Trunk Sway Research Articles

Does vibrotactile biofeedback for postural control interfere with cognitive processes?

BackgroundDirectional vibrotactile biofeedback for balance control can be instructed in the form of Repulsive (to move in the opposite direction of vibrations) or Attractive (to move in the direction of vibrations) stimulus encodings. However, which of these encodings is less cognitively demanding and poses less interference with high-level cognitive processes of conflict resolution remains unresolved.MethodsIn two between-subject studies with 30 (16 females) and 35 (23 females) healthy young adults, respectively, we investigated the cognitive load of Attractive and Repulsive vibrotactile biofeedback on 1) working memory (Study I) and 2) cognitive conflict resolution (Study II). Both studies also examined the effectiveness of both feedback stimulus encodings on balance control during quiet standing with eyes closed.ResultsBoth Attractive and Repulsive vibrotactile biofeedback increased balance stability (reduced trunk sway variability) in both the working memory and the conflict resolution study (Study I and II, respectively) with a greater increase of stability for the Repulsive encoding during multitasking demanding cognitive conflict resolution (Study II). Cognitive costs, measured in terms of the Linear Integrated Speed-Accuracy Score (LISAS), were greater for the Attractive encoding during multitasking with working memory demands. When cognitive conflict resolution was required as a secondary cognitive task, both stimulus encodings increased cognitive costs equally.ConclusionsThe effects of instructed Repulsive and Attractive stimulus encodings for the response-related interpretation of vibrotactile biofeedback of body sway were contrasted with respect to cognitive processing demands and balance stabilisation benefits. Both encodings improved balance stability but at certain cognitive costs. Regarding interference with specific high-level cognitive processes, however, a distinction has to be made between both encodings. Repulsive feedback encoding seems to cause less cognitive costs on working memory load and slightly greater stabilisation when cognitive conflict resolution is required. These results are discussed in the context of the known benefits of avoidance actions on cognitive control.

Investigating spatiotemporal and kinematic gait parameters in individuals with Parkinson's disease with a history of freezing of gait and exploring the effects of dopaminergic therapy on freezing of gait subtypes.

Freezing of Gait (FOG) is a prevalent and debilitating symptom in idiopathic Parkinson's disease (PD). This study evaluated spatiotemporal and kinematic gait parameters in individuals with PD with a history of FOG and explored the effects of dopaminergic therapy on FOG subtypes. One hundred and nine individuals with PD underwent clinical assessments and quantitative biomechanical measures during walking cycles before and after dopaminergic therapy. Individuals with FOG were classified into levodopa-responsive and levodopa-unresponsive groups. Individuals with FOG displayed longer disease duration and higher Unified Parkinson's Disease Rating Scale (UPDRS) II, III, IV scores, and total scores and levodopa equivalent dose, than those without FOG (all p < 0.0001). Following propensity score matching of 15 pairs based on UPDRS total score and disease duration during the off-medication state, the analysis comparing the FOG and non-FOG groups revealed no significant differences in spatiotemporal and kinematic parameters. In 39 cases of FOG, dopaminergic therapy improved gait performance in individuals with PD, enhancing spatiotemporal parameters (speed, stride length, step length, step variability) and kinematic parameters (shoulder and elbow flexion/extension range of motion (ROM), pelvic rotation, and hip abduction/adduction ROM) regardless of FOG responsiveness to dopaminergic therapy. A significant difference in trunk sway ROM (p = 0.029) remained before and after dopaminergic therapy, even after adjusting for disease duration and clinical severity. Dopaminergic therapy had varying effects on PD with FOG, improving several spatiotemporal and kinematic gait parameters but being less effective in levodopa-unresponsive cases. Quantitative biomechanical measures offer detailed insights into gait performance, aiding personalized fall risk assessment and guiding individualized rehabilitation programs.

Towards an explanation for 'unexplained' dizziness in older people.

Subjective unsteadiness or dizziness, usually without increase in body sway, is common in older people. The absence of mechanistic understanding of such symptoms renders clinical management difficult. Here, we explore the mechanisms behind such idiopathic dizziness (ID), focusing on postural control abnormalities. Thirty patients with ID and 30 age-matched controls stood on a moving platform. Platform oscillations were randomly delivered at different velocities (from 0 to 0.2m/s). Markers of postural control, including objective sway (trunk sway path, recorded via a sensor attached to vertebrae C7), stepping responses, subjective instability and anxiety ratings were obtained. MRI scans were available for correlations with levels of cerebral small vessel disease in 28 patients and 24 controls. We observed a significant relationship between objective and subjective instability in all groups. The slope of this fit was significantly steeper for patients than controls, indicating greater perceived instability for the same body sway. Stepwise linear regression showed that the slopes of this objective-subjective instability relationship were best explained by concerns about falling (Falls Efficacy Scale-International), clinical physical functioning (Short Physical Performance Battery) and, to some degree, by neuroimaging markers of cerebral small vessel disease. In addition, patients had a reduced stepping threshold, suggesting an overly cautious postural response. The distorted perception of instability and subtle impairments in balance control, including abnormal and overly cautious stepping responses, underlies the emergence of ID. It appears to relate to changes in postural performance, psychological functioning and disruption of postural brain networks associated with cerebral small vessel disease.

