in cortical re-organisation between subgroups were detected. Differences in M1 organisation in subgroups of low back pain supports tailoring of treatment based on pain mechanism and motor adaptation.

Hip muscle activity in male football players with hip-related pain; a comparison with asymptomatic controls during walking

OBJECTIVES

Compare muscle activity between male football players with and without hip-related pain. Morphological and intra-articular features of hip-related pain are proposed pre-cursors to hip osteoarthritis. Altered muscle activity is a feature of severe hip osteoarthritis, but it is not known whether differences exist earlier in the pathological spectrum.

DESIGN

Cross-sectional; SETTING: University laboratory; PARTICIPANTS: Forty-two male football players with hip-related pain; and 19 asymptomatic controls.

MAIN OUTCOME MEASURES

Hip muscle activity (Gluteus maximus, gluteus medius, tensor facia latae, adductor longus and rectus femoris) was recorded during walking using surface electromyography (EMG).

RESULTS

Men with hip-related pain had sustained rectus femoris activity prior to toe-off (47-51% of the gait cycle) (p = 0.01, ES = 0.51) unlike controls who had reduced activity. In men with severe hip-related pain, gluteus maximus EMG was sustained into mid-stance (12-20% of the gait cycle) (F = 6.15, p < 0.01) compared to controls.

CONCLUSIONS

Differences in rectus femoris and gluteus maximus activity were identified between male footballers with and without hip-related pain. The pattern of gluteus maximus EMG relative to peak, approaching mid-stance in severe hip-related pain, is consistent with observations in severe hip osteoarthritis. This supports the hypothesis that symptom severity may influence muscle activity across the spectrum of hip degeneration.

The influence of prostatectomy and body position on location and displacement of pelvic landmarks with pelvic floor muscle contraction

AIMS

To compare pelvic floor muscle (PFM) anatomy and function (i) between pre- and post-prostatectomy in standing, and (ii) between sitting and standing postprostatectomy.

METHODS

Thirty-two men scheduled to undergo a prostatectomy volunteered to participate. Transperineal ultrasound imaging was used to visualize five anatomical pelvic landmarks that have been validated to reflex anatomy and activity of PFMs (pubic symphysis, anorectal junction [ARJ], mid-urethra [MU], bulb of penis [BP], and urethrovesical junction [UVJ]). Both before and after prostatectomy, participants performed three submaximal PFM contractions in sitting and/or standing positions while ultrasound data were recorded.

RESULTS

Postprostatectomy the UVJ location was more caudal and dorsal, the ARJ (puborectalis) vector was longer, the BP was more ventral than preprostatectomy, and these landmarks moved less ventrally with contraction. After prostatectomy, the MU, BP, and ARJ were more ventral in standing than sitting. The UVJ was more caudal and elevated more with contraction in standing than sitting after prostatectomy.

CONCLUSION

These data demonstrate differences in the anatomy and mechanics of PFMs post- versus pre-prostatectomy, and between sitting and standing positions postprostatectomy. Findings are consistent with surgical changes to the bladder and urethral anatomy. Reduced passive support for the urethra and bladder are likely to may contribute to differences between standing and sitting postprostatectomy.

Differential activation of psoas major and rectus femoris during active straight leg raise to end range

The purpose of this study was to investigate the activation of the hip flexor and abdominal muscles during an active straight leg raise (ASLR) to end range of hip flexion. Data were recorded from nine healthy men. Fine-wire electromyography (EMG) electrodes were inserted into psoas major (PM), and surface electrodes were placed over rectus femoris (RF), rectus abdominis, obliquus externus abdominis (OE), and obliquus internus abdominis/transversus abdominis (OI/TrA). EMG and kinematic data were obtained during concentric, hold (at end range) and eccentric phases of an ASLR. Concentric and eccentric movements were divided into three phases (early, mid, and late). Onsets of EMG relative to the onset of the ALSR movement and EMG amplitudes in each phase were compared between muscles. Onsets of the PM (-33 ± 245 ms) and RF (-3 ± 119 ms) EMG prior to leg elevation were significantly earlier than those of the OE and OI/TrA. PM EMG showed highest activation in the late concentric, hold, early eccentric phase, and was significantly higher than RF EMG. OI/TrA EMG was significantly greater in mid and late concentric, hold, and early eccentric phase than other phases. During the ASLR, unlike RF, PM EMG continues to increase towards the end range of hip flexion. Activation of OI/TrA muscle may be involved in control trunk and pelvic movement.

