The Effectiveness of Pain Science Education on Caregiver and Children's Knowledge, Beliefs, Attitudes, and Behaviors-A Systematic Review and Meta-Analysis.

Pain science education (PSE) can be used as part of treatment and prevention for chronic pain in children. We assessed the effectiveness of PSE on knowledge, beliefs, attitudes, and behaviors in children and the people that care for children. We set a minimum criterion for education to address pain biology knowledge. We included studies aimed at both treatment and prevention of chronic pain. We conducted searches using 5 databases. We assessed the risk of bias using the Cochrane Risk of Bias 2 tool. Data were pooled using a random-effects meta-analysis or assessed using a narrative synthesis. The certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation. We screened 14,505 records and included 7 studies involving 351 caregivers and 1,285 children. Four studies were included in meta-analyses. We found low-certainty evidence that PSE has a large beneficial effect on caregiver knowledge and beliefs compared with alternative education (standardized mean difference = 1.14 [95% confidence interval: .88-1.42]; I2 = 0%). We found no difference in functional disability in children with chronic pain after PSE (Functional Disability Inventory score mean difference = .73 [95% confidence interval: -.81 to 2.27; I = 0%]). Narrative syntheses showed low-certainty evidence for improved knowledge and beliefs in children with preventative and treatment effects. Overall, we found few studies, and along with high risk of bias, this significantly contributed to the low certainty of findings. The effect of learning pain science for both preventative and treatment effects in children, carers, and the child/carer dyad remains mostly unknown. This review was prospectively registered with The international Prospective register of systematic reviews (CRD42022344382) on July 22, 2022. PERSPECTIVE: This review examines the effect of PSE on pain-related knowledge, beliefs, attitudes, and behaviors in children and the people that care for children (0-18). The findings contribute to knowledge about pain treatments and health promotion for caregivers and their children with and without chronic pain.

Interacting with virtual characters, objects and environments: investigating immersive virtual reality in rehabilitation.

PURPOSE: This pilot study aimed to (a) investigate opportunities for immersive Virtual Reality (VR) technology in communication, physical, and visual rehabilitation by examining the interaction of people without disabilities in a range of structured virtual environments; and (b) validate research protocols that might be used to evaluate the physical, visual, and verbal interaction of users in virtual worlds, and their safety while using the technology. METHODS: Thirteen adults identifying as people without disability were exposed to VR via a head-mounted display. A video-review method was used to qualitatively code and analyse each participant's communication, movement, orientation, and support needs. RESULTS: All participants oriented to their virtual environments sufficiently to use applications. Their spoken language was effective for interaction, although unconventional social behaviours were also observed. Two participants reported minor adverse reactions consistent with mild cybersickness. CONCLUSION: The results provide insight into the types of environments and characters that support the greatest communicative, physical, and visual interaction in immersive VR. The tested protocols are useful to assess safety when using VR, and to observe communicative, physical, and visual interaction with virtual environments and characters. Implications for future research and use of VR with people with communication, physical and visual disability are discussed.

Safe use of virtual reality in rehabilitation requires careful assessment. Comprehensive observational protocols were sufficient to manage safety concerns.Rehabilitation applications need rapid responsivity in verbal interactions to ensure users are immersed in interactions.Non-verbal cues from virtual avatars best direct user attention in the environment.Novice virtual reality users largely controlled technology using their dominant hand. They could control VR successfully with one hand.

Spatial Neglect: An Exploration of Clinical Assessment Behaviour in Stroke Rehabilitation.