Trunk Instability in the Pitch, Yaw, and Roll Planes during Clinical Balance Tests: Axis Differences and Correlations to vHIT Asymmetries Following Acute Unilateral Vestibular Loss.

Clinical dynamic posturography concentrates on the pitch and roll but not on the yaw plane instability measures. This emphasis may not represent the axis instability observed in clinical stance and gait tasks for patients with balance deficits in comparison to healthy control (HC) subjects, nor the expected instability based on correlations with vestibulo-ocular reflex (VOR) deficits. To examine the axis stability changes with vestibular loss, we measured trunk sway in all three directions (pitch, roll, and yaw) during the stance and gait tasks of patients with acute unilateral vestibular neuritis (aUVN) and compared the results with those of HC. Concurrent changes in VORs were also examined and correlated with trunk balance deficits. The results of 11 patients (mean age of 61 years) recorded within 6 days of aUVN onset were compared within those of 8 age-matched healthy controls (HCs). All subjects performed a two-legged stance task-standing with eyes closed on foam (s2ecf), a semi-gait task-walking eight tandem steps (tan8), and four gait tasks-walking 3 m with head rotating laterally, pitching, or eyes closed (w3hr, w3hp, w3ec), and walking over four barriers 24 cm high, spaced 1 m apart (barr). The tasks' peak-to-peak yaw, pitch and roll angles, and angular velocities were measured with a gyroscope system (SwayStarTM) mounted at L1-3 and combined into three, axis-specific, balance control indexes (BCI), using angles (a) for the tandem gait and barriers task, and angular velocities (v) for all other tasks, as follows: axis BCI = (2 × 2ecf)v + 1.5 × (w3hr + w3hp + w3ec)v + (tan8 + 12 × barr)a. Yaw and pitch BCIs were significantly (p ≤ 0.004) greater (88 and 30%, respectively) than roll BCIs for aUVN patients. For HCs, only yaw but not pitch BCIs were greater (p = 0.002) than those of roll (72%). The order of BCI aUVN vs. HC differences was pitch, yaw, and roll at 55, 44, and 31%, respectively (p ≤ 0.002). This difference with respect to roll corresponded to the known greater yaw plane than roll plane asymmetry (40 vs. 22%) following aUVN based on VOR responses. However, the lower pitch plane asymmetry (3.5%) in VOR responses did not correspond with the pitch plane instability observed in the balance control tests. The increases in pitch plane instability in UVL subjects were, however, highly correlated with those of roll and yaw. These results indicate that greater yaw than pitch and roll trunk motion during clinical balance tasks is common for aUVN patients and HCs. However, aUVN leads to a larger increase in pitch than yaw plane instability and a smaller increase in roll plane instability. This difference with respect to roll corresponds to the known greater yaw plane than roll plane asymmetry (40 vs. 22%) following aUVN observed in VOR responses. However, the lower pitch plane asymmetry (3.5%) in VOR responses does not correspond with the enhanced movements in the pitch plane, observed in balance control tasks. Whether asymmetries in vestibular-evoked myogenic potentials (Vemps) are better correlated with the deficits in pitch plane balance control remains to be investigated. The current results provide a strong rationale for the clinical testing of directional specific balance responses, especially yaw and pitch, and the linking of balance results for yaw and roll to VOR asymmetries.

EFFECTIVENESS OF STEP SQUARE EXERCISES TO PREVENT FALLS IN MULTIPLE SCLEROSIS PATIENTS – A NARRATIVE REVIEW

In this study the literature review focus on the available evidence for the physiotherapy intervention to prevent falls in among multiple sclerosis. Research involved a computerized data base pertaining to studies that include the physiotherapy among multiple sclerosis patients 15 articles that showed outcomes relative to falls, physiotherapy intervention to prevent falls among selected multiple sclerosis patients with multiple sclerosis are more likely to fall, especially when walking, due to their slower proactive equilibrium reactions, decreased ability to maintain balance when reaching, central integration impairment, slow somatosensory conduction, fatigue, delayed reaction, attention deficit, difficulty maintaining stability in the presence of external disturbances, and overload fatigue of the motor cortex. Stand-related trunk instability was observed in MS patients, a rise in trunk sway, and a rise in postural sway when performing two tasks at once. Minimal literature on falls prevention there is scarcity of study which intervention among Step square exercises and Wii board exercises. AIM: The study aimed to find the effectiveness of Step square exercises to prevent falls in MS patients. KEY WORDS: Multiple sclerosis, intervention, equilibrium reactions, integration impairment, somatosensory conduction, attention deficit, motor cortex, trunk stability, trunk sway,