Exploring why people with back pain use the pain management strategies they do: Is research looking in the wrong places?

 

Low back pain (LBP) is a significant issue with considerable impact on people's lives and economies. A plethora of research investigates interventions to manage LBP. However, despite considerable knowledge translation efforts, individuals with the condition frequently use management strategies considered to be 'ineffective'. To address this concern, our aim was to explore why people with LBP choose the management strategies they do.

METHODS

We employed a predominantly inductive, descriptive qualitative design. We interviewed 20 Australian adults who have, or have had, LBP to investigate the management strategies they have employed and why. Data were analysed thematically.

RESULTS

Analysis identified three interrelated themes that highlight that participants chose management strategies, at least in part, because they: 1) reduce symptoms in the very short-term (e.g., immediately, a few hours); 2) have effects beyond the condition (e.g., low cost, lack of negative side effects, convenience, social effects); and 3) are pleasurable.

DISCUSSION

These outcomes suggest that people with LBP are likely to have nuanced reasons for choosing the management strategies they use, and this can contrast with the outcomes tested in empirical studies. Our findings suggest that researchers may need to broaden or rethink which outcomes they measure and how, including by meaningfully engaging consumers in research design. Further, clinicians could better explore their patient's reasons for using the strategies they do, before suggesting they discard existing strategies, or offering new ones.

Effectiveness of a coordinated support system linking public hospitals to a health coaching service compared with usual care at discharge for patients with chronic low back pain: protocol for a randomised controlled trial

Background

Although many people with chronic low back pain (LBP) improve following conservative treatment, one in five will experience worsening symptoms after discharge from treatment and seek health care again. The current LBP clinical care pathway in many health services lacks a well-integrated, systematic approach to support patients to remain physically active and self-manage their symptoms following discharge from treatment. Health coaching can support people to improve physical activity levels and may potentially reduce health care utilisation for LBP. The primary aim of this study is to evaluate the effect of introducing a coordinated support system (linking hospital outpatient physiotherapy services to a public health coaching service) at discharge from LBP treatment, on the future use of hospital, medical, and health services for LBP, compared with usual care provided at discharge.

Methods

Three hundred and seventy-four adults with chronic non-specific LBP will be recruited from the outpatient physiotherapy departments of public hospitals in New South Wales, Australia. Participants will be individually randomised to a support system (n = 187) or usual care group (n = 187). All participants will receive usual care provided at discharge from treatment. Participants allocated to the support system will also receive up to 10 telephone-based health coaching sessions, delivered by the Get Healthy Service®, over a 6-month period. Health coaches will monitor and support participants to improve physical activity levels and achieve personal health-related goals. The primary outcome is the total number of encounters with hospital, medical, and health services for LBP, at 12 months from baseline. A within-trial economic evaluation will quantify the incremental costs and benefits of the support system from a health system perspective, to support reimbursement decision making.

Discussion

This study will establish the effect of a coordinated support system, introduced at discharge from treatment, on the future use of hospital, medical, and health services for LBP and various health outcomes.

Conclusion

Innovative community-driven solutions to support people with chronic LBP after discharge from treatment are urgently needed. Study findings will help inform health care policy and clinical practice in Australia.

Trial Registration

Prospectively registered on the Australian New Zealand Clinical Trials Registry (ACTRN12620000889954) on 10/09/2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04479-z.

Does the Interaction between Local and Systemic Inflammation Provide a Link from Psychology and Lifestyle to Tissue Health in Musculoskeletal Conditions?

