Transauricular vagus nerve stimulation at auricular acupoints Kindey (CO10), Yidan (CO11), Liver (CO12) and Shenmen (TF4) can induce auditory and limbic cortices activation measured by fMRI

Publication date: Available online 24 December 2017
Source:Hearing Research
Author(s): Liyan Peng, Ketao Mu, Aiguo Liu, liangqiang Zhou, Yueyue Gao, Imrit Tejvansh Shenoy, Zhigang Mei, Qingguo Chen
The purpose of this study was to explore the central mechanism of transauricular vagus nerve stimulation (taVNS) to human by fMRI and to find a suitable taVNS site for potential tinnitus treatment. 24 healthy subjects aged between 28 and 38 years were enrolled in the experiment. 8 subjects were stimulated in the auricular acupoints Kindey (CO10), Yidan (CO11), Liver (CO12) and Shenmen (TF4) in the left ear, 8 subjects were stimulated at the anterior wall of the auditory canal and left lower limb as an anterior stimulation group; 8 persons who were arranged in a sham group received taVNS at the left ear lobe and tail of the helix. Functional magnetic resonance imaging (fMRI) data from the cortices was collected and an Alphasim analysis was performed. We found that taVNS at auricular acupoints CO10-12, TF4 can instantly and effectively generate blood oxygenation level dependent (BOLD) signal changes in the prefrontal, auditory and limbic cortices of healthy subjects by fMRI. When comparing the acupoints group and the sham group in the left brain, the signals from the prefrontal cortex, the auditory ascending pathway including superior temporal gyrus, middle temporal gyrus, thalamus and limbic system regions such as putamen, caudate, posterior cingulate cortex, amygdala and parahippocampal gyrus were increased under our stimulation. The difference of the BOLD signal in the left brain between acupoints group and anterior group was in the superior temporal gyrus. We could also find signal differences in several regions of right brain among the groups. In conclusion, taVNS at acupoints CO10-12, TF4 could activate the prefrontal, auditory and limbic cortices of healthy brain and this scheme could be a promising tool for tinnitus treatment.



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How do walkers behave when crossing the way of a mobile robot that replicates human interaction rules?

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Christian Vassallo, Anne-Hélène Olivier, Philippe Souères, Armel Crétual, Olivier Stasse, Julien Pettré
Previous studies showed the existence of implicit interaction rules shared by human walkers when crossing each other. Especially, each walker contributes to the collision avoidance task and the crossing order, as set at the beginning, is preserved along the interaction. This order determines the adaptation strategy: the first arrived increases his/her advance by slightly accelerating and changing his/her heading, whereas the second one slows down and moves in the opposite direction. In this study, we analyzed the behavior of human walkers crossing the trajectory of a mobile robot that was programmed to reproduce this human avoidance strategy. In contrast with a previous study, which showed that humans mostly prefer to give the way to a non-reactive robot, we observed similar behaviors between human-human avoidance and human-robot avoidance when the robot replicates the human interaction rules. We discuss this result in relation with the importance of controlling robots in a human-like way in order to ease their cohabitation with humans.



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Perceptual-motor regulation in locomotor pointing while approaching a curb

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Steven van Andel, Michael H. Cole, Gert-Jan Pepping
Locomotor pointing is a task that has been the focus of research in the context of sport (e.g. long jumping and cricket) as well as normal walking. Collectively, these studies have produced a broad understanding of locomotor pointing, but generalizability has been limited to laboratory type tasks and/or tasks with high spatial demands. The current study aimed to generalize previous findings in locomotor pointing to the common daily task of approaching and stepping on to a curb.Sixteen people completed 33 repetitions of a task that required them to walk up to and step onto a curb. Information about their foot placement was collected using a combination of measures derived from a pressure-sensitive walkway and video data. Variables related to perceptual-motor regulation were analyzed on an inter-trial, intra-step and inter-step level.Similar to previous studies, analysis of the foot placements showed that, variability in foot placement decreased as the participants drew closer to the curb. Regulation seemed to be initiated earlier in this study compared to previous studies, as shown by a decreasing variability in foot placement as early as eight steps before reaching the curb. Furthermore, it was shown that when walking up to the curb, most people regulated their walk in a way so as to achieve minimal variability in the foot placement on top of the curb, rather than a placement in front of the curb. Combined, these results showed a strong perceptual-motor coupling in the task of approaching and stepping up a curb, rendering this task a suitable test for perceptual-motor regulation in walking.



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Does additional patella tendon shortening influence the effects of multilevel surgery to correct flexed knee gait in cerebral palsy: A randomized controlled trial

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): M.C.M. Klotz, Britta K. Krautwurst, K. Hirsch, M. Niklasch, M.W. Maier, S.I. Wolf, T. Dreher
BackgroundThe aims of this study were to investigate if patellar tendon shortening (PTS) as a part of SEMLS (single event multilevel surgery) is effective for reduction of flexed knee gait in children with cerebral palsy (CP) and, if PTS leads to stiff knee gait.MethodsIn a randomized controlled study 22 children with flexed knee gait (age: 10.4 ± 2.6 years, GMFCS Level I–III) were randomized and allocated to two groups (1: SEMLS + PTS; 2: SEMLS no PTS): SEMLS was performed for correction of flexed knee gait either with or without additional PTS. Before and after surgery (follow up: 12.7 ± 1.6 months) kinematics (3-D motion analysis) and clinical parameters were compared.ResultsTwo children were lost to follow up. Maximum knee extension improved significantly in both groups after SEMLS while the patients with additional PTS showed much more correction (SEMLS + PTS: 37.6° to 11.4°, p = 0.007; SEMLS no PTS: 35.1° to 21.8°, p = 0.016). After surgery peak knee flexion decreased significantly (14.6°, p = 0.004) in the “SEMLS + PTS” group while there was no relevant change in the other group. There was a trend of increase in anterior pelvic tilt after surgery in both groups, but no statistical significant difference. After surgery knee flexion contracture (15.9°, p < 0.001) and popliteal angle (27.2, p = 0.009) measured on clinical examination only decreased significantly in the “SEMLS + PTS” group.ConclusionPTS is effective for correction of flexed knee gait and knee flexion contracture leading to superior stance phase knee extension. However, additional PTS may lead to stiff knee gait and a higher increase of anterior pelvic tilt.

Graphical abstract

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A systematic review of the gait characteristics associated with Cerebellar Ataxia

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Ellen Buckley, Claudia Mazzà, Alisdair McNeill
BackgroundCerebellar Ataxias are a group of gait disorders resulting from dysfunction of the cerebellum, commonly characterised by slowly progressing incoordination that manifests as problems with balance and walking leading to considerable disability. There is increasing acceptance of gait analysis techniques to quantify subtle gait characteristics that are unmeasurable by current clinical methods This systematic review aims to identify the gait characteristics able to differentiate between Cerebellar Ataxia and healthy controls.MethodsFollowing systematic search and critical appraisal of the literature, gait data relating to preferred paced walking in Cerebellar Ataxia was extracted from 21 studies. A random-effect model meta-analysis was performed for 14 spatiotemporal parameters. Quality assessment was completed to detect risk of bias.ResultsThere is strong evidence that compared with healthy controls, Cerebellar Ataxia patients walk with a reduced walking speed and cadence, reduced step length, stride length, and swing phase, increased walking base width, stride time, step time, stance phase and double limb support phase with increased variability of step length, stride length, and stride time.ConclusionThe consensus description provided here, clarifies the gait pattern associated with ataxic gait disturbance in a large cohort of participants. High quality research and reporting is needed to explore specific genetic diagnoses and identify biomarkers for disease progression in order to develop well-evidenced clinical guidelines and interventions for Cerebellar Ataxia.



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Comprehensive biomechanical characterization of feet in USMA cadets: Comparison across race, gender, arch flexibility, and foot types

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Jinsup Song, Kersti Choe, Michael Neary, Rebecca A. Zifchock, Kenneth L. Cameron, Michael Trepa, Marian T. Hannan, Howard Hillstrom
Lower extremity musculoskeletal injuries are common, complex, and costly problems. Literature supports associations between static foot structure and dynamic foot function, as well as between overuse injury and demographic characteristics. Previous studies failed to provide a comprehensive biomechanical foot characteristics of at-risk military personnel. In this study, foot structure, function, and arch height flexibility (AHF) were objectively measured in 1090 incoming cadets (16.3% female, mean age of 18.5years and BMI of 24.5kg/m²) of the United States Military Academy at the start of their training. A Generalized Linear Model with an identity link function was used to examine the effects of race, gender, foot types, and AHF while accounting for potential dependence in bilateral data. Planus and flexible feet independently demonstrated over-pronation, as measured by reduced Center of Pressure Excursion Index (CPEI). When comparing across race, Black participants showed a significantly lower arch height index (AHI), a larger malleolar valgus index (MVI), and a higher prevalence of pes planus (91.7% versus 73.3% overall). However, Asian participants with flexible arches, rather than Black with low arch, displayed over-pronation in gait. Females showed no significant difference in standing AHI and MVI but demonstrated a significantly greater AHF and a reduced CPEI than male participants. This was the first large scale investigation that comprehensively characterized biomechanical foot in a cohort of young at-risk individuals with lower limb musculoskeletal injuries. Long-term goal is to examine the relationship between these biomechanical features and injuries, ultimately to develop effective preventive measures.