OBJECTIVE: There is a large gap between evidence-based recommendations for spatial neglect assessment and clinical practice in stroke rehabilitation. We aimed to describe factors that may contribute to this gap, clinician perceptions of an ideal assessment tool, and potential implementation strategies to change clinical practice in this area. DESIGN: Qualitative focus group investigation. Focus group questions were mapped to the Theoretical Domains Framework and asked participants to describe their experiences and perceptions of spatial neglect assessment. SETTING: Online stroke rehabilitation educational bootcamp. PARTICIPANTS: A sample of 23 occupational therapists, three physiotherapists, and one orthoptist that attended the bootcamp. INTERVENTION: Prior to their focus group, participants watched an hour-long educational session about spatial neglect. MAIN MEASURES: A deductive analysis with the Theoretical Domains Framework was used to describe perceived determinants of clinical spatial neglect assessment. An inductive thematic analysis was used to describe perceptions of an ideal assessment tool and practice-change strategies in this area. RESULTS: Participants reported that their choice of spatial neglect assessment was influenced by a belief that it would positively impact the function of people with stroke. However, a lack of knowledge about spatial neglect assessment appeared to drive low clinical use of standardised functional assessments. Participants recommended open-source online education involving a multidisciplinary team, with live-skill practice for the implementation of spatial neglect assessment tools. CONCLUSIONS: Our results suggest that clinicians prefer functional assessments of spatial neglect, but multiple factors such as knowledge, training, and policy change are required to enable their translation to clinical practice.

Clinical trial registration has become more prevalent in physical therapy but it is still inadequate: A meta-research study.

BACKGROUND: A study using data from 2009 showed low prevalence and inadequate trial registration in physiotherapy. In 2013, a joint editorial recommended prospective registration in physiotherapy journals. Ten years later it is unclear whether the joint editorial achieved its intended benefit. OBJECTIVES: To investigate the proportion of randomized trials adequately registered and the extent of selective reporting of outcomes in trials of physiotherapy interventions published in 2019 and to compare these data with equivalent published data from 2009. DESIGN: Meta-research study. METHOD: A random sample of 200 trials published in 2019 was used. Evidence of registration was sought on trial registers and by contacting authors. Data from the article was compared with data from the trial registration. Data from this sample of trial published in 2019 were compared with equivalent published data from 2009. RESULTS: In 2019, the proportion of trials that were registered was 63% versus 34% in 2009 (absolute difference 29%). In 2019, 18% of the trials were prospectively registered compared to 6% in 2009 (absolute difference 12%). Unambiguous primary outcomes (i.e., method and timepoints of measurement clearly defined in the trial registry entry) were registered for 30% in 2019. Registration was adequate (i.e., prospective with unambiguous primary outcomes) for 8%, compared with 3% in 2009 (absolute difference 5%). Selective outcome reporting occurred in 73% of the trials in which it was assessable; in 2009 this proportion was 47% (absolute difference 26%). CONCLUSIONS: Registration of randomized trials in physiotherapy increased in the past decade, but it is still inadequate. More effort is still required to implement and enforce adequate registration.

Regression-based prognostic models for functional independence after postacute brain injury rehabilitation are not transportable: a systematic review.

BACKGROUND AND OBJECTIVES: To identify and summarize validated multivariable prognostic models for the Functional Independence Measure® (FIM®) at discharge from post-acute inpatient rehabilitation in adults with acquired brain injury (ABI). METHODS: This review was conducted based on the recommendations of the Cochrane Prognosis Methods Group and adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Three databases were systematically searched in May 2021 and updated in April 2022. Main inclusion criteria were: a) adult patients with ABI, b) validated multivariable prognostic model, c) time of prognostication within 1-week of admission to post-acute rehabilitation, and d) outcome was the FIM® at discharge from post-acute rehabilitation. RESULTS: The search yielded 3,169 unique articles. Three articles fulfilled the inclusion criteria, accounting for n = 6 internally and n = 2 externally validated prognostic models. Discrimination was estimated as an area under the curve between 0.76 and 0.89. Calibration was deemed to be assessed insufficiently. The included models were judged to be of high risk of bias. CONCLUSION: Current prognostic models for the FIM® in post-acute rehabilitation for patients with ABI lack the methodological rigor to support clinical use outside the development setting. Future studies addressing functional independence should ensure appropriate model validation and conform to uniform reporting standards for prognosis research.

Assessing the Reconceptualization of Pain in Graduate-Entry Physiotherapy Students Using the Concept of Pain Inventory for Adults: The University of Technology Sydney Physiotherapy Student Surveys Project.

