Center-of-pressure total trajectory length is a complementary measure to maximum excursion to better differentiate multidirectional standing limits of stability between individuals with incomplete spinal cord injury and able-bodied individuals

The alteration of static and dynamic postural stability among women with breast cancer during taxane-based chemotherapy: a descriptive study

INTRODUCTION

Women with breast cancer who underwent taxane-based chemotherapy demonstrate diminished postural stability. However, the data concerning dynamic postural stability among women with breast cancer during taxane-based chemotherapy remains insufficient.

PURPOSE

To investigate postural stability among women with breast cancer during taxane-based chemotherapy.

METHODS

Fifteen women with breast cancer participated in this study. Postural stabilities were assessed at five intervals during the course of chemotherapy treatment. Static postural stability was measured during single leg with eyes open (SEO) and eyes closed (SEC) conditions, while dynamic postural stability was measured during performance of the limit of stability test (LOS). Postural stability was described using 95% confidence ellipse area (EA), center of pressure (COP) path length (PL), and COP average velocity (AV).

RESULTS

For static postural stability assessment, SEO condition was found to have significant increases in EA, PL, and AV (p = .001, p < .001, and p = .02, respectively). For dynamic postural stability assessment, a significant difference in EA was observed in the forward, backward, right, and left directions (p = .02, p = .02, p < .001, and p = .01, respectively). In addition, a significant difference in PL was found while performing in a backward direction (p = .02).

CONCLUSIONS

The findings showed that women with breast cancer may have experienced decreased static and dynamic postural stability.

The relationship between balance control and thigh muscle strength and muscle activity in persons with incomplete spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

A spinal cord injury (SCI) can compromise the ability to maintain sufficient balance control during activities in an upraised position. The objective of the study was to explore the relationship between balance control and muscle strength and muscle activation in the lower extremities in persons with incomplete SCI (iSCI).

SETTING

Sunnaas Rehabilitation Hospital, Norway.

METHODS

Thirteen men and two women with iSCI and 15 healthy, matched controls were included. Performance of the Berg Balance Scale (BBS) short version (7 items) was used to indicate balance control. Maximal voluntary contraction (MVC) was performed to measure isometric muscle strength in thigh muscles (knee extension/flexion), while surface electromyography (EMG) was measured from M. Vastus Lateralis and M. Biceps Femoris. The relative activation of each muscle during each of the BBS tasks was reported as the percentage of the maximal activation during the MVC (%EMGmax).

RESULTS

The iSCI participants had a significantly lower BBS sum score and up to 40% lower muscle strength in knee- flexion and extension compared to the matched healthy controls. They also exhibited a significantly higher %EMGmax, i.e. a higher muscle activation, during most of the balance tests. Univariate regression analysis revealed a significant association between balance control and mean values of %EMGmax in Biceps Femoris, averaged over the seven BBS tests.

CONCLUSIONS

The participants with iSCI had poorer balance control, reduced thigh muscle strength and a higher relative muscle activation in their thigh muscles, during balance-demanding activities.

The sex effect on balance control while standing on vestibular-demanding tasks with/without vestibular simulations: implication for sensorimotor training for future space missions

Background: Anatomical differences between sexes in the vestibular system have been reported. It has also been demonstrated that there is a sex difference in balance control while standing on vestibular-demanding tasks. In 2024, NASA expects to send the first female to the Moon. Therefore, to extend the current knowledge, this study attempted to examine whether different sexes respond differently to vestibular-disrupted and vestibular-demanding environments. Method: A total of fifteen males and fifteen females participated in this study. The vestibular function was quantified through different SOT conditions (SOT1: baseline; SOT5: vestibular demanding by standing with blindfolded and sway reference surface). The vestibular stimulation (VS) was applied either unilaterally or bilaterally to vestibular system to induce the sensory-conflicted and challenging tasks. Thus, a total of 6 conditions (2 SOT conditions X 3 VSs: no-VS, unilateral VS, and bilateral VS) were randomly given to these participants. Three approaches can be quantified the balance control: 1) the performance ratio (PR) of center of gravity trajectories (CoG), 2) the sample entropy measure (SampEn) of CoG, and 3) the total traveling distance of CoG. A mixed three-way repeated ANOVA measure was used to determine the interaction among the sex effect, the effect of SOT, and the effect of VS on balance control. Results: A significant sex effect on balance control was found in the PR of CoG in the anterior-posterior (AP) direction (p = 0.026) and in the SampEn of CoG in both AP and medial-lateral (ML) directions (p = 0.025, p < 0.001, respectively). Also, a significant interaction among the sex effect, the effect of SOT, and the effect of VS on balance control was observed in PR of CoG in the ML direction (p < 0.001), SampEn of CoG in the AP and ML directions (p = 0.002, p < 0.001, respectively), and a traveling distance in AP direction (p = 0.041). Conclusion: The findings in the present study clearly revealed the necessity to take sex effect into consideration while standing in vestibular-perturbed or/and vestibular demanding tasks. Also, the results in the present study could be a fundamental reference for future sensorimotor training.

Clinical Static Balance Assessment: A Narrative Review of Traditional and IMU-Based Posturography in Older Adults and Individuals with Incomplete Spinal Cord Injury

Maintaining a stable upright posture is essential for performing activities of daily living, and impaired standing balance may impact an individual's quality of life. Therefore, accurate and sensitive methods for assessing static balance are crucial for identifying balance impairments, understanding the underlying mechanisms of the balance deficiencies, and developing targeted interventions to improve standing balance and prevent falls. This review paper first explores the methods to quantify standing balance. Then, it reviews traditional posturography and recent advancements in using wearable inertial measurement units (IMUs) to assess static balance in two populations: older adults and those with incomplete spinal cord injury (iSCI). The inclusion of these two groups is supported by their large representation among individuals with balance impairments. Also, each group exhibits distinct aspects in balance assessment due to diverse underlying causes associated with aging and neurological impairment. Given the high vulnerability of both demographics to balance impairments and falls, the significance of targeted interventions to improve standing balance and mitigate fall risk becomes apparent. Overall, this review highlights the importance of static balance assessment and the potential of emerging methods and technologies to improve our understanding of postural control in different populations.

Influences of smart glasses on postural control under single- and dual-task conditions for ergonomic risk assessment

Head worn displays have become increasingly popular at workplaces in logistics and assembly lines in recent years. Such displays are expected to improve productivity and safety at the workplace. However, their impact on balance in the workforce is still an open research question. Therefore, we investigated the influence of the Vuzix M400 and Realwear HMT1 smart glasses on postural control. A laboratory study was conducted with eleven participants. Balance parameters were recorded during bilateral quiet stance, together with parameters of cognitive load. The two different smart glasses used in this study were compared with a monitor and a tablet under single-task conditions and while performing a spatial 2-back task. As balance parameters, the prediction ellipse and sample entropy in anteroposterior as well as mediolateral direction of the center-of-pressure data were examined. No significant differences were observed in the cognitive task performance between the devices. The prediction ellipse of the smart glasses was smaller than the tablets but larger than the smartboard. The dynamic of sample entropy data suggests that the use of the spatial 2-back task induces postural sway in the participants. This effect was most profound when looking at the monitor and least recognizable in the data of the tablet.

