Dynamic Balance Control Research Articles

Association of Foot Sole Sensibility with Quiet and Dynamic Body Balance in Morbidly Obese Women

An important health-related problem of obesity is reduced stance stability, leading to increased chance of falling. In the present experiment, we aimed to compare stability in quiet and in dynamic body balance between women with morbid obesity (n = 13, body mass index [BMI] > 40 Kg/m2, mean age = 38.85 years) and with healthy body weight (lean) (n = 13; BMI < 25 Kg/m2, mean age = 37.62 years), evaluating the extent to which quiet and dynamic balance stability are associated with plantar sensibility. Quiet stance was evaluated in different visual and support base conditions. The dynamic task consisted of rhythmic flexion—extension movements at the hip and shoulder, manipulating vision availability. The plantar sensibility threshold was measured through application of monofilaments on the feet soles. The results showed that the morbidly obese, in comparison with the lean women, had higher plantar sensibility thresholds, and a reduced balance stability in quiet standing. Mediolateral stance stability on the malleable surface was strongly correlated with plantar sensibility in the obese women. Analysis of dynamic balance showed no effect of obesity and weaker correlations with plantar sensibility. Our results suggest that reduced plantar sensibility in morbidly obese women may underlie their diminished stance stability, while dynamic balance control seems to be unaffected by their reduced plantar sensibility.

Evaluation of sitting and standing postural balance in cerebral palsy by center-of-pressure measurement using force plates: comparison with clinical measurements

BackgroundCenter-of-pressure (CoP) measurements have been studied for assessing balance control. While CoP measurements using force plates have been used to assess standing balance in children with cerebral palsy (CP), it has not been assessed in a sitting position, which specifically reflects trunk postural control. Research questionThe purpose of this study was to compare CoP measurements using force plates during both standing and sitting trials with the Pediatric Balance Scale (PBS) in children with spastic CP. MethodsWe recruited 26 children with spastic CP (7.8 ± 3.4 years, 4–13 years) and used the PBS, a validated evaluation tool that measures static and dynamic balance control. We took CoP measurements using force plates during sitting and standing. For both trials, subjects stayed still for 10 s with their eyes open or closed. We calculated the CoP velocity, mediolateral (ML) and anteroposterior (AP) velocity, and ML and AP displacements of CoP. Results and SignificanceDuring standing trials, static PBS standing scores negatively correlated with more AP displacement and velocity than ML displacement and velocity (p < 0.05). During sitting trials, dynamic PBS sitting scores negatively correlated with ML displacement and velocity (p < 0.05). CoP parameters in the ML direction of the sitting position and CoP parameters in the AP direction of the standing position may better reflect the balance control in children with spastic CP.

Development of the Relationships Among Dynamic Balance Control, Inter-limb Coordination, and Torso Coordination During Gait in Children Aged 3-10 Years.

Knowledge about the developmental process of dynamic balance control comprised of upper arms and upper legs coordination and trunk and pelvis twist coordination is important to advance effective balance assessment for abnormal development. However, the mechanisms of these coordination and stability control during gait in childhood are unknown.This study examined the development of dynamic postural stability, upper arm and upper leg coordination, and trunk and pelvic twist coordination during gait, and investigated the potential mechanisms integrating the central nervous system with inter-limb coordination and trunk and pelvic twist coordination to control extrapolated center of the body mass (XCOM). This study included 77 healthy children aged 3–10 years and 15 young adults. The child cohort was divided into four groups by age: 3–4, 5–6, 7–8, and 9–10 years. Participants walked barefoot at a self-selected walking speed along an 8 m walkway. A three-dimensional motion capture system was used for calculating the XCOM, the spatial margin of stability (MoS), and phase coupling movements of the upper arms, upper legs, trunk, and pelvic segments. MoS in the mediolateral axis was significantly higher in the young adults than in all children groups. Contralateral coordination (ipsilateral upper arm and contralateral upper leg combination) gradually changed to an in-phase pattern with increasing age until age 9 years. Significant correlations of XCOMML with contralateral coordination and with trunk and pelvic twist coordination (trunk/pelvis coordination) were found. Significant correlations between contralateral coordination and trunk/pelvis coordination were observed only in the 5–6 years and at 7–8 years groups.Dynamic postural stability during gait was not fully mature at age 10. XCOM control is associated with the development of contralateral coordination and trunk and pelvic twist coordination. The closer to in-phase pattern of contralateral upper limb coordination improved the XCOM fluctuations. Conversely, the out-of-phase pattern (about 90 degrees) of the trunk/pelvis coordination increased theXCOM fluctuation. Additionally, a different control strategy was used among children 3–8 years of age and individuals over 9 years of age, which suggests that 3–4-year-old children showed a disorderly coordination strategy between limb swing and torso movement, and in children 5–8 years of age, limb swing depended on trunk/pelvis coordination.