INTRODUCTION: Validly and reliably assessing conceptual change is essential for evaluating the effectiveness of pain science education for physiotherapy students. We aimed to 1) evaluate concept of pain before and after a 14-week pain science education university subject, 2) assess structural validity of the Concept of Pain Inventory for Adults (COPI-Adult) in postgraduate entry-level physiotherapy students, and 3) explore possible relationships between baseline variables and baseline COPI-Adult scores. REVIEW OF LITERATURE: As the COPI-Adult is a newly developed questionnaire, there is a lack of data regarding its psychometric properties. SUBJECTS: Of 129 enrolled students at an Australian university, 124 (96%) and 114 (88%) completed the baseline and follow-up questionnaires, respectively. METHODS: In this prospective cohort study, students who commenced the degree in 2020 or 2021 completed online questionnaires, including the COPI-Adult, at the start and end of their first semester. This semester included a 14-week pain science education subject and other physiotherapy-related subjects. Higher COPI-Adult scores (range = 0-52) indicate better alignment with contemporary pain science. We 1) compared differences in concept of pain before and after the semester, 2) performed a confirmatory factor analysis on the COPI-Adult, and 3) performed exploratory regression analyses. RESULTS: Concept of Pain Inventory for Adults scores increased from baseline (median [interquartile range]: 39 [36-44]) to follow-up (48 [44-51]). The COPI-Adult retained its 1-factor structure, with acceptable internal consistency (Cronbach's alpha = 0.80). Exploratory analysis showed that previously completing a subject on pain was related to higher COPI-Adult baseline scores. Age, gender, and mental health diagnosis did not relate to baseline COPI-Adult scores. DISCUSSION AND CONCLUSION: Following a 14-week pain science education subject embedded within a physiotherapy degree, students improved their concept of pain. The COPI-Adult maintains a 1-factor structure in this population. Completing a previous subject on pain was associated with higher COPI-Adult scores.

Identifying common core outcome domains from core outcome sets of musculoskeletal conditions: protocol for a systematic review.

BACKGROUND: Core outcome sets (COSs) aim to reduce outcome heterogeneity in clinical practice and research by suggesting a minimum number of agreed-upon outcomes in clinical trials. Most COSs in the musculoskeletal field are developed for specific conditions. We propose that there are likely to be common core domains within existing musculoskeletal COSs that may be used as a starting point in the development of future COSs. We aim to identify common core domains from existing COSs and to facilitate the development of new COSs for musculoskeletal conditions. As a secondary aim, we will assess the development quality of these COSs. METHODS: A systematic review including musculoskeletal COSs. We will search Core Outcome Measures in Effectiveness Trials (COMET) database, MEDLINE, EMBASE, Scopus, Cochrane Methodology Register and International Consortium for Health Outcome Measurement (ICHOM). Studies will be included if related to the development of a COS in adults with musculoskeletal conditions and for any type of intervention. Quality will be assessed using the Core Outcome Set-Standards for Development (COS-STAD) recommendations. Data extracted will include scope of the COS, health condition, interventions and outcome domains. Primary outcomes will be all core domains recommended within each COS. We define a common core outcome domain as one present in at least 67% of all COSs. All findings will be summarized and presented using descriptive statistics. DISCUSSION: This systematic review of COSs will describe the core domains recommended within each musculoskeletal COS. Common domains found may be used in the initial stages of development of future musculoskeletal COSs. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42021239141.

Fitbits for Monitoring Depressive Symptoms in Older Aged Persons: Qualitative Feasibility Study.

BACKGROUND: In 2022, an estimated 1.105 billion people used smart wearables and 31 million used Fitbit devices worldwide. Although there is growing evidence for the use of smart wearables to benefit physical health, more research is required on the feasibility of using these devices for mental health and well-being. In studies focusing on emotion recognition, emotions are often inferred and dependent on external cues, which may not be representative of true emotional states. OBJECTIVE: The aim of this study was to evaluate the feasibility and acceptability of using consumer-grade activity trackers for apps in the remote mental health monitoring of older aged people. METHODS: Older adults were recruited using criterion sampling. Participants were provided an activity tracker (Fitbit Alta HR) and completed weekly online questionnaires, including the Geriatric Depression Scale, for 4 weeks. Before and after the study period, semistructured qualitative interviews were conducted to provide insight into the acceptance and feasibility of performing the protocol over a 4-week period. Interview transcripts were analyzed using a hybrid inductive-deductive thematic analysis. RESULTS: In total, 12 participants enrolled in the study, and 9 returned for interviews after the study period. Participants had positive attitudes toward being remotely monitored, with 78% (7/9) of participants experiencing no inconvenience throughout the study period. Moreover, 67% (6/9) were interested in trialing our prototype when it is implemented. Participants stated they would feel more comfortable if mental well-being was being monitored by carers remotely. CONCLUSIONS: Fitbit-like devices were an unobtrusive and convenient tool to collect physiological user data. Future research should integrate physiological user inputs to differentiate and predict depressive tendencies in users.