Dissociated cerebellar contributions to feedforward gait adaptation

The cerebellum is important for motor adaptation. Lesions to the vestibulo-cerebellum selectively cause gait ataxia. Here we investigate how such damage affects locomotor adaptation when performing the ‘broken escalator’ paradigm. Following an auditory cue, participants were required to step from the fixed surface onto a moving platform (akin to an airport travellator). The experiment included three conditions: 10 stationary (BEFORE), 15 moving (MOVING) and 10 stationary (AFTER) trials. We assessed both behavioural (gait approach velocity and trunk sway after stepping onto the moving platform) and neuromuscular outcomes (lower leg muscle activity, EMG). Unlike controls, cerebellar patients showed reduced after-effects (AFTER trials) with respect to gait approach velocity and leg EMG activity. However, patients with cerebellar damage maintain the ability to learn the trunk movement required to maximise stability after stepping onto the moving platform (i.e., reactive postural behaviours). Importantly, our findings reveal that these patients could even initiate these behaviours in a feedforward manner, leading to an after-effect. These findings reveal that the cerebellum is crucial for feedforward locomotor control, but that adaptive locomotor behaviours learned via feedback (i.e., reactive) mechanisms may be preserved following cerebellum damage.

The Effects of Optical Flow Perturbations on Standing Balance in People With Multiple Sclerosis.

Multiple sclerosis is a neurodegenerative disease that causes balance deficits, even in early stages. Evidence suggests that people with multiple sclerosis (PwMS) rely more on vision to maintain balance, and challenging balance with optical flow perturbations may be a practical screening for balance deficits. Whether these perturbations affect standing balance in PwMS is unknown. Therefore, the purpose of this study was to examine how optical flow perturbations affect standing balance in PwMS. We hypothesized that perturbations would cause higher variability in PwMS compared with matched controls during standing and that standing balance would be more susceptible to anterior-posterior (A-P) perturbations than medial-lateral (M-L) perturbations. Thirteen PwMS and 13 controls stood under 3 conditions: unperturbed, M-L perturbation, and A-P perturbations. A-P perturbations caused significantly higher A-P trunk sway variability in PwMS than controls, although both groups had similar center-of-pressure variability. Both perturbations increased variability in A-P trunk sway and center of pressure. Trunk variability data supported the hypothesis that PwMS were more susceptible to optical flow perturbations than controls. However, the hypothesis that A-P perturbations would affect balance more than M-L perturbations was partially supported. These results suggest potential for optical flow perturbations to identify balance deficits in PwMS.

IMPACT OF DUAL-TASKING AND DEMENTIA DISEASE SEVERITY ON POSTURE, GAIT, AND FUNCTIONAL MOBILITY IN RESIDENTIAL CARE

Abstract Dual-tasking may be a useful tool for fall-risk screening among people living with dementia (PWD), but more evidence is needed. Our aims were to compare single- and dual-task posture, gait and functional mobility; and examine the relationship between dementia severity and dual-task interference among PWD. Thirty PWD (Age:81.8±7.3years; 35% Female; Montreal Cognitive Assessment:10.5±6.1points) from two residential care facilities wore six APDM inertial sensors and completed two trials of single- (feet apart) and dual-task posture (feet apart while counting backwards by 1’s), single- (walk 4m) and dual-task gait (walk 4m while naming words), and single- (timed-up-and-go (TUG)); and dual-task functional mobility (TUG while completing a category task). Results revealed that greater frequency, jerk, and area were observed during dual- than single-task posture (ps&amp;lt; 0.05), with no differences in velocity. Slower gait speed, greater double limb support, shorter stride length, and reduced elevation at mid-swing were detected during dual- relative to single-task gait (ps&amp;lt; 0.05), with no differences in medial-lateral trunk sway. Dual-tasking resulted in a longer duration, reduced turn angle, and slower turn velocity than single-tasking for the TUG (ps&amp;lt; 0.05), with no differences in sit-to-stand lean angle. Dual-task interference (greater jerk, faster gait speed) was related to moderate-to-severe compared to mild dementia (ps&amp;lt; 0.05). Dual-tasking was more sensitive to detect impairments in posture, gait, and functional mobility than single-tasking. Moderate to severe PWD had poorer dynamic stability and a reduced ability to appropriately select cautious gait during dual-tasking than those with mild dementia, which should be considered in fall-risk screening.