Influence of intermittent pneumatic compression on foot sensation and balance control in chemotherapy-induced peripheral neuropathy patients

BackgroundChemotherapy-induced peripheral neuropathy, a side effect of cancer treatment, presents several issues to patients, including reduced sensation and increased fall risk. Previously, massage therapy has been shown to improve chemotherapy-induced peripheral neuropathy symptoms, possibly through increased blood flow. A custom built intermittent pneumatic compression device, previously shown to increase lower leg blood flow, was tested as a plausible treatment modality. MethodsSeven cancer survivors suffering from chemotherapy-induced peripheral neuropathy were recruited. Foot sensation (Semmes-Weinstein test) as well as static (dual and tandem stance) and dynamic (timed-up-and-go) balance control tests were performed both pre and post a 5-min intermittent pneumatic compression intervention. Self-reported feedback was provided by participants following testing and 24-h later. FindingsFive participants reported positive changes in their feet immediately following intermittent pneumatic compression treatment while four of those participants reported positive changes up to 24 h after intervention. Foot sensation was unchanged regardless of location tested (P ≥ 0.23). Postural sway path length and sway area were unchanged following intervention during dual stance (P ≥ 0.14), but path length was significantly reduced (~19.9%) following intervention during tandem stance (P = 0.033). Timed-up-and-go duration was also significantly reduced (~7.0%, P = 0.012). InterpretationOverall, these findings demonstrate that intermittent pneumatic compression may be a plausible treatment modality for improving self-reported foot sensation as well as static and dynamic balance control. As a pilot study, this study provides sufficient context for further research exploring the efficacy of intermittent pneumatic compression as a treatment using a randomized control trial design.

The relationship between the anteroposterior and mediolateral margins of stability in able-bodied human walking

Control of dynamic balance in human walking is essential to remain stable and can be parameterized by the margins of stability. While frontal and sagittal plane margins of stability are often studied in parallel, they may covary, where increased stability in one plane could lead to decreased stability in the other. Hypothetically, this negative covariation may lead to critically low lateral stability during step lengthening. Is there a relationship between frontal and sagittal plane margins of stability in able-bodied humans, during normal walking and imposed step lengthening? Fifteen able-bodied adults walked on an instrumented treadmill in a normal walking and a step lengthening condition. During step lengthening, stepping targets were projected onto the treadmill in front of the participant to impose longer step lengths. Covariation between frontal and sagittal plane margins of stability was assessed with linear mixed-effects models for normal walking and step lengthening separately. We found a negative covariation between frontal and sagittal plane margins of stability during normal walking, but not during step lengthening. These results indicate that while a decrease in anterior instability may lead to a decrease in lateral stability during normal walking, able-bodied humans can prevent lateral instability due to this covariation in critical situations, such as step lengthening. These findings improve our understanding of adaptive dynamic balance control during walking in able-bodied humans and may be utilized in further research on gait stability in pathological and aging populations.

