• 17 Feb 2017 by Chris Todd

    The Prevention of Falls Network for Dissemination (ProFouND www.profound.eu.com) is a thematic network of 20 partners and 14 associate members across Europe. ProFouND organises a yearly Falls Festival to discuss pressing topics in relation to falls in older people. Falls and injurious falls represent a major public health challenge for European countries, and across the world, not in the least due to a high associated cost. Falls cost about 1-1.5% of national health care expenditure.

     

    Despite an increasing amount of evidence regarding programmes that work and programmes that do not work, there is wide disparity in fall prevention across EU and the world. Some regions are running ambitious programmes, whilst others lag behind. ProFouND, EU Falls Festival Scientific Committee, European Innovation Partnership on Active and Healthy Ageing Action Group on Falls and E-NO FALLS working groups wrote a Silver Paper[i] to address this and suggest ways of how research can help to close the implementation gap in falls prevention.

     

    There is sufficiently strong evidence of what works to create best practice models. The challenge remains how these models can be implemented coherently and comprehensively. The EC Blueprint on Digital Health and Care Innovation for Europe’s Ageing Society[ii] argues the need for models of self-organisation and citizen empowerment for social transformation facilitated by digital and technological innovation. However, in order to have successful self-management, more potential barriers need to be conquered. For example, the challenge with evidence based strength and balance programmes (for groups and for individuals at home) is that they need to be attractive to older people so that they not only start the programme but also adhere to them long term to be beneficial.

     

    Figure. Self-management of falls prevention through the use of exergames

    Technologies can help facilitate the implementation of such strategies, but they must be attractive to older people[iii]. Technologies need to be developed for the prediction, detection, assessment and prevention of falls, which provide alerts and feedback useful to the multiple stakeholders, including health and social care professionals, whilst prioritising older people and their families and taking account of older people’s needs and preferences for technologies[iv]. We are following the blog with great interest and see exciting research from the ISPGR research community coming our way, showing great promise in making this happen. Keep up the good work!

     

     

    Events: www.eufallsfest.eu

     

    Chris Todd

    Professor of Primary Care and Community Health

    School of Health Sciences

    University of Manchester, UK

    E: chris.todd@manchester.ac.uk

     

    Chris is Professor of Primary Care and Community Health in The School of Health Sciences, The University of Manchester UK. (Link for Orcid) He is a Chartered Psychologist and Associate Fellow of The British Psychological Society. He has held and/or currently holds grants from the Department of Health, NHS, various research charities, MRC, NIHR and the European Commission.  He was a member of the European Commission DG12 Expert Working Party on research into postural stability and fall prevention in the elderly population. He wrote The World Health Organisation’s policy synopsis on the prevention of falls amongst older people and was a member of the group which wrote the 2007 WHO Global Report on Falls Prevention.

     

     

     

    [iv] Helbostad J et al. Mobile health applications to promote active and healthy ageing. Sensors, 2017 Forthcoming http://www.mdpi.com/journal/sensors/special_issues/body_wbs

     

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  • 06 Feb 2017 by Jochen Klenk

    Recent advances in body-worn sensor technology make it possible to objectively measure real-world fall events. These exciting new developments in research areas of software engineering, biomechanics and big data management can improve our understanding of fall events in older people. However, there is one problem: These events are rare and hence challenging to capture. This has been the motivation behind the EU-funded FARSEEING consortium, who, together with associated partners, have started building a meta-database of real-world falls.

    Between January 2012 and December 2015, a large number of real-world fall events measured by inertial sensors have been reported to the database. A signal processing and fall verification procedure has been developed and applied to the data. Currently, more than 200 verified real-world fall events are available for analyses. The fall events have been recorded within several studies, with different methods, and in different populations. All sensor signals include at least accelerometer measurements and 58 % also include gyroscope and magnetometer measurements. The collection of data is ongoing and open to further partners contributing with fall signals.

    Figure 3 shows a real-world fall signal example (acceleration) with labeled activities and fall phases. The sensor (Samsung Galaxy S3) was attached at the lower back, sampling at 100 Hz. The faller reported a backwards fall while pushing the door opener. The person was upright at the beginning, indicated by the vertical axis (blue) showing 10 m/s2, including some walking. During the fall the vertical signal changes to 0 m/s2 and the anterior-posterior axis (red) to 10 m/s2, indicating a backward fall. After a short period of resting, the person recovered with an intermediate resting position and continued walking.

    This meta-database is currently the largest collection of real-world falls using inertial sensors. It will help to substantially improve the understanding of falls and enable new approaches in fall risk assessment, fall prevention, and fall detection. The FARSEEING consortium aims to share the falls data with other researchers. A dataset of 20 selected fall events is available on request via the project website. Researchers are also invited to collaborate with the FARSEEING consortium on specific research questions.

    More information about the project and the data sharing policy can be found on the FARSEEING website (www.farseeingresearch.eu).

     

    Publication

    Klenk J, Schwickert L, Palmerini L, Mellone S, Bourke A, Ihlen EAF, Kerse N, Hauer K, Pijnappels M, Synofzik M, Srulijes K, Maetzler W, Helbostad JL, Zijlstra W, Aminian K, Todd C, Chiari L, Becker C. The FARSEEING real-world fall repository: a large-scale collaborative database to collect and share sensor signals from real-world falls. European Review of Aging and Physical Activity. 2016;13:8.

    http://https://eurapa.biomedcentral.com/articles/10.1186/s11556-016-0168-9

     

    The author

    Jochen Klenk, Department of Clinical Gerontology, Robert Bosch Hospital Stuttgart and Institute of Epidemiology and Medical Biometry, Ulm University, Germany

    Jochen Klenk is a Senior Research Scientist at the Robert-Bosch-Hospital (RBK) and at the Institute of Epidemiology and Medical Biometry at Ulm University. He leads the working group on fall signal analysis at the RBK and is the FARSEEING database manager. Further research interests are longitudinal data analysis of large observational studies and physical activity monitoring.

     

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  • 01 Feb 2017 by James Richardson

    The young woman trips on an uneven sidewalk, recovers smoothly and resumes texting. The older woman encounters the same perturbation and crashes.

    My colleagues and I have been trying to identify the key neuromuscular attributes responsible for successful response to perturbation in our clinical practice for quite some time. We have been particularly interested in older people with diabetic neuropathy since this population is advised to walk for exercise, and yet commonly falls. Traditionally, we looked at hip muscle strength generation and ankle proprioceptive precision to explain unipedal stance time and gait speed. However, against our expectations these neuromuscular attributes did not predict lateral gait variability or the few major injuries sustained by our study participants.

    Since the neuromuscular variables were unrevealing, I looked for relationships between step width variability and Simple Reaction Time and Complex Reaction Accuracy using our ReacStick device (see Figure). The ReacStick is a rigid, lightweight rod with a rectangular box at one end. To determine SRT the participant sits with an open hand around the box, and as quickly as possible catches the suspended device, which is dropped at random intervals by the examiner. When determining Complex Reaction Accuracy, the participant catches the device solely when the LED lights illuminate on the housing when dropped during 50% of the trials. If the LED lights do not illuminate then the participant is asked to let the device fall to the floor, requiring a Jedi-quick decision as the ReacStick hits the floor in about 400 msec (an interval similar to the swing phase of gait).

    Our results showed that the ratio of Complex Reaction Accuracy to Simple Reaction Time, which rewards accuracy and/or quick reaction, was strongly and inversely associated with uneven surface gait variability in participants suffering from neuropathy (R2 = .61). Further, the participants with major fall-related injuries appeared less accurate and slower than those without. The effects were less prominent in the older participants without neuropathy.

    The results suggest that people with lower limb neuromuscular impairment rely on neurocognitive speed, as determined by the ability to perceive a stimulus and quickly inhibit a motor response, to maintain postural control when navigating an uneven surface and, possibly, to prevent severe injury in the event of a fall.