Frequency-dependent tuning of the human vestibular "sixth sense" by transcranial oscillatory currents

OBJECTIVE

The vestibular cortex is a multisensory associative region that, in neuroimaging investigations, is activated by slow-frequency (1-2 Hz) galvanic stimulation of peripheral receptors. We aimed to directly activate the vestibular cortex with biophysically modeled transcranial oscillatory current stimulation (tACS) in the same frequency range.

METHODS

Thirty healthy subjects and one rare patient with chronic bilateral vestibular deafferentation underwent, in a randomized, double-blind, controlled trial, to tACS at slow (1 or 2 Hz) or higher (10 Hz) frequency and sham stimulations, over the Parieto-Insular Vestibular Cortex (PIVC), while standing on a stabilometric platform. Subjective symptoms of motion sickness were scored by Simulator Sickness Questionnaire and subjects' postural sways were monitored on the platform.

RESULTS

tACS at 1 and 2 Hz induced symptoms of motion sickness, oscillopsia and postural instability, that were supported by posturographic sway recordings. Both 10 Hz-tACS and sham stimulation on the vestibular cortex did not affect vestibular function. As these effects persisted in a rare patient with bilateral peripheral vestibular areflexia documented by the absence of the Vestibular-Ocular Reflex, the possibility of a current spread toward peripheral afferents is unlikely. Conversely, the 10 Hz-tACS significantly reduced his chronic vestibular symptoms in this patient.

CONCLUSIONS

Weak electrical oscillations in a frequency range corresponding to the physiological cortical activity of the vestibular system may generate motion sickness and postural sways, both in healthy subjects and in the case of bilateral vestibular deafferentation.

SIGNIFICANCE

This should be taken into account as a new side effect of tACS in future studies addressing cognitive functions. Higher frequencies of stimulation applied to the vestibular cortex may represent a new interventional option to reduce motion sickness in different scenarios.

A novel porcine model of CLN3 Batten disease recapitulates clinical phenotypes

Mouse models of CLN3 Batten disease, a rare lysosomal storage disorder with no cure, have improved our understanding of CLN3 biology and therapeutics through their ease of use and a consistent display of cellular pathology. However, the translatability of murine models is limited by disparities in anatomy, body size, life span and inconsistent subtle behavior deficits that can be difficult to detect in CLN3 mutant mouse models, thereby limiting their use in preclinical studies. Here, we present a longitudinal characterization of a novel miniswine model of CLN3 disease that recapitulates the most common human pathogenic variant, an exon 7-8 deletion (CLN3Δex7/8). Progressive pathology and neuron loss is observed in various regions of the CLN3Δex7/8 miniswine brain and retina. Additionally, mutant miniswine present with retinal degeneration and motor abnormalities, similar to deficits seen in humans diagnosed with the disease. Taken together, the CLN3Δex7/8 miniswine model shows consistent and progressive Batten disease pathology, and behavioral impairment mirroring clinical presentation, demonstrating its value in studying the role of CLN3 and safety/efficacy of novel disease-modifying therapeutics.

The effectiveness of dance movement therapy for individuals with Down syndrome: a pilot randomised controlled trial

BACKGROUND

Individuals with Down syndrome (DS) exhibit deficits in static and dynamic balance abilities and maladaptive functions. This study aimed to determine the effectiveness of dance movement therapy (DMT) group intervention in individuals with DS.

METHODS

The 31 participating individuals with DS, aged 5-29 years, were randomly divided into intervention (n = 16) and control (n = 15) groups. Posturography was used for static balance measurement, timed up and go test for dynamic balance measurement and the Achenbach System of Empirically Based Assessment (ASEBA) questionnaire for adaptive function and behavioural problem measurement in participants before and after the DMT interventions. The intervention group underwent 60-min DMT intervention once a week for 10 times, while the control group had usual daily activities.

RESULTS

The results revealed a statistically significant difference and large effect sizes in dynamic balance [(f(1, 29) = 4.52, P = 0.04, η_p   ² = 0.14)] in the intervention group compared with the control group. There were no statistically significant differences in static balance and ASEBA scores between the groups.

CONCLUSIONS

This study found that the DMT interventions helped to improve the dynamic balance in individuals with DS.

Validation of inertial measurement units for the assessment of trunk control in subjects with spinal cord injury

BACKGROUND

Trunk control (TC) constitutes one of the main objectives in the rehabilitation of people with a spinal cord injury (SCI), but there are few clinically validated tests to assess it. Accelerometers have been proposed as sensitive and suitable procedures to assess TC.

OBJECTIVE

To evaluate test-retest reliability, construct and criterion validity of accelerometer parameters to assess TC in people with SCI.

METHODS

A cross-sectional study of simultaneous application of Clinical Trunk Control Test (CTCT) and accelerometer evaluation was conducted. Accelerometers were placed on the trunks of 27 people with SCI and 15 people without SCI. Reliability was assessed by three repeated measures in random order of selected static and dynamic TC tasks. Acceleration on three axes was analyzed using five metrics. Criterion validity was assessed by analyzing correlation of acceleration to CTCT scores. Construct validity was assessed by analyzing capacity of inertial measurement units (IMU) to differentiate individual's characteristics, ASIA Impairment scale, gait capacity, level of TC, and neurological level of injury.

RESULTS

Reliable IMU data were obtained in people with SCI and without SCI, of all accelerometer axes, metrics, and tested items of the CTCT. Reliability of acceleration decreases with the increasing demand for TC tasks. Ten acceleration parameters showed construct and criterion validity.

CONCLUSION

Accelerometer parameters are reliable, valid, and sensitive to evaluate TC in people with SCI.

SIGNIFICANCE

A set of IMU parameters were validated as reliable and valid measures to evaluate TC, which could be useful for the assessment of progression of people with SCI and clinical interventions.