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Reliability of upper limb and trunk joint angles in healthy adults during activities of daily living

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Susannah M. Engdahl, Deanna H. Gates
Assessments of upper limb performance should require participants to perform tasks that challenge the limits of their ability. In order to select appropriate tasks, it is important to know which joints are used to perform the movement and how reliably those movements can be measured. The purpose of this work was to quantify the reliability of upper limb and trunk joint angles in healthy adults during common activities of daily living (ADLs). Nineteen participants performed six ADLs with the right arm (applying deodorant, turning a doorknob, answering a desk telephone, placing a pushpin in a bulletin board, wiping a plate with a towel, and pouring water from a pitcher) during two separate sessions. Within- and between-session reliability was quantified using intraclass correlation coefficients (ICCs) and minimum detectable change values (MDCs). Reliability was generally better within-session than between-session. The ICCs exceeded 0.75 for 88% of the joint angles and exceeded 0.90 for 32% of the angles. All MDCs were less than 25° and 61% were also less than 10°. The MDCs represented a larger percent of the average angles for the trunk (61%) and wrist (62%) compared to the shoulder (18%) and elbow (26%). Although these results show that most angles can be measured reliably for these six ADLs, reliability varied considerably between joints. It is therefore important to select tasks for assessing of upper limb performance based on which specific joints need to be evaluated.



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The iFST: An instrumented version of the Fukuda Stepping Test for balance assessment

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Valeria Belluscio, Elena Bergamini, Marco Iosa, Marco Tramontano, Giovanni Morone, Giuseppe Vannozzi
The maintenance of the upright posture during dynamic balance requires the integration of sensory inputs regulated by the brain. After a neurological event, the assessment of balance control impairments is crucial for supporting health professionals in the design of personalized rehabilitation protocols. A commonly used test to assess balance ability is the Fukuda Stepping Test (FST). However, the clinical parameters traditionally considered are not fully representative of the patient’s motor ability. The purpose of this study was to devise an instrumented version of the FST (iFST) that embodies inertial sensors and allows to obtain individual motor strategy information. Twenty-seven sub-acute stroke patients and 18 healthy adults performed a repeated stepping task with closed eyes wearing five inertial sensors located on both distal tibiae and at pelvis, sternum, and head levels. From final foot position, body rotation and linear displacements were measured. A set of indices related to upper-body stability were estimated from pelvis, sternum, and head accelerations: Root Mean Square, Attenuation Coefficients, and improved Harmonic Ratio. Two additional parameters based on upper-body angular velocities were devised to assess step-by-step repeatability and inter-segment velocity variations. The results suggest that the clinical parameters do not provide enough information about the two groups’ motor strategies. Conversely, five iFST parameters were identified as predictors of patients’ motor ability, discriminating not only between healthy and pathological subjects, but also between different motor deficit levels within the same pathology. The iFST could be included in the clinical routine assessment of balance impairments, supporting the design of personalized treatments.



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Sympathetic nervous system activity measured by skin conductance quantifies the challenge of walking adaptability tasks after stroke

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): David J. Clark, Sudeshna A. Chatterjee, Theresa E. McGuirk, Eric C. Porges, Emily J. Fox, Chitralakshmi K. Balasubramanian
BackgroundWalking adaptability tasks are challenging for people with motor impairments. The construct of perceived challenge is typically measured by self-report assessments, which are susceptible to subjective measurement error. The development of an objective physiologically-based measure of challenge may help to improve the ability to assess this important aspect of mobility function. The objective of this study to investigate the use of sympathetic nervous system (SNS) activity measured by skin conductance to gauge the physiological stress response to challenging walking adaptability tasks in people post-stroke.MethodsThirty adults with chronic post-stroke hemiparesis performed a battery of seventeen walking adaptability tasks. SNS activity was measured by skin conductance from the palmar surface of each hand. The primary outcome variable was the percent change in skin conductance level (ΔSCL) between the baseline resting and walking phases of each task. Task difficulty was measured by performance speed and by physical therapist scoring of performance. Walking function and balance confidence were measured by preferred walking speed and the Activities-specific Balance Confidence Scale, respectively.ResultsThere was a statistically significant negative association between ΔSCL and task performance speed and between ΔSCL and clinical score, indicating that tasks with greater SNS activity had slower performance speed and poorer clinical scores. ΔSCL was significantly greater for low functioning participants versus high functioning participants, particularly during the most challenging walking adaptability tasks.ConclusionThis study supports the use of SNS activity measured by skin conductance as a valuable approach for objectively quantifying the perceived challenge of walking adaptability tasks in people post-stroke.



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The effect of augmented somatosensory feedback on standing postural sway

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Angela Smalley, Scott C. White, Robert Burkard
Impaired balance resulting from reduced postural control occurs with aging and various medical conditions. Sensory input for balance control is provided by the visual, vestibular and somatosensory systems. Previous research suggests that increased proprioceptive feedback from various lower extremity devices improves balance. Mixed results have been reported with the use of orthoses such as ankle foot orthoses (AFOs). In this study, 20 healthy subjects wore footplates in their shoes or straps around their lower legs in order to imitate the somatosensory feedback produced by wearing AFOs, but without providing ankle restriction. Subjects’ standing balance was assessed using force plates and computerized dynamic posturography (the sensory organization test-SOT) to determine if either the footplates or the lower-leg straps would affect standing balance. The results revealed no significant difference with the use of the footplates, however, wearing the straps resulted in reduced postural sway for conditions when visual cue deprivation was combined with manipulation of somatosensory or vestibular feedback. This effect was more pronounced in participants with the poorest baseline measures of balance. These findings suggest that lower extremity devices, such as AFOs, may augment somatosensory feedback that could improve balance during challenging sensory deprivation conditions, independent of orthotic support at the ankle.



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The effect of spatial auditory landmarks on ambulation

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Adham M. Karim, Kavelin Rumalla, Laurie A. King, Timothy E. Hullar
The maintenance of balance and posture is a result of the collaborative efforts of vestibular, proprioceptive, and visual sensory inputs, but a fourth neural input, audition, may also improve balance. Here, we tested the hypothesis that auditory inputs function as environmental spatial landmarks whose effectiveness depends on sound localization ability during ambulation. Eight blindfolded normal young subjects performed the Fukuda-Unterberger test in three auditory conditions: silence, white noise played through headphones (head-referenced condition), and white noise played through a loudspeaker placed directly in front at 135 centimeters away from the ear at ear height (earth-referenced condition). For the earth-referenced condition, an additional experiment was performed where the effect of moving the speaker azimuthal position to 45, 90, 135, and 180° was tested. Subjects performed significantly better in the earth-referenced condition than in the head-referenced or silent conditions. Performance progressively decreased over the range from 0° to 135° but all subjects then improved slightly at the 180° compared to the 135° condition. These results suggest that presence of sound dramatically improves the ability to ambulate when vision is limited, but that sound sources must be located in the external environment in order to improve balance. This supports the hypothesis that they act by providing spatial landmarks against which head and body movement and orientation may be compared and corrected. Balance improvement in the azimuthal plane mirrors sensitivity to sound movement at similar positions, indicating that similar auditory mechanisms may underlie both processes. These results may help optimize the use of auditory cues to improve balance in particular patient populations.



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The coupled effects of crouch gait and patella alta on tibiofemoral and patellofemoral cartilage loading in children

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Scott C.E. Brandon, Darryl G. Thelen, Colin R. Smith, Tom F. Novacheck, Michael H. Schwartz, Rachel L. Lenhart
BackgroundElevated tibiofemoral and patellofemoral loading in children who exhibit crouch gait may contribute to skeletal deformities, pain, and cessation of walking ability. Surgical procedures used to treat crouch frequently correct knee extensor insufficiency by advancing the patella. However, there is little quantitative understanding of how the magnitudes of crouch and patellofemoral correction affect cartilage loading in gait.MethodsWe used a computational musculoskeletal model to simulate the gait of twenty typically developing children and fifteen cerebral palsy patients who exhibited mild, moderate, and severe crouch. For each walking posture, we assessed the influence of patella alta and baja on tibiofemoral and patellofemoral cartilage contact.ResultsTibiofemoral and patellofemoral contact pressures during the stance phase of normal gait averaged 2.2 and 1.0 MPa. Crouch gait increased pressure in both the tibofemoral (2.6–4.3 MPa) and patellofemoral (1.8–3.3 MPa) joints, while also shifting tibiofemoral contact to the posterior tibial plateau. For extended-knee postures, normal patellar positions (Insall-Salvatti ratio 0.8–1.2) concentrated contact on the middle third of the patellar cartilage. However, in flexed knee postures, both normal and baja patellar positions shifted pressure toward the superior edge of the patella. Moving the patella into alta restored pressure to the middle region of the patellar cartilage as crouch increased.ConclusionsThis work illustrates the potential to dramatically reduce tibiofemoral and patellofemoral cartilage loading by surgically correcting crouch gait, and highlights the interaction between patella position and knee posture in modulating the location of patellar contact during functional activities.