    The texting young woman likely has a quicker brain… which may be clinically detectable.

    Figure A   

    A participant’s hand appropriately grasping the falling ReacStick device, which shows illuminated lights.

    Figure B

    Scatterplot demonstrating that greater (more accurate and/or faster) ReacStick performance was associated with reduce step width range on the uneven surface.

                                                             

    Publication

    Richardson JK, Eckner JT, Allet LA, Kim H, Ashton-Miller JA. Complex and simple clinical reaction times are associated with gait, balance, and major fall injury in older subjects with diabetic peripheral neuropathy. Am J Phys Med Rehabil 2017;96:8-16.

    http://journals.lww.com/ajpmr/Citation/2017/01000/Complex_and_Simple_Clinical_Reaction_Times_Are.2.aspx

     

    The Author

    Dr. Richardson is a Professor of Physical Medicine/Rehabilitation at the University of Michigan where he directs the Electrodiagnostic Laboratory and is actively engaged in patient care and teaching.His primary research interests include investigating the influence of peripheral nerve function on gait/balance, and translating insights from the biomechanics laboratory into the clinical realm. 

     

     

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  • 26 Jan 2017 by Michele Callisaya

    Falls continue to be a major cause of injury and loss of independence in older people.  Therefore, screening for fall risk is an important part of geriatric care.   We previously identified that there is a cumulative effect on fall risk if people suffer from both poorer physical and cognitive function ( https://www.ncbi.nlm.nih.gov/pubmed/23410920). The current study built further on these findings by only using clinical measures, which are quick and easy to administer (without the need of a qualified health professional) to make them feasible in a clinical setting. Therefore, we searched for a measure that incorporated both gait and cognition and was quick and easy to administer.

    We used the Motoric Cognitive Risk (MCR) syndrome - developed by Prof Joe Verghese (Albert Einstein College of Medicine, USA) – which is characterised by both slow gait and presence of a subjective cognitive complaint, and therefore ideal for our purposes.

    Our study aimed to examine if MCR increased the risk of falls and if the diagnosis of the combined MCR was a stronger risk factor for falls than its components (i.e. slow gait or cognitive complaint). Using data from five longitudinal population-based studies (n=6204), we found that 45% of participants reported a cognitive complaint, 13.8% had slow gait, 7.5% had a diagnosis of MCR, and 33.9% reported any fall (see Figure for individual study results).  MCR was associated with a 44% increase of falls in the pooled analysis of all studies.  This increased risk of falls of the combined MCR was higher than for gait speed (30%) or subjective cognitive complaints (25%) alone.

     

     

     

     

     

     

     

     

     

     

    Figure MCR status plotted against the percentage of people who reported any fall

    Reprinted from Journal of Alzheimers Disease, , 18;53(3): Callisaya ML,  Ayers E, Barzilai N et al. Motoric Cognitive Risk Syndrome and Falls A multi-center study1043-52. Copyright (2016), with permission from IOS Press”.  The publication is available at IOS Press through http://dx.doi.org/10.3233/JAD-160230

    The simplicity and low cost of MCR makes this an attractive falls-risk screening tool for the busy clinician. People with MCR should then proceed to a more thorough multifactorial falls assessment, to understand the cause of the slow gait (e.g. balance assessment) and poor cognitive function (e.g. neuropsychological assessment), and guide a tailored intervention program.

     

    Publication

    Callisaya ML, Ayers E, Barzilai N, Ferrucci L, Guralnik JM, Lipton RB, Otahal P, Srikanth VK, Verghese J.  Motoric Cognitive Risk Syndrome and Falls Risk: A Multi-Center Study.

    J Alzheimers Dis. 2016 Jun 18;53(3):1043-52. doi: 10.3233/JAD-160230.  http://dx.doi.org/10.3233/JAD-160230

     

    Dr Michele Callisaya

    Michele leads the Brain Ageing group at the University of Tasmania and is an Aged Care and Rehabilitation physiotherapist at the Royal Hobart Hospital, Australia.   She motivates herself to go trail running with thoughts of improving her strength, balance and reaction time as age inevitably creeps up. 

     

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  • 26 Jan 2017 by Yoshiyuki Kobayashi

    Recent advances in sensor technology allow for the science of gait features to be applied to new services. These services may comprise of e.g. onsite customisation of footwear or garments, sensor-based applications such as activity monitoring systems, and detailed surveillance monitoring. At the Japanese National Institute of Advanced Industrial Science and Technology, we conducted a study to describe sex- and age-differences in gait features of healthy individuals to support others developing services based on gait features.

    In this study, we analysed a large dataset of gait in healthy individuals (99 males and 92 females aged 20 to 75) measured in our laboratory. The dataset comprised of 3D positional data obtained using 55 reflective makers and a 3D motion capture system during a 10m overground walk. This dataset is now available online as part of the AIST Gait Database. The AIST Gait Database site is currently only available in Japanese but please contact "dhrc-liaison-ml@aist.go.jp" for assistance in English. We used a principal component analysis (PCA) to identify sex and age effects on walking patterns in the data. PCA can help identify waveform-features from continuous data specific to certain groups, where previous studies disregarded large amount of data and only investigated selected variables at discrete time points. In addition, the waveforms can be reconstructed from the scores of the principal component vectors (PCV), which enabled us to classify a range of different gait patterns. Using this analysis, we identified 6 PCVs which explain more than 5 % of the total variance in the data as shown in Figure 1. Of these, we found a significant interaction between sex and age on PCV 1 and a significant effect of sex on PCV 6, which indicates that these PCVs contain sex differences in the walking patterns. An animation of reconstructed gait with amplified sex differences can be seen in Figure 1 [figure 1(a): PCV1 and figure 1(b): PCV 6].

    Our findings advance the understanding of the nature of human gait. We identified clear sex differences in walking patterns, and showed that some of these patterns are affected by ageing while others are not. We believe that these finding are applicable to various health-related services. For example, we can now express gait features of an individual as a score and compare it to a reference group based on the current study’s PCVs. This information might be essential for optimising gait interventions and tracking changes over time. We are now focusing on launching new gait characteristics assessment services for healthy people based on the results of this study.
     

     

     Figure 1: Reconstructed gait patterns related to (a) PCV1 and (b) PCV 6. (a) Since young females tend to exhibit larger scores on PCV1, PCV1 + 3 SD figures (red line) indicate extremely young female-like gait patterns, and PCV1 – 3 SD figures (green line) indicate extremely male-like gait patterns; (b) Since females tend to exhibit larger scores on PCV6, PCV6 + 3SD figures (red line) indicate extremely female-like gait patterns and PCV6 - 3SD figures (green line) indicate extremely male-like gait patterns.

     

    Publication

    Kobayashi Y, Hobara H, Heldoorn TA, Kouchi M, Mochimaru M. (2016). Age-independent and age-dependent sex differences in gait pattern determined by principal component analysis. Gait Posture. 2016 May;46:11-7.

    https://www.ncbi.nlm.nih.gov/pubmed/27131170

     

     

    The author

    ·      Yoshiyuki Kobayashi (Ph.D.)

    ·      Senior research scientist, Digital Human Research Group, Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology

    ·      Yoshiyuki Kobayashi Ph.D. is a Senior Research Scientist at Digital Human Research Group, Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology. The goal of his research is the prevention of falling during latter stage of one’s life. To achieve this goal, he is now working with various private companies in Japan to build a system to describe and feedback the gait features of users.

     

     

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  • 14 Jan 2017 by Anat Mirelman

    The prevalence of falls in older adults is huge: one out of every 3 adults aged 65 years or older will fall at least once per year. These numbers are even higher in neurodegenerative conditions such as in Parkinson’s disease and in people with cognitive impairments.  Recent studies showed that certain aspects of cognition, especially executive function, are critical for safe ambulation.  This makes sense intuitively if we imagine the cognitive skills needed just to cross a busy intersection or to negotiate obstacles. We aimed to use virtual reality to safely train the motor aspects that are important for fall risk, while also implicitly teaching participants to improve cognitive functions vital to safe ambulation.