Differences in balance control between healthy younger and older adults during steady-state walking

Each year approximately one third of older adults fall and experience extensive musculoskeletal injuries and functional disabilities. An important element in maintaining dynamic balance is the regulation of whole-body angular momentum, which is achieved by proper foot placement with respect to the body center-of-mass as well as generation of appropriate ground reaction forces. Analyzing these quantities in younger and older adults may provide insight into differences in their underlying mechanics for maintaining dynamic balance. This study examined three-dimensional whole-body angular momentum in 13 healthy older (71.8 ± 8.3 years) and 9 younger (23.2 ± 2.8 years) adults walking at their self-selected and fastest-comfortable speeds. The older adults had a significantly higher range of frontal-plane angular momentum compared to the younger adults at both speeds, suggesting poorer mediolateral balance control. This difference was related to the older adults having a wider foot placement with respect to the body center-of-mass, which when combined with the vertical ground reaction force, created a higher destabilizing external moment during single-limb stance that acts to rotate the body towards the contralateral swing leg. To counteract this destabilizing moment, the older adults generated a higher hip abduction moment. There were no differences in the range of sagittal- and transverse-plane angular momentum between age groups at either speed. These results suggest that control of dynamic balance in the frontal-plane is more challenging than in the sagittal-plane for older adults and highlight the importance of proper weight transfer mechanisms and hip abductor force production for maintaining mediolateral balance during walking.

Temporal But Not Spatial Gait Parameters Associated With Lower Balance Capacity in Moderate-High Functioning Persons With Stroke.

Falls are a major health concern after stroke. Spatial and temporal gait asymmetry and variability can contribute to instability and increased fall risk in persons with stroke (PwS). We aimed to quantify gait spatiotemporal symmetry and variability parameters in PwS undergoing rehabilitation in the subacute stage of the disease, by comparison to healthy participants, and to examine the associations between these parameters and patients' reactive and proactive balance capacity. Twenty-two PwS and 12 healthy adults walked over a computerized treadmill system at their self-selected walking speed. Symmetry and variability of gait parameters (step length, swing time, and stance time) as well as upper extremity and lower extremity angular range of motion in the sagittal plane were extracted. In addition, the Berg Balance Scale (BBS) and the fall threshold in response to sudden surface translations at increasing intensities were assessed. PwS demonstrated significantly higher asymmetry in all gait parameters in comparison to controls. Also, PwS demonstrated increased stance time variability in comparison to healthy controls and increased swing time variability in the paretic lower extremity. Significant negative associations were found between fall threshold and stance time asymmetry in PwS (r = -0.48, P = 0.022), between the BBS and swing time asymmetry (r = -0.50, P = 0.018), and between the BBS and stance time variability of the paretic lower extremity (r = -0.56, P = 0.006). Findings highlight the importance of gait temporal symmetry and variability measures for dynamic balance control after stroke. These parameters should be considered when assessing gait recovery and safety in PwS.Video Abstract available for more insight from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A355).

Relationship of proprioception, cutaneous sensitivity, and muscle strength with the balance control among older adults

