Dynamic Balance Control Research Articles

Management of postural sensory conflict and dynamic balance control in late-stage Parkinson's disease

Parkinson's disease (PD) is known to affect postural control, especially in situations needing a change in balance strategy or when a concurrent task is simultaneously performed. However, few studies assessing postural control in patients with PD included homogeneous population in late stage of the disease. Thus, this study aimed to analyse postural control and strategies in a homogeneous population of patients with idiopathic advanced (late-stage) PD, and to determine the contribution of peripheral inputs in simple and more complex postural tasks, such as sensory conflicting and dynamic tasks. Twenty-four subjects with advanced PD (duration: median (M)=11.0 years, interquartile range (IQR)=4.3 years; Unified Parkinson's Disease Rating Scale (UPDRS): M "on-dopa"=13.5, IQR=7.8; UPDRS: M "off-dopa"=48.5, IQR=16.8; Hoehn and Yahr stage IV in all patients) and 48 age-matched healthy controls underwent static (SPT) and dynamic posturographic (DPT) tests and a sensory organization test (SOT). In SPT, patients with PD showed reduced postural control precision with increased oscillations in both anterior-posterior and medial-lateral planes. In SOT, patients with PD displayed reduced postural performances especially in situations in which visual and vestibular cues became predominant to organize balance control, as was the ability to manage balance in situations for which visual or proprioceptive inputs are disrupted. In DPT, postural restabilization strategies were often inefficient to maintain equilibrium resulting in falls. Postural strategies were often precarious, postural regulation involving more hip joint than ankle joint in patients with advanced PD than in controls. Difficulties in managing complex postural situations, such as sensory conflicting and dynamic situations might reflect an inadequate sensory organization suggesting impairment in central information processing.

The effects of attention capacity on dynamic balance control following concussion

The purpose of this study was to examine how individuals modulate attention in a gait/cognition dual task during a 4-week period following a concussion. Ten individuals suffering from a grade 2 concussion and 10 matched controls performed a single task of level walking, a seated auditory Stroop task and a simultaneous auditory Stroop and walking task. Reaction time and accuracy were measured from the Stroop task. Dynamic balance control during gait was measured by the interaction (displacement and velocity) between the center of mass (CoM) and center of pressure (CoP) in the coronal and sagittal planes. Concussed individuals shifted from conservative control of balance (shorter separation between CoM and CoP) immediately after injury to normal balance control over 28 days post-injury. Immediately after injury, correlations analyses using each subject on each testing day as a data point showed that there was a spectrum of deficient performance among concussed individuals on the first testing day. Within a testing session, deficiencies in reaction time of processing involved in the Stroop task were commonly seen with reduce dynamic balance control. However, the prioritization was not always towards the same task between trials. There were no correlations in the control group. Information provided in this study would enhance our understanding of the interaction between attention and gait following concussion.

Impact of Visual and Somatosensory Deprivation on Dynamic Balance in Adolescent Idiopathic Scoliosis

A cross-sectional study of balance control in adolescents with idiopathic scoliosis (AIS). To investigate the impact of visual and somatosensory deprivation on the dynamic balance in AIS patients and to discuss electromyographic (EMG) and posture sway findings. Most studies focus on posture sway in quiet standing controls with little effort on examining muscle-activated patterns in dynamic standing controls. Twenty-two AIS patients and 22 age-matched normal subjects were studied. To understand how visual and somatosensory information could modulate standing balance, balance tests with the Biodex stability system were performed on a moving platform under 3 conditions: visual feedback provided (VF), eyes closed (EC), and standing on a sponge pad with visual feedback provided (SV). Muscular activities of bilateral lumbar multifidi, gluteus medii, and gastrocnemii muscles were recorded with a telemetry EMG system. AIS patients had normal balance index and amplitude and duration of EMG similar to those of normal subjects in the balance test. However, the onset latency of right gastrocnemius was earlier in AIS patients than in normal subjects. In addition, body-side asymmetry was noted on muscle strength and onset latency in AIS subjects. Under EC condition, lumbar multifidi, and gluteus medii activities were higher than those under SV and VF conditions (P < 0.05). Under SV condition, the medial-lateral tilting angle was less than that under VF and EC conditions. In addition, the active duration of right gluteus medius was shorter under SV condition (P < 0.05). The dynamic balance control is particularly disruptive under visual deprivation with increasing lumbar multifidi and gluteus medii activities for compensation. Sponge pad can cause decrease in frontal plane tilting and gluteus medii effort. The asymmetric muscle strength and onset timing are attributed to anatomic deformation as opposed to neurologic etiological factors.