Collaborative co-design and evaluation of an immersive virtual reality application prototype for communication rehabilitation (DISCOVR prototype).

PURPOSE: Virtual reality (VR) lends itself to communication rehabilitation by creating safe, replicable, and authentic simulated environments in which users learn and practice communication skills. The aim of this research was to obtain the views of health professionals and technology specialists on the design characteristics and usability of a prototype VR application for communication rehabilitation. MATERIALS AND METHODS: Nine professionals from different health and technology disciplines participated in an online focus group or individual online interview to evaluate the application and use of the VR prototype. Data sources were analysed using a content thematic analysis. RESULTS: Four main themes relating to VR design and implementation in rehabilitation were identified: (i) designing rehabilitation-focused virtual worlds; (ii) understanding and using VR hardware; (iii) making room for VR in rehabilitation and training; and (iv) implementing VR will not replace the health professional's role. DISCUSSION: Health professionals and technology specialists engaged in co-design while evaluating the VR prototype. They identified software features requiring careful consideration to ensure improved usability, client safety, and success in communication rehabilitation outcomes. Continuing inclusive co-design, engaging health professionals, clients with communication disability, and their families will be essential to creating useable VR applications and integrating these successfully into rehabilitation. Implications for rehabilitationHealth and technology professionals, along with clients, are integral to the co-design of new VR technology applications.Design of VR applications needs to consider the client's communication, physical, cognitive, sensory, psychosocial, and emotional needs for greater usability of these programs.Realism and authenticity of interactions, characters, and environments are considered important factors to allow users to be fully immersed in virtual simulations to enhance rehabilitation.

Blood flow restriction exercise of the tibialis anterior in people with stroke: a preliminary study.

BACKGROUND: Blood flow restriction exercise (BFR-E) could be a useful training adjunct for patients with weakness after stroke to augment the effects of exercise on muscle activity. We aimed to examine neurophysiological changes (primary aim) and assess patient perceptions (secondary aim) following BFR-E. METHODS: Fourteen participants with stroke performed BFR-E (1 session) and exercise without blood flow restrictsion (Exercise only) (1 session), on two days, ≈7 days apart. In each session, two sets of tibialis anterior (TA) contractions were performed and electromyography (EMG) was recorded. Eight participants underwent transcranial magnetic stimulation (single-pulse stimulation, short interval intracortical inhibition (SICI), intracortical facilitation (ICF)) and peripheral electrical stimulation (maximal peak-to-peak M-wave (M-max)) of the TA before, immediately-after, 10-min-after and 20-min-after BFR-E and Exercise only. Numerical rating scores (NRS) for pain, discomfort, fatigue, safety, focus and difficulty were collected for all subjects (n = 14). Paired comparisons and linear mixed models assessed the effects of BFR-E and Exercise only. RESULTS: No adverse events due to exercise were reported. There was no contraction-number × condition interaction for EMG amplitude during exercise (p = 0.15), or time × condition interaction for single-pulse stmulation, SICI, ICF or M-max amplitude (p = 0.34 to p = 0.97). There was no difference between BFR-E and Exercise only in NRS scores (p = 0.10 to p = 0.50). CONCLUSION: Using our training paradigm, neurophysiological parameters, feasibility, tolerability and perceptions of safety were not different between BFR-E and Exercise only. As participants were generally well-functioning, our results are not generalizable to lower functioning people with stroke, different (more intense) exercise protocols or longer term training over weeks or months.