BackgroundBalance impairment is one of the strongest risk factors for falls. Proprioception, cutaneous sensitivity, and muscle strength are 3 important contributors to balance control in older adults. The relationship that dynamic and static balance control has to proprioception, cutaneous sensitivity, and muscle strength is still unclear. This study was performed to investigate the relationship these contributors have to dynamic and static balance control. MethodsA total of 164 older adults (female = 89, left dominant = 15, age: 73.5 ± 7.8 years, height: 161.6 ± 7.1 cm, weight: 63.7 ± 8.9 kg, mean ± SD) participated in this study. It tested the proprioception of their knee flexion/extension and ankle dorsi/plantarflexion, along with cutaneous sensitivity at the great toe, first and fifth metatarsals, arch, and heel, and the muscle strength of their ankle dorsi/plantarflexion and hip abduction. The Berg Balance Scale (BBS) and the root mean square (RMS) of the center of pressure (CoP) were collected as indications of dynamic and static balance control. A partial correlation was used to determine the relationship between the measured outcomes variables (BBS and CoP-RMS) and the proprioception, cutaneous sensitivity, and muscle strength variables. ResultsProprioception of ankle plantarflexion (r = –0.306, p = 0.002) and dorsiflexion (r = –0.217, p = 0.030), and muscle strength of ankle plantarflexion (r = 0.275, p = 0.004), dorsiflexion (r = 0.369, p < 0.001), and hip abduction (r = 0.342, p < 0.001) were weakly to moderately correlated with BBS. Proprioception of ankle dorsiflexion (r = 0.218, p = 0.020) and cutaneous sensitivity at the great toe (r = 0.231, p = 0.041) and arch (r = 0.285, p = 0.002) were weakly correlated with CoP-RMS in the anteroposterior direction. Proprioception of ankle dorsiflexion (r = 0.220, p = 0.035), knee flexion (r = 0.308, p = 0.001) and extension (r = 0.193, p = 0.040), and cutaneous sensitivity at the arch (r = 0.206, p = 0.028) were weakly to moderately correlated with CoP-RMS in the mediolateral direction. ConclusionThere is a weak-to-moderate relationship between proprioception and dynamic and static balance control, a weak relationship between cutaneous sensitivity and static balance control, and a weak-to-moderate relationship between muscle strength and dynamic balance control.

Cortical correlates in upright dynamic and static balance in the elderly

Falls are the second most frequent cause of injury in the elderly. Physiological processes associated with aging affect the elderly’s ability to respond to unexpected balance perturbations, leading to increased fall risk. Every year, approximately 30% of adults, 65 years and older, experiences at least one fall. Investigating the neurophysiological mechanisms underlying the control of static and dynamic balance in the elderly is an emerging research area. The study aimed to identify cortical and muscular correlates during static and dynamic balance tests in a cohort of young and old healthy adults. We recorded cortical and muscular activity in nine elderly and eight younger healthy participants during an upright stance task in static and dynamic (core board) conditions. To simulate real-life dual-task postural control conditions, the second set of experiments incorporated an oddball visual task. We observed higher electroencephalographic (EEG) delta rhythm over the anterior cortex in the elderly and more diffused fast rhythms (i.e., alpha, beta, gamma) in younger participants during the static balance tests. When adding a visual oddball, the elderly displayed an increase in theta activation over the sensorimotor and occipital cortices. During the dynamic balance tests, the elderly showed the recruitment of sensorimotor areas and increased muscle activity level, suggesting a preferential motor strategy for postural control. This strategy was even more prominent during the oddball task. Younger participants showed reduced cortical and muscular activity compared to the elderly, with the noteworthy difference of a preferential activation of occipital areas that increased during the oddball task. These results support the hypothesis that different strategies are used by the elderly compared to younger adults during postural tasks, particularly when postural and cognitive tasks are combined. The knowledge gained in this study could inform the development of age-specific rehabilitative and assistive interventions.

State-of-charge dynamic balancing strategy for distributed energy storage system in DC shipboard microgrid

In this paper, a State-of-Charge (SoC) dynamic balancing control strategy considering system communication failure and energy storage capacity difference is proposed to reach the SoC balancing and proper current sharing for distributed energy storage units (DESUs) in DC shipboard microgrid. Firstly, the distributed equalization algorithm is applied in the DESU’s controller when the system communication is normal, each DESU exchanges their SoC information through low bandwidth communication (LBC) and dynamically adjusts the droop coefficient according to the change of their SoC, so as to realize the SoC dynamic balance of the energy storage system. Secondly, the DESU’s controller is switched to the decentralized equalization algorithm with communication failure, each DESU can reach SoC balancing and load current reasonable distribution only according to the local information. After that, a DC bus voltage compensation method is introduced to solve the problem of bus voltage deviation caused by the proposed SoC equalization. Finally, the simulation model comprised of three DESUs is implemented and the results show that the proposed control strategy can make each DESU reach SoC equilibrium state quickly and effectively reduce the bus voltage deviation under the normal and failure communication conditions.