Effect of virtual reality training on standing balance in individuals with incomplete spinal cord injury

Recovery of balance ability during standing is one of the primary and essential aims of rehabilitative programs in individuals with incomplete spinal cord injury (iSCI). A sample of ten participants (mean age: 35.7 years, range: 25-63 years) with traumatic or non-traumatic iSCI (AIS grade C or D) and were able to stand with or without the support of an assistive device for a minimum of 2 min were recruited from the rehabilitation department of the Indian Spinal Injuries Centre, New Delhi, India. The participants received Virtual Reality (VR) based balance training for one hour, three times a week for four weeks on the Nintendo Wii gaming console. Participants were assessed three times: pre-intervention, post-intervention and follow-up assessment for the total ellipse area (TEA), total sway perimeter (TSP), sway range (anterior-posterior/medio-lateral (AP/ML)) and limits of stability (LOS). At post-intervention assessment, significant increases in comparison with pre-intervention scores was found in LOS (P=0.00), TEA with eyes open (EO) (P=0.00) and eyes closed (EC) (P=0.00), TSP with EO (P=0.00) and EC (P=0.00), sway range in AP direction (SD-AP) with EO (P=0.01) and EC (P=0.02) and sway range in ML direction (SD-ML) with EO (P=0.02) and EC (P=0.01). At follow-up assessment, a significant improvement in comparison to post intervention scores was found in TEA measured both in EO (P=0.01) and EC conditions (P=0.02), TSP measured with EO (P=0.01) and SD-ML both with EO (P=0.04) and EC (P=0.01). No significant changes were found in LOS (P=0.89), TSP measured with EC (P=0.38) and SD-AP both with EO (P=0.50) and EC (P=1). However, significant improvement was seen on comparing follow-up assessment scores with pre-intervention scores for all variables, such as LOS (P=0.00), TEA in EO (P=0.00) and EC (P=0.00), TSP with EO (P=0.00) and EC (P=0.00), SD-AP with EO (P=0.01) and EC (P=0.02) and SD-ML with EO (P=0.01) and EC (P=0.00). VR-based balance training intervention was able to elicit improvements in balance ability and maintain it during follow-up despite a small training dosage suggesting that it is a promising intervention for standing balance rehabilitation among individuals with iSCI. The VR-based balance training challenges elements of balance, which physical therapists may want to consider when designing a comprehensive rehabilitation program.

Clinical Trials Registry-India: CTRI/2018/12/016814.

Relationship between static balance and gait parameters in preschool children

BACKGROUND

Postural sway while standing reflects the degree of sensory integration function. The relationship between static balance and gait parameters in preschool children is essential for understanding which component of gait function is linked to the sensory integration function.

RESEARCH QUESTION

We aimed to clarify the relationship between static balance and gait in children, aged 2-6 years, with typical development METHODS: A total of 105 children (48 girls, 57 boys) participated in this study. Static balance parameters were computed using positions at the center of pressure (COP) while standing (COP length, velocity, and sway area). Spatiotemporal parameters during gait were analyzed for stride length, step width, stance time, cadence, coefficient of variation (CV) of step length, and CV of stance time as gait variability. Pearson correlation coefficients were estimated to explore the relationship between age and static balance or gait parameters. Partial correlation analysis controlling for age was also performed to examine the relationship between static balance and gait parameters.

RESULTS

A moderate association between age and static balance parameters and between age and gait parameters was found. Partial correlation analysis revealed that the variability parameters of gait were associated with the static balance parameters. No relationship was found between both spatial and temporal gait parameters and static balance parameters.

SIGNIFICANCE

Among the gait parameters that are considered to develop in early childhood, gait variability was associated with COP sway while standing, whereas stride length with increasing age was independent of any static balance parameters. Of the spatial, temporal, and variability parameters of gait, only gait variability maybe associated with the development of sensory integration function.

Efficacy of prosthetic rehabilitation in rotationplasty following Ewing's sarcoma: A case study

PURPOSE

Restoration of functional mobility including gait and balance are fundamental to prosthetic rehabilitation in children with rotationplasty. The literature to characterize and investigate the correlation between postural balance and gait following rotationplasty are scarce. This study examines the characteristics of balance and prosthetic gait in a subject with rotationplasty and checks whether any association exists between them.

METHODS

A 14-year-old boy with rotationplasty following Ewing's sarcoma was fitted with a custom made prosthesis. Center of pressure (COP) measures using the HUMAC® Balance & Tilt System (CSMi, Stoughton, MA), temporal-spatial gait parameters, and energy expenditure measured by a 10 meter walk test were recorded using the new and old prosthesis. A control subject was used for comparison.

RESULTS

The stability score, path length, and average velocity of COP improved in a new prosthesis for both standing conditions. Gait parameters were improved and energy expenditure was marginally reduced with the new prosthesis. However, overall prosthetic gait was significantly different compared to the control subject.

CONCLUSION

This subject-centric approach successfully improved balance, gait parameters, and energy expenditure by providing better alignment, fit, and comfort with a custom prosthesis.

Invasive and Non-Invasive Approaches of Electrical Stimulation to Improve Physical Functioning after Spinal Cord Injury

This review of literature provides the latest evidence involving invasive and non-invasive uses of electrical stimulation therapies that assist in restoring functional abilities and the enhancement of quality of life in those with spinal cord injuries. The review includes neuromuscular electrical stimulation and functional electrical stimulation activities that promote improved body composition changes and increased muscular strength, which have been shown to improve abilities in activities of daily living. Recommendations for optimizing electrical stimulation parameters are also reported. Electrical stimulation is also used to enhance the skills of reaching, grasping, standing, and walking, among other activities of daily living. Additionally, we report on the use of invasive and non-invasive neuromodulation techniques targeting improved mobility, including standing, postural control, and assisted walking. We attempt to summarize the effects of epidural stimulation on cardiovascular performance and provide a mechanistic explanation to the current research findings. Future trends such as the combination of epidural stimulation and exoskeletal-assisted walking are also discussed.

The effect of visual field manipulations on standing balance control in people with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is associated with an increased risk of falls, degeneration of sensory organization, and possible increased reliance on vision for balance control.

RESEARCH QUESTION

The aim of this study was to assess differences in standing postural control between people with MS and age and sex matched controls during medial-lateral (ML) oscillations of the visual field, with and without blinders to the lower periphery.

METHODS

Ten persons with MS (mean age 54.0 ± 5.3 years) and ten age and sex matched controls (mean age: 56.3 ± 6.0 years) participated in this study. Balance control was assessed while participants stood in a Christie Cave system while wearing stereoscopic glasses that projected an immersive forest scene. Visual conditions consisted of 2 m ML visual oscillations of the scene at five frequencies (0.0, 0.3, 0.6, 0.7 and 0.8 Hz) with and without blinders to block the lower periphery.