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Effects of plantar hypothermia on quasi-static balance: Two different hypothermic procedures

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Andresa M.C. Germano, Tobias Heß, Daniel Schmidt, Thomas L. Milani
Inducing hypothermia to examine its effects on balance is performed with various approaches. However, data interpretations of underlying postural mechanisms often do not consider the applied hypothermic protocol. In this context, the effects of diminished plantar mechanoreceptor activity on quasi-static balance performance were investigated, examining the applicability of a continuously cooling thermal platform in comparison with conventional ice pads. Increased instability for the thermal platform compared to cooling with ice pads was hypothesized, since we expected increased temperatures for the ice pad group directly after balance tests. Similar scores on a Visual Analogue Scale (VAS) were predicted regarding subjective pain. Results showed that both cooling procedures successfully induced plantar hypothermia. However, the thermal platform was more effective with respect to reaching and maintaining the desired temperature throughout the trials, especially when comparing temperatures before and after balance tests. Therefore, balance tests indeed demonstrated increased COP parameters exclusively after permanent cooling via the thermal platform as early as after the first 10 min of cooling. Reduced plantar input may result in this postural instability, but without the need of other sensory systems to compensate. The VAS generally demonstrated higher pain scores for the ice pads, rejecting our hypothesis. This is an important finding, since pain is known to influence balance. Therefore, permanent and controllable cooling via the thermal platform should be taken into consideration when conducting related research.



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Influence of handrail height and fall direction on center of mass control and the physical demands of reach-to-grasp balance recovery reactions

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Vicki Komisar, Konika Nirmalanathan, Alison C. Novak
The ability to maintain and recover center of mass (COM) and trunk control after a destabilization is critical for avoiding falls and fall-related injuries. Handrails can significantly enhance a person’s ability to recover from large destabilizations, by enabling the person to grasp and apply high forces to the rail to stabilize their COM. However, the influence of handrail height and falling direction on COM control and the demands of grasping are unknown. We investigated the effect of handrail height (34, 38, 42 in.) and fall direction (forward, backward) on COM and trunk control, and the corresponding physical demands of reach-to-grasp balance reactions. Thirteen young adults were destabilized with platform perturbations, and reached to grasp a nearby handrail to recover balance without stepping. COM kinematics and applied handrail forces were collected. COM control was evaluated in terms of: (1) COM range and peak displacement, velocity and momentum in all Cartesian axes; and (2) trunk angular displacement, velocity and momentum in the roll and pitch axes. The physical demands of grasping were estimated via resultant handrail impulse. Compared to forward-directed falling, backward-directed falling was generally associated with greater peak COM and trunk angular displacement, velocity and momentum, along with greater handrail impulse. Higher handrails generally resulted in reduced peak COM and trunk angular displacement, velocity and momentum, as well as reduced handrail impulse. These results suggest that higher handrails may provide a stability advantage within the range of handrail heights tested, with better COM control achieved with lower physical demands of grasping.



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How accurate is visual determination of foot strike pattern and pronation assessment

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Frédéric Meyer, Mathieu Falbriard, Kamiar Aminian, Gregoire P. Millet
Nowadays, choosing adequate running shoes is very difficult, due to the high number of different designs. Nevertheless, shoes have two main characteristics to fit runners’ technique and morphology: drop and arch support. Retailers’ advices are usually based on the visual assessment of the customer’s running technique. Such method is subjective and requires an experimented examiner while objective methods require expensive material, such as 3D motion system and pressure insoles. Therefore, the aim of this study was to determine the accuracy of foot strike pattern and pronation assessment using video cameras, compared to a gold standard motion tracking system and pressure insoles. 34 subjects had to run at 8, 12 and 16 Km/h shod and 12 Km/h barefoot during 30 s trials on a treadmill. Agreement between foot strike pattern assessment methods was between 88% and 92%. For pronation, agreement on assessment methods was between 42% and 56%. The results obtained indicate a good accuracy on foot strike pattern assessment, and a high difficulty to determine pronation with enough accuracy. There is therefore a need to develop new tools for the assessment of runner’s pronation.



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Increasing mediolateral standing sway is associated with increasing corticospinal excitability, and decreasing M1 inhibition and facilitation

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Tulika Nandi, Beth E. Fisher, Tibor Hortobágyi, George J. Salem
In standing, corticospinal excitability increases and primary motor cortex (M1) inhibition decreases in response to anterior posterior or direction unspecific manipulations that increase task difficulty. However, mediolateral (ML) sway control requires greater active neural involvement. Therefore, the primary purpose of this study was to determine the pattern of change in neural excitability when ML postural task difficulty is manipulated and to test whether the neural excitability is proportional to ML sway magnitude across conditions. Tibialis anterior corticospinal excitability was quantified using motor evoked potential (MEP) and postural sway was indexed using ML center of pressure (COP) velocity. Additionally, we examined inhibition and facilitation processes in the primary motor cortex using the paired pulse short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) techniques respectively. Measurements were repeated in four conditions with quiet stance as a control. Differences between conditions were tested using one-way repeated measures ANOVAs, on log transformed data. Associations were quantified using Spearman’s Rank Correlation Coefficient. There was a significant main effect of condition on all the neural excitability measures with MEP (p<0.001) being highest in the most difficult condition, and SICI (p=0.01), ICF (p<0.001) being lowest in the most difficult condition. Increasing ML COP velocity was significantly associated with increasing MEP amplitude (r=0.68, p<0.001), but decreasing SICI (r=0.24, p=0.03) and ICF (r=−0.54, p<0.001). Our results show that both corticospinal and M1 excitability in standing are scaled in proportion to ML task difficulty.



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Accuracy evaluation of a method to partition ground reaction force and center of pressure in cane-assisted gait using an instrumented cane with a triaxial force sensor

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Arinori Kamono, Mizuki Kato, Naomichi Ogihara
Clarifying the biomechanics of cane-assisted gait in elderly individuals and patients with gait disorders is important for developing better therapeutic interventions in the fields of rehabilitation and orthopedics. However, if the foot and the cane in the ipsilateral hand are placed on the same force plate simultaneously, the force plate cannot separate the forces as it records the sum of the forces. To overcome this indeterminacy problem of the ground reaction force (GRF) and the center of pressure (COP) in cane-assisted gait analysis, a method to partition the GRF and COP using an instrumented cane with a force transducer has been proposed. However, the accuracy and precision of the estimated GRF and COP has not been evaluated previously. We therefore reestablished a framework to partition the foot and cane forces during walking using an instrumented cane with a triaxial force sensor and evaluated the accuracy and precision of the method using a force plate array. Cane-assisted gait of healthy adults and hemiplegic patients were measured. Mean accuracy and precision associated with the GRF and COP measurements were approximately 0.4±1.4N and 0.2±2.7mm, respectively, indicating that the separations of the GRF and COP were sufficiently accurate for kinetic gait analysis. Although some methodological limitations certainly apply, this system will serve as a useful tool for improved therapeutic interventions.



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How do walkers behave when crossing the way of a mobile robot that replicates human interaction rules?

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Christian Vassallo, Anne-Hélène Olivier, Philippe Souères, Armel Crétual, Olivier Stasse, Julien Pettré
Previous studies showed the existence of implicit interaction rules shared by human walkers when crossing each other. Especially, each walker contributes to the collision avoidance task and the crossing order, as set at the beginning, is preserved along the interaction. This order determines the adaptation strategy: the first arrived increases his/her advance by slightly accelerating and changing his/her heading, whereas the second one slows down and moves in the opposite direction. In this study, we analyzed the behavior of human walkers crossing the trajectory of a mobile robot that was programmed to reproduce this human avoidance strategy. In contrast with a previous study, which showed that humans mostly prefer to give the way to a non-reactive robot, we observed similar behaviors between human-human avoidance and human-robot avoidance when the robot replicates the human interaction rules. We discuss this result in relation with the importance of controlling robots in a human-like way in order to ease their cohabitation with humans.



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Perceptual-motor regulation in locomotor pointing while approaching a curb

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Steven van Andel, Michael H. Cole, Gert-Jan Pepping
Locomotor pointing is a task that has been the focus of research in the context of sport (e.g. long jumping and cricket) as well as normal walking. Collectively, these studies have produced a broad understanding of locomotor pointing, but generalizability has been limited to laboratory type tasks and/or tasks with high spatial demands. The current study aimed to generalize previous findings in locomotor pointing to the common daily task of approaching and stepping on to a curb.Sixteen people completed 33 repetitions of a task that required them to walk up to and step onto a curb. Information about their foot placement was collected using a combination of measures derived from a pressure-sensitive walkway and video data. Variables related to perceptual-motor regulation were analyzed on an inter-trial, intra-step and inter-step level.Similar to previous studies, analysis of the foot placements showed that, variability in foot placement decreased as the participants drew closer to the curb. Regulation seemed to be initiated earlier in this study compared to previous studies, as shown by a decreasing variability in foot placement as early as eight steps before reaching the curb. Furthermore, it was shown that when walking up to the curb, most people regulated their walk in a way so as to achieve minimal variability in the foot placement on top of the curb, rather than a placement in front of the curb. Combined, these results showed a strong perceptual-motor coupling in the task of approaching and stepping up a curb, rendering this task a suitable test for perceptual-motor regulation in walking.