     

    We carried out a randomized controlled trial at five clinical centers. Adults aged 60−90 years with a high risk of falls, i.e., two or more falls in the 6 months before the study, and with varied motor and cognitive deficits were randomly assigned to receive 6 weeks of treadmill training plus VR or treadmill training alone. Both groups aimed to train three times per week for 6 weeks, with each session lasting about 45 minutes. The VR system consisted of a motion-capture camera and a computer-generated simulation that includes real-life challenges such as obstacles, multiple pathways, and distracters that requires continual adjustment of the stepping pattern. The subject’s gait was measured in real-time and projected on into the VR that was displayed on a large screen. The primary outcome was the incident rate of falls during the 6 months after the end of training.

     

    Data from 282 participants (VR group n=154, and treadmill training alone group n=148) was analyzed. Before training, the falls incident rate was similar in both training arms. Six months after the end of training, the rate decreased in both groups, but it was 42% significantly lower in the treadmill training plus VR group, compared to the treadmill training alone group (figure 1).

    Figure 1:  On the left is a picture of the Virtual Reality setting. The user walks on the treadmill while engaging in tasks in the virtual scene. The figure on the right shows the reduction in incident fall rate ,6 months post intervention , in the treadmill  training plus virtual reality group compared to the active control group of treadmill training.

     

    The study has important implications for research and clinical practice. Treadmill training plus VR successfully reduced in fall rates in a diverse group of older adults at high risk for falls. Adherence and participation were very high, no serious adverse events were observed, and participants reported high satisfaction and enjoyment. This RCT demonstrates the added value of the VR component and suggests that this approach could be a viable option for improving motor-cognitive function and reducing fall risk in older adults.

     

    Publication

     

    Addition of a non-immersive virtual reality component to treadmill training to reduce fall risk in older adults (V-TIME): a randomized controlled trial.

    Mirelman A, Rochester L, Maidan I, Del Din S, Alcock L, Nieuwhof F, Rikkert MO, Bloem BR, Pelosin E, Avanzino L, Abbruzzese G, Dockx K, Bekkers E, Giladi N, Nieuwboer A, Hausdorff JM.

    Lancet. 2016 Sep 17;388(10050):1170-82. doi: 10.1016/S0140-6736(16)31325-3.

     

    http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)31325-3/abstract

     

    The author

    Anat Mirelman, PhD

    Laboratory for the study of Early Markers Of  Neurodegeneration (LEMON)

    Center for the study of Movement , Cognition and Mobility

    Neurological Institute, Tel Aviv Medical Center

    Sackler School of Medicine, Tel Aviv University, Israel

     

    Anat Mirelman  is the director of the Laboratory for Early Markers of Neurodegeneration at the Tel Aviv Medical Centre and a senior lecturer at Sackler school of Medicine at Tel Aviv University. Dr. Mirelman’s main research interests are in the assessment and treatment of motor-cognitive impairments in neurodegenerative conditions and in identifying early markers of disease in populations at risk.

     

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  • 07 Dec 2016 by Stephen Lord

    Motor impairment includes impairments in the control of movement which incorporates the central nervous system, muscle function and motor performance https://motorimpairment.neura.edu.au/. Motor Impairment can therefore be seen as a pathway that causes physical disability in a wide range of these diseases (Figure 1). Our research has used falls as a paradigm to investigate to which extent various motor outputs, such as reaching, standing, stepping and walking, are dysfunctional.  Within the motor impairment framework, falls can be viewed of what constitutes normal physiological performance.

    Figure 1. A conceptual model for the control of movement which emphasises that afferent feedback from muscles and motor actions arises continuously. This feedback needs to be processed with feedback from centrally generated motor signals. Deficits at any level are likely to impairments related to standing and locomotion.

    The purpose of this article was to describe a physiological profiling approach for documenting motor impairments in older people at risk of falls and clinical groups with balance disorders. In essence, this approach involves the quantitative assessment of important physiological capacities required for stable mobility and fall avoidance, and the compilation of normative data that can be used as a reference for individual and disease group-based assessments. The article collated and summarised data from several studies that have used the Physiological Profile Assessment (PPA). It presented physiological profiles across a number of seemingly ‘single’ diseases or disability groups including people with multiple sclerosis, stroke, cognitive impairment, depressed mood, macular degeneration, lower limb osteoarthritis and prior polio. It emphasized that (i) motor impairment arises via reductions in a wide range of sensorimotor abilities; (ii) the PPA approach not only gives a snapshot of the physiological capacity of an individual, but also provides insight into the deficits among groups of individuals with particular diseases; and (iii) deficits in seemingly restricted and disparate physiological domains (e.g. vision, strength, cognition) are funnelled into balance and mobility impairments.

    Figure 2. The overall PPA fall-risk scores is visualised for the clinical populations in relation to age, with the fall risk categorised from ‘very low’ to ‘very marked’. Ageing is associated with functional decline.  The clinical groups all have high scores compared to their peers of the same age.

    When used on an individual basis, the PPA can provide measurements of physiological frailty and fall risk, which can be used to guide subsequent personalised interventions to enhance mobility and reduce fall risk. Further, when viewed from the perspective of disease groups, this approach can provide insight into the physiology of tasks such as standing and walking and how these tasks are commonly affected in different diseases. With the challenges of population ageing, systematic approaches to motor impairment documentation and amelioration may assist older people and those with balance disorders to maintain functional abilities and independence.

    Publication

    Lord SR, Delbaere K, Gandevia SC. Use of a physiological profile to document motor impairment in ageing and in clinical groups. Journal of Physiology 2016;594:4513-4523. http://onlinelibrary.wiley.com/doi/10.1113/JP271108/pdf

    Affiliation

    Professor and Senior Principal Research Fellow, Neuroscience Research Australia, University of New South Wales, Sydney, Australia

    Bio

    Stephen Lord is a Senior Principal Research Scientist at Neuroscience Research Australia and chief investigator on NeuRA’s Motor Impairment Program https://motorimpairment.neura.edu.au/. He has published over 400 papers in the areas of balance, gait and falls in older people and is acknowledged as a leading international researcher in his field. His research follows two main themes: the identification of physiological risk factors for falls and the development and evaluation of fall prevention strategies.

     

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  • 01 Dec 2016 by Matija Milosevic

         Individuals with cervical spinal cord injury (SCI) usually sustain impairments of the trunk as well as the lower and upper limb muscles, resulting in compromised sitting balance. They are often unable to maintain unsupported sitting balance and rely on their feet and arms for support. However, foot support forces have often been ignored during sitting balance assessments. Therefore, the objectives of this study were to: 1) present an experimental setup for measuring postural control during sitting balance that includes contributions of the foot support forces; and 2) compare postural control of individuals with cervical SCI to able-bodied individuals during sitting balance.

         Ten able-bodied individuals and six individuals with cervical SCI were recruited and asked to maintain upright quiet sitting posture on an instrumented chair during two 60 second trials. The forces on the seat and the foot support surfaces were measured separately using two force plates (Figure 1A). The global center of pressure sway (COPG) was obtained from the measurements on the two force plates according to Equation 1, and the sway on the seat (COPS) and foot support (COPF) force plates was calculated individually. The results illustrated in Figure 1B showed that global and seat support sway of individuals with cervical SCI was twice as large compared to able-bodied individuals, while foot support sway was not significantly different between the two groups. Comparison between global and seat sways showed that anterior-posterior velocity of global sway was larger compared to the seat sway in both groups.

         Our study presented the experimental setup for measuring postural control during sitting balance of individuals with SCI that includes contributions of the foot support forces. The results suggest that postural control of individuals with cervical SCI was worse than that of able-bodied individuals. The trunk swayed more in individuals with SCI, while the stabilization effect of the feet did not differ between the groups. Foot support affected anterior-posterior fluctuations in both groups equally. Thus, trunk control is the dominant mechanism contributing to sitting balance in both able-bodied and SCI individuals, whereas foot support forces provide passive support, which is important for sitting stability. Overall, these results suggest that rehabilitation should focus on recovering trunk function as well as on optimizing foot placement to provide additional support.