Are Static and Dynamic Postural Balance Assessments Two Sides of the Same Coin? A Cross-Sectional Study in the Older Adults

The aim of this study was to investigate if the combination of static and dynamic postural balance assessments gives more accurate indications on balance performance among healthy older adults. We also aimed at studying the effect of a dual-task condition on static and dynamic postural balance control. Fifty-seven healthy older adults (age = 73.2 ± 5.0 year, height = 1.66 ± 0.08 m, and body mass = 72.8 ± 13.8 kg) completed the study. Static and dynamic balance were assessed both in single-task and dual-task conditions through a force plate and an oscillating platform. The dominant handgrip strength was also measured with a dynamometer. Pearson’s correlation revealed non-statistically significant correlations between static and dynamic balance performance. The dual-task worsened the balance performance more in the dynamic (+147.8%) than in the static (+25.10%, +43.45%, and +72.93% for ellipse area, sway path, and AP oscillations, respectively) condition (p < 0.001). A weak correlation was found between dynamic balance performance and handgrip strength both in the single (p < 0.05; r = −0.264) and dual (p < 0.05; r = −0.302) task condition. The absence of correlations between static and dynamic balance performance suggests including both static and dynamic balance tests in the assessment of postural balance alterations among older adults. Since cognitive-interference tasks exacerbated the degradation of the postural control performance, dual-task condition should also be considered in the postural balance assessment.

Strategies for maintaining dynamic balance in persons with neurological disorders during overground walking.

Maintaining a stable gait requires a dynamic balance control, that can be altered in persons with Multiple Sclerosis (MS), Stroke (ST), and Parkinson's disease (PD). The understanding of the strategy for Center of Mass (CoM) positioning adopted by patients during walking is important to be able to program treatments aimed at improving gait control and preventing falls. Forty-four persons with a mild-to-moderate neurological disorder (20 with MS, 14 with ST, 10 with PD) underwent clinical examination and gait analysis. Ten Healthy Subjects (HS) walking at matched speed provided the normative data. Dynamic balance was assessed using the margin of stability (MoS). It was calculated as the distance between the extrapolated Center of Pressure and the extrapolated CoM at mid-stance. The MoS values for lower limbs were calculated in patients and compared with speed-matched values of HS. Persons with neurological disorder showed increased MoS in the medio-lateral direction with respect to HS. Within-group comparison analysis showed a symmetry between lower limbs in HS (Mean (95%CI) [mm], dominant vs non-dominant limb, 43.3 (31.9-54.6) vs 42.9 (28.8-56.9)) and PD (less affected vs more affected limb, 71.1 (59.8-82.5) vs 72.5 (58.5-86.6)), while a significant asymmetry was found in MS (54.4 (46.4-62.4) vs 81.1 (71.2-91.1)) and ST (52.1 (42.6-61.7) vs 74.7 (62.8-86.6)) participants. The history of falls was comparable among PD, MS, and ST groups, and the MoS in the frontal plane showed a strong correlation with these records. Objective assessment of MoS revealed pathology-specific strategies showing different impacts in MS, ST, and PD on the ability to control CoM information to manage the balance between limbs during gait. MoS evaluation will provide useful information to address a tailored rehabilitation program and to monitor disease progression.

Acute and Subacute Changes in Dynamic Postural Control After Hip Arthroscopy and Postoperative Rehabilitation.