Gait symmetry improves in childhood—A 4-year follow-up of foot loading data

Children under 10 years of age are less efficient than adults regarding their dynamic balance control [1]. The development of the somatosensory system is necessary for the control of posture and balance. The foot, as the final link between body and ground, transfers internal forces during gait. The coordination of force transfer needs to be balanced between both feet thus leading to a potential asymmetry of foot loading. The magnitude of asymmetry in infants’ gait has been previously studied. However, the individual development and improvement of gait symmetry should also be considered. Therefore, the aim of this study was to retrospectively evaluate the longitudinal development of foot loading symmetries from the onset of independent walking. Sixty-two healthy infants were followed over the course of 4 years by means of plantar pressure distribution measurements (mean age of 15 months at study start and 63 months at the end). The subjects attended a total of nine measurements scheduled every 6 months. Foot loading data was recorded during walking with the emed ® pressure platform to evaluate contact area, peak pressure, force-time integral, relative maximum force and contact time. An absolute symmetry index was calculated for all parameters. Furthermore, the infants’ data were compared to the data of 26 healthy adults. The adults were measured once and the data acquisition followed exactly the same procedures as the infants’ data. In conclusion, foot loading is asymmetric with the onset of independent walking and shows improved symmetry with increasing age dependent on the foot loading parameters.

On the role of knee joint in balance control and postural strategies: Effects of total knee replacement in elderly subjects with knee osteoarthritis

This study aimed to evaluate the role of the knee joint in the neurosensory organization of balance control and the generation of postural sensorimotor strategies. Ten patients, aged over 60 years and having undergone unilateral total knee replacement (TKR) for osteoarthritis, and 20 controls were submitted to static and dynamic posturographic tests and to a sensory organization test (SOT) aiming at evaluating postural control in quiet stance and during movement. The patients were submitted to these evaluations after the disappearance of pain (TKR 1) and at the end of a 6-week rehabilitation program (TKR 2). Balance control being greatly improved at TKR2 compared to TKR1, the patients attain a quality of postural regulation similar to that of the controls; some postural abnormalities did however persist for the static test. Moreover, SOT values at TKR 2 close to those of the controls highlighted an improvement in motor response, better management in altered proprioceptive information situations, and greater use of the ankle to control balance. This model of intervention on the knee joint, namely knee replacement due to osteoarthritis, has shown that gradual functional sensorimotor restoration after TKR, due to intrasensory proprioceptive compensation either at knee, or at other joint levels (hip/ankle), improves dynamic balance control. This reacquisition allows the knee joint to recover its corrective compensatory role in postural regulation allowing, through neuroplasticity, the modification of muscular activation sequences and, thus, the implementation of anticipatory sensorimotor strategies.

Support vector machine optimal control for mobile wheeled inverted pendulums with unmodelled dynamics

The dynamic balance and motion control based on LS-SVM (least squares support vector machine) are considered for mobile wheeled inverted pendulums (WIP), in the presence of parametric and functional dynamics uncertainties. Based on Lyapunov synthesis, the proposed control mechanisms use the advantage of LS-SVM combined with on-line parameters estimation strategy in order to have an efficient approximation. Under the controller designed, we can ensure that the outputs of the system track the given bounded reference signals within a small neighborhood of zero, and guarantee semi-global uniform boundedness of all the closed loop signals. Simulation results are presented to verify the effectiveness of the proposed control.