RESULTS AND SIGNIFICANCE

The results demonstrated that, in comparison to controls, participants with MS had a significantly larger center of pressure sway in both the ML and AP direction to ML visual oscillations. Additionally, participants with MS and controls both increased center of pressure frequency content to the visual oscillation frequency, while participants with MS also increased relative power at the visual oscillation frequency in the AP direction. Blinders of lower periphery reduced the percent power at the visual oscillation frequency in both groups and reduced overall sway in participants with MS during visual oscillations. Overall, results indicate that postural balance is sensitive to visual feedback in people with MS. The elicited AP sway to ML visual oscillation could reflect errors in visual processing for the control of balance, and decreased sway in response to blocking vision of the lower peripheral field could indicate an increased reliance on visual cues to maintain balance.

Use of Pressure-Measuring Insoles to Characterize Gait Parameters in Simulated Reduced-Gravity Conditions

Prior researchers have observed the effect of simulated reduced-gravity exercise. However, the extent to which lower-body positive-pressure treadmill (LBPPT) walking alters kinematic gait characteristics is not well understood. The purpose of the study was to investigate the effect of LBPPT walking on selected gait parameters in simulated reduced-gravity conditions. Twenty-nine college-aged volunteers participated in this cross-sectional study. Participants wore pressure-measuring insoles (Medilogic GmBH, Schönefeld, Germany) and completed three 3.5-min walking trials on the LBPPT (AlterG, Inc., Fremont, CA, USA) at 100% (normal gravity) as well as reduced-gravity conditions of 40% and 20% body weight (BW). The resulting insole data were analyzed to calculate center of pressure (COP) variables: COP path length and width and stance time. The results showed that 100% BW condition was significantly different from both the 40% and 20% BW conditions, p < 0.05. There were no significant differences observed between the 40% and 20% BW conditions for COP path length and width. Conversely, stance time significantly differed between the 40% and 20% BW conditions. The findings of this study may prove beneficial for clinicians as they develop rehabilitation strategies to effectively unload the individual's body weight to perform safe exercises.

Delayed and reduced intralimb muscular coupling during postural reactions in individuals with incomplete spinal cord injury

BACKGROUND

Postural strategies are enabled by rapid muscle activation sequences to prevent a fall. Intralimb muscular couplings underlie these postural strategies are likely impaired after incomplete spinal cord injury (iSCI), leading to inappropriate postural reactions and increased fall risk; yet, the nature of these changes is unknown.

RESEARCH QUESTION

Identify changes occurring in intralimb coupling following a perturbation in individuals with iSCI.

METHODS

Ten men with iSCI and eight age-matched controls (CTRL) stood on a force-platform that was randomly tilted forward or backward. Electromyographic (EMG) activity of the lower limb muscles was recorded, and coactivation or simultaneous facilitation/suppression between pairs of muscles was analyzed. Onset and duration of coupling latency, intralimb coupling delay, and amplitude ratios were measured in the distal (soleus [SOL]/tibialis anterior [TA]), proximal (biceps femoris [BF]/vastus lateralis [VL]), anterior (TA-VL), and posterior (SOL-BF) muscle couplings.

RESULTS

In forward tilt, the main coupling was TA-SOL co-contraction for both groups, but the latency was longer and the duration shorter in SCI participants. In backward tilt, the TA-VL co-activation was the main coupling in CTRL (88 %), although it was also expressed by 60 % of SCI participant with a delayed latency. The facilitation/suppression of TA-SOL was the main coupling in SCI group (80 % vs 63 % in CTRL). Delayed coupling latencies were more pronounced in individuals with cervical iSCI and were correlated with the strength of lower limbs.

SIGNIFICANCE

Similar muscular couplings are present in both groups but are delayed, which might contribute to postural reaction deficits in individuals with iSCI.

Functional Electrical Stimulation of Peroneal Muscles on Balance in Healthy Females

Balance improvement could contribute to ankle stability for the prevention of ankle sprains. Functional electrical stimulation (FES) is an effective way of augmenting muscle activity and improving balance. This study investigated the effect of FES of peroneal muscles on single-and double-leg balance. Fifteen healthy females (age = 23.1 ± 1.6 years, height = 1.63 ± 0.07 m, and weight = 63.7 ± 9.9 kg) performed single- and double-leg standing balance tests with eyes open and closed before and after 15-minute FES intervention during treadmill running at a comfortable, self-selected pace. FES of peroneal muscles was provided bilaterally, using an Odstock Dropped Foot Stimulator. The total excursion of the centre of pressure (COP) was calculated to assess the standing balance control ability. The total excursion of COP in single- and double-leg stance with eyes open reduced significantly after FES intervention by 14.7% (p < 0.001) and 5.9% (p = 0.031), respectively. The eyes-closed condition exhibited a 12.7% (p = 0.002) reduction in single-leg stance but did not significantly change in double-leg stance (p > 0.05). Limb preference did not account for balance postintervention. No significant difference in total excursion of COP was found between preferred and less preferred limbs with both visual conditions (p > 0.05). FES of peroneal muscles improved standing balance control with eyes open in double-leg and single-leg stance and with eyes closed in double-leg stance. The improvements in balance control with FES treatment did not vary concerning limb preference.

Alteration of H-reflex amplitude modulation is a marker of impaired postural responses in individuals with incomplete spinal cord injury

Individuals with incomplete spinal cord injury (iSCI) show altered postural reactions leading to increased risk of falls. To investigate neural correlates underlying this deficit, we assessed the modulation pattern of the Soleus H-reflex in iSCI individuals following unexpected perturbations of a base of support. Ten men with iSCI (AIS D) and 8 age-matched controls (CTRL) stood on a force-platform randomly tilted forward or backward. The center of pressure (CoP) excursion, 95% confidence ellipse area and electromyographic (EMG) activity of the Soleus (SOL) and Tibialis Anterior (TA) muscles were analyzed. SOL H-reflex amplitude was assessed by stimulating the tibial nerve prior to and at 100, 150 and 200 ms following perturbation onset. Although SOL and TA short-latency EMG responses were comparable in both groups, long-latency EMG responses occurred later in the iSCI group for both directions: during backward tilt, a decrease in H-reflex amplitude was observed at all stimulus timings post-tilt in CTRL, but only at 200 ms in iSCI. The decrease in H-reflex amplitude was smaller in iSCI participants. During forward tilt, an increase in H-reflex amplitude was observed at 150 and 200 ms in the CTRL group, but no increase was observed in the iSCI group. Decreased and delayed SOL H-reflex amplitude modulation in the iSCI group accompanied impaired balance control as assessed clinically with the Berg Balance Scale and biomechanically through CoP displacement. Overall, delayed and reduced spinal reflex processing may contribute to impaired balance control in people with iSCI.

Characterizing inter-limb synchronization after incomplete spinal cord injury: A cross-sectional study

BACKGROUND

Individuals with incomplete spinal cord injury (iSCI) demonstrate greater postural sway and increased dependency on vision to maintain balance compared to able-bodied individuals. Research on standing balance after iSCI has focused on the joint contribution of the lower limbs; however, inter-limb synchrony in quiet standing is a sensitive measure of individual limb contributions to standing balance control in other neurological populations. It is unknown if and how reduced inter-limb synchrony contributes to the poor standing balance of individuals with iSCI.