Comparison between 2000 and 2018 on the reporting of statistical significance and clinical relevance in physiotherapy clinical trials in six major physiotherapy journals: a meta-research design.

DESIGN: Meta-research. OBJECTIVE: To compare the prevalence of reporting p values, effect estimates and clinical relevance in physiotherapy randomised controlled trials (RCTs) published in the years 2000 and 2018. METHODS: We performed a meta-research study of physiotherapy RCTs obtained from six major physiotherapy peer-reviewed journals that were published in the years 2000 and 2018. We searched the databases Embase, Medline and PubMed in May 2019, and extracted data on the study characteristics and whether articles reported on statistical significance, effect estimates and confidence intervals for baseline, between-group, and within-group differences, and clinical relevance. Data were presented using descriptive statistics and inferences were made based on proportions. A 20% difference between 2000 and 2018 was regarded as a meaningful difference. RESULTS: We found 140 RCTs: 39 were published in 2000 and 101 in 2018. Overall, there was a high prevalence (>90%) of reporting p values for the main (between-group) analysis, with no difference between years. Statistical significance testing was frequently used for evaluating baseline differences, increasing from 28% in 2000 to 61.4% in 2018. The prevalence of reporting effect estimates, CIs and the mention of clinical relevance increased from 2000 to 2018 by 26.6%, 34% and 32.8% respectively. Despite an increase in use in 2018, over 40% of RCTs failed to report effect estimates, CIs and clinical relevance of results. CONCLUSION: The prevalence of using p values remains high in physiotherapy research. Although the proportion of reporting effect estimates, CIs and clinical relevance is higher in 2018 compared to 2000, many publications still fail to report and interpret study findings in this way.

Therapist perceptions of the Danish Physiotherapy Research Database for assessing patients with chronic disease.

BACKGROUND: The Danish Physiotherapy Research Database for chronic patients receiving Free of Charge Physiotherapy (PhysDB-FCP) was piloted over a 1-year period. The purpose of the PhysDB-FCP is to provide a user friendly digital online structured tool that standardizes initial and follow up clinical assessments generating data that can be used for clinical decision making and support future research in physiotherapy for patients with chronic disease. Although initial assessments were completed, the attrition rate was 73% and 90% at 3- and 6- months, respectively, which suggests problems with the current tool. OBJECTIVE: To evaluate the perspectives of the physiotherapists that used the PhysDB-FCP and propose changes to the tool based on this feedback. MATERIALS AND METHODS: Fifty of the 103 physiotherapists introduced to the PhysDB-FCP completed an anonymous online survey. Physiotherapists were asked Likert/categorical and yes/no questions on experiences with the PhysDB-FCP within their practice, perceptions of patient experiences, suitability of the resources and support provided by the PhysDB-FCP working group and the ideal administration frequency of the assessments within the PhysDB-FCP. Open ended feedback on possible improvements to the PhysDB-FCP was also collected. RESULTS: Physiotherapists agreed that the PhysDB-FCP was useful for taking a physiotherapy assessment (74%) and the patient survey was useful for goal setting (72%). Although physiotherapists felt the PhysDB-FCP was well-defined (82%), only 36% would like to use a similar tool again. Generally, the PhysDB-FCP was too time-consuming, administered too frequently and included irrelevant items. For example, 72% of physiotherapists took >45 min to administer the assessment in the first consultation which was performed over multiple sessions. CONCLUSIONS: The perspectives of physiotherapists using The PhysDB-FCP suggest specific changes that will ensure better use of the tool in future practice. Changes will likely involve administering the assessment less frequently (every 6-months to 1-year), shortening the assessment, and using diagnosis-specific assessment items.

Has Reporting on Physical Therapy Interventions Improved in 2 Decades? An Analysis of 140 Trials Reporting on 225 Interventions.