     

    Figure 1: A) Experimental setup for sitting balance, where COPS represents trunk sway on the seat surface, COPF represents foot support sway on the ground, and COPG represents the global sway. Vertical forces on the seat surface (FzS and FzS), shear forces on the foot support surface (FxF and FyF) and the height between the seat and foot support force places (h) are also shown in Equation 1. B) Example of the sway for COPG, COPS, and COPF sway for one able-bodied individual (AB) and one individual with spinal cord injury (SCI), where AP is anterior-posterior and ML is medial-lateral sway.

     

    Publication
    Milosevic M, Masani K, Kuipers MJ, Rahouni H, Verrier MC, McConville KM, Popovic MR (2015). Trunk control impairment is responsible for postural instability during quiet sitting in individuals with cervical spinal cord injury. Clin Biomech (Bristol, Avon). 2015 Jun;30(5):507-12. doi: 10.1016/j.clinbiomech.2015.03.002.
    Link: https://www.ncbi.nlm.nih.gov/pubmed/25812727
     

    The author
    Matija Milosevic, Ph.D.
    University of Tokyo
    Department of Life Sciences, Graduate School of Arts and Sciences

    Matija Milosevic received the Ph.D. degree in biomedical engineering from the University of Toronto, Canada, in 2015. He is currently an NSERC Post-Doctoral Fellow at the University of Tokyo, Japan. His research interests include postural control, biomechanics, neurophysiology, neural systems, functional electrical stimulation, spinal cord injury and rehabilitation engineering.
     

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  • 16 Nov 2016 by Masahiro Fujimoto

    People at increased risk of falls may be less able to control their balance. The ability to control balance is loosely defined as the ability to maintain the body’s center of mass (COM) within the base of support (BOS) formed by the feet. During dynamic activities such as walking, this definition does not hold as the COM frequently travels out of the BOS without leading to falls. Dynamic balance control during walking has therefore been quantified based on the position and velocity of the COM with respect to the BOS, where an inability to regulate the COM velocity or momentum could be a cause for gait imbalance. Given that acceleration induces changes in velocity, COM acceleration could enhance our understanding of how momentum is controlled during gait, which would allow us to better understand and identify individuals with balance control difficulties. In this study, we compared dynamic momentum control among healthy young adults, elderly non-fallers and elderly fallers during walking.

     

    The control of the COM in forward-backward direction was examined during walking in 15 healthy young adults, 15 elderly non-fallers and 15 elderly fallers. Using a single-link-plus-foot inverted pendulum model, we determined the boundaries of the region of stability in two ways. One used conventional method based on the COM position at toe-off and its instantaneous velocity. The other used our novel method based on the peak acceleration of the COM prior to toe-off. Although there was no significant difference in the peak forward COM velocity between healthy young adults and elderly non-fallers, the peak forward COM acceleration differed significantly, suggesting age-related differences in momentum control during walking (Fig.1a). Elderly fallers demonstrated significantly lower forward COM velocities and accelerations and placed their COM significantly more forward at toe-off than the other groups, which resulted in their COM position-velocity or COM position-acceleration combination to stay within or close to the forward boundaries of the region of stability (Fig.1b, c). This suggests that elderly fallers adopted a more conservative gait balance strategy compared to healthy subjects, demonstrating larger stability margins. Importantly, our novel method was capable of distinguishing elderly non-fallers from the young group.

     

    Healthy young adults and elderly non-fallers utilized similar momentum to propel the body forward, but controlled this momentum differently. Our elderly participants demonstrated significantly smaller COM acceleration, which could be indicative of their poor momentum control perhaps due to reduced muscular functions and a protective strategy for potential falls. Since a fall could be induced by a sudden change in momentum, such as trips or slips, inability to properly control COM momentum would result in imbalance in response to such external perturbations, predisposing them to a greater risk of falls. Examining the COM acceleration in addition to its velocity would provide a better understanding of a person’s momentum control. This would facilitate early identification of older individuals at a high risk of falls and implementation of fall prevention interventions.

    Figure 1: (a) Peak forward COM velocity and acceleration during walking in healthy young participants (Young), elderly non-fallers (Elderly) and elderly fallers (Fallers). (b) Region of stability (ROS) calculated based on the conventional method using COM velocity and position. The black and gray solid lines indicate the forward and backward boundaries of the ROS, respectively. (c) ROS calculated based on our method using peak COM acceleration and position. Solid and dashed curves indicate the forward boundaries of the ROS averaged for each subject group. *†‡p<0.05.

     

    Publication

    Fujimoto M, Chou LS. (2016). Sagittal plane momentum control during walking in elderly fallers. Gait Posture. 2016 Mar;45:121-6. doi: 10.1016/j.gaitpost.2016.01.009.
    http://www.ncbi.nlm.nih.gov/pubmed/26979893

     

    The author

    Masahiro Fujimoto, Ph.D.
    Assistant Professor
    College of Sport and Health Science, Ritsumeikan University, Japan

    Masahiro Fujimoto received his Ph.D. in Biomechanics at the University of Oregon and worked as a Postdoctoral Fellow in the University of Maryland School of Medicine. His research interests include fall risk assessment and fall prevention in older adults through a better understanding of the biomechanics and motor control of human balance and movement.

     

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  • 11 Nov 2016 by Soichiro Fujiki

    The ability to adapt our walking pattern to the environment is essential for everyday locomotion. This adaptive locomotion is achieved through highly coordinated movements within (intra) and between (inter) our limbs. However, it is not clear what mechanisms exist behind this coordination. Adaptation strategies during walking have previously been examined using split-belt treadmills. In these experiments, the treadmill has two independently controlled belts that force the legs to move at different speeds. In such split-belt treadmill walking, two types of adaptations have been observed: early and late adaptations. Early adaptations appear as rapid changes in inter-limb (e.g. relative phase between the legs) and intra-limb (e.g. stance duration per gait cycle) coordination. By contrast, late adaptations occur gradually after the early adaptations and only involve inter-limb coordination. Furthermore, inter-limb coordination shows after-effects when the belt speeds are equalized. It has been suggested that these adaptations are governed primarily by the spinal cord and cerebellum, but the underlying mechanism remains unclear. To understand the mechanism of these adaptations, we developed a control model based on the physiological findings, and investigated its adaptive behavior via split-belt treadmill walking experiments using both computer simulations and an experimental bipedal robot (Fig. A).

    We assumed that the foot contact timing plays a crucial role for these adaptations because previous studies have showed that the vertical ground reaction forces and ankle stiffness remarkably change at foot contact due to changes in the belt speed condition. We developed a two-layered control model composed of spinal and cerebellar models (Fig. B). The spinal model generates rhythmic motor commands using an oscillator network based on a central pattern generator (CPG). It modulates the command timings formulated in immediate response to foot contact, while the cerebellar model modifies motor commands (only affecting the temporal pattern) through learning based on error information related to differences between the predicted and actual foot contact timings of each leg.

    Our results showed that the robot exhibited rapid changes in inter-limb and intra-limb coordination that were similar to the early adaptations observed in humans. In addition, despite the lack of direct inter-limb coordination control, gradual changes and after-effects in the inter-limb coordination appeared in a manner that was similar to the late adaptations and after-effects observed in humans (Fig. C). Our results suggest that the modulation of the foot contact timing of each limb could induce the appropriate modulation of the whole body motion (i.e. achieving inter-limb coordination). The model studies are expected to be a useful tool to investigate hypotheses, such as ours, which are difficult to examine from the human measurement experiments.