RESEARCH QUESTION

How does an iSCI affect inter-limb synchrony and weight-bearing symmetry in standing?

METHODS

Eighteen individuals with non-progressive motor iSCI and 15 age- and sex-matched able-bodied individuals (M-AB) were included in the study. Participants stood in a standardized position on two adjacent force plates in eyes open and closed conditions for 70 s per condition. Net centre-of-pressure (COP) root mean square (RMS), net COP velocity, COP inter-limb synchrony (i.e. cross-correlation between left and right COP), and weight-bearing asymmetry (i.e. vertical force from each limb over total vertical force) were calculated. Muscle strength of the lower limbs was assessed with manual muscle testing.

RESULTS

Individuals with iSCI demonstrated reduced inter-limb synchrony when standing with eyes open and eyes closed, but did not differ to M-AB with respect to weight-bearing asymmetry. They also produced greater net COP RMS and velocity when compared to M-AB. Muscle strength of the two lower limbs demonstrated an overall asymmetry in individuals with iSCI.

SIGNIFICANCE

Individuals with iSCI demonstrated impaired balance control as evidenced by reduced inter-limb synchrony and greater COP RMS and velocity compared to M-AB individuals. This increased understanding of how balance control is impaired following iSCI may inform balance assessment and intervention for this population. Future work examining the association between inter-limb synchrony and the occurrence of falls in iSCI is warranted.

Posture and gait in the early course of schizophrenia

While correlations between postural stability deficits and schizophrenia are well documented, information on dynamic motor alterations in schizophrenia are still scarce, and no data on their onset are available yet. Therefore, the aim of this study was i) to measure gait pattern(s) in patients with schizophrenia; ii) to identify posture and gait alterations which could potentially be used as a predictive clinical tool of the onset of the disorder. Body composition, posture and gait parameters were assessed in a group of 30 patients with schizophrenia and compared to 25 healthy subjects. Sway area was significantly higher in the schizophrenia group compared to controls regardless of whether the participants were in eyes open or eyes closed condition. Gait cadence and speed were significantly lower in patients with schizophrenia, while stride length was similar. We concluded that the combination of an increased sway area (independent from eye closure) and a gait cadence reduction—in the presence of normal gait speed and stride length—might be considered peculiar postural and gait profile characteristic of early schizophrenia.

Characterization of standing balance after incomplete spinal cord injury: Alteration in integration of sensory information in ambulatory individuals

BACKGROUND

Up to one-third of individuals with a recent spinal cord injury (SCI) and most of the individuals with an incomplete lesion are able to regain partial balance and walking ability after the first-year post-injury. However, most individuals experience injurious falls while standing and frequent losses of balance post-rehabilitation, which can result in physical injuries and a fear of falling.

RESEARCH QUESTION

Control of balance during quiet standing depends on the integration of sensory information. Since SCI causes sensory and motor impairments, understanding the underlying mechanisms of how postural control is regulated is of significant importance for targeted and guided rehabilitation post-SCI.

METHODS

We characterized the impact of a variety of challenging conditions on the standing balance for eight participants with incomplete SCI with walking ability compared to twelve age-matched able-bodied individuals using a waist-mounted inertial measurement unit (IMU). We compared balance biomarkers derived from IMUs' readouts under conditions that challenged balance by affecting somatosensory (i.e., standing on hard vs. foam surfaces) and visual (i.e., eyes open vs. closed) inputs. We performed a three-way ANOVA or a Kruskal-Wallis test to characterize changes in postural control post-SCI based on reliance on somatosensory and visual information using balance biomarkers.

RESULTS

We observed a reduced stability performance, an increased control demand, and a less effective active correction post-SCI in all standing conditions. Due to impaired somatosensory feedback, individuals with incomplete SCI showed a higher and lower reliance on visual and somatosensory information, respectively, for maintaining balance (p < 0.05).

SIGNIFICANCE

Using a single waist-mounted IMU, the proposed method could characterize standing balance in individuals with incomplete SCI compared to able-bodied participants. Having high clinical utility and sufficient resolution with discriminatory ability, our method could be used in the future to objectively evaluate the effectiveness of rehabilitative interventions on the balance performance of individuals with SCI.

Crossed Corticospinal Facilitation Between Arm and Trunk Muscles Correlates With Trunk Control After Spinal Cord Injury

Objective: To investigate whether crossed corticospinal facilitation between arm and trunk muscles is preserved following spinal cord injury (SCI) and to elucidate these neural interactions for postural control during functional arm movements.

Methods: Using transcranial magnetic stimulation (TMS) in 22 subjects with incomplete SCI motor evoked potentials (MEPs) in the erector spinae (ES) muscle were examined when the contralateral arm was at rest or performed 20% of maximal voluntary contraction (MVC) of biceps brachii (BB) or triceps brachii (TB). Trunk function was assessed with rapid shoulder flexion and forward-reaching tasks.

Results: MEP amplitudes in ES were increased during elbow flexion in some subjects and this facilitatory effect was more prominent in subjects with thoracic SCI than in the subjects with cervical SCI. Those who showed the increased MEPs during elbow flexion had faster reaction times and quicker anticipatory postural adjustments of the trunk in the rapid shoulder flexion task. The onset of EMG activity in ES during the rapid shoulder flexion task correlated with the trunk excursion in forward-reaching.

Conclusions: Our findings demonstrate that crossed corticospinal facilitation in the trunk muscles can be preserved after SCI and is reflected in trunk control during functional arm movements.

Postural control strategy after incomplete spinal cord injury: effect of sensory inputs on trunk-leg movement coordination

BACKGROUND

Postural control is affected after incomplete spinal cord injury (iSCI) due to sensory and motor impairments. Any alteration in the availability of sensory information can challenge postural stability in this population and may lead to a variety of adaptive movement coordination patterns. Hence, identifying the underlying impairments and changes to movement coordination patterns is necessary for effective rehabilitation post-iSCI. This study aims to compare the postural control strategy between iSCI and able-bodied populations by quantifying the trunk-leg movement coordination under conditions that affects sensory information.

METHODS

13 individuals with iSCI and 14 aged-matched able-bodied individuals performed quiet standing on hard and foam surfaces with eyes open and closed. We used mean Magnitude-Squared Coherence between trunk-leg accelerations measured by accelerometers placed over the sacrum and tibia.

RESULTS

We observed a similar ankle strategy at lower frequencies (f ≤ 1.0 Hz) between populations. However, we observed a decreased ability post-iSCI in adapting inter-segment coordination changing from ankle strategy to ankle-hip strategy at higher frequencies (f > 1.0 Hz). Moreover, utilizing the ankle-hip strategy at higher frequencies was challenged when somatosensory input was distorted, whereas depriving visual information did not affect balance strategy.