OBJECTIVES: To investigate the completeness of reporting of physical therapy interventions in randomized controlled trials before and after publication of the Template for Intervention Description and Replication (TIDieR) checklist (a reporting guideline for interventions). DESIGN: Meta-research. METHODS: We searched 6 journals for trials using physical therapy interventions that were published in 2000 and 2018. Two independent assessors scored the TIDieR checklist and extracted descriptive information, including Physiotherapy Evidence Database (PEDro) scale scores. We identified control or treatment interventions, exercise-based interventions, and area of physical therapy. We performed a descriptive analysis and defined a priori a 20% difference between studies published in 2000 and 2018 as meaningful. We assessed correlations between TIDieR and PEDro scale scores for all interventions. RESULTS: In total, 140 articles that met selection criteria evaluated 225 interventions (2000, n = 61; 2018, n = 164). Mean ± SD TIDieR score (2000, 7.52 ± 2.62; 2018, 8.26 ± 2.26) did not show a meaningful difference between years for all interventions (+5%), controls (+6%), treatment interventions (+6%), exercise-based interventions (+9%), or musculoskeletal (+4%) or neurological (+7%) physical therapy. For exercise interventions, number of sessions was reported more (+21%) in 2018 than in 2000. For musculoskeletal trials, 2 items were reported more completely in 2018 than in 2000 (materials, +29%; individual versus group, +22%) and 3 items were reported more completely in neurological trials (mode of delivery, +20%, [item 8.1] when +45%, and assessment of fidelity, +20%). The item "Who delivered the intervention?" was reported less completely (-23%) in 2018 than in 2000 in neurological trials. We found no correlation (r = 0.12) between PEDro scale score and TIDieR score. CONCLUSION: There were few meaningful improvements in how physical therapy interventions were described after publication of the TIDieR reporting guideline. J Orthop Sports Phys Ther 2021;51(10):503-509. doi:10.2519/jospt.2021.10642.

Externally validated model predicting gait independence after stroke showed fair performance and improved after updating.

OBJECTIVE: To externally validate recent prognostic models that predict independent gait following stroke. STUDY DESIGN AND SETTING: A systematic search identified recent models (<10 years) that predicted independent gait in adult stroke patients, using easily obtainable predictors. Predictors from the original models were assigned proxies when required, and model performance was evaluated in the validation cohort (n = 957). Models were updated to determine if performance could be improved. RESULTS: Three prognostic models met our criteria, all with high Risk of Bias. Validation data was only available for the Australian model. This model used National Institute of Health Stroke Scale (NIHSS) and age to predict independent gait, using Motor Assessment Scale (MAS) walking item. For validation, Scandinavian Stroke Scale (SSS) was a proxy for NIHSS, and Functional Independence Measure (FIM) locomotion item was a proxy for MAS. The Area Under the Curve was 0.77 (0.74-0.80) and had good calibration in the validation dataset. Adjustment of the intercept and regression coefficients slightly improved discrimination. By adding paretic leg strength, the model further improved (AUC 0.82). CONCLUSION: External validation of the Australian model with proxies showed fair discrimination and good calibration. Updating the model by adding paretic leg strength further improved model performance.

Cohort profile: Design and implementation of the Danish Physiotherapy Research Database for patients receiving primary care with chronic disease.

PURPOSE: Free of charge physiotherapy (FCP) is free physiotherapy provided by the Danish government for patients with a range of chronic diseases. To date, the population has not been described in depth making evaluation and decision making difficult. The purpose of this study was to (1) describe the development and the content of a novel clinical physiotherapy database for FCP (PhysDB-FCP) and (2) present the cohort profile based on the data collected. PARTICIPANTS: Ninety-nine clinics (17 460 FCP patients) were invited to participate in the development process from 2018 to 2019. Eleven clinics consented (2780 FCP patients) and 534 patients performed the physiotherapy assessment using the PhysDB-FCP tool, with 393/534 completing the patient survey. FINDINGS TO DATE: The content of the PhysDB-FCP was developed through an iterative process involving consensus between clinical and research workgroups. Prior to using the tool all consenting sites received training to use/administer the tool. All data were collected/stored using the PhysDB-FCP. Items finally chosen for the PhysDB-FCP included demographic information, questions about health status and daily functioning, functional tests, treatment plan and validated questionnaires. The initial patient cohort composed of 63.4% women with main diagnoses of multiple sclerosis (22.7%) and Parkinson's disease (17.0%). The ability to perform personal/instrumental activities of daily living and functional ability varied widely. Other non-physiotherapy related issues were identified in numerous patients (ie, 34.9% of patients were at risk of depression) and multidisciplinary interventional approaches could be considered. FUTURE PLANS: The current study has provided a comprehensive description of patients receiving FCP, using data collected from the novel PhysDB-FCP. Collected information can be used to facilitate microlevel to macrolevel programme evaluation and decisions. Although the PhysDB-FCP is promising, the tool requires optimisation before it is implemented regionally and/or nationally.