Hip pain is associated with impairments in postural control and balance. The Star Excursion Balance Test (SEBT) is a reliable and valid method for measuring dynamic postural control. To examine changes in dynamic postural control after hip arthroscopy and subsequent rehabilitation from baseline to 3 and 6 months postsurgery. Case series. Physiotherapy department. Sixty-seven individuals (47 men, 20 women; age = 31 ± 8 years, height = 1.78 ± 0.09 m, mass = 83 ± 15 kg) scheduled for hip arthroscopy to address chondrolabral conditions were matched with 67 healthy individuals serving as controls (47 men, 20 women; age = 31 ± 8 years, height = 1.77 ± 0.09 m, mass = 80 ± 16 kg). The hip arthroscopy group underwent postoperative rehabilitation including SEBT training. The SEBT reach normalized to limb length was collected before surgery (baseline) and at 3 and 6 months after arthroscopy and compared with that of the healthy matched control group. Repeated-measures analysis of variance was used to evaluate whether SEBT reach differed among the 3 time points, and t tests were used to evaluate between-limbs and between-groups differences. The SEBT reach in the hip arthroscopy group at baseline was less than that of the control group in all directions (P values < .001). At 3 months after arthroscopy, SEBT reach increased in the posteromedial (PM; P = .007), posterolateral (PL; P < .001), and anterolateral (AL; P < .001) directions from baseline. At 6 months after arthroscopy, all directions of reach had increased (P values < .001) from baseline. The anteromedial (mean difference [MD] = -2.9%, P = .02), PM (MD = -5.2%, P = .002), and AL (MD = -2.5%, P = .04) reach distances remained shorter at 6 months after surgery in the hip arthroscopy group than in the control group. No difference existed between the control and hip arthroscopy groups for reach in the PL direction (MD = -3.6%; P = .06). Dynamic balance control in the hip arthroscopy group at baseline was poorer than in a matched control group as measured using the SEBT. At 3 months after hip arthroscopy, we observed improvements in dynamic balance in the PM, PL, and AL SEBT directions. By 6 months after arthroscopy, all directions of SEBT reach had improved, but only the PL reach improved to the level of healthy control individuals.

The Importance of Being in Touch.

This paper describes a series of studies resulting from the finding that when free floating in weightless conditions with eyes closed, all sense of one's spatial orientation with respect to the aircraft can be lost. But, a touch of the hand to the enclosure restores the sense of spatial anchoring within the environment. This observation led to the exploration of how light touch of the hand can stabilize postural control on Earth even in individuals lacking vestibular function, and can override the effect of otherwise destabilizing tonic vibration reflexes in leg muscles. Such haptic stabilization appears to represent a long loop cortical reflex with contact cues at the hand phase leading EMG activity in leg muscles, which change the center of pressure at the feet to counteract body sway. Experiments on dynamic control of balance in a device programmed to exhibit inverted pendulum behavior about different axes and planes of rotation revealed that the direction of gravity not the direction of balance influences the perceived upright. Active control does not improve the accuracy of indicating the upright vs. passive exposure. In the absence of position dependent gravity shear forces on the otolith organs and body surface, drifting and loss of control soon result and subjects are unaware of their ongoing spatial position. There is a failure of dynamic path integration of the semicircular canal signals, such as occurs in weightless conditions.

Different visual manipulations have similar effects on quasi-static and dynamic balance responses of young and older people.

BackgroundStudies demonstrated that the older adults can be more susceptible to balance instability after acute visual manipulation. There are different manipulation approaches used to investigate the importance of visual inputs on balance, e.g., eyes closed and blackout glasses. However, there is evidence that eyes open versus eyes closed results in a different organization of human brain functional networks. It is, however, unclear how different visual manipulations affect balance, and whether such effects differ between young and elderly persons. Therefore, this study aimed to determine whether different visual manipulation approaches affect quasi-static and dynamic balance responses differently, and to investigate whether balance responses of young and older adults are affected differently by these various visual conditions.MethodsThirty-six healthy participants (20 young and 16 older adults) performed balance tests (quasi-static and unexpected perturbations) under four visual conditions: Eyes Open, Eyes Closed, Blackout Glasses, and Dark Room. Center of pressure (CoP) and muscle activation (EMG) were quantified.ResultsAs expected, visual deprivation resulted in larger CoP excursions and higher muscle activations during balance tests for all participants. Surprisingly, the visual manipulation approach did not influence balance control in either group. Furthermore, quasi-static and dynamic balance control did not differ between young or older adults. The visual system plays an important role in balance control, however, similarly for both young and older adults. Different visual deprivation approaches did not influence balance results, meaning our results are comparable between participants of different ages. Further studies should investigate whether a critical illumination level may elicit different postural responses between young and older adults.