     

    Publication

    Fujiki S, Aoi S, Funato T, Tomita N, Senda K, Tsuchiya K (2015). Adaptation mechanism of interlimb coordination in human split-belt treadmill walking through learning of foot contact timing: a robotics study. J. R. Soc. Interface. 2015 Jul 12:20150542. doi:10.1098/rsif.2015.0542.

    http://dx.doi.org/10.1098/rsif.2015.0542

     

    The author

    Soichiro Fujiki is an assistant professor at the University of Tokyo. He obtained a PhD in Engineering at the Kyoto University, Japan. The goal of his research is to elucidate the mechanism behind motor control during locomotion.  To investigate the control mechanism in humans and animals, he measures the motions of humans and animals and conducts numerical simulations and the robot experiments.

     

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  • 10 Nov 2016 by Brad Manor

    When standing or walking, we often perform additional cognitive tasks such as talking, reading or listening to a friend.  This “dual tasking” is critical to the completion of activities of daily living.  Dual-tasking often results in reduced performance in one or both tasks, especially in older adults. The observation that dual tasking comes at a “cost” to performance means that the involved tasks use shared brain networks. Strategies designed to increase brain network excitability and/or efficiency thus hold great promise to improve dual task capacity across the lifespan. Transcranial direct current stimulation (tDCS) is one safe and non-invasive method that uses low-level electrical currents to temporarily change brain excitability. The purpose of this experiment was to determine the immediate effects of tDCS on dual task balance performance in older adults.

     

    Thirty-seven adults aged 60-85 years completed two laboratory visits separated by one week.  They received 20-minutes of tDCS during each visit. On one visit, they received tDCS designed to increase the excitability of the left dorsolateral prefrontal cortex—a region closely linked to cognition and motor control.  On the other visit, they received “sham,” (i.e. placebo) stimulation.  Participants and study personnel were blinded to tDCS condition.  Before and after each tDCS session, participants completed a dual task paradigm comprising trials of standing and walking both with and without performance of a mental arithmetic task.  The Figure below illustrates the effects of tDCS on single- and dual-task standing postural sway in a selected participant.  Results indicated that real tDCS reduced the dual task cost to both standing postural sway area and walking speed compared to sham stimulation. It also effectively mitigated the cost of walking on performance within the serial subtraction task. Intriguingly, tDCS did not alter standing, walking, or serial-subtraction performance within single task conditions. The reduction in dual task costs was instead spurred by significantly improved performance in each outcome specifically within dual task conditions.

     

    This study demonstrated for the first time that dual tasking performance can be enhanced by modulating prefrontal brain excitability using non-invasive electrical brain stimulation. These results suggest that following just 20 minutes of stimulation, older adults may be able to more safely stand and walk while completing additional, unrelated cognitive tasks.  These results also suggest that the cost of dual tasking is not a fixed, obligatory consequence of aging, and identify tDCS as a novel approach to preserving dual tasking and balance into old age.

     

    Publication

    Manor B, Zhou J, Jor’dan A, Zhang J, Fang J, Pascual-Leone A. (2016). Reduction of dual-task costs by noninvasive modulation of prefrontal activity in healthy elders. Journal of Cognitive Neuroscience. Doi: 10.1162/jocn_a_00897.
    https://www.ncbi.nlm.nih.gov/pubmed/26488591

     

    The author

    Brad Manor, PhD
    Assistant Scientist II, Institute for Aging Research, Hebrew SeniorLife
    Assistant Professor of Medicine, Harvard Medical School

    Brad Manor is the Director of the Mobility and Brain Function Research Program at Hebrew SeniorLife’s Institute for Aging Research and Harvard Medical School.  His research combines brain imaging, non-invasive brain stimulation, and advanced signal processing techniques to understand and enhance the neural control of balance in aging and disease.  

     

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  • 07 Nov 2016 by Masahiro Shinya

    Reflex is the first line of defense for preventing falls when you are perturbed. The reflex system, especially medium-latency or long-latency reflex system, is very flexible and it has been known that the central nervous system takes advantage of prior knowledge about potential upcoming perturbations for modulating postural reflexes. In other words, if you know that may be perturbed, you can prepare for the perturbation. There are two distinct aspects of prior knowledge: spatial and temporal. This study investigated how each of spatial and temporal prior knowledge contributes to the shortening of muscle response latency.

     

    Eleven participants walked on a split-belt treadmill. They were perturbed by sudden and unexpected acceleration or deceleration of the right belt at right foot contact. Spatial prior knowledge was given by verbal instruction of possible direction (only acceleration, only deceleration, or both might occur) of upcoming perturbation at the beginning of an experimental session. Temporal prior knowledge was given to participants by warning tones at foot contact during three consecutive strides before the perturbation. In response to acceleration perturbation, reflexive muscle activity was observed in soleus and gastrocnemius muscles. Onset latency of the gastrocnemius response was shorter (72 ms vs. 58 ms) when participants knew the timing of the upcoming perturbation, whereas the latency was independent no matter whether the participants knew the direction of the perturbation. Soleus latency (44 ms) was not influenced by directional or temporal prior knowledge.

     

    The results suggest that excitability in the supra-spinal neural circuit, which mediates the long-latency reflex, might be enhanced by knowing the timing of the upcoming perturbation. On the other hand, excitability in the spinal neural circuit, which mediates the short-latency reflex, was not influenced by the prior knowledge. Future research should investigate whether it is possible for older people to anticipate both predictable and unpredictable perturbations and find a way to train the Central Nervous Systems to prepare for the postural responses by guessing about potential perturbation.

     

    Figure. Knowing the timing of upcoming perturbation shortens reflex latency.

     

    Publication

    Shinya M, Kawashima N, Nakazawa K (2016). Temporal, but not Directional, Prior Knowledge Shortens Muscle Reflex Latency in Response to Sudden Transition of Support Surface During Walking. Front Hum Neurosci. 2016 Feb 8;10:29. doi: 10.3389/fnhum.2016.00029.

    https://www.ncbi.nlm.nih.gov/pubmed/26903838

     

    The author

    Masahiro SHINYA, assistant professor at Sports Science Laboratory, Department of Life Sciences, the University of Tokyo, works on human motor control during walking and standing. He got his PhD in Human and Environmental Studies at the Kyoto University, Japan. Before he got this position, he worked as a postdoc fellow with Prof. Pearson at University of Alberta where he studied spatial working memory during animal and human locomotion.

     

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  • 31 Oct 2016 by Lisa Alcock

    Falls remain a major public health issue in people with Parkinson’s Disease (PD). Trip-related falls are common in PD, due to a combination of inadequate foot clearance and insufficient postural responses. Walking within a real-world environment presents additional cognitive and motor challenge, which might explain inadequate responses to trips during daily life activities. Dual-task paradigms are often used to simulate a similar attentional load as experienced in real-life. This study characterised foot clearance in healthy older adults and in PD during dual-task walking using both conventional (minimum and maximum foot clearance) and novel (gradients of foot clearance) metrics to enhance our understanding of the factors underpinning trip risk.

    Seventy-six people with early PD and 81 healthy older adults walked for 2-minutes around a 25-metre circuit. A subset of this cohort completed the same walk under dual-task (maximum digit recall) conditions (PD n=40, older adults n=48). Temporal-spatial gait was measured using an instrumented walkway and foot (heel and toe) trajectories were obtained using high-speed motion capture (See Figure.1 for extracted metrics). PD walked more slowly with a reduced step length during both single- and dual-task. Interestingly, a shorter step length was most strongly associated with reduced foot clearance in both older adults and PD (r=0.41-0.89) beyond associations reported for gait speed and step time. The maximum heel (H1) and toe (T1, T3) clearance were lower in both groups during dual-task. The toe gradient was shallower during dual-task in both groups and the heel gradient was shallower in PD compared to the healthy older adults during both single- and dual task walking (p<.001).