History-dependence of muscle slack length in humans: effects of contraction intensity, stretch amplitude, and time.

The slack length of a relaxed skeletal muscle can be reduced by isometric contraction at short lengths ("contract-short conditioning"). This study explored how the effect of contract-short conditioning on muscle slack length is modified by 1) the intensity of the contraction, 2) the delay between the contraction and measurement of slack length, and 3) the amplitude of a stretch delivered to the relaxed muscle after the contraction. Muscle fascicles in the human vastus lateralis muscle were observed with ultrasound imaging while the relaxed muscle was lengthened by flexing the knee. The knee angle at which muscle fascicle slack was taken up was used as a proxy for muscle slack length. Conditioning the muscle with voluntary isometric (fixed-end) contractions at short muscle lengths reduced vastus lateralis muscle slack length, measured 60 s later, by a mean of 10°. This effect was independent of contraction intensity from 5% to 100% maximal voluntary contraction. The effect was largest when first observed 5 s after the contraction, decayed about one-third by 60 s, and then remained nearly constant until the last observation 5 min after the contraction. A slow stretch given to the relaxed muscle after contract-short conditioning increased slack length (i.e., reduced the effect of contract-short conditioning). Slack length increased nonlinearly with stretch amplitude. Very large stretches (>30°, possibly as large as 90°) were required to abolish the effect of contract-short conditioning. The phenomena described here share some characteristics with, and may involve similar mechanisms to, passive force enhancement and muscle thixotropy.NEW & NOTEWORTHY The slack length of a relaxed human skeletal muscle is not fixed; it can be modified by contraction and stretch. Contraction of the human vastus lateralis muscle at short lengths reduces the muscle's slack length. Even very weak contractions are sufficient to induce this effect. The effect persists for at least 5 min but can be reduced or abolished with a large-amplitude passive stretch.

Neuromuscular effects of dorsiflexor training with and without blood flow restriction.

Blood flow restriction training (BFRT) has been proposed for elderly and clinical populations with weakness. Before being used in these populations it is important to understand the neurological effects of, and subject perceptions to, BFRT. Seventeen healthy subjects were recruited and performed 2 experimental sessions, BFRT and training without blood flow restriction (TR-only), on separate days. Four sets of concentric/eccentric dorsiflexion contractions against theraband resistance were performed. Surface electromyography of the tibialis anterior was recorded during exercise and for the electrophysiological measures. At baseline, immediately-post, 10-min-post and 20-min-post exercise, motor evoked potentials (MEPs) from single pulse transcranial magnetic stimulation (TMS), paired-pulse TMS with interstimulus intervals of 2-ms (SICI) and 15-ms (ICF), and the M-max amplitude were recorded in the resting TA. Following training, subjects provided a numerical rating of the levels of pain, discomfort, fatigue, focus and difficulty during training. Muscle activation was higher in the last 20 contractions during BFRT compared to TR. There was no difference (time × condition interaction) between BFRT and TR for single-pulse MEP, SICI, ICF or M-max amplitude. There was a significant main effect of timepoint for single-pulse MEP and M-max amplitudes with both significantly reduced for 20-min-post exercise. No reductions were observed for SICI and ICF amplitudes. Taken together, BFRT and TR-only were only different during exercise and both regimes induced similar significant reductions in M-Max and MEP-amplitude post-training. Due to the lack of changes in SICI and ICF, it is unlikely that changes occurred in cortical sites related to these pathways. The increased surface electromyography activity in the last 20 contractions, indicate that the training regimes are different and that BFRT possibly induces more fatigue than TR. As such, BFRT could be used as an adjunct to conventional training. However, as subjects perceived BFRT as more painful, difficult and uncomfortable than TR-only, people should be selected carefully to undertake BFRT.