Multibody Modeling and Balance Control of a Reaction Wheel Inverted Pendulum Using LQR Controller

In this study, modeling and LQR control of a reaction wheel inverted pendulum system is described. The reaction wheel inverted pendulum model is created by using a 3D CAD platform and exported to Simscape Multibody. The multibody model is linearized to derive a state-space representation. A LQR (Linear-quadratic regulator) controller is designed and applied for balance control of the pendulum. The results show that deriving a state-space representation from multibody is an easy and effective way to model dynamic systems and balance control of the reaction wheel inverted pendulum is successfully achieved by LQR controller. Results are given in the form of graphics.

Effect of whole-body vibration on craniovertebral angle and balance control in forward head posture: Single-Blinded randomized controlled trial

Background. A fault posture of head can disturb the body balance. Forward head posture (FHP) is one of common faulty postures seen among university students. Whole Body Vibration (WBV) is a quick method of neuromuscular training used to increase muscle strength, improve dynamic balance control and eventually correct posture. Purpose. A randomized controlled trial was designed to investigate the effect of WBV training on craniovertebral angle and dynamic balance control in subjects with forward head posture. Methods. Forty-five participants (11 males and 34 females, 18-23 years old) were randomly allocated into 3 equal groups: group (A) received traditional treatment (stretching and strengthening exercises) + postural advices, group (B) received whole body vibration training + postural advices, group (C) received traditional treatment + whole body vibration training + postural advices, 3 sessions /week for 4 weeks. Outcome measures included craniovertebral angle (CVA), overall stability index (OSI), anteroposterior stability index (APSI) and mediolateral stability index (MLSI) that were assessed at baseline and 4 weeks post-intervention. Results. Comparing all groups post training revealed that there were statistically significant increases (p &lt; 0.05) in all measured variables (CVA, OSI, APSI and MLSI) in favour of group (C), while there were statistically non-significant differences between group A &amp; B (p &gt; 0.05). Conclusion. The conjugation of WBV training with traditional treatment of FHP improved craniovertebral angle and dynamic balance control in subjects with forward head posture.

Impaired Weight-Shift Amplitude in People with Parkinson's Disease with Freezing of Gait.

People with Parkinson's disease and freezing of gait (FOG; freezers) suffer from pronounced postural instability. However, the relationship between these phenomena remains unclear and has mostly been tested in paradigms requiring step generation. To determine if freezing-related dynamic balance deficits are present during a task without stepping and determine the influence of dopaminergic medication on dynamic balance control. Twenty-two freezers, 16 non-freezers, and 20 healthy age-matched controls performed mediolateral weight-shifts at increasing frequencies when following a visual target projected on a screen (MELBA task). The amplitude and phase shift differences between center of mass and target motion were measured. Balance scores (Mini-BESTest), 360° turning speed and the freezing ratio were also measured. Subjects with Parkinson's disease were tested ON and partial OFF (overnight withdrawal) dopaminergic medication. Freezers had comparable turning speed and balance scores to non-freezers and took more levodopa. Freezers produced hypokinetic weight-shift amplitudes throughout the MELBA task compared to non-freezers (p = 0.002), which were already present at task onset (p < 0.001). Freezers also displayed an earlier weight-shift breakdown than controls when OFF-medication (p = 0.008). Medication improved mediolateral weight-shifting in freezers and non-freezers. Freezers decreased their freezing ratio in response to medication. Hypokinetic weight-shifting proved a marked postural control deficit in freezers, while balance scores and turning speed were similar to non-freezers. Both weight-shift amplitudes and the freezing ratio were responsive to medication in freezers, suggesting axial motor vigor is levodopa-responsive. Future work needs to test whether weight-shifting and freezing severity can be further ameliorated through training.