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Does additional patella tendon shortening influence the effects of multilevel surgery to correct flexed knee gait in cerebral palsy: A randomized controlled trial

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): M.C.M. Klotz, Britta K. Krautwurst, K. Hirsch, M. Niklasch, M.W. Maier, S.I. Wolf, T. Dreher
BackgroundThe aims of this study were to investigate if patellar tendon shortening (PTS) as a part of SEMLS (single event multilevel surgery) is effective for reduction of flexed knee gait in children with cerebral palsy (CP) and, if PTS leads to stiff knee gait.MethodsIn a randomized controlled study 22 children with flexed knee gait (age: 10.4 ± 2.6 years, GMFCS Level I–III) were randomized and allocated to two groups (1: SEMLS + PTS; 2: SEMLS no PTS): SEMLS was performed for correction of flexed knee gait either with or without additional PTS. Before and after surgery (follow up: 12.7 ± 1.6 months) kinematics (3-D motion analysis) and clinical parameters were compared.ResultsTwo children were lost to follow up. Maximum knee extension improved significantly in both groups after SEMLS while the patients with additional PTS showed much more correction (SEMLS + PTS: 37.6° to 11.4°, p = 0.007; SEMLS no PTS: 35.1° to 21.8°, p = 0.016). After surgery peak knee flexion decreased significantly (14.6°, p = 0.004) in the “SEMLS + PTS” group while there was no relevant change in the other group. There was a trend of increase in anterior pelvic tilt after surgery in both groups, but no statistical significant difference. After surgery knee flexion contracture (15.9°, p < 0.001) and popliteal angle (27.2, p = 0.009) measured on clinical examination only decreased significantly in the “SEMLS + PTS” group.ConclusionPTS is effective for correction of flexed knee gait and knee flexion contracture leading to superior stance phase knee extension. However, additional PTS may lead to stiff knee gait and a higher increase of anterior pelvic tilt.

Graphical abstract

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A systematic review of the gait characteristics associated with Cerebellar Ataxia

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Ellen Buckley, Claudia Mazzà, Alisdair McNeill
BackgroundCerebellar Ataxias are a group of gait disorders resulting from dysfunction of the cerebellum, commonly characterised by slowly progressing incoordination that manifests as problems with balance and walking leading to considerable disability. There is increasing acceptance of gait analysis techniques to quantify subtle gait characteristics that are unmeasurable by current clinical methods This systematic review aims to identify the gait characteristics able to differentiate between Cerebellar Ataxia and healthy controls.MethodsFollowing systematic search and critical appraisal of the literature, gait data relating to preferred paced walking in Cerebellar Ataxia was extracted from 21 studies. A random-effect model meta-analysis was performed for 14 spatiotemporal parameters. Quality assessment was completed to detect risk of bias.ResultsThere is strong evidence that compared with healthy controls, Cerebellar Ataxia patients walk with a reduced walking speed and cadence, reduced step length, stride length, and swing phase, increased walking base width, stride time, step time, stance phase and double limb support phase with increased variability of step length, stride length, and stride time.ConclusionThe consensus description provided here, clarifies the gait pattern associated with ataxic gait disturbance in a large cohort of participants. High quality research and reporting is needed to explore specific genetic diagnoses and identify biomarkers for disease progression in order to develop well-evidenced clinical guidelines and interventions for Cerebellar Ataxia.



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Comprehensive biomechanical characterization of feet in USMA cadets: Comparison across race, gender, arch flexibility, and foot types

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Jinsup Song, Kersti Choe, Michael Neary, Rebecca A. Zifchock, Kenneth L. Cameron, Michael Trepa, Marian T. Hannan, Howard Hillstrom
Lower extremity musculoskeletal injuries are common, complex, and costly problems. Literature supports associations between static foot structure and dynamic foot function, as well as between overuse injury and demographic characteristics. Previous studies failed to provide a comprehensive biomechanical foot characteristics of at-risk military personnel. In this study, foot structure, function, and arch height flexibility (AHF) were objectively measured in 1090 incoming cadets (16.3% female, mean age of 18.5years and BMI of 24.5kg/m²) of the United States Military Academy at the start of their training. A Generalized Linear Model with an identity link function was used to examine the effects of race, gender, foot types, and AHF while accounting for potential dependence in bilateral data. Planus and flexible feet independently demonstrated over-pronation, as measured by reduced Center of Pressure Excursion Index (CPEI). When comparing across race, Black participants showed a significantly lower arch height index (AHI), a larger malleolar valgus index (MVI), and a higher prevalence of pes planus (91.7% versus 73.3% overall). However, Asian participants with flexible arches, rather than Black with low arch, displayed over-pronation in gait. Females showed no significant difference in standing AHI and MVI but demonstrated a significantly greater AHF and a reduced CPEI than male participants. This was the first large scale investigation that comprehensively characterized biomechanical foot in a cohort of young at-risk individuals with lower limb musculoskeletal injuries. Long-term goal is to examine the relationship between these biomechanical features and injuries, ultimately to develop effective preventive measures.



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Reliability of upper limb and trunk joint angles in healthy adults during activities of daily living

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Susannah M. Engdahl, Deanna H. Gates
Assessments of upper limb performance should require participants to perform tasks that challenge the limits of their ability. In order to select appropriate tasks, it is important to know which joints are used to perform the movement and how reliably those movements can be measured. The purpose of this work was to quantify the reliability of upper limb and trunk joint angles in healthy adults during common activities of daily living (ADLs). Nineteen participants performed six ADLs with the right arm (applying deodorant, turning a doorknob, answering a desk telephone, placing a pushpin in a bulletin board, wiping a plate with a towel, and pouring water from a pitcher) during two separate sessions. Within- and between-session reliability was quantified using intraclass correlation coefficients (ICCs) and minimum detectable change values (MDCs). Reliability was generally better within-session than between-session. The ICCs exceeded 0.75 for 88% of the joint angles and exceeded 0.90 for 32% of the angles. All MDCs were less than 25° and 61% were also less than 10°. The MDCs represented a larger percent of the average angles for the trunk (61%) and wrist (62%) compared to the shoulder (18%) and elbow (26%). Although these results show that most angles can be measured reliably for these six ADLs, reliability varied considerably between joints. It is therefore important to select tasks for assessing of upper limb performance based on which specific joints need to be evaluated.



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The iFST: An instrumented version of the Fukuda Stepping Test for balance assessment

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Valeria Belluscio, Elena Bergamini, Marco Iosa, Marco Tramontano, Giovanni Morone, Giuseppe Vannozzi
The maintenance of the upright posture during dynamic balance requires the integration of sensory inputs regulated by the brain. After a neurological event, the assessment of balance control impairments is crucial for supporting health professionals in the design of personalized rehabilitation protocols. A commonly used test to assess balance ability is the Fukuda Stepping Test (FST). However, the clinical parameters traditionally considered are not fully representative of the patient’s motor ability. The purpose of this study was to devise an instrumented version of the FST (iFST) that embodies inertial sensors and allows to obtain individual motor strategy information. Twenty-seven sub-acute stroke patients and 18 healthy adults performed a repeated stepping task with closed eyes wearing five inertial sensors located on both distal tibiae and at pelvis, sternum, and head levels. From final foot position, body rotation and linear displacements were measured. A set of indices related to upper-body stability were estimated from pelvis, sternum, and head accelerations: Root Mean Square, Attenuation Coefficients, and improved Harmonic Ratio. Two additional parameters based on upper-body angular velocities were devised to assess step-by-step repeatability and inter-segment velocity variations. The results suggest that the clinical parameters do not provide enough information about the two groups’ motor strategies. Conversely, five iFST parameters were identified as predictors of patients’ motor ability, discriminating not only between healthy and pathological subjects, but also between different motor deficit levels within the same pathology. The iFST could be included in the clinical routine assessment of balance impairments, supporting the design of personalized treatments.