Static and Dynamic Balance Control in Older Golfers

To determine whether older golfers have better static and dynamic balance control than older but nongolfing healthy adults. Eleven golfers and 12 control participants (all male; 66.2 +/- 6.8 and 71.3 +/- 6.6 yr old, respectively) were recruited. Duration of static single-leg stance was timed. Control of body sway was assessed in single-leg stance during forward and backward platform perturbations. The lunge distance normalized with respect to each participant's height was used to compare the 2 groups in a forward-lunge test. Golfers maintained significantly longer duration in static single-leg stance. They achieved less anteroposterior body sway in perturbed single-leg stance and lunged significantly farther than did control participants. The better static and dynamic balance control exhibited by older golfers possibly reflects the effects of weight transfers from repeated golf swings during weight shift from 2-leg to predominantly 1-leg stance and from walking on uneven fairways.

Age dependency of neuromuscular function and dynamic balance control

The purpose of the present study was to examine whether static and dynamic balance control are related to neuromuscular function and ageing. For this purpose, we constructed a new dynamic balance measurement system that simulates natural falling. Ten young (age 21–31 years) and 20 elderly (age 60–70 years) men participated in the experiment. Maximal isometric torque (MVC) and activation level were measured from the quadriceps and plantar flexor muscles. The H-reflex, V-wave, and maximal M-wave were measured from the soleus muscle. In dynamic balance control, anterior-posterior centre-of-pressure swaying was 74±8.1 mm in the young men and 91.5±19.4 mm in the elderly men (P<0.05), whereas in the static condition there were no significant differences between the two groups. Knee extension MVC (young: 181±42 N·m; elderly: 135±39 N·m; P<0.01), torque after 500 ms (young: 147±36 N·m; elderly: 108±39 N·m; P<0.05), and activation level (young: 96.2±0.8%; elderly: 93.8±2.1%; P<0.01) were higher in the young than the elderly men; no differences were observed in plantar flexion. The amount of re-stabilization after a sudden disturbance seems to be an age-related phenomenon, which is seen as a connection between balance control and rapid force production.

Ankle-foot orthoses in stroke: Effects on functional balance, weight-bearing asymmetry and the contribution of each lower limb to balance control

Background Ankle-foot orthoses are often provided to improve walking in stroke patients, although the evidence of effects on walking and balance control is still inconsistent. This could be caused by a lack of insight into the influence of orthoses on the underlying impairments. These impairments can be assessed with dual plate posturography to determine the relative contribution of each lower limb to balance control and weight-bearing. This study examined the effects of ankle-foot orthoses on functional balance, static and dynamic weight-bearing asymmetry and dynamic balance control of the paretic and non-paretic lower limbs. Methods Twenty stroke subjects (time since stroke 5–127 months) completed the study. Subjects were assessed with and without ankle-foot orthosis. Functional balance was assessed using the Berg Balance Scale, Timed Up & Go test, Timed Balance Test, 10-m walking test and Functional Ambulation Categories. Weight-bearing asymmetry and dynamic balance control were assessed with force plates on a movable platform. Findings No significant effects of ankle-foot orthoses were found for weight-bearing asymmetry and dynamic balance control, but significant differences in favour of ankle-foot orthosis use were found for most functional tests. Interpretation Although ankle-foot orthoses had no effect on weight-bearing asymmetry or dynamic balance contribution of the paretic lower limb, functional tests were performed significantly better with orthoses. Apparently, improvements at functional level cannot be readily attributed to a greater contribution of the paretic lower limb to weight-bearing or balance control. This finding suggests that ankle-foot orthoses influence compensatory mechanisms.

Different gait tasks distinguish immediate vs. long-term effects of concussion on balance control.