Musculoskeletal conditions are known to involve biological, psychological, social and, often, lifestyle elements. However, these domains are generally considered in isolation from each other. This siloed approach is unlikely to be adequate to understand the complexity of these conditions and likely explains a major component of the disappointing effects of treatment. This paper presents a hypothesis that aims to provide a foundation to understand the interaction and integration between these domains. We propose a hypothesis that provides a plausible link between psychology and lifestyle factors with tissue level effects (such as connective tissue dysregulation/accumulation) in musculoskeletal conditions that is founded on understanding the molecular basis for interaction between systemic and local inflammation. The hypothesis provides plausible and testable links between mind and body, for which empirical evidence can be found for many aspects. We present this hypothesis from the perspective of connective tissue biology and pathology (fibrosis), the role of inflammation locally (tissue level), and how this inflammation is shaped by systemic inflammation through bidirectional pathways, and various psychological and lifestyle factors via their influence on systemic inflammation. This hypothesis provides a foundation for new consideration of the development and refinement of personalized multidimensional treatments for individuals with musculoskeletal conditions.

Intermittent short-arm centrifugation is a partially effective countermeasure against upright balance deterioration following 60-day head-down tilt bed rest

This study investigated whether artificial gravity (AG), induced by short-radius centrifugation, mitigated deterioration in standing balance and anticipatory postural adjustments (APAs) of trunk muscles following 60-day head-down tilt bed rest. Twenty-four participants were allocated to one of three groups: control group (n = 8); 30-min continuous AG daily (n = 8); and intermittent 6 × 5 min AG daily (n = 8). Before and immediately after bed rest, standing balance was assessed in four conditions: eyes open and closed on both stable and foam surfaces. Measures including sway path, root mean square, and peak sway velocity, sway area, sway frequency power, and sway density curve were extracted from the center of pressure displacement. APAs were assessed during rapid arm movements using intramuscular or surface electromyography electrodes of the rectus abdominis; obliquus externus and internus abdominis; transversus abdominis; erector spinae at L1, L2, L3, and L4 vertebral levels; and deep lumbar multifidus muscles. The relative latency between the EMG onset of the deltoid and each of the trunk muscles was calculated. All three groups had poorer balance performance in most of the parameters (all P < 0.05) and delayed APAs of the trunk muscles following bed rest (all P < 0.05). Sway path and sway velocity were deteriorated, and sway frequency power was less in those who received intermittent AG than in the control group (all P < 0.05), particularly in conditions with reduced proprioceptive feedback. These data highlight the potential of intermittent AG to mitigate deterioration of some aspects of postural control induced by gravitational unloading, but no protective effects on trunk muscle responses were observed.NEW & NOTEWORTHY This study presents novel insights into the effect of artificial gravity (AG) on the deterioration of standing balance and anticipatory postural adjustments (APAs) of trunk muscles induced by 60-day strict head-down bed rest. The results indicated severe balance dysfunction and delayed APAs during rapid arm movement. AG partially mitigated the deterioration in standing balance and may thus be considered as a potential countermeasure for future planetary surface explorations. Optimization of AG protocols might enhance effects.

The repeatability of measurements of male pelvic floor anatomy and function made from transperineal ultrasound images of healthy men and those before and after prostatectomy

AIMS

To investigate the inter- and intratester repeatability of measurement of the location and displacement of five pelvic landmarks related to pelvic floor muscles with transperineal ultrasound (TPUS) imaging recorded from healthy men and men before and after prostatectomy.

METHODS

TPUS images were selected from four different participant groups: healthy men, men awaiting prostatectomy, men 2 weeks after prostatectomy, and men 12 months after prostatectomy. On two separate occasions, two assessors with different levels of experience performed analysis of location and displacement of five pelvic landmarks in images made at rest and during voluntary contraction. A two-way mixed effects, single measurement, absolute agreement intraclass correlation coefficient (ICC) was used to investigate the repeatability.

RESULTS

Intertester reliability of all locations at rest for all groups was excellent (ICCs > 0.8) except for the craniocaudal coordinate of the ventral urethrovesical junction for men 2 weeks postprostatectomy and the anorectal junction for men with a cancerous prostate. Intertester reliability of the measurement of landmark displacement was acceptable (>0.5) for the dorsoventral axis of motion but not for the craniocaudal axis of motion for all landmarks across all groups. The more experienced assessor was consistently more repeatable. More deeply placed landmarks were more often excluded from analysis and had poorer reliability.