Balance strategies for recovery from perturbed overground walking

Bipedal locomotion is naturally unstable and requires active control. Walking is believed to be primarily stabilized through the selection of foot placements; however, other strategies are available, including regulation of ankle inversion/eversion, ankle push-off, and angular momentum through trunk postural adjustments. The roles of these strategies in maintaining overall stability are often masked by the dominant foot placement strategy. The objectives of this study were to describe how the four strategies are used to respond to medial or lateral ground perturbations during overground walking in healthy individuals and determine reliance on each strategy. Fifteen healthy adults walked with and without perturbations applied to the right foot at heel strike while body kinematics and surface electromyographic activity were measured. Medial perturbations resulted in decreased step width on the first step after the perturbation, increased ankle inversion, increased ankle push-off, and rightward trunk sway. Lateral perturbations resulted in increased step width, decreased ankle inversion, no change in ankle push-off, and leftward trunk sway. EMG activity was consistent with the observed strategies (e.g. increased peroneus longus EMG activity during ankle eversion) with the exception of increased bilateral erector spinae activity for all perturbations. Foot placement was the dominant strategy in response to perturbations, with other strategies showing reduced, yet significant, roles. This work demonstrates that multiple strategies are recruited to improve the balance response in addition to foot placement alone. These results can serve as a reference for future studies of populations with impaired balance to identify potential deficits in strategy selection.

Digital Motor Biomarkers of Cerebellar Ataxia Using an RGB-Depth Camera-Based Motion Analysis System.

This study aimed to identify quantitative biomarkers of motor function for cerebellar ataxia by evaluating gait and postural control using an RGB-depth camera-based motion analysis system. In 28 patients with degenerative cerebellar ataxia and 33 age- and sex-matched healthy controls, motor tasks (short-distance walk, closed feet stance, and stepping in place) were selected from a previously reported protocol, and scanned using Kinect V2 and customized software. The Clinical Assessment Scale for the Assessment and Rating of Ataxia (SARA) was also evaluated. Compared with the normal control group, the cerebellar ataxia group had slower gait speed and shorter step lengths, increased step width, and mediolateral trunk sway in the walk test (all P < 0.001). Lateral sway increased in the stance test in the ataxia group (P < 0.001). When stepping in place, the ataxia group showed higher arrhythmicity of stepping and increased stance time (P < 0.001). In the correlation analyses, the ataxia group showed a positive correlation between the total SARA score and arrhythmicity of stepping in place (r = 0.587, P = 0.001). SARA total score (r = 0.561, P = 0.002) and gait subscore (ρ = 0.556, P = 0.002) correlated with mediolateral truncal sway during walking. These results suggest that the RGB-depth camera-based motion analyses on mediolateral truncal sway during walking and arrhythmicity of stepping in place are useful digital motor biomarkers for the assessment of cerebellar ataxia, and could be utilized in future clinical trials.

Impact of mobile phone use on accidental falls risk in young adult pedestrians

BackgroundMobile phone use is known to be a distraction to pedestrians, increasing their likelihood of crossing into oncoming traffic or colliding with other people. However, the effect of using a mobile phone to text while walking on gait stability and accidental falls in young adults remains inconclusive. This study uses a 70 cm low friction slip hazard and the threat of hazard to investigate the effects of texting while walking on gait stability, the ability to recover balance after a slip hazard and accidental falls. MethodsFifty healthy young adults performed six walking tasks, and one seated texting task in random order. The walks were conducted over a 10-m walkway. Four progressive hazard levels were used: 1) Seated; 2) Normal Walk (walking across the walkway with no threat of a slip); 3) Threat (walking with the threat of a slip); and 4) Slip (walking with an actual 70 cm slip hazard). The three walking conditions were repeated twice with and without the mobile phone texting dual-task. Gait kinematics and trunk posture were recorded using wearable sensors attached to the head, trunk, pelvis and feet. Study outcomes were analyzed using repeated measures analysis of variance with significance set to P≤.05. ResultsMobile phone use significantly impaired postural balance recovery when slipping, as demonstrated by increased trunk sway. Mobile phone use negatively impacted gait stability as demonstrated by increased step time variability and decreased harmonic ratios. Increased hazard levels also led to reduced texting accuracy. ConclusionsUsing a mobile phone to text while walking may compete with locomotor tasks, threat assessment and postural balance control mechanisms, which leads to an increased risk of accidental falls in young adults. Pedestrians should therefore be discouraged through new educational and technology-based initiatives (for example a “texting lock” on detection of walking) from texting while walking on roadside footpaths and other environments where substantial hazards to safety exist.