Effects of augmented somatosensory input using vibratory insoles to improve walking in individuals with chronic post-stroke hemiparesis

BackgroundStroke survivors suffer from hemiparesis and somatosensory impairments, which adversely impact walking performance, placing them at higher risks for trips and falls. Post-stroke, somatosensory deficits are commonly observed as impaired interpretation of afferent input and increased threshold. Diminishing or augmenting somatosensory inputs via various techniques have been demonstrated to be able to modify static and dynamic balance, postural and locomotor control in non-neurologically impaired as well as neurologically impaired individuals.Research question: We sought to investigate whether enhancing somatosensory input using vibratory insoles, can improve post-stroke gait. We hypothesized that with augmentation of somatosensory input at the soles via vibratory insoles would improve post-stroke gait via increased propulsive forces, decreased braking forces and increased ankle angle movements in the paretic legs of individuals with chronic post-stroke hemiparesis. MethodsFifteen individuals with chronic post-stroke hemiparesis and 15 age-similar non-neurologically impaired controls participated in this cross-sectional study. Enhanced somatosensory stimulation was delivered using a pair of tactor-embedded insoles, providing suprathreshold vibratory stimulation to the bottom of the feet. Participants walked over an instrumented treadmill with self-selected speeds, under 5 conditions: no insole in shoe (NT), insoles in shoe with no vibration (BOFF), vibration under both feet (BON), vibration under one foot only (ION, CON). Kinetics and kinematics during walking were recorded and analyzed offline. ResultsSuprathreshold vibratory stimulations did not alter gait kinetics under any stimulation conditions. We observed increased paretic ankle dorsiflexions in the paretic legs, when vibratory stimuli were applied unilaterally. SignificanceVibratory stimulations applied at suprathreshold intensity to the bottom of the feet to augment somatosensory feedback can potentially be used as a low-cost solution to address the inadequate toe clearance during walking in people post-stroke, which is an important goal in post-stroke rehabilitation.

Brain connectivity during simulated balance in older adults with and without Parkinson's disease

Individuals with Parkinson’s disease often experience postural instability, a debilitating and largely treatment-resistant symptom. A better understanding of the neural substrates contributing to postural instability could lead to more effective treatments. Constraints of current functional neuroimaging techniques, such as the horizontal orientation of most MRI scanners (forcing participants to lie supine), complicates investigating cortical and subcortical activation patterns and connectivity networks involved in healthy and parkinsonian balance control. In this cross-sectional study, we utilized a newly-validated MRI-compatible balance simulator (based on an inverted pendulum) that enabled participants to perform balance-relevant tasks while supine in the scanner. We utilized functional MRI to explore effective connectivity underlying static and dynamic balance control in healthy older adults (n = 17) and individuals with Parkinson’s disease while on medication (n = 17). Participants performed four tasks within the scanner with eyes closed: resting, proprioceptive tracking of passive ankle movement, static balancing of the simulator, and dynamic responses to random perturbations of the simulator. All analyses were done in the participant's native space without spatial transformation to a common template. Effective connectivity between 57 regions of interest was computed using a Bayesian Network learning approach with false discovery rate set to 5%. The first 12 principal components of the connection weights, binomial logistic regression, and cross-validation were used to create 4 separate models: contrasting static balancing vs {rest, proprioception} and dynamic balancing vs {rest, proprioception} for both controls and individuals with Parkinson’s disease. In order to directly compare relevant connections between controls and individuals with Parkinson’s disease, we used connections relevant for predicting a task in either controls or individuals with Parkinson’s disease in logistic regression with Least Absolute Shrinkage and Selection Operator regularization. During dynamic balancing, we observed decreased connectivity between different motor areas and increased connectivity from the brainstem to several cortical and subcortical areas in controls, while individuals with Parkinson’s disease showed increased connectivity associated with motor and parietal areas, and decreased connectivity from brainstem to other subcortical areas. No significant models were found for static balancing in either group. Our results support the notion that dynamic balance control in individuals with Parkinson’s disease relies more on cortical motor areas compared to healthy older adults, who show a preference of subcortical control during dynamic balancing.