    Our experimental dual-task paradigm confirmed that trip risk is increased during dual-task conditions, due to a significantly reduced toe clearance gradient in both PD and healthy older adults. During the single-task condition, a reduced heel gradient was observed in this mild PD cohort which may be an early indication of PD-related gait deficits such as shuffling. Furthermore, the strong association between a shorter step length and lower foot clearance adds to our understanding of how spatial determinants of gait and disease progression (i.e. hypokinesia, bradykinesia) influence foot clearance. Our findings will guide the development of tailored interventions geared towards reducing trip-related falls in PD by evaluating whether enhancing step length may translate into improved foot clearance.

    Figure.1 – Determination of extracted variables from the heel and toe trajectories.
    ESW, MSW and LSW denote early-, mid- and late- swing.

     

     

    Publication: Lisa Alcock, Brook Galna, Sue Lord & Lynn Rochester, (2016). Characterisation of foot clearance during overground walking in ageing and Parkinson’s disease: Deficits associated with a dual task. Journal of Biomechanics. doi:10.1016/j.jbiomech.2016.06.007.

     

    The author

    Lisa Alcock, Research Associate and Gait Laboratory Manager, Institute of Neuroscience, Newcastle University, UK.

    Lisa completed her PhD in 2012 in Clinical Biomechanics at the University of Hull. Lisa currently works within the Brain and Movement Research Group at Newcastle University and her research is concerned with characterising the functional (visual, attentional, motor) demands of movement and neural control required for the safe completion of daily locomotor tasks. She is interested in how these demands are heightened as a result of both ageing and pathology and in applying this knowledge to better inform the design and development of physical interventions and environmental modifications to reduce falls.

     

     

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  • 25 Oct 2016 by Trinidad Valenzuela

    Older people who fall, often have reduced strength, poor balance and limited functional abilities, all of which can be improved through well-designed exercise interventions. However, exercise participation and adherence in older adults is also often low. Technology-based exercise programs (also known as exergames) have the potential to improve exercise adherence by reducing a number of perceived barriers to exercise (including lack of time, accessibility, boredom and fear of falling). We completed a systematic review to look at the current literature regarding older adults’ acceptability and adherence to technology-based exercise interventions.

    Twenty-two studies were included in the systematic review with participants’ ages ranging between 67 and 86 years. Ten studies compared outcomes between technology-based and traditional exercise programs. Both types of interventions reported high adherence rates, which can be partly attributed to the supervised nature of the interventions and short follow-up periods (median 91.25% and 83.58%, respectively). Nonetheless, adherence rates were higher for technology-based interventions compared to traditional interventions independent of study site, level of supervision, and delivery mode. The majority of the studies used commercially available gaming technologies (e.g. Nintendo Wii).

    Findings from this systematic review suggest that technology offers a well-accepted method to provide older adults with engaging exercise opportunities while maintaining high adherence rates for at least the first 12 weeks (study lengths ranged from 3 weeks to 20 weeks). More research is required to investigate the feasibility, acceptability, and effectiveness of technology-based exercise programs undertaken by older people at home over extended trial periods.

     

     

     

     

     

     

     

     

     

     

     

     

     

     

    Figure: Example of a technology-based exercise program (exergame) to reduce fall related risk factors in older people. 

     

    Publication

    Valenzuela T, Okubo Y, Woodbury A, Lord SR, Delbaere K (2016). Adherence to technology-based exercise programs in older adults: a systematic review. Journal of Geriatric Physical Therapy. June 29 [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/27362526 https://www.ncbi.nlm.nih.gov/pubmed/27362526

     

    The author

    Trinidad Valenzuela has a background in Exercise Physiology with a focus on exercise for the prevention and treatment of chronic conditions. She has recently completed her doctoral research at the University of New South Wales and the Falls, Balance and Injury Research Centre at Neuroscience Research Australia with Prof. Kim Delbaere, Prof. Stephen Lord and Dr Husna Razee. Her research focuses on understanding and improving exercise adherence in older people, and developing novel exercise interventions using technology to prevent falls.

     

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  • 19 Oct 2016 by Lars Schwickert

    12 Oct 2016 by L. Schwickert

     

    Everyone is familiar with the horrific stories about older adults who are unable to get up after a fall. Getting up after a fall is indeed problematic for many older adults, which often leads them to remain incapacitated on the floor for a long time. It is a strong interest of clinicians and health-care providers to prevent these so-called “long-lies” as they can cause serious medical problems. A valuable approach to assist with the development of technologies to detect and prevent falls is to identify the act of standing up from a lying position. Kinematic analysis to objectively describe and assess standing up performance from inertial sensors is currently lacking. Hence, our main aim was to assess kinematic features during lie-to-stand transfers and describe age-related differences. In our study in Sensors, we present an easily deployable method to assess standing up based on inertial sensor signals.

     

    Fourteen younger participants between 20 and 50 years of age, and 10 healthy older community dwellers aged 60 years and older, were asked to stand up from different initial lying postures on the floor (lying on their back, front, left and right sides). All participants were able to repeatedly stand up without help. The participants were asked to initiate the transfers voluntarily and to end the transfers in an erect standing position without considerable body movement. Kinematic data were recorded with Opal sensors (Figure 1, APDM, Portland, OR, USA) located on the sternum and lower back, which sampled 3D accelerations, angular velocity and magnetic fields at 128 Hz.

     

    Figure 1: Lower-back tri-axial (anterior-posterior (AP), medio-lateral (ML) and superior-inferior (SI)) acceleration signal of a lie-to-stand transfer in a younger (A) and older adult (B). C and D show the correspondent vertical velocity traces, with the start and end points marking the main elevation events measured at the lower back.

     

    Our results show that temporal and kinematic measures of transfer performance, such as duration, angular velocity, maximum vertical acceleration, maximum vertical velocity, smoothness, fluency, total rotation, were significantly different between younger and older participants. These results showed the feasibility of using body-worn sensors for the analysis of lie-to-stand movements and describe how younger and older adults stand up from the floor. This will help to better understand sensor signals of recovery after real world falls.

     

    Understanding kinematics and different movement patterns underlying lie-to-stand transfers will help to develop autonomous technologies to detect long lies after falls and provide suitable exercise interventions for their prevention. Our results motivate further application of kinematic analysis on recovery patterns after real-world falls.

     

    Publication:

    L. Schwickert, R. Boos, J. Klenk, A. Bourke, C. Becker and W. Zijlstra (2016). Inertial Sensor Based Analysis of Lie-to-Stand Transfers in Younger and Older Adults. Sensors, online August 2016. http://www.mdpi.com/1424-8220/16/8/1277

     

     

    The author:

    Lars Schwickert is a research fellow at the Department of Clinical Gerontology at Robert-Bosch-Hospital in Stuttgart, Germany, working with Prof. Dr. Clemens Becker. He has a background in sports and exercise science with a medical focus, and he is currently in the final stage of his doctoral research at the Institute of Movement and Sport Gerontology of the German Sport University Cologne with Prof. Wiebren Zijlstra. His research focuses on the recovery after a fall measured with body-worn sensors.

     

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  • 14 Oct 2016 by Nadia Dominici

    Every year about 500,000 people become disabled as a result of spinal cord injuries (SCI). The communication lines between the brain and spinal cord below the injury are cut or dramatically diminished, depending on the severity of the event, which leads to a range of motor disabilities.

    It is possible to access the surviving circuits and pathways to alleviate these deficits via epidural electrical stimulation (EES). Walking requires the activation of spatially distributed spinal motor circuits following precise temporal sequences that are continuously adjusted through sensory feedback. Therefore, current neuromodulation therapies - which deliver stimulation to restricted spinal cord locations and remain constant throughout gait execution - are not optimal. In the present work, we argued that targeted stimulation in space and time of the spinal cord, matching the natural dynamics of spinal motor circuit activation, can restore walking and improve motor control after spinal cord injury.