CONCLUSIONS

Analysis of TPUS images across clinical groups is repeatable for both location and displacement of pelvic landmarks related to pelvic floor muscles when measures are made twice. Analysis experience, landmark depth and optimization of ultrasound settings appear to be important factors in reliability.

Lumbar muscle atrophy and increased relative intramuscular lipid concentration are not mitigated by daily artificial gravity after 60-day head-down tilt bed rest

Exposure to axial unloading induces adaptations in paraspinal muscles, as shown after spaceflights. This study investigated whether daily exposure to artificial gravity (AG) mitigated lumbar spine flattening and muscle atrophy associated with 60-day head-down tilt (HDT) bed rest (Earth-based space analog). Twenty-four healthy individuals participated in the study: 8 received 30-min continuous AG; 8 received 6 × 5-min AG interspersed with rest periods; and 8 received no AG exposure (control group). Magnetic resonance imaging (MRI) of the lumbopelvic region was conducted at baseline (BDC) and at day 59 of HDT (HDT59). Longitudinal relaxation time (T1)-weighted images were used to assess morphology of the lumbar spine (spinal length, intervertebral disk angles, disk area) and volumes of the lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles from L₁/L₂ to L₅/S₁ vertebral levels. A chemical shift-based two-point lipid/water Dixon sequence was used to evaluate muscle composition. Results showed that spinal length and disk area increased (P < 0.05); intervertebral disk angles (P < 0.05) and muscle volumes of LM, LES, and QL reduced (P < 0.01); and lipid-to-water ratio for the LM and LES muscles increased (P < 0.01) after HDT59 in all groups. Neither of the AG protocols mitigated the lumbar spinae deconditioning induced by HDT bed rest. The increase in lipid-to-water ratio in LM and LES muscles indicates an increased relative intramuscular lipid concentration. Altered muscle composition in atrophied muscles may impair lumbar spine function after body unloading, which could increase injury risk to vulnerable soft tissues. This relationship needs further investigation.NEW & NOTEWORTHY This study presents novel insights into the morphological adaptations occurring in the lumbar spine after 60-day head-down bed rest and the potential role of artificial gravity (AG) to mitigate them. Results demonstrated no protective effect of AG protocols used in this study. In atrophied paraspinal muscles, the ratio of lipids versus intramuscular water increased in the postural lumbar muscles, which could impair muscle function during upright standing. These findings have relevance for future space explorations.

Sense of effort is distorted in people with chronic low back pain

BACKGROUND

Proprioceptive deficits in people with low back pain (LBP) have traditionally been attributed to altered paraspinal muscle spindle afference and its central processing. Studies conducted in the upper limb demonstrated that sense of effort is also an important source of kinaesthetic information.

OBJECTIVES

To better understand proprioceptive deficits in people with chronic LBP (cLBP), this study aimed to test whether sense of effort is affected in people with cLBP.

DESIGN

Cross-sectional study.

METHOD

Fourteen participants with cLBP and fourteen healthy participants performed a 120 s force matching task with their trunk extensor muscles at a low intensity.

RESULTS

When visual feedback of the generated force was provided, both groups performed the task accurately. Removal of visual feedback resulted in an increase in error for both groups (p < 0.0001), but the increase in error was significantly larger for the cLBP group (p = 0.023). This larger error could be attributed to undershooting of the target force (p = 0.020). The control group did not consistently undershoot or overshoot the target force (p = 0.93). Furthermore, the amount of undershooting for the cLBP group increased as the task progressed (p = 0.016), which was not observed for the control group (p = 0.80).

CONCLUSIONS

The results of this study revealed that sense of effort is affected in cLBP. People with cLBP overestimated the trunk extension force they generated, and the error increased as the trial progressed. With visual feedback however, people with cLBP were able to compensate and perform the task as accurately as people without cLBP.