Effect of masticatory movements on head and trunk sways, and sitting and foot pressure distributions during sitting position.

The purpose of this study was to test the hypothesis in healthy subjects that masticatory movements affect head and trunk sways, and sitting and foot pressure distributions during sitting position. A total of 30 healthy male subjects with an average age of 25.3 years (range, 22-32 years) were evaluated. The CONFORMatTM and MatScanTM system were used to analyze changes in sitting pressure distribution (center of sitting pressure: COSP) and changes in foot pressure distribution (center of foot pressure: COFP) respectively, and the 3-dimensional motion analysis system was used to analyze changes in head and trunk postures while subjects remained sitting position with rest position, centric occlusion, and chewing. The total trajectory length of COSP/COFP, COSP/COFP area, and head and trunk sway values were compared between the three conditions to evaluate whether masticatory movement affected the stability of head and trunk sways, and sitting and foot pressure distributions. Total trajectory length of COSP and COSP area during chewing were significantly shorter and smaller respectively than it was in rest position and centric occlusion (p < 0.016). Head sway value during chewing was significantly larger than it was in rest position and centric occlusion (p < 0.016). Masticatory movements affect sitting pressure distribution and head movements during sitting position.

The Effects of Vibro-Tactile Biofeedback Balance Training on Balance Control and Dizziness in Patients with Persistent Postural-Perceptual Dizziness (PPPD).

Patients with persistent postural-perceptual dizziness (PPPD) frequently report having problems with balance control. Artificial systems providing vibro-tactile feedback (VTfb) of trunk sway to the patient could aid recalibration of "falsely" programmed natural sensory signal gains underlying unstable balance control and dizziness. Thus, the question we examine, retrospectively, is whether such artificial systems improve balance control in PPPD patients and simultaneously reduce the effects of dizziness on their living circumstances. Therefore, we assessed in PPPD patients the effects of VTfb of trunk sway on balance control during stance and gait tests, and on their perceived dizziness. Balance control was assessed in 23 PPPD patients (11 of primary PPPD origin) using peak-to-peak amplitudes of trunk sway measured in the pitch and roll planes with a gyroscope system (SwayStar™) during 14 stance and gait tests. The tests included standing eyes closed on foam, walking tandem steps, and walking over low barriers. The measures of trunk sway were combined into a Balance Control Index (BCI) and used to determine whether the patient had a quantified balance deficit (QBD) or dizziness only (DO). The Dizziness Handicap Inventory (DHI) was used to assess perceived dizziness. The subjects first underwent a standard balance assessment from which the VTfb thresholds in eight directions, separated by 45 deg, were calculated for each assessment test based on the 90% range of the trunk sway angles in the pitch and roll directions for the test. A headband-mounted VTfb system, connected to the SwayStar™, was active in one of the eight directions when the threshold for that direction was exceeded. The subjects trained for 11 of the 14 balance tests with VTfb twice per week for 30 min over a total of 2 consecutive weeks. The BCI and DHI were reassessed each week and the thresholds were reset after the first week of training. On average, the patients showed an improved balance control in the BCI values after 2 weeks of VTfb training (24% p = 0.0001). The improvement was greater for the QBD patients than for the DO patients (26 vs. 21%), and greater for the gait tests than the stance tests. After 2 weeks, the mean BCI values of the DO patients, but not the QBD patients, were significantly less (p = 0.0008) than the upper 95% limit of normal age-matched reference values. A subjective benefit in balance control was spontaneously reported by 11 patients. Lower (36%), but less significant DHI values were also achieved after VTfb training (p = 0.006). The DHI changes were identical for the QBD and DO patients and approximately equal to the minimum clinical important difference. These initial results show, as far as we are aware for the first time, that providing VTfb of trunk sway to PPPD subjects yields a significant improvement in balance control, but a far less significant change in DHI-assessed dizziness. The intervention benefitted the gait trials more than the stance trials and benefited the QBD group of PPPD patients more than the DO group. This study increases our understanding of the pathophysiologic processes underlying PPPD and provides a basis for future interventions.

Training reactive balance using trips and slips in people with multiple sclerosis: A blinded randomised controlled trial.