The purpose of this study was to longitudinally compare the sensitivity of previously documented paradigms for measuring balance control during gait following a concussion. We hypothesized that gait with a concurrent cognitive task would be most sensitive to the effects of concussion on dynamic balance control. Individuals with concussion (n = 30) and matched controls (n = 30) performed a single task of level walking, attention divided walking, and an obstacle-crossing task at two heights. Testing occurred four times post-injury. Balance control during gait was assessed with whole-body center of mass and center of pressure motion. The single-task level walking task did not result in any significant differences in balance control between individuals with concussion and control subjects. Within 48 hours post-injury, individuals with concussion walked slower and allowed less motion of their center of mass in the sagittal plane when attention was divided during walking, but there were no group differences by day 6 for this task. Group differences in balance control during obstacle crossing was unremarkable during the first two testing sessions, but by day 14 individuals with concussion displayed less mediolateral motion of their center of mass. Attention divided gait is able to better distinguish gait adaptations immediately following a concussion, but obstacle crossing can be used further along in the recovery process to detect new gait adaptations.

Fuzzy Sliding-Mode Underactuated Control for Autonomous Dynamic Balance of an Electrical Bicycle

The purpose of this paper is to stabilize the running motion of an electrical bicycle. In order to do so, two strategies are employed in this paper. One is to control the bike's center of gravity (CG), and the other is to control the angle of the bike's steering handle. As in general, the control of the CG applies a pendulum. An additional factor is the lean angle with respect to the gravitational direction of the bicycle in motion. In this total, the proposed system produces three outputs that will affect the dynamic balance of an electrical bicycle: the bike's pendulum angle, lean angle, and steering angle. Based on the data of input-output, two scaling factors are first employed to normalize the sliding surface and its derivative. According to the concept of the if-then rule, an appropriate rule table for the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</i> th subsystem is obtained. Then, the output scaling factor based on Lyapunov stability is determined. The purpose of using the proposed fuzzy sliding-mode underactuated control (FSMUAC) is to deal with the huge uncertainties of a bicycle system often caused by different ground conditions and gusts of wind. Finally, the simulations for the electrical bicycle in motion under ordinary PID control, modified proportional-derivative control, and FSMUAC are compared to judge the efficiency of our proposed control method.

Effect of a 10-Week Traditional Dance Program on Static and Dynamic Balance Control in Elderly Adults

This preliminary study examined the effect of a 10-wk traditional Greek dance program on static and dynamic balance indices in healthy elderly adults. Twenty-six community-dwelling older adults were randomly assigned to either an intervention group who took supervised Greek traditional dance classes for 10 wk (1 hr, 2 sessions/week, n = 14), or a control group (n = 12). Balance was assessed pre- and postintervention by recording the center-of-pressure (COP) variations and trunk kinematics during performance of the Sharpened-Romberg test, 1-leg (OL) stance, and dynamic weight shifting (WS). After practice, the dance group significantly decreased COP displacement and trunk sway in OL stance. A significant increase in the range of trunk rotation was noted during performance of dynamic WS in the sagittal and frontal planes. These findings support the use of traditional dance as an effective means of physical activity for improving static and dynamic balance control in the elderly.

Gait planning for quadruped robot based on dynamic stability: landing accordance ratio

In this article, the method for increasing dynamic stability of quadruped robot is proposed. Previous researches on dynamic walking of quadruped robots have used only walking pattern called central pattern generator (CPG). In this research, different from walking generation with only CPG, a instinctive stability measure called landing accordance ratio, is proposed and used for increasing dynamic stability. In addition, dynamic balance control and control to adjust walking trajectory for increasing dynamic stability measure is also proposed. Proposed methods are verified with dynamic simulation and a large number of experiments with quadruped robot platform.

Adaptive Robust Dynamic Balance and Motion Controls of Mobile Wheeled Inverted Pendulums

Adaptive robust dynamic balance and motion control are considered for mobile wheeled inverted pendulums, in the presence of parametric and functional uncertainties. Based on Lyapunov synthesis, the proposed control mechanisms using physical properties of wheeled inverted pendulums ensure that the outputs of the system track the given bounded reference signals within a small neighborhood of zero and guarantees semi-global uniform boundedness of all of the closed-loop signals. Simulation results are presented to verify the effectiveness of the proposed adaptive robust control.