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Sympathetic nervous system activity measured by skin conductance quantifies the challenge of walking adaptability tasks after stroke

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): David J. Clark, Sudeshna A. Chatterjee, Theresa E. McGuirk, Eric C. Porges, Emily J. Fox, Chitralakshmi K. Balasubramanian
BackgroundWalking adaptability tasks are challenging for people with motor impairments. The construct of perceived challenge is typically measured by self-report assessments, which are susceptible to subjective measurement error. The development of an objective physiologically-based measure of challenge may help to improve the ability to assess this important aspect of mobility function. The objective of this study to investigate the use of sympathetic nervous system (SNS) activity measured by skin conductance to gauge the physiological stress response to challenging walking adaptability tasks in people post-stroke.MethodsThirty adults with chronic post-stroke hemiparesis performed a battery of seventeen walking adaptability tasks. SNS activity was measured by skin conductance from the palmar surface of each hand. The primary outcome variable was the percent change in skin conductance level (ΔSCL) between the baseline resting and walking phases of each task. Task difficulty was measured by performance speed and by physical therapist scoring of performance. Walking function and balance confidence were measured by preferred walking speed and the Activities-specific Balance Confidence Scale, respectively.ResultsThere was a statistically significant negative association between ΔSCL and task performance speed and between ΔSCL and clinical score, indicating that tasks with greater SNS activity had slower performance speed and poorer clinical scores. ΔSCL was significantly greater for low functioning participants versus high functioning participants, particularly during the most challenging walking adaptability tasks.ConclusionThis study supports the use of SNS activity measured by skin conductance as a valuable approach for objectively quantifying the perceived challenge of walking adaptability tasks in people post-stroke.



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The effect of augmented somatosensory feedback on standing postural sway

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Angela Smalley, Scott C. White, Robert Burkard
Impaired balance resulting from reduced postural control occurs with aging and various medical conditions. Sensory input for balance control is provided by the visual, vestibular and somatosensory systems. Previous research suggests that increased proprioceptive feedback from various lower extremity devices improves balance. Mixed results have been reported with the use of orthoses such as ankle foot orthoses (AFOs). In this study, 20 healthy subjects wore footplates in their shoes or straps around their lower legs in order to imitate the somatosensory feedback produced by wearing AFOs, but without providing ankle restriction. Subjects’ standing balance was assessed using force plates and computerized dynamic posturography (the sensory organization test-SOT) to determine if either the footplates or the lower-leg straps would affect standing balance. The results revealed no significant difference with the use of the footplates, however, wearing the straps resulted in reduced postural sway for conditions when visual cue deprivation was combined with manipulation of somatosensory or vestibular feedback. This effect was more pronounced in participants with the poorest baseline measures of balance. These findings suggest that lower extremity devices, such as AFOs, may augment somatosensory feedback that could improve balance during challenging sensory deprivation conditions, independent of orthotic support at the ankle.



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The effect of spatial auditory landmarks on ambulation

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Adham M. Karim, Kavelin Rumalla, Laurie A. King, Timothy E. Hullar
The maintenance of balance and posture is a result of the collaborative efforts of vestibular, proprioceptive, and visual sensory inputs, but a fourth neural input, audition, may also improve balance. Here, we tested the hypothesis that auditory inputs function as environmental spatial landmarks whose effectiveness depends on sound localization ability during ambulation. Eight blindfolded normal young subjects performed the Fukuda-Unterberger test in three auditory conditions: silence, white noise played through headphones (head-referenced condition), and white noise played through a loudspeaker placed directly in front at 135 centimeters away from the ear at ear height (earth-referenced condition). For the earth-referenced condition, an additional experiment was performed where the effect of moving the speaker azimuthal position to 45, 90, 135, and 180° was tested. Subjects performed significantly better in the earth-referenced condition than in the head-referenced or silent conditions. Performance progressively decreased over the range from 0° to 135° but all subjects then improved slightly at the 180° compared to the 135° condition. These results suggest that presence of sound dramatically improves the ability to ambulate when vision is limited, but that sound sources must be located in the external environment in order to improve balance. This supports the hypothesis that they act by providing spatial landmarks against which head and body movement and orientation may be compared and corrected. Balance improvement in the azimuthal plane mirrors sensitivity to sound movement at similar positions, indicating that similar auditory mechanisms may underlie both processes. These results may help optimize the use of auditory cues to improve balance in particular patient populations.



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The coupled effects of crouch gait and patella alta on tibiofemoral and patellofemoral cartilage loading in children

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Scott C.E. Brandon, Darryl G. Thelen, Colin R. Smith, Tom F. Novacheck, Michael H. Schwartz, Rachel L. Lenhart
BackgroundElevated tibiofemoral and patellofemoral loading in children who exhibit crouch gait may contribute to skeletal deformities, pain, and cessation of walking ability. Surgical procedures used to treat crouch frequently correct knee extensor insufficiency by advancing the patella. However, there is little quantitative understanding of how the magnitudes of crouch and patellofemoral correction affect cartilage loading in gait.MethodsWe used a computational musculoskeletal model to simulate the gait of twenty typically developing children and fifteen cerebral palsy patients who exhibited mild, moderate, and severe crouch. For each walking posture, we assessed the influence of patella alta and baja on tibiofemoral and patellofemoral cartilage contact.ResultsTibiofemoral and patellofemoral contact pressures during the stance phase of normal gait averaged 2.2 and 1.0 MPa. Crouch gait increased pressure in both the tibofemoral (2.6–4.3 MPa) and patellofemoral (1.8–3.3 MPa) joints, while also shifting tibiofemoral contact to the posterior tibial plateau. For extended-knee postures, normal patellar positions (Insall-Salvatti ratio 0.8–1.2) concentrated contact on the middle third of the patellar cartilage. However, in flexed knee postures, both normal and baja patellar positions shifted pressure toward the superior edge of the patella. Moving the patella into alta restored pressure to the middle region of the patellar cartilage as crouch increased.ConclusionsThis work illustrates the potential to dramatically reduce tibiofemoral and patellofemoral cartilage loading by surgically correcting crouch gait, and highlights the interaction between patella position and knee posture in modulating the location of patellar contact during functional activities.



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Effects of plantar hypothermia on quasi-static balance: Two different hypothermic procedures

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Andresa M.C. Germano, Tobias Heß, Daniel Schmidt, Thomas L. Milani
Inducing hypothermia to examine its effects on balance is performed with various approaches. However, data interpretations of underlying postural mechanisms often do not consider the applied hypothermic protocol. In this context, the effects of diminished plantar mechanoreceptor activity on quasi-static balance performance were investigated, examining the applicability of a continuously cooling thermal platform in comparison with conventional ice pads. Increased instability for the thermal platform compared to cooling with ice pads was hypothesized, since we expected increased temperatures for the ice pad group directly after balance tests. Similar scores on a Visual Analogue Scale (VAS) were predicted regarding subjective pain. Results showed that both cooling procedures successfully induced plantar hypothermia. However, the thermal platform was more effective with respect to reaching and maintaining the desired temperature throughout the trials, especially when comparing temperatures before and after balance tests. Therefore, balance tests indeed demonstrated increased COP parameters exclusively after permanent cooling via the thermal platform as early as after the first 10 min of cooling. Reduced plantar input may result in this postural instability, but without the need of other sensory systems to compensate. The VAS generally demonstrated higher pain scores for the ice pads, rejecting our hypothesis. This is an important finding, since pain is known to influence balance. Therefore, permanent and controllable cooling via the thermal platform should be taken into consideration when conducting related research.



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Influence of handrail height and fall direction on center of mass control and the physical demands of reach-to-grasp balance recovery reactions

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Vicki Komisar, Konika Nirmalanathan, Alison C. Novak
The ability to maintain and recover center of mass (COM) and trunk control after a destabilization is critical for avoiding falls and fall-related injuries. Handrails can significantly enhance a person’s ability to recover from large destabilizations, by enabling the person to grasp and apply high forces to the rail to stabilize their COM. However, the influence of handrail height and falling direction on COM control and the demands of grasping are unknown. We investigated the effect of handrail height (34, 38, 42 in.) and fall direction (forward, backward) on COM and trunk control, and the corresponding physical demands of reach-to-grasp balance reactions. Thirteen young adults were destabilized with platform perturbations, and reached to grasp a nearby handrail to recover balance without stepping. COM kinematics and applied handrail forces were collected. COM control was evaluated in terms of: (1) COM range and peak displacement, velocity and momentum in all Cartesian axes; and (2) trunk angular displacement, velocity and momentum in the roll and pitch axes. The physical demands of grasping were estimated via resultant handrail impulse. Compared to forward-directed falling, backward-directed falling was generally associated with greater peak COM and trunk angular displacement, velocity and momentum, along with greater handrail impulse. Higher handrails generally resulted in reduced peak COM and trunk angular displacement, velocity and momentum, as well as reduced handrail impulse. These results suggest that higher handrails may provide a stability advantage within the range of handrail heights tested, with better COM control achieved with lower physical demands of grasping.