This study examined the feasibility and efficacy of reactive balance training for improving stepping performance and reducing laboratory-induced falls in people with multiple sclerosis (MS). Thirty people diagnosed with MS (18-70 years) participated in a blinded randomized controlled trial (ACTRN12618001436268). The intervention group (n=14) underwent two 50-minute sessions (total 100min) that exposed them to a total of 24 trips and 24 slips in mixed order, over one week. The control group (n=16) received sham training (stepping over foam obstacles) with equivalent dosage. The primary outcome was falls into the harness (defined as >30% body weight) when exposed to trips and slips that were unpredictable in timing, location and type at post-assessment. Physical and psychological measures were also assessed at baseline and post assessments. The intervention and control groups completed 86% and 95% of the training protocols respectively. Incidence rate ratios (95% confidence intervals) of the intervention group relative to the control group were 0.57 (0.25, 1.26) for all falls, 0.80 (0.30, 2.11) for slip falls and 0.20 (0.04, 0.96) for trip falls in the laboratory. Kinematic analyses indicated the intervention participants improved dynamic stability, with higher centre of mass position and reduced trunk sway during recovery steps following a trip, compared to control. There were no significant differences between the intervention and control participants at post-assessment for other secondary outcome measures. Reactive balance training improved trip-induced dynamic stability, limb support, trunk control and reduced falls in people with MS. More research is required to optimise the training protocol and determine whether the beneficial effects of reactive balance training can be retained long term and generalize to fewer daily-life falls.

Effect of sitting posture with and without sole-ground contact on chewing stability and masticatory performance.

To verify the effect of sitting posture with and without sole-ground contact on chewing stability and masticatory performance. Thirty healthy subjects were evaluated. The Conformat was used to analyze the center of sitting pressure (COSP), and the three-dimensional motion analysis system was used to analyze changes in head and trunk postures while subjects remained in a sitting position with and without sole-ground contact. The parameters of masticatory performance and movement were calculated as follows. For evaluating masticatory performance, the amount of glucose extraction (AGE) during chewing of a gummy jelly was measured. For evaluating masticatory movements, the movement of the mandibular incisal point was recorded using the Motion Visi-Trainer V1, and parameters of the stabilities of movement path and rhythm were calculated. Head and trunk sway values and the displacement of COSP were significantly smaller with sole-ground contact than those without sole-ground contact. The masticatory movement path with sole-ground contact showed less variation in the opening distance and more stable movement path compared to those without sole-ground contact. The AGE was significantly greater with sole-ground contact than that without sole-ground contact. Sitting posture with and without sole-ground contact affects chewing stability and masticatory performance.

Discriminative Changes in Sitting and Standing Postural Steadiness in Patients With Chronic Low Back Pain.

Postural control is reduced in patients with low back pain (LBP), which is considered an important factor attributing to the chronicity of LBP and a target for treatment. It is proposed that the changes in postural steadiness in sitting reflect the trunk control better than those in standing, but the previous study results are inconsistent. Thus, this study aimed to compare trunk sway parameters during standing and sitting between patients with chronic LPB (CLBP) and controls using a tracker-based posturography to record the trunk displacement trajectories at the lumbar level (TD [Formula: see text]. A total of 64 participants (32 patients with CLBP and 32 pain-free controls) were included in this study. The postural sway was measured under four conditions, sitting or standing on unstable surface, with eyes open or closed. The TDL parameters were compared between the two groups to explore their discriminative ability. The CLBP group had more body sway than the control group, characterized by several TDL parameters in sitting with eyes closed and standing with eyes open. The TDL parameters with the highest area under the curve according to the receiver operating characteristic curve analysis were the root mean square distance and mean frequency in the medial-lateral direction obtained in the sitting with eyes closed. In conclusion, we confirmed the advantage of using sitting posturographic parameters as a sensitive measure to detect impaired trunk control in patients with CLBP. The results would help choose sensitive outcome measures to reflect the postural control of patients with LBP.

Systematic Assessment of Prosthesis Stiffness on User Biomechanics Using the Lower Leg Trajectory Error Framework and Its Implication for the Design and Evaluation of Ankle-Foot Prostheses.

Advances in understanding the effects the mechanical characteristics of prosthetic feet on user biomechanics have enabled passive prostheses to improve the walking pattern of people with lower limb amputation. However, there is no consensus on the design methodology and criteria required to maximize specific user outcomes and fully restore their mobility. The Lower Leg Trajectory Error (LLTE) framework is a novel design methodology based on the replication of lower leg dynamics. The LLTE value evaluates how closely a prosthetic foot replicates a target walking pattern. Designing a prosthesis that minimizes the LLTE value, optimizes its mechanical function to enable users to best replicate the target lower leg trajectory. Here, we conducted a systematic sensitivity investigation of LLTE-optimized prostheses. Five people with unilateral transtibial amputation walked overground at self-selected speeds using five prototype energy storage and return feet with varying LLTE values. The prototypes' LLTE values were varied by changing the stiffness of the participant's LLTE-optimized design by 60%, 80%, 120%, and 167%. Users most closely replicated the target able-bodied walking pattern with the LLTE-optimized stiffness, experimentally demonstrating that the predicted optimum was a true optimum. Additionally, the predicted LLTE values were correlated to the user's ability to replicate the target walking pattern, user preferences, and clinical outcomes including roll-over geometries, trunk sway, prosthetic energy return, and peak push-off power. This study further validates the use of the LLTE framework as a predictive and quantitative tool for designing and evaluating prosthetic feet.