    We first conducted anatomical and functional experiments to visualize the spatiotemporal pattern of hindlimb motoneuron activation in intact rats (Figure 1a). We found that walking involves the alternating activation of spatially restricted hotspots underlying extensor versus flexor muscle synergies. We then developed neuromodulation strategies that specifically target proprioceptive feedback circuits in the dorsal roots in order to access these hotspots. Computer simulations determined the optimal electrode locations to recruit specific subsets of dorsal roots. These results steered the design of spatially selective spinal implants and real–time control software to modulate extensor versus flexor muscle synergies with precise temporal resolution adjusted through movement feedback. This conceptually new stimulation strategy reinforced extension versus flexion components for each hindlimb independently and improved a range of important gait features after complete SCI (see Figure 1b).

    We considered that spinal implants designed to activate the proprioceptive afferents projecting to the identified flexor and extensor hot spots would engage muscle synergies encoders related to extension and flexion. Our results showed that tailored spinal implants targeting specific subset of dorsal roots with electrodes enabled a gradual control over the degree of flexion and extension on the left and right hindlimbs. Although challenges lie ahead, we believe that spatiotemporal neuromodulation of the spinal cord will become a viable way to accelerate and augment functional recovery in humans with SCI.

    Figure 1: Spatiotemporal neuromodulation reproduces the natural pattern of motoneuron activation. From left to right and top to down. (a) Tracer injections into muscles spanning each hindlimb joint, to visualize the spatial location of hindlimb motoneurons. We decomposed the muscle activity during locomotion recorded in all the traced muscles into functional models (muscle synergies). To link muscle synergies to the activation of the burst (‘hotspot’) of motoneuron activity, we extracted the spinal map for each synergy independently. A model of spinal segments showing the temporal sequence underlying the recruitment of muscle synergies and the corresponding activation of extensor and flexor hot spots. (b) Rats received complete SCI at T7 and a spinal implant with conventional midline electrodes (black) and spatially selective lateral electrodes (blue and red). Locomotion in rats on a treadmill without stimulation and with continuous neuromodulation applied over the midline of lumbar and sacral segments (black electrodes) and during spatiotemporal neuromodulation (blue and red electrodes). On the right the results for an intact rat is showed.

    Publication

    Wenger N, Moraud EM, Gandar J, Musienko P, Capogrosso M, Baud L, Le Goff CG, Barraud Q, Pavlova N, Dominici N, Minev IR, Asboth L, Hirsch A, Duis S, Kreider J, Mortera A, Haverbeck O, Kraus S, Schmitz F, DiGiovanna J, van den Brand R, Bloch J, Detemple P, Lacour SP, Bézard E, Micera S, Courtine G (2016). "Spatiotemporal neuromodulation therapies engaging muscle synergies improve motor control after spinal cord injury." Nature Medicine. Feb;22(2):138-45. http://www.nature.com/nm/journal/v22/n2/full/nm.4025.html

    The author

    Nadia Dominici, Associate Professor at the Department of Human Movement Sciences, Faculty of Behavioural and Movement Science at the Vrije Universiteit of Amsterdam, Research Institute MOVE, The Netherlands.

    Nadia Dominici works on the interplay between brain and muscular activity underlying independent walking in children, as well as on the biomechanics of human locomotion. After a master diploma in Physics, she obtained a PhD in Neuroscience at the University of Rome “Tor Vergata”. She has held research positions at the Laboratory of Neuromotor Physiology of the Santa Lucia Foundation in Rome, where she focused on central pattern generation networks and on the development of locomotion in children, and at the University of Zürich, and EPFL in Lausanne, where she developed neurorehabilitation techniques to restore walking in animals after spinal cord injuries.

     

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  • 15 Aug 2016 by M. Encarna Micó-Amigo

    For most of us, walking is a common activity in daily-life. The ability to walk is essential for mobility and independence. Moreover, the way we walk reflects aspects of the integrity of the neuromuscular system and mirrors our health status. Thus, the evaluation of gait is important in a clinical context, especially for the diagnosis, treatment, and rehabilitation of motor disorders. The quantitative evaluation of gait, by parameters such as step duration, step length, walking speed and cadence, requires objective and reliable technology. Gait evaluation in a clinical setting is often restrained by the available space. Hence, the technology should be able to evaluate short distances and should be easy to implement. In our study in JNR, we present an easily deployable method to evaluate gait based on body-fixed-sensors. Our main aim in this study was to develop a new algorithm for the calculation of step durations from acceleration signals of short duration.

     

    Twenty healthy older adults, with an average age of 74 years, were invited to walk a distance of only 5 meters. They wore body-fixed-sensors on their heels and lower back, which recorded linear accelerations in 3D. In addition, we used a 3D motion tracking system for validation of our accelerometry-based algorithms. The performance of the algorithm was assessed by comparing differences in step duration between three methods: step detection from the 3D motion tracking system, step detection from the application of the algorithm to low-back accelerations, and step detection from the application of the algorithm to heel accelerations.

     

    The proposed algorithm detected all steps with differences in step duration between methods of below 4%. Our novel method provides opportunities to evaluate walking patterns from short walking distances as are commonly assessed in clinical settings. It employs body-worn-sensors which are small, lightweight and easy to wear, and allow the assessment of gait at relative low cost and with low interference. Our method might also have value for a daily-life context (outside a laboratory). In addition, our results motivate further investigation of the utility of body-fixed-sensors in a clinical context, opening paths for the objective evaluation of the health status of humans.

     

    Figure 1. Low-Back acceleration signal in the anterior-posterior direction (with a sampling rate of 100 samples/s) and detected events.

     

    Publication:

    “A novel accelerometry-based algorithm for the detection of step durations over short episodes of gait in healthy elderly”. Journal of Neuroengineering and Rehabilitation. Published on April 2016. M. E. Micó-Amigo, I. Kingma, E. Ainsworth, S. Walgaard, M. Niessen, R.C. van Lummel. J.H. van Dieën.

    https://jneuroengrehab.biomedcentral.com/articles/10.1186/s12984-016-0145-6

     

    The author:

    M. Encarna Micó-Amigo is in the final stage of her doctoral research at MOVE Research Institute Amsterdam, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands. She studied biomedical engineering in a multi-disciplinary and international context and currently pursuits a doctoral degree at the Vrije Universiteit Amsterdam. The goal of her research is the identification of preclinical and progression parameters of Parkinson’s disease through the analysis of gait using acceleration and angular velocity signals in collaboration with Prof. Dr. Walter Mätzler.

     

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  • 25 Jul 2016 by Jonathan Singer

    Stepping is often a critical last-resort response to recover balance following a slip or trip. Interestingly, when older adults step to regain forward balance, they often lose stability, tipping over in the sideways direction. This sideways instability likely arises during restabilisation, after they have placed their stepping foot on the ground, and is particularly relevant because of its relationship to sideways falls and hip fracture. This work focuses on the biomechanics of the “restabilisation phase” of the stepping response, to better understand what causes sideways instability when older adults try to regain balance in the forward direction.

    Twenty healthy younger adults (mean age: 24 years) and twenty healthy older adults (mean age: 71 years) participated in the study. The experimental setup tested participants’ forward stepping responses using a single step, which was provoked with a tether release from a standardized forward leaning position (Fig. 1a). A motion analysis system and four force platforms were used to record whole body movements and applied forces, as participants took a step and restabilised. Instability was defined by how far the whole-body centre of mass (COM) progressed in a sideways direction. We also examined the divergence between the ground reaction force vector and the whole-body COM at two specific instances, which we believed were related to instability. Our previous work has suggested the first peak divergence (P1) may arise from pre-planned muscle activation, initiated before stepping foot contact. The second peak divergence (P2) is believed to arise in response to instability after foot contact. We observed that older adults had greater sideways COM movement. There were no age-related differences in the amount of divergence between the ground reaction force and the COM. The timing of the P2 peak divergence, however, was increased among older adults (Fig. 1b). Further, the extent of sideways COM movement was correlated with the length of time needed to achieve the P2 peak divergence.