The Influence of Aging on the Center of Pressure Trajectory: a Comparison of Crossing an Obstacle and Stepping onto a Curb from a Position of Quiet Stance

[Purpose] The purpose of this study was to investigate how young and older adults modulate the center of pressure (COP) trajectory and stance time during obstacle negotiation. [Subjects] Fifteen healthy young adults and fifteen healthy older adults participated in the study. [Methods] The subjects stepped over an obstacle (18 cm in height, 10 cm in breadth and 140 cm in width) and a curb (18 cm in height, 140 cm in breadth and 140 cm in width) at a self-paced speed from a position of quiet stance. Performance was assessed by recording changes in the displacement of COP in the anteroposterior (A-P) and mediolateral (M-L) directions, and by measuring the average velocity of the COP and stance time using a force platform. [Results] The A-P and M-L displacement of COP and the average velocity of COP of the older adults were significantly less than those of the young adults (p<0.01). The stance time of the the older adults was significantly greater than that of the young adults (p<0.01). However, the COP variables between the stepping tasks were not significantly different. [Conclusion] The COP shift and velocity and stance time during obstacle negotiation might be appropriate parameters for evaluating the dynamic balance and motor control strategies of older adults.

Impaired Dynamic Balance Control in Adolescents With Idiopathic Scoliosis and Abnormal Somatosensory Evoked Potentials

Both balance control dysfunction and dysfunction of the central nervous system have been proposed as being causative factors in adolescent idiopathic scoliosis (AIS), yet the relationship between these factors has not been investigated in detail. An intergroup comparative study was conducted to investigate the effect of abnormal somatosensory function on the dynamic balance parameters of girls with AIS. The relationship between dynamic balance control and abnormal somatosensory function seen in AIS patients was examined by studying the dynamic balance parameters in normal controls, in AIS patients with normal posterior tibial nerve somatosensory cortical evoked potentials (PTN-SCEPs), and in AIS patients with abnormal PTN-SCEPs. Gait parameters were recorded in 18 AIS girls (8 showing abnormal PTN-SCEPs and 10 showing normal PTN-SCEPs). Eight healthy age-matched volunteers served as a control group. No significant left-right asymmetry of gait parameters was found for the controls or the AIS patients with normal PTN-SCEPs, whereas significantly higher gait parameters were found on the side of the curvature in the AIS patients with abnormal PTN-SCEPs. Somatosensory dysfunction in AIS patients shows to have an impact on dynamic balance control. Further studies to examine the association between somatosensory dysfunction and balance control and how they may be related to the etiology of AIS are recommended. Diagnostic study, level IV (case-control study).

Adaptive fuzzy logic control of dynamic balance and motion for wheeled inverted pendulums

In this paper, adaptive fuzzy logic control of dynamic balance and motion is investigated for wheeled inverted pendulums with parametric and functional uncertainties. The proposed adaptive fuzzy logic control based on physical properties of wheeled inverted pendulums makes use of a fuzzy logic engine and a systematic online adaptation mechanism to approximate the unknown dynamics. Based on Lyapunov synthesis, the fuzzy control ensures that the system outputs track the given bounded reference signals to within a small neighborhood of zero, and guarantees semi-global uniform boundedness of all closed-loop signals. The effectiveness of the proposed control is verified through extensive simulations.