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How accurate is visual determination of foot strike pattern and pronation assessment

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Frédéric Meyer, Mathieu Falbriard, Kamiar Aminian, Gregoire P. Millet
Nowadays, choosing adequate running shoes is very difficult, due to the high number of different designs. Nevertheless, shoes have two main characteristics to fit runners’ technique and morphology: drop and arch support. Retailers’ advices are usually based on the visual assessment of the customer’s running technique. Such method is subjective and requires an experimented examiner while objective methods require expensive material, such as 3D motion system and pressure insoles. Therefore, the aim of this study was to determine the accuracy of foot strike pattern and pronation assessment using video cameras, compared to a gold standard motion tracking system and pressure insoles. 34 subjects had to run at 8, 12 and 16 Km/h shod and 12 Km/h barefoot during 30 s trials on a treadmill. Agreement between foot strike pattern assessment methods was between 88% and 92%. For pronation, agreement on assessment methods was between 42% and 56%. The results obtained indicate a good accuracy on foot strike pattern assessment, and a high difficulty to determine pronation with enough accuracy. There is therefore a need to develop new tools for the assessment of runner’s pronation.



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Increasing mediolateral standing sway is associated with increasing corticospinal excitability, and decreasing M1 inhibition and facilitation

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Tulika Nandi, Beth E. Fisher, Tibor Hortobágyi, George J. Salem
In standing, corticospinal excitability increases and primary motor cortex (M1) inhibition decreases in response to anterior posterior or direction unspecific manipulations that increase task difficulty. However, mediolateral (ML) sway control requires greater active neural involvement. Therefore, the primary purpose of this study was to determine the pattern of change in neural excitability when ML postural task difficulty is manipulated and to test whether the neural excitability is proportional to ML sway magnitude across conditions. Tibialis anterior corticospinal excitability was quantified using motor evoked potential (MEP) and postural sway was indexed using ML center of pressure (COP) velocity. Additionally, we examined inhibition and facilitation processes in the primary motor cortex using the paired pulse short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) techniques respectively. Measurements were repeated in four conditions with quiet stance as a control. Differences between conditions were tested using one-way repeated measures ANOVAs, on log transformed data. Associations were quantified using Spearman’s Rank Correlation Coefficient. There was a significant main effect of condition on all the neural excitability measures with MEP (p<0.001) being highest in the most difficult condition, and SICI (p=0.01), ICF (p<0.001) being lowest in the most difficult condition. Increasing ML COP velocity was significantly associated with increasing MEP amplitude (r=0.68, p<0.001), but decreasing SICI (r=0.24, p=0.03) and ICF (r=−0.54, p<0.001). Our results show that both corticospinal and M1 excitability in standing are scaled in proportion to ML task difficulty.



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Accuracy evaluation of a method to partition ground reaction force and center of pressure in cane-assisted gait using an instrumented cane with a triaxial force sensor

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Arinori Kamono, Mizuki Kato, Naomichi Ogihara
Clarifying the biomechanics of cane-assisted gait in elderly individuals and patients with gait disorders is important for developing better therapeutic interventions in the fields of rehabilitation and orthopedics. However, if the foot and the cane in the ipsilateral hand are placed on the same force plate simultaneously, the force plate cannot separate the forces as it records the sum of the forces. To overcome this indeterminacy problem of the ground reaction force (GRF) and the center of pressure (COP) in cane-assisted gait analysis, a method to partition the GRF and COP using an instrumented cane with a force transducer has been proposed. However, the accuracy and precision of the estimated GRF and COP has not been evaluated previously. We therefore reestablished a framework to partition the foot and cane forces during walking using an instrumented cane with a triaxial force sensor and evaluated the accuracy and precision of the method using a force plate array. Cane-assisted gait of healthy adults and hemiplegic patients were measured. Mean accuracy and precision associated with the GRF and COP measurements were approximately 0.4±1.4N and 0.2±2.7mm, respectively, indicating that the separations of the GRF and COP were sufficiently accurate for kinetic gait analysis. Although some methodological limitations certainly apply, this system will serve as a useful tool for improved therapeutic interventions.



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How do walkers behave when crossing the way of a mobile robot that replicates human interaction rules?

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Christian Vassallo, Anne-Hélène Olivier, Philippe Souères, Armel Crétual, Olivier Stasse, Julien Pettré
Previous studies showed the existence of implicit interaction rules shared by human walkers when crossing each other. Especially, each walker contributes to the collision avoidance task and the crossing order, as set at the beginning, is preserved along the interaction. This order determines the adaptation strategy: the first arrived increases his/her advance by slightly accelerating and changing his/her heading, whereas the second one slows down and moves in the opposite direction. In this study, we analyzed the behavior of human walkers crossing the trajectory of a mobile robot that was programmed to reproduce this human avoidance strategy. In contrast with a previous study, which showed that humans mostly prefer to give the way to a non-reactive robot, we observed similar behaviors between human-human avoidance and human-robot avoidance when the robot replicates the human interaction rules. We discuss this result in relation with the importance of controlling robots in a human-like way in order to ease their cohabitation with humans.



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Perceptual-motor regulation in locomotor pointing while approaching a curb

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Steven van Andel, Michael H. Cole, Gert-Jan Pepping
Locomotor pointing is a task that has been the focus of research in the context of sport (e.g. long jumping and cricket) as well as normal walking. Collectively, these studies have produced a broad understanding of locomotor pointing, but generalizability has been limited to laboratory type tasks and/or tasks with high spatial demands. The current study aimed to generalize previous findings in locomotor pointing to the common daily task of approaching and stepping on to a curb.Sixteen people completed 33 repetitions of a task that required them to walk up to and step onto a curb. Information about their foot placement was collected using a combination of measures derived from a pressure-sensitive walkway and video data. Variables related to perceptual-motor regulation were analyzed on an inter-trial, intra-step and inter-step level.Similar to previous studies, analysis of the foot placements showed that, variability in foot placement decreased as the participants drew closer to the curb. Regulation seemed to be initiated earlier in this study compared to previous studies, as shown by a decreasing variability in foot placement as early as eight steps before reaching the curb. Furthermore, it was shown that when walking up to the curb, most people regulated their walk in a way so as to achieve minimal variability in the foot placement on top of the curb, rather than a placement in front of the curb. Combined, these results showed a strong perceptual-motor coupling in the task of approaching and stepping up a curb, rendering this task a suitable test for perceptual-motor regulation in walking.



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Does additional patella tendon shortening influence the effects of multilevel surgery to correct flexed knee gait in cerebral palsy: A randomized controlled trial

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): M.C.M. Klotz, Britta K. Krautwurst, K. Hirsch, M. Niklasch, M.W. Maier, S.I. Wolf, T. Dreher
BackgroundThe aims of this study were to investigate if patellar tendon shortening (PTS) as a part of SEMLS (single event multilevel surgery) is effective for reduction of flexed knee gait in children with cerebral palsy (CP) and, if PTS leads to stiff knee gait.MethodsIn a randomized controlled study 22 children with flexed knee gait (age: 10.4 ± 2.6 years, GMFCS Level I–III) were randomized and allocated to two groups (1: SEMLS + PTS; 2: SEMLS no PTS): SEMLS was performed for correction of flexed knee gait either with or without additional PTS. Before and after surgery (follow up: 12.7 ± 1.6 months) kinematics (3-D motion analysis) and clinical parameters were compared.ResultsTwo children were lost to follow up. Maximum knee extension improved significantly in both groups after SEMLS while the patients with additional PTS showed much more correction (SEMLS + PTS: 37.6° to 11.4°, p = 0.007; SEMLS no PTS: 35.1° to 21.8°, p = 0.016). After surgery peak knee flexion decreased significantly (14.6°, p = 0.004) in the “SEMLS + PTS” group while there was no relevant change in the other group. There was a trend of increase in anterior pelvic tilt after surgery in both groups, but no statistical significant difference. After surgery knee flexion contracture (15.9°, p < 0.001) and popliteal angle (27.2, p = 0.009) measured on clinical examination only decreased significantly in the “SEMLS + PTS” group.ConclusionPTS is effective for correction of flexed knee gait and knee flexion contracture leading to superior stance phase knee extension. However, additional PTS may lead to stiff knee gait and a higher increase of anterior pelvic tilt.

Graphical abstract

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A systematic review of the gait characteristics associated with Cerebellar Ataxia

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Ellen Buckley, Claudia Mazzà, Alisdair McNeill
BackgroundCerebellar Ataxias are a group of gait disorders resulting from dysfunction of the cerebellum, commonly characterised by slowly progressing incoordination that manifests as problems with balance and walking leading to considerable disability. There is increasing acceptance of gait analysis techniques to quantify subtle gait characteristics that are unmeasurable by current clinical methods This systematic review aims to identify the gait characteristics able to differentiate between Cerebellar Ataxia and healthy controls.MethodsFollowing systematic search and critical appraisal of the literature, gait data relating to preferred paced walking in Cerebellar Ataxia was extracted from 21 studies. A random-effect model meta-analysis was performed for 14 spatiotemporal parameters. Quality assessment was completed to detect risk of bias.ResultsThere is strong evidence that compared with healthy controls, Cerebellar Ataxia patients walk with a reduced walking speed and cadence, reduced step length, stride length, and swing phase, increased walking base width, stride time, step time, stance phase and double limb support phase with increased variability of step length, stride length, and stride time.ConclusionThe consensus description provided here, clarifies the gait pattern associated with ataxic gait disturbance in a large cohort of participants. High quality research and reporting is needed to explore specific genetic diagnoses and identify biomarkers for disease progression in order to develop well-evidenced clinical guidelines and interventions for Cerebellar Ataxia.