    Figure 1. Depiction of the tether-release experimental setup (A, left); Experimental results (B, right): Angle of divergence of the ground reaction force relative to the COM (top); sideways COM displacement. Increasing magnitude indicates greater movement toward the stepping limb (bottom).

    Older adults appear to have the capacity to control sideways instability, but do so with inappropriate timing. Our results suggest that sideways falls among older adults during forward stepping reactions may be caused by a delay in either detecting or responding to lateral instability arising after foot-contact. Balance training programs, to reduce falls among older adults, could include tasks to challenge restabilisation, such as prescribing foot placement or changing stepping surfaces. Future work is required to understand the specific sensory and/or motor components responsible for sideways instability.    

    Publication

    Singer, J.C., Prentice, S.D., McIlroy, W.E. (2016). Age-related challenges in reactive control of mediolateral stability during compensatory stepping: a focus on the dynamics of restabilisation. J. Biomech, 49(5), 749-755. http://dx.doi.org/10.1016/j.jbiomech.2016.02.001

    The Author

    Jonathan Singer, Faculty of Kinesiology and Recreation Management, University of Manitoba, Canada

    Jon obtained his PhD from the University of Waterloo and received post-doctoral training with the Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto. His research aims to understand the neuromechanical mechanisms by which humans maintain stability, and to reduce the challenges in stability control faced by older adults.

     

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  • 27 Jul 2016 by Janet van Uem

     

     

    Wearable inertial sensors can be used to measure movements in everyday life. Advanced algorithms translate these movements into metrics that can be interpreted by clinicians, patients and consumers. We believe that these wearables are the future for movement assessment and can empower patients towards taking control of their own health. They are relatively cheap, small, can be worn over longer periods of time, are easy to handle, and collect data objectively and unobtrusively. Especially in progressive movement disorders, such as Parkinson's disease, it is important to monitor the course of the disease and the effects of therapy.  

    We were interested in whether wearing wearables over a longer time period would affect Health-Related Quality of Life in people with Parkinson's disease. A 12-week study over three centres in Europe (Tromsø, Lisbon and Tübingen) included 22 people with Parkinson disease. Half of these people received a sensor set with three wearables for the day and one wearable during the night; the other half did not receive a sensor set. During the first four weeks the sensor group did not receive feedback on their movement behaviour. In the following eight weeks, the sensor group received feedback on their movement behaviour. Health-Related Quality of Life was assessed after four, twelve and fourteen weeks (follow-up). We assessed: i) overall Health-Related Quality of Life, ii) Health-Related Quality of Life in the mobility domain, and iii) Health-Related Quality of Life in the activities of daily living domain. After the first four weeks, no significant changes in Health-Related Quality of Life between groups could be identified. After twelve weeks, a tendency towards an improved Health-Related Quality of Life in the mobility domain was seen in the sensor group compared to the non-sensor group. After fourteen weeks, a significantly improved Health-Related Quality of Life in the mobility domain was detected in the sensor group.

    These findings indicate a high acceptance of wearable sensor systems by people with Parkinson’s disease, even over longer periods of time. Under certain circumstances (e.g., when providing useful feedback about their movement behaviour) wearables may even have a positive effect on (aspects of) Health-Related Quality of Life. This may be best explained by a positive effect of increased self-knowledge. Self-knowledge can enable patients to actively take part in the decision-making process during treatment and increase self-empowerment, eventually leading to better teamwork between physician and patient, better health outcomes, and increased patient satisfaction. 

     

    Publication

    van Uem JMT, Maier KS, Hucker S, Scheck O, Hobert MA, Santos AT, Fagerbakke Ø, Larsen F, Ferreira JJ, Maetzler W. Twelve-Week Sensor Assessment in Parkinson’s Disease: Impact on Quality of Life. Mov Disord. 2016; May 31. doi:10.1002/mds.26676.

     

    Author

    Janet van Uem is a PhD Candidate at the Graduate Training Centre of Neuroscience, International Max Planck Research School, at the University of Tübingen and Hertie Institute for clinical neuroscience in Tübingen, Germany.

    Janet’s research aims to better understand Health-Related Quality of Life in Parkinson's Disease. There is a need from both sides i) clinicians and researchers, and ii) Parkinson's disease patients to measure Parkinson's disease features objectively. In her thesis she explores the relationship between objective measurement of Parkinson's disease features and Health-Related-Quality of Life, and how objective measurement can possibly improve Health-Related-Quality of Life. Janet is currently in the final phase of her PhD programme.

     

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  • 20 Sep 2016 by Elmar Kal

    Many stroke patients have difficulty with performing multiple tasks at the same time, like walking and talking. This negatively affects their mobility and fall risk. One way to target this problem is to enhance patients’ automaticity of movement, such that more attention is available for secondary task performance. But how can they achieve this? According to the “Constrained Action Hypothesis”, the answer is simple: instruct patients to direct attention externally on the movement goal, rather than internally on movement execution itself. In a previous study, we found that leg-stepping performance in healthy adults was unaffected by the imposition of a dual-task when they focused externally (on where to place their feet), but deteriorated when they focused internally (on flexing/extending their leg). The current study aimed to replicate these findings in patients with stroke.

    Thirty-nine chronic hemiparetic stroke patients (Mage=62.6 years) performed a seated stepping task (Figure 1). Both legs were tested separately. Stepping speed was measured with accelerometers. In dual-task conditions, patients were tested on two different dual-tasks: a reaction time task and an executive function task. Using a counterbalanced, cross-over design, single- and dual-task performance was assessed under both external focus and internal focus conditions (Figure 1). Prior to the experiment, patients completed motor and cognitive tests, and a questionnaire regarding the degree to which they preferred internal or external focus in daily life. Results showed that single-task stepping speed in stroke patients was similar in both focus conditions (p=.34). Planned follow-up analysis revealed that patients performed best with the focus they preferred to use in daily life (p=.01). Regarding dual-task performance, patients performed better when they focused internally (p=.06; Figure 1). Also, their attentional capacity was more predictive of their dual-task performance in external compared to internal focus conditions (p=.05).

    Different from healthy adults, external focus instructions did not improve single- or dual-task performance post-stroke. In fact, dual-task performance seemed better with an internal focus. One explanation for these findings is that the overall strong internal focus preference in our sample made switching to a relatively unfamiliar external focus so attention-demanding that it affected automaticity. This would also explain why attentional capacity was most important for dual-task performance in external focus conditions. In conclusion, our results implicate that stroke patients do not necessarily benefit from an external focus. Further research should explore how attentional focus influences dual-task performance post-stroke, specifically taking into account patients’ individual focus preferences.

     

    Figure 1. Leg-stepping task (A, left) and dual-task results (B, right). The leg-stepping task was performed both in external and internal focus conditions. In external focus condition (A, lower panel) patients were instructed to focus on placing their foot in front of/behind a line that was taped on the floor. In the internal focus condition (A, lower panel) patients were instructed to focus on flexing and extending their leg. Dual-task performance (B, right) is expressed in dual-task costs (DTCs; STperformance – DTperformance / STperformance *100%). DTCs were calculated separately for the leg-stepping and cognitive tasks. Lower DTCs reflect better dual-task performance.

     

    Publication

    Kal EC, Van der Kamp J, Houdijk H, Van Bennekom C, Scherder EJA. (2016) Stay focused! The effects of internal and external focus of attention on movement automaticity in patients with stroke. PLoS One 10(8): e0136917. doi:10.1371/journal.pone.0136917 http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0136917

     

    The author

    Elmar Kal

    1. Research & Development, Heliomare Rehabilitation Centre, Wijk aan Zee, The Netherlands
    2. Faculty of Behavioural and Human Movement Sciences, VU University Amsterdam, Amsterdam The Netherlands


    Elmar Kal works as a PhD student on a joint project of Heliomare Rehabilitation Centre and VU University Amsterdam, The Netherlands. His project focuses on the effectiveness of implicit learning strategies for enhancing motor and motor-cognitive dual-task performance in people with stroke.

     

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