The influence of focal cerebellar lesions on the control and adaptation of gait

Cerebellar ataxic gait is influenced greatly by balance disorders, most likely caused by lesions of the medial zone of the cerebellum. The contributions of the intermediate and lateral zone to the control of limb dynamics for gait and the adaptation of locomotor patterns are less well understood. In this study, we analysed locomotion and goal-directed leg movements in 12 patients with chronic focal lesions after resection of benign cerebellar tumours. The extent of the cortical lesion and possible involvement of the cerebellar nuclei was determined by 3D-MR imaging. The subjects (age range 13-39 years, mean 20.3; seven female; ICARS score: mean 5.7, SD 6.3) performed three tasks: goal-directed leg placement, walking and walking with additional weights on the shanks. Based on the performance on the first two tasks, patients were categorized as impaired or unimpaired for leg placement and for dynamic balance control in gait. The subgroup with impaired leg placement but not the subgroup with impaired balance showed abnormalities in the adaptation of locomotion to additional loads. A detailed analysis revealed specific abnormalities in the temporal aspects of intra-limb coordination for leg placement and adaptive locomotion. These findings indicate that common neural substrates could be responsible for intra-limb coordination in both tasks. Lesion-based MRI subtraction analysis revealed that the interposed and the adjacent dentate nuclei were more frequently affected in patients with impaired compared to unimpaired leg placement, whereas the fastigial nuclei (and to a lesser degree the interposed nuclei) were more frequently affected in patients with impaired compared with unimpaired dynamic balance control. The intermediate zone appears thus to be of particular importance for multi-joint limb control in both goal-directed leg movements and in locomotion. For locomotion, our results indicate an influence of the intermediate zone on dynamic balance control as well as on the adaptation to changes in limb dynamics.

Short-term Recovery of Balance Control after Total Hip Arthroplasty

Hip osteoarthritis leads to chronic pain and deteriorated joint function, which affect weightbearing and balance during gait. THA effectively restores hip function but it is not known whether THA restores balance during gait. We hypothesized patients would have greater frontal plane and smaller sagittal plane center of mass-center of pressure inclination angles preoperatively compared with control subjects, and THA would improve these inclination angles by 16 weeks postsurgery. Compared with control subjects, we observed greater frontal plane inclination angles and smaller sagittal plane angles preoperatively, indicating gait imbalance. These inclination angles were improved postoperatively, providing better balance control. Despite improvement, patients differed in frontal and sagittal plane inclination angles compared with control subjects. This suggests residual deficits in dynamic balance control in patients undergoing THA before and up to 4 months after surgery.

Effects of Shoe Characteristics on Dynamic Stability When Walking on Even and Uneven Surfaces in Young and Older People

Menant JC, Perry SD, Steele JR, Menz HB, Munro BJ, Lord SR. Effects of shoe characteristics on dynamic stability when walking on even and uneven surfaces in young and older people. Objective To systematically investigate the effects of various shoe features (sole hardness, heel height, heel collar height, tread pattern) on dynamic balance control and perceptions of comfort and stability in young and older people walking over even and uneven surfaces. Design A mixed-design 3-way repeated measures with age as a between-subjects factor and surface and shoe conditions as within-subjects factors. Setting Gait laboratory. Participants Young adults (n=11) and community-dwelling older adults (n=15). Interventions Not applicable. Main Outcome Measures Center of mass (COM)−base of support (BOS) margins, vertical and braking loading rates, and subjective ratings of perceived shoe comfort and stability. Results Overall, compared with the standard shoes, the soft sole shoes led to greater lateral COM-BOS margin ( P<.001), whereas the elevated heel shoes caused reductions in posterior COM-BOS margin ( P=.001) and in vertical and braking loading rates (both, P<.001). Subjects rated the elevated heel shoes as significantly less comfortable ( P<.001) and less stable ( P<.001) than the standard shoes. Only the young subjects perceived the soft-sole shoes to be less stable than the standard shoes ( P=.003). Conclusions Both young and older subjects adopted a conservative walking pattern in the elevated heel shoes and exhibited impaired mediolateral balance control in the soft-sole shoes. In contrast, increased sole hardness (above that found in a standard shoe), a tread sole, and a raised collar height did not improve walking stability in either group. It is concluded that shoes with elevated heels or soft soles should not be recommended for older people and that a standard laced shoe with a low collar and a sole of standard hardness with or without a tread provides optimal dynamic stability when walking on even and uneven surfaces.