CONCLUSION

Trunk-leg movement coordination assessment showed sensitivity, discriminatory ability, and excellent test-retest reliability to identify changes in balance control strategy post-iSCI and due to altered sensory inputs. Trunk-leg movement coordination assessment using wearable sensors can be used for objective outcome evaluation of rehabilitative interventions on postural control post-iSCI.

Augmented reality-assisted training with selected Tai-Chi movements improves balance control and increases lower limb muscle strength in older adults: A prospective randomized trial

Background

Tai-Chi benefits older adults by enhancing balance control and increasing the muscle strength of the lower limbs. However, a complete set of traditional Tai-Chi exercises is sometimes too difficult for beginners. We investigated whether practicing augmented reality-assisted training with selected Tai-Chi movements tailored to the practitioner’s ability (selected Tai-Chi, or sTC) is as effective as performing a complete set of Tai-Chi sequences (complete traditional Tai-Chi, or tTC).

Methods

In this prospective randomized trial carried out in the Beitou District of Taipei City, Taiwan, community-dwelling adults aged ≥65 and without any debilitating diseases (n = 28) were included. Participants were randomly assigned to the sTC group (n = 14) or the tTC group (n = 14). Participants in the sTC group practiced selected Tai-Chi movements using the augmented reality Tai-Chi training system. Participants of the tTC group were asked to complete the 24-form Yang-style Tai-Chi following the instructions of Tai-Chi masters. Each training session lasted 30 min, with 3 sessions per week for 8 weeks. Pre- and post-intervention evaluations included functional balance tests, comprising the Berg Balance Scale (BBS), Timed Up and Go test (TUG), and Functional Reach Test (FRT), as well as muscle strength measurements of the lower extremities.

Results

Pre-intervention evaluations showed significant differences in FRT (p = 0.034) and left hip abductor muscle strength (p = 0.046) between the sTC and tTC groups. After 8 weeks of training, the BBS, TUG, and FRT scores in the sTC group showed significant improvement overall. Although all three functional balance test scores improved in the tTC group, only the improvement in BBS was statistically significant (p = 0.001). After 8 weeks, all muscle strength measurements increased by an average of 3.1 ± 1.0 kgw in the sTC group and 1.6 ± 0.8 kgw in the tTC group.

Conclusions

The augmented reality-assisted training with selected Tai-Chi movements, designed based on objective measurements of the practitioner’s capability, improved balance control and muscle strength of lower limbs at least as effectively as the complete sequence of traditional Tai-Chi exercises.

Trial registration

This study was approved by the Institutional Review Board of National Yang-Ming University (IRB number: 1000087). Written informed consent was obtained from all participants.

Test-retest reliability of stability outcome measures during treadmill walking in patients with balance problems and healthy controls

BACKGROUND

Improvement of balance control is an important rehabilitation goal for patients with motor and sensory impairments. To quantify balance control during walking, various stability outcome measures have described differences between healthy controls and patient groups with balance problems. To be useful for the evaluation of interventions or monitoring of individual patients, stability outcome measures need to be reliable.

RESEARCH QUESTION

What is the test-retest reliability of six stability outcome measures during gait?

METHODS

Patients with balance problems (n = 45) and healthy controls (n = 20) performed two times a two-minute walk test (2MWT). The intraclass correlation coefficient (ICC) and Bland-Altman analysis (coefficient of repeatability; CR) were used to evaluate the test-retest reliability of six stability outcome measures: dynamic stability margin (DSM), margin of stability (MoS), distance between the extrapolated centre of mass (XCoM) and centre of pressure (CoP) in anterior-posterior (XCoM-CoP_AP) and medial-lateral (XCoM-CoP_ML) direction, and inclination angle between centre of mass (CoM) and CoP in anterior-posterior (CoM-CoP_AP-angle) and medial-lateral (CoM-CoP_ML-angle) direction. A two way mixed ANOVA was performed to reveal measurement- and group-effects.

RESULTS

The ICCs of all stability outcome measures ranged between 0.51 and 0.97. Significant differences between the measurements were found for the DSM (p = 0.017), XCoM-CoP_AP (p = 0.008) and CoM-CoP_AP-angle (p = 0.001). Significant differences between controls and patients were found for all stability outcome measures (p < 0.01) except for the MoS (p = 0.32). For the XCoM-CoP distances and CoM-CoP angles, the CRs were smaller than the difference between patients and controls.

SIGNIFICANCE

Based on the ICCs, the reliability of all stability outcome measures was moderate to excellent. Since the XCoM-CoP_ML and CoM-CoP_ML-angle showed no differences between the measurements and smaller CRs than the differences between patients and controls, the XCoM-CoP_ML and CoM-CoP_ML-angle seem the most promising stability outcome measures to evaluate interventions and monitor individual patients.

The Effect of Functional Electrical Stimulation and Therapeutic Exercises on Trunk Muscle Tone and Dynamic Sitting Balance in Persons with Chronic Spinal Cord Injury: A Crossover Trial

Background and objectives: Functional electrical stimulation (FES) has shown good results in improving static and dynamic sitting balance in persons with spinal cord injuries. There is limited information about how regular surface FES combined with therapeutic exercise (TE) affect dynamic sitting balance and muscle tone. The objective of this study was to evaluate the effectiveness of a six-week physical therapy program consisting of FES and TE on muscle tone and sitting balance in persons with spinal cord injury (SCI). It was also important to explore the relationship between muscle tone and dynamic sitting balance. The third objective was to assess the change of characteristics over a six month period, when no intervention was carried out. Material and methods: Five men with SCI were alternately allocated to two study groups: SCI_FES+TE and SCI_TE. Eight healthy control group participants were recruited to collect reference data. SCI participants’ intervention lasted for six weeks in their homes. SCI_FES+TE conducted exercises with FES applied on erector spinae (ES) and rectus abdominis (RA) muscles. SCI_TE conducted exercises only. Muscle oscillation frequency (MOF; characterizing muscle tone) and limits of stability (LOS; characterizing sitting balance) were measured. A crossover study design was used. The time between the initial intervention and the crossover was seven months (ClinicalTrials registration ID NCT03517787). Results: MOF in SCI_FES+TE increased by 6.0% for ES and 6.1% for RA muscles. LOS of flexion increased 30.1% in SCI_FES+TE. Increase in lateral directions was similar for both study groups. Moderate to high negative correlation was found between MOF and LOS. After seven months, MOF of ES decreased 0.8%, MOF or RA decreased 1.4%, LOS of flexion decreased 31.9%, and LOS of lateral flexion to the left decreased 46.4%. Conclusions: The six-week therapy program combining FES and TE increased trunk muscle tone and dynamic sitting balance in flexion more than TE alone. Higher antagonist muscle tone negatively affects dynamic sitting balance and center of pressure (COP) trajectory distance in various directions. After seven months, a slight decline in trunk muscles tone values and an extensive decrease in sitting balance values were noticed.