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Comprehensive biomechanical characterization of feet in USMA cadets: Comparison across race, gender, arch flexibility, and foot types

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Jinsup Song, Kersti Choe, Michael Neary, Rebecca A. Zifchock, Kenneth L. Cameron, Michael Trepa, Marian T. Hannan, Howard Hillstrom
Lower extremity musculoskeletal injuries are common, complex, and costly problems. Literature supports associations between static foot structure and dynamic foot function, as well as between overuse injury and demographic characteristics. Previous studies failed to provide a comprehensive biomechanical foot characteristics of at-risk military personnel. In this study, foot structure, function, and arch height flexibility (AHF) were objectively measured in 1090 incoming cadets (16.3% female, mean age of 18.5years and BMI of 24.5kg/m²) of the United States Military Academy at the start of their training. A Generalized Linear Model with an identity link function was used to examine the effects of race, gender, foot types, and AHF while accounting for potential dependence in bilateral data. Planus and flexible feet independently demonstrated over-pronation, as measured by reduced Center of Pressure Excursion Index (CPEI). When comparing across race, Black participants showed a significantly lower arch height index (AHI), a larger malleolar valgus index (MVI), and a higher prevalence of pes planus (91.7% versus 73.3% overall). However, Asian participants with flexible arches, rather than Black with low arch, displayed over-pronation in gait. Females showed no significant difference in standing AHI and MVI but demonstrated a significantly greater AHF and a reduced CPEI than male participants. This was the first large scale investigation that comprehensively characterized biomechanical foot in a cohort of young at-risk individuals with lower limb musculoskeletal injuries. Long-term goal is to examine the relationship between these biomechanical features and injuries, ultimately to develop effective preventive measures.



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Reliability of upper limb and trunk joint angles in healthy adults during activities of daily living

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Susannah M. Engdahl, Deanna H. Gates
Assessments of upper limb performance should require participants to perform tasks that challenge the limits of their ability. In order to select appropriate tasks, it is important to know which joints are used to perform the movement and how reliably those movements can be measured. The purpose of this work was to quantify the reliability of upper limb and trunk joint angles in healthy adults during common activities of daily living (ADLs). Nineteen participants performed six ADLs with the right arm (applying deodorant, turning a doorknob, answering a desk telephone, placing a pushpin in a bulletin board, wiping a plate with a towel, and pouring water from a pitcher) during two separate sessions. Within- and between-session reliability was quantified using intraclass correlation coefficients (ICCs) and minimum detectable change values (MDCs). Reliability was generally better within-session than between-session. The ICCs exceeded 0.75 for 88% of the joint angles and exceeded 0.90 for 32% of the angles. All MDCs were less than 25° and 61% were also less than 10°. The MDCs represented a larger percent of the average angles for the trunk (61%) and wrist (62%) compared to the shoulder (18%) and elbow (26%). Although these results show that most angles can be measured reliably for these six ADLs, reliability varied considerably between joints. It is therefore important to select tasks for assessing of upper limb performance based on which specific joints need to be evaluated.



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The iFST: An instrumented version of the Fukuda Stepping Test for balance assessment

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Valeria Belluscio, Elena Bergamini, Marco Iosa, Marco Tramontano, Giovanni Morone, Giuseppe Vannozzi
The maintenance of the upright posture during dynamic balance requires the integration of sensory inputs regulated by the brain. After a neurological event, the assessment of balance control impairments is crucial for supporting health professionals in the design of personalized rehabilitation protocols. A commonly used test to assess balance ability is the Fukuda Stepping Test (FST). However, the clinical parameters traditionally considered are not fully representative of the patient’s motor ability. The purpose of this study was to devise an instrumented version of the FST (iFST) that embodies inertial sensors and allows to obtain individual motor strategy information. Twenty-seven sub-acute stroke patients and 18 healthy adults performed a repeated stepping task with closed eyes wearing five inertial sensors located on both distal tibiae and at pelvis, sternum, and head levels. From final foot position, body rotation and linear displacements were measured. A set of indices related to upper-body stability were estimated from pelvis, sternum, and head accelerations: Root Mean Square, Attenuation Coefficients, and improved Harmonic Ratio. Two additional parameters based on upper-body angular velocities were devised to assess step-by-step repeatability and inter-segment velocity variations. The results suggest that the clinical parameters do not provide enough information about the two groups’ motor strategies. Conversely, five iFST parameters were identified as predictors of patients’ motor ability, discriminating not only between healthy and pathological subjects, but also between different motor deficit levels within the same pathology. The iFST could be included in the clinical routine assessment of balance impairments, supporting the design of personalized treatments.



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Sympathetic nervous system activity measured by skin conductance quantifies the challenge of walking adaptability tasks after stroke

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): David J. Clark, Sudeshna A. Chatterjee, Theresa E. McGuirk, Eric C. Porges, Emily J. Fox, Chitralakshmi K. Balasubramanian
BackgroundWalking adaptability tasks are challenging for people with motor impairments. The construct of perceived challenge is typically measured by self-report assessments, which are susceptible to subjective measurement error. The development of an objective physiologically-based measure of challenge may help to improve the ability to assess this important aspect of mobility function. The objective of this study to investigate the use of sympathetic nervous system (SNS) activity measured by skin conductance to gauge the physiological stress response to challenging walking adaptability tasks in people post-stroke.MethodsThirty adults with chronic post-stroke hemiparesis performed a battery of seventeen walking adaptability tasks. SNS activity was measured by skin conductance from the palmar surface of each hand. The primary outcome variable was the percent change in skin conductance level (ΔSCL) between the baseline resting and walking phases of each task. Task difficulty was measured by performance speed and by physical therapist scoring of performance. Walking function and balance confidence were measured by preferred walking speed and the Activities-specific Balance Confidence Scale, respectively.ResultsThere was a statistically significant negative association between ΔSCL and task performance speed and between ΔSCL and clinical score, indicating that tasks with greater SNS activity had slower performance speed and poorer clinical scores. ΔSCL was significantly greater for low functioning participants versus high functioning participants, particularly during the most challenging walking adaptability tasks.ConclusionThis study supports the use of SNS activity measured by skin conductance as a valuable approach for objectively quantifying the perceived challenge of walking adaptability tasks in people post-stroke.



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The effect of augmented somatosensory feedback on standing postural sway

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Angela Smalley, Scott C. White, Robert Burkard
Impaired balance resulting from reduced postural control occurs with aging and various medical conditions. Sensory input for balance control is provided by the visual, vestibular and somatosensory systems. Previous research suggests that increased proprioceptive feedback from various lower extremity devices improves balance. Mixed results have been reported with the use of orthoses such as ankle foot orthoses (AFOs). In this study, 20 healthy subjects wore footplates in their shoes or straps around their lower legs in order to imitate the somatosensory feedback produced by wearing AFOs, but without providing ankle restriction. Subjects’ standing balance was assessed using force plates and computerized dynamic posturography (the sensory organization test-SOT) to determine if either the footplates or the lower-leg straps would affect standing balance. The results revealed no significant difference with the use of the footplates, however, wearing the straps resulted in reduced postural sway for conditions when visual cue deprivation was combined with manipulation of somatosensory or vestibular feedback. This effect was more pronounced in participants with the poorest baseline measures of balance. These findings suggest that lower extremity devices, such as AFOs, may augment somatosensory feedback that could improve balance during challenging sensory deprivation conditions, independent of orthotic support at the ankle.



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The effect of spatial auditory landmarks on ambulation

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Adham M. Karim, Kavelin Rumalla, Laurie A. King, Timothy E. Hullar
The maintenance of balance and posture is a result of the collaborative efforts of vestibular, proprioceptive, and visual sensory inputs, but a fourth neural input, audition, may also improve balance. Here, we tested the hypothesis that auditory inputs function as environmental spatial landmarks whose effectiveness depends on sound localization ability during ambulation. Eight blindfolded normal young subjects performed the Fukuda-Unterberger test in three auditory conditions: silence, white noise played through headphones (head-referenced condition), and white noise played through a loudspeaker placed directly in front at 135 centimeters away from the ear at ear height (earth-referenced condition). For the earth-referenced condition, an additional experiment was performed where the effect of moving the speaker azimuthal position to 45, 90, 135, and 180° was tested. Subjects performed significantly better in the earth-referenced condition than in the head-referenced or silent conditions. Performance progressively decreased over the range from 0° to 135° but all subjects then improved slightly at the 180° compared to the 135° condition. These results suggest that presence of sound dramatically improves the ability to ambulate when vision is limited, but that sound sources must be located in the external environment in order to improve balance. This supports the hypothesis that they act by providing spatial landmarks against which head and body movement and orientation may be compared and corrected. Balance improvement in the azimuthal plane mirrors sensitivity to sound movement at similar positions, indicating that similar auditory mechanisms may underlie both processes. These results may help optimize the use of auditory cues to improve balance in particular patient populations.