Defining "Postural Control" in Interventions for Musculoskeletal Pain

<h3>Objective(s)</h3> To identify and describe how "postural control" is measured in therapeutic interventions for musculoskeletal pain, and to provide recommendations on assessment methods when "postural control" is a primary outcome measure. <h3>Data Sources</h3> PubMed and CINAHL were searched using terms encompassing concepts "postural control", "intervention", and "musculoskeletal pain" including MeSH terms and truncations. Limits were applied for human studies published in English. <h3>Study Selection</h3> 1,553 results were screened by title, then abstract to include only those studies providing an intervention to a human population experiencing musculoskeletal pain. Studies were included if they described a specific intervention or protocol, and identified a relevant keyword that could be related to "postural control." 136 articles were full-text reviewed to identify if a study had specific outcome measures for measuring postural control. Consensus was achieved between the first and last authors identifying a final list of 20 studies meeting inclusion criteria. <h3>Data Extraction</h3> Specific measurement tools for postural control and their methods of use were extracted from each study. Agreement on how "postural control" was measured in a study was achieved between at least two staff for each study. <h3>Data Synthesis</h3> Frequency counts were used to identify 3 measurement categories for "postural control": trunk sway or center of pressure during static standing, muscle activation or body position in response to or anticipating perturbation, and segmental coordination during movement. The most frequently used assessment was center of pressure during static standing, then velocity and amplitude of trunk sway, then relative joint angles. <h3>Conclusions</h3> Results indicate "postural control" is defined in multiple ways in musculoskeletal interventions for pain. Three broad concepts were identified as being measures of "postural control:" body position during static standing, anticipatory & reactive movements, and relative joint positions. Measures traditionally associated with "balance" were the most frequent measures of "postural control." Given the theoretical importance of postural control in musculoskeletal pain and it's multifaceted nature, we recommend including outcome measures that encompass reactive and dynamic activities to differentiate "postural control" from "balance." <h3>Author(s) Disclosures</h3> None to disclose.

Overcoming the Limitations of the Berg Balance Scale (BBS)

Research Objectives To increase the sensitivity of the BBS tasks to effectively determine and track the falls risk of individuals. Design The BBS is commonly used to measure falls risk in older adults, but can only be utilized during face-to-face assessments. Due to COVID-19, a virtual health method of assessing falls risk in older adults is necessary. Markerless motion capture was used to provide a quantitative approach to static and dynamic elements of the BBS. This new protocol was dubbed the Enhanced Virtual BBS, or eV-BBS. The eV-BBS provides significantly more objective information than the current BBS, thereby improving its sensitivity and reproducibility. Setting University of Alberta Rehab Robotics Lab, Edmonton, Canada, during the COVID-19 pandemic. Participants A convenience sample of 10 healthy participants were selected. Interventions A test-retest reliability model determined the inter- and intra-participant variability when conducting the sit-to-stand and balance test in the BBS. Main Outcome Measures Novel parameters were created to represent the characteristics of the sit-to-stand and balance components of the BBS, such as rise height, drop height, and root mean square of trunk sway. Results The study revealed significant test-retest reliability (ICC = 0.81 to 0.99) and repeatability (COV < 20%) for the static stability tasks. The sensitivity of the eV-BBS to detect changes between participants was revealed during the analysis of the dynamic stability tasks, which had poor reliability (ICC = 0.10 to 0.60) and repeatability (COV > 20%). Conclusions The results indicate that the current BBS focuses on qualitative measures of sway and task timing. The dynamic and static components (of the sit-to-stand test in particular) are not identified, yet we know these are critical to assessing falling risk. The variability seen in the dynamic data of eV-BBS is likely to be attributable to subtle differences in participant performance of the task. Sensitivity of eV-BBS is high, but the level of sensitivity needed will only become apparent when participants at risk for falling are included in a future study. Author(s) Disclosures The authors have no conflicts of interest to declare. To increase the sensitivity of the BBS tasks to effectively determine and track the falls risk of individuals. The BBS is commonly used to measure falls risk in older adults, but can only be utilized during face-to-face assessments. Due to COVID-19, a virtual health method of assessing falls risk in older adults is necessary. Markerless motion capture was used to provide a quantitative approach to static and dynamic elements of the BBS. This new protocol was dubbed the Enhanced Virtual BBS, or eV-BBS. The eV-BBS provides significantly more objective information than the current BBS, thereby improving its sensitivity and reproducibility. University of Alberta Rehab Robotics Lab, Edmonton, Canada, during the COVID-19 pandemic. A convenience sample of 10 healthy participants were selected. A test-retest reliability model determined the inter- and intra-participant variability when conducting the sit-to-stand and balance test in the BBS. Novel parameters were created to represent the characteristics of the sit-to-stand and balance components of the BBS, such as rise height, drop height, and root mean square of trunk sway. The study revealed significant test-retest reliability (ICC = 0.81 to 0.99) and repeatability (COV < 20%) for the static stability tasks. The sensitivity of the eV-BBS to detect changes between participants was revealed during the analysis of the dynamic stability tasks, which had poor reliability (ICC = 0.10 to 0.60) and repeatability (COV > 20%). The results indicate that the current BBS focuses on qualitative measures of sway and task timing. The dynamic and static components (of the sit-to-stand test in particular) are not identified, yet we know these are critical to assessing falling risk. The variability seen in the dynamic data of eV-BBS is likely to be attributable to subtle differences in participant performance of the task. Sensitivity of eV-BBS is high, but the level of sensitivity needed will only become apparent when participants at risk for falling are included in a future study.