Effects of individualized Tai-Chi on balance and lower-limb strength in older adults

Background

To investigate whether a simplified and personalized Tai-Chi program could be beneficial for practitioners. A prospective quasi-experimental observer-blinded controlled trial was done in Beitou District of Taipei City.

Methods

Community-dwelling adults aged 65 and older without debilitating disease (N = 50) participated the study. Those who were willing to participate in exercise program were assigned to individualized Tai-Chi (iTC) group (n = 20), receiving iTC training for 8 weeks, and traditional Tai-Chi (tTC) group (n = 15), receiving tTC training for 8 weeks. Those who were not willing to participate in exercise training were included in the control group (n = 15). Functional balance tests, the Berg Balance Scale (BBS), timed up-and-go (TUG) test, functional-reach test, and measurement of lower-extremity muscle strength were conducted before and 8 weeks after the intervention.

Results

Significant improvements were noted in all functional balance tests and strength assessments of 16 major lower-limb muscle groups in participants of the iTC group compared to the control group, whereas only BBS and muscle strength of hips and ankles were improved in the tTC group. Practitioners of iTC outperformed tTC in BBS and strength of two major muscles.

Conclusions

Personalized Tai-Chi training designed based on an objective measurement and conducted according to graded intensity and complexity benefitted practitioners after a short period.

Trial registration

Trial registration number: ClinicalTrials.gov ID: NCT03659396, Unique Protocol ID: 1000087

Date of registration: 03/28/2017

The trial was registered retrospectively

Experimental Implementation of Automatic Control of Posture-Dependent Stimulation in an Implanted Standing Neuroprosthesis

Knowledge of the upper extremity (UE) effort exerted under real-world conditions is important for understanding how persons with motor or sensory disorders perform the postural shifts necessary to complete many activities of daily living while standing. To this end, a feedback controller, named the “Posture Follower Controller”, was developed to aid in task-dependent posture shifting by individuals with spinal cord injury standing with functional neuromuscular stimulation. In this experimental feasibility study, the controller modulated activation to the paralyzed lower extremity muscles as a function of the position of overall center of pressure (CoP), which was prescribed to move in a straight line in forward and diagonal directions. Posture-dependent control of stimulation enabled leaning movements that translated the CoP up to 48 mm away from the nominal position during quiet standing. The mean 95% prediction ellipse area, a measure of the CoP dispersion in the forward, forward-right, and forward-left directions, was 951.0 ± 341.1 mm², 1095.9 ± 251.2 mm², and 1364.5 ± 688.2 mm², respectively. The average width of the prediction ellipses across the three directions was 15.1 mm, indicating that the CoP deviated from the prescribed path as task-dependent postures were assumed. The average maximal UE effort required to adjust posture across all leaning directions was 24.1% body weight, which is only slightly more than twice of what is required to maintain balance in an erect standing posture. These preliminary findings suggest that stimulation can be modulated to effectively assume user-specified, task-dependent leaning postures characterized by the CoP shifts that deviate away from the nominal position and which require moderate UE effort to execute.

Manual wheelchair users gradually face fewer postural stability and control challenges with increasing rolling resistance while maintaining a rear-wheel wheelie

Teaching manual wheelchair users to perform wheelies using various rolling resistances is expected to facilitate learning of this advanced wheelchair skill. However, limited scientific evidence is available to support this approach. This study aimed to measure and compare postural stability and control requirements when maintaining a stationary wheelie on different rolling resistances. Eighteen manual wheelchair users with a spinal cord injury performed in a random order and maintained four 30-second wheelies on four rolling resistances: natural hard floor (NAT), 5-cm thick soft foam (LOW), 5-cm thick memory foam (MOD), and rear wheels blocked by wooden blocks (HIGH). All wheelies were performed over a large instrumented force plate to continuously record the center of pressure (CoP). To quantify postural stability, resultant and directional time- and frequency-domain CoP measures were computed and compared across all four rolling resistances. All resultant time-domain measures confirmed increased postural stability from NAT to LOW and from MOD to HIGH rolling resistances. Most time-domain measures confirmed a shift in postural control from an anticipatory to a predominantly compensatory strategy, accompanied by increased reliance on proprioceptive feedback, especially from NAT to LOW and from MOD to HIGH rolling resistances. Postural stability gradually increased with various rolling resistances while maintaining a stationary wheelie, whereas the postural control strategy shifted from an anticipatory to a reactive strategy. Blocking the rear wheels is recommended when first teaching this advanced wheelchair skill. Rapid progression on foam and natural surfaces is advocated to refine learning and enhance proper postural control strategies.

The effect of virtual reality-based balance training on motor learning and postural control in healthy adults: a randomized preliminary study

Background

Adults with sedentary lifestyles seem to face a higher risk of falling in their later years. Several causes, such as impairment of strength, coordination, and cognitive function, influence worsening health conditions, including balancing ability. Many modalities can be applied to improve the balance function and prevent falling. Several studies have also recorded the effects of balance training in elderly adults for fall prevention. Accordingly, the aim of this study is to define the effect of virtual reality-based balance training on motor learning and postural control abilities in healthy adults.

Methods

For this study, ten subjects were randomly allocated into either the conventional exercise (CON) or the virtual reality (VR) group. The CON group underwent physical balance training, while the VR group used the virtual reality system 4 weeks. In the VR group, the scores from three game modes were utilized to describe the effect of motor learning and define the learning curves that were derived with the power law function. Wilcoxon Signed Ranks Test was performed to analyze the postural control in five standing tasks, and data were collected with the help of a force plate.

Results

The average score was used to describe the effect of motor learning by deriving the mathematical models for determining the learning curve. Additionally, the models were classified into two exponential functions that relied on the aim and requirement skills. A negative exponential function was observed in the game mode, which requires the cognitive-motor function. In contrast, a positive exponential function was found in the game with use of only the motor skill. Moreover, this curve and its model were also used to describe the effect of learning in the long term and the ratio of difficulty in each game. In the balance performance, there was a significant decrease in the center of pressure parameters in the VR group, while in the CON group, there was a significant increase in the parameters during some foot placements, especially in the medio-lateral direction.

Conclusion

The proposed VR-based training relies on the effect of motor learning in long-term training though different kinds of task training. In postural analysis, both exercise programs are emphasized to improve the balance ability in healthy adults. However, the virtual reality system can promote better outcomes to improve postural control post exercising.