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The coupled effects of crouch gait and patella alta on tibiofemoral and patellofemoral cartilage loading in children

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Scott C.E. Brandon, Darryl G. Thelen, Colin R. Smith, Tom F. Novacheck, Michael H. Schwartz, Rachel L. Lenhart
BackgroundElevated tibiofemoral and patellofemoral loading in children who exhibit crouch gait may contribute to skeletal deformities, pain, and cessation of walking ability. Surgical procedures used to treat crouch frequently correct knee extensor insufficiency by advancing the patella. However, there is little quantitative understanding of how the magnitudes of crouch and patellofemoral correction affect cartilage loading in gait.MethodsWe used a computational musculoskeletal model to simulate the gait of twenty typically developing children and fifteen cerebral palsy patients who exhibited mild, moderate, and severe crouch. For each walking posture, we assessed the influence of patella alta and baja on tibiofemoral and patellofemoral cartilage contact.ResultsTibiofemoral and patellofemoral contact pressures during the stance phase of normal gait averaged 2.2 and 1.0 MPa. Crouch gait increased pressure in both the tibofemoral (2.6–4.3 MPa) and patellofemoral (1.8–3.3 MPa) joints, while also shifting tibiofemoral contact to the posterior tibial plateau. For extended-knee postures, normal patellar positions (Insall-Salvatti ratio 0.8–1.2) concentrated contact on the middle third of the patellar cartilage. However, in flexed knee postures, both normal and baja patellar positions shifted pressure toward the superior edge of the patella. Moving the patella into alta restored pressure to the middle region of the patellar cartilage as crouch increased.ConclusionsThis work illustrates the potential to dramatically reduce tibiofemoral and patellofemoral cartilage loading by surgically correcting crouch gait, and highlights the interaction between patella position and knee posture in modulating the location of patellar contact during functional activities.



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Effects of plantar hypothermia on quasi-static balance: Two different hypothermic procedures

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Andresa M.C. Germano, Tobias Heß, Daniel Schmidt, Thomas L. Milani
Inducing hypothermia to examine its effects on balance is performed with various approaches. However, data interpretations of underlying postural mechanisms often do not consider the applied hypothermic protocol. In this context, the effects of diminished plantar mechanoreceptor activity on quasi-static balance performance were investigated, examining the applicability of a continuously cooling thermal platform in comparison with conventional ice pads. Increased instability for the thermal platform compared to cooling with ice pads was hypothesized, since we expected increased temperatures for the ice pad group directly after balance tests. Similar scores on a Visual Analogue Scale (VAS) were predicted regarding subjective pain. Results showed that both cooling procedures successfully induced plantar hypothermia. However, the thermal platform was more effective with respect to reaching and maintaining the desired temperature throughout the trials, especially when comparing temperatures before and after balance tests. Therefore, balance tests indeed demonstrated increased COP parameters exclusively after permanent cooling via the thermal platform as early as after the first 10 min of cooling. Reduced plantar input may result in this postural instability, but without the need of other sensory systems to compensate. The VAS generally demonstrated higher pain scores for the ice pads, rejecting our hypothesis. This is an important finding, since pain is known to influence balance. Therefore, permanent and controllable cooling via the thermal platform should be taken into consideration when conducting related research.



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Influence of handrail height and fall direction on center of mass control and the physical demands of reach-to-grasp balance recovery reactions

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Vicki Komisar, Konika Nirmalanathan, Alison C. Novak
The ability to maintain and recover center of mass (COM) and trunk control after a destabilization is critical for avoiding falls and fall-related injuries. Handrails can significantly enhance a person’s ability to recover from large destabilizations, by enabling the person to grasp and apply high forces to the rail to stabilize their COM. However, the influence of handrail height and falling direction on COM control and the demands of grasping are unknown. We investigated the effect of handrail height (34, 38, 42 in.) and fall direction (forward, backward) on COM and trunk control, and the corresponding physical demands of reach-to-grasp balance reactions. Thirteen young adults were destabilized with platform perturbations, and reached to grasp a nearby handrail to recover balance without stepping. COM kinematics and applied handrail forces were collected. COM control was evaluated in terms of: (1) COM range and peak displacement, velocity and momentum in all Cartesian axes; and (2) trunk angular displacement, velocity and momentum in the roll and pitch axes. The physical demands of grasping were estimated via resultant handrail impulse. Compared to forward-directed falling, backward-directed falling was generally associated with greater peak COM and trunk angular displacement, velocity and momentum, along with greater handrail impulse. Higher handrails generally resulted in reduced peak COM and trunk angular displacement, velocity and momentum, as well as reduced handrail impulse. These results suggest that higher handrails may provide a stability advantage within the range of handrail heights tested, with better COM control achieved with lower physical demands of grasping.



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How accurate is visual determination of foot strike pattern and pronation assessment

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Frédéric Meyer, Mathieu Falbriard, Kamiar Aminian, Gregoire P. Millet
Nowadays, choosing adequate running shoes is very difficult, due to the high number of different designs. Nevertheless, shoes have two main characteristics to fit runners’ technique and morphology: drop and arch support. Retailers’ advices are usually based on the visual assessment of the customer’s running technique. Such method is subjective and requires an experimented examiner while objective methods require expensive material, such as 3D motion system and pressure insoles. Therefore, the aim of this study was to determine the accuracy of foot strike pattern and pronation assessment using video cameras, compared to a gold standard motion tracking system and pressure insoles. 34 subjects had to run at 8, 12 and 16 Km/h shod and 12 Km/h barefoot during 30 s trials on a treadmill. Agreement between foot strike pattern assessment methods was between 88% and 92%. For pronation, agreement on assessment methods was between 42% and 56%. The results obtained indicate a good accuracy on foot strike pattern assessment, and a high difficulty to determine pronation with enough accuracy. There is therefore a need to develop new tools for the assessment of runner’s pronation.



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Increasing mediolateral standing sway is associated with increasing corticospinal excitability, and decreasing M1 inhibition and facilitation

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Tulika Nandi, Beth E. Fisher, Tibor Hortobágyi, George J. Salem
In standing, corticospinal excitability increases and primary motor cortex (M1) inhibition decreases in response to anterior posterior or direction unspecific manipulations that increase task difficulty. However, mediolateral (ML) sway control requires greater active neural involvement. Therefore, the primary purpose of this study was to determine the pattern of change in neural excitability when ML postural task difficulty is manipulated and to test whether the neural excitability is proportional to ML sway magnitude across conditions. Tibialis anterior corticospinal excitability was quantified using motor evoked potential (MEP) and postural sway was indexed using ML center of pressure (COP) velocity. Additionally, we examined inhibition and facilitation processes in the primary motor cortex using the paired pulse short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) techniques respectively. Measurements were repeated in four conditions with quiet stance as a control. Differences between conditions were tested using one-way repeated measures ANOVAs, on log transformed data. Associations were quantified using Spearman’s Rank Correlation Coefficient. There was a significant main effect of condition on all the neural excitability measures with MEP (p<0.001) being highest in the most difficult condition, and SICI (p=0.01), ICF (p<0.001) being lowest in the most difficult condition. Increasing ML COP velocity was significantly associated with increasing MEP amplitude (r=0.68, p<0.001), but decreasing SICI (r=0.24, p=0.03) and ICF (r=−0.54, p<0.001). Our results show that both corticospinal and M1 excitability in standing are scaled in proportion to ML task difficulty.



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Accuracy evaluation of a method to partition ground reaction force and center of pressure in cane-assisted gait using an instrumented cane with a triaxial force sensor

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Arinori Kamono, Mizuki Kato, Naomichi Ogihara
Clarifying the biomechanics of cane-assisted gait in elderly individuals and patients with gait disorders is important for developing better therapeutic interventions in the fields of rehabilitation and orthopedics. However, if the foot and the cane in the ipsilateral hand are placed on the same force plate simultaneously, the force plate cannot separate the forces as it records the sum of the forces. To overcome this indeterminacy problem of the ground reaction force (GRF) and the center of pressure (COP) in cane-assisted gait analysis, a method to partition the GRF and COP using an instrumented cane with a force transducer has been proposed. However, the accuracy and precision of the estimated GRF and COP has not been evaluated previously. We therefore reestablished a framework to partition the foot and cane forces during walking using an instrumented cane with a triaxial force sensor and evaluated the accuracy and precision of the method using a force plate array. Cane-assisted gait of healthy adults and hemiplegic patients were measured. Mean accuracy and precision associated with the GRF and COP measurements were approximately 0.4±1.4N and 0.2±2.7mm, respectively, indicating that the separations of the GRF and COP were sufficiently accurate for kinetic gait analysis. Although some methodological limitations certainly apply, this system will serve as a useful tool for improved therapeutic interventions.



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Editorial Board

Publication date: January 2018
Source:Hearing Research, Volume 357





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Editorial Board

Publication date: January 2018
Source:Hearing Research, Volume 357





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Editorial Board

Publication date: January 2018
Source:Hearing Research, Volume 357





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