Assessment of trunk control and core stability in spinal cord injured subjects

Objective measures for evaluating active trunk movements and postural control in sitting are important for the assessment of people with Spinal Cord Injury (SCI) and for tailoring rehabilitative interventions. However, studies addressing this issue are limited [1]. This work fills this gap by proposing a modular protocol for the kinematic and muscular quantitative assessment of trunk control, specifically designed for SCI subjects. We used hunova® (Movendo Technology), a medical robotic device for the sensory-motor assessment and training of postural control in standing and sitting [2]. consisted of two different tests: a reaching (R) and an adaptive exercise (A), both performed while sitting on hunova®. The test R aims to assess the volitional component of trunk control: six reaching exercises, where subjects need to actively tilt the seat platform to move a cursor on the screen and reach targets, are alternating with two different platform inclinations: 3.5 and 5° (1° corresponds to 1 cm of cursor motion on the screen). The test A aims to assess how subjects adapt to predictable perturbations imposed by the seat platform [3]: six repetitions of an adaptive task, where subjects need to stabilize themselves while the seat platform moves following a given infinite-shape trajectory, is repeated once with eyes open (EO) and eyes close (EC), with different inclinations of the seat platform: 3, 5 and 7°. After testing the device and protocol on 18 healthy subjects, 10 SCI subjects (with different lesion level) participated in the study. Both the reaching block and the adaptive block (Fig. 1) started with the easiest testing condition and gradually increases the difficulty of the exercises. This allowed all SCI subjects, with different lesion level, to participate in the assessment. Electromyography (EMG) was recorded bilaterally from the following muscles: obliquus externus abdominis, trapezius descendens, trapezius transversalis, trapezius ascendens, erector spinae longissimus, erector spinae iliocostalis, multifidus, latissimus dorsi, soleus, tibialis anterior, vastus medialis, semitendinosus, gluteus medium. The leg muscles were recorded only for SCI subjects with an incomplete lesion of the spinal cord. For each subject, we characterized postural responses in terms of kinematics and muscular activity, estimating the correspondent spatiotemporal organization of the motoneuronal activity in the spinal cord [4]. All subjects with an incomplete SCI could finish the whole protocol. This was not the case for subjects with a complete lesion. Only one subject (lesion level D12) completed both blocks and had movement performance like SCI subjects with an incomplete lesion. The other subjects (two with lesion level D6 and one D3) performed few repetitions of R as they found difficult to control the seat platform, and the tasks with 3 and 5° of inclination for A. Concerning the performance, for R all subjects, independently on their type of lesion, reached a greater number of targets across repetitions. During A, all subjects had a bigger trunk sway for higher inclinations of the seat platform, with higher values in the repetitions with EC. Each SCI subject used his/her own muscular strategy for reaching the different targets and also for adapting to the seat motion, despite it was continuous and predictable. This assessment highlighted the differences in the muscular control among subjects, also due to the different lesions. This modular protocol evaluated in a quantitative, objective, repeatable, and comprehensive manner the kinematic and muscular strategies adopted by SCI subjects when performing dynamic tasks while sitting. The device hunova® allowed us to evaluate different aspects related to trunk control, the volitional and the feedforward control of balance while adapting to predictable and continuous perturbations. The results of this assessment will be used to tailor specific rehabilitative interventions.