Trial registration Retrospectively registered on 25 April 2018. Trial number TCTR20180430005

Electronic supplementary material

The online version of this article (10.1186/s12938-018-0550-0) contains supplementary material, which is available to authorized users.

Neuromuscular control of ankle and hip during performance of the star excursion balance test in subjects with and without chronic ankle instability

BACKGROUND/PURPOSE

Ankle sprains are common and potentially disabling musculoskeletal injuries that often lead to chronic ankle instability (CAI). CAI has been linked to impairments in postural and neuromuscular control; however, inconsistent findings have been reported. Individuals who experience a lateral ankle sprain, but do not develop instability, termed copers, may adapt different neuromuscular control strategies after injury. This study aimed to compare postural control and electromyographic (EMG) activity of hip and ankle muscles during the performance of the Star Excursion Balance Test (SEBT) in subjects with and without CAI.

METHOD

48 participants were classified into three groups (16 control, 16 copers, 16 CAI) based on ankle sprain history and Cumberland Ankle Instability Tool score. Outcome measures included normalized reach distance, center of pressure (COP), and integrated EMG activation of gluteus medius (Gmed), gluteus maximus (Gmax), tibialis anterior (TA), and peroneus longus (PL) during each reach direction of SEBT.

RESULTS

Compared to copers and controls, CAI group demonstrated significantly diminished postural control (reach distance and COP measures, p< 0.05) and less EMG activity of TA during the anterior direction (CAI: 33.1% ± 10.1% versus copers: 44.8% ± 12.7% versus controls: 51.7% ± 8.4%, p<0.01) and Gmax in the posterolateral direction (CAI: 25.6% ± 9.4% versus copers: 37.5% ± 13.8% versus controls: 40.2% ± 17.2%, p = 0.011).

CONCLUSION

Alteration in proximal and distal muscle activity appears to negatively affect postural control and quality of movement, which may lead to prolonged functional impairments. Hence, implementing hip and ankle muscle exercises in the rehabilitation of ankle instability might benefit these patients.

Analysis of sensory system aspects of postural stability during quiet standing in adolescent idiopathic scoliosis patients

Background

The aim of this study was to quantitatively analyze quite standing postural stability of adolescent idiopathic scoliosis (AIS) patients in respect to three sensory systems (visual, vestibular, and somatosensory).

Method

In this study, we analyzed the anterior-posterior center of pressure (CoP) signal using discrete wavelet transform (DWT) between AIS patients (n = 32) and normal controls (n = 25) during quiet standing.

Result

The energy rate (∆E_EYE%) of the CoP signal was significantly higher in the AIS group than that in the control group at levels corresponding to vestibular and somatosensory systems (p < 0.01).

Conclusions

This implies that AIS patients use strategies to compensate for possible head position changes and spinal asymmetry caused by morphological deformations of the spine through vestibular and somatosensory systems. This could be interpreted that such compensation could help them maintain postural stability during quiet standing. The interpretation of CoP signal during quiet standing in AIS patients will improve our understanding of changes in physical exercise ability due to morphological deformity of the spine. This result is useful for evaluating postural stability before and after treatments (spinal fusion, bracing, rehabilitation, and so on).

Balance, gait, and falls in spinal cord injury

This chapter covers balance, gait, and falls in individuals with spinal cord injury (SCI) from a clinical perspective. First, the consequences of an SCI on functioning are explained, including etiology, clinical presentation, classification, and epidemiologic data. Then, the specific aspects of balance disorders, gait disorders, and falls are discussed with respect to motor complete (cSCI) and incomplete (iSCI) SCI. Typically, these activities are affected by impaired afferent and efferent nerves, but not by central nervous processing. Performance of daily life activities in cSCI depends on the ability to control the interaction between the center of mass and the base of support or limits of stability. In iSCI, impaired proprioception and muscle strength are important factors for completing balancing tasks and for walking. Falls are common in patients with SCI. Subsequent sections describe therapy approaches aimed at modifying balance, gait, and the risk for falls by means of therapeutic exercises, assistive devices like robots or functional electric stimulation, and environmental adaptations. The last part covers recent developments and future directions. These encompass interventions for maximizing residual neural function and regeneration of axons, as well as technical solutions like epidural or intraspinal electric stimulation, powered exoskeletons, and brain computer interfaces.

Accuracy of Base of Support Using an Inertial Sensor Based Motion Capture System

The potential of miniature inertial sensors for human balance and gait analysis appears promising. Base of support (BOS), together with its interaction with center of mass, is a critical indicator in above mentioned research fields. This study aims to evaluate the accuracy of Xsens MVN BIOMECH, a commercial widely used inertial sensor-based motion capture system, for measuring static BOS and examine the effect of different task complexity on the accuracy. Eleven young males participated in this study and went through eleven different experimental tasks. Results showed there were considerable errors in estimating BOS area (error ranged from −12.6% to +64.6%) from Xsens MVN and a large error in foot separation distance when there was knee flexion. The estimated BOS area from MVN was smaller than the ground truth from footprint when there was no knee flexion, and larger when there was knee flexion, and it increased monotonically along with the knee flexion angles. Wrongly estimated foot separations, mainly caused by knee flexion, and the initial system estimation error on BOS, were two major reasons for error and instability of BOS estimation. The findings suggested that caution should be taken when using Xsens MVN BIOMECH to estimate BOS and foot position-related measurements, especially for postures/motions with knee flexion.

Balance Confidence Is Related to Features of Balance and Gait in Individuals with Chronic Stroke

BACKGROUND

Reduced balance confidence is associated with impairments in features of balance and gait in individuals with subacute stroke. However, an understanding of these relationships in individuals at the chronic stage of stroke recovery is lacking. This study aimed to quantify the relationships between balance confidence and specific features of balance and gait in individuals with chronic stroke.

METHODS

Participants completed a balance confidence questionnaire and clinical balance assessment (quiet standing, walking, and reactive stepping) at 6 months postdischarge from inpatient stroke rehabilitation. Regression analyses were performed using balance confidence as a predictor variable, and quiet standing, walking, and reactive stepping outcome measures as the dependent variables.

RESULTS

Walking velocity was positively correlated with balance confidence, whereas mediolateral center of pressure excursion (quiet standing) and double support time, step width variability, and step time variability (walking) were negatively correlated with balance confidence.

CONCLUSIONS

This study provides insight into the relationships between balance confidence and balance and gait measures in individuals with chronic stroke, suggesting that individuals with low balance confidence exhibited impaired control of quiet standing as well as walking characteristics associated with cautious gait strategies. Future work should identify the direction of these relationships to inform community-based stroke rehabilitation programs for individuals with chronic stroke, and determine the potential utility of incorporating interventions to improve balance confidence into these programs.