Postural control in older adults.
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Accidental Falls↗
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Results for “Postural control”
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[Mental stimulation strategy affects postural control].
Recent studies have proposed that the mental rotation of body parts can be accomplished by calling upon visual and somatomotor resources which, at a functional level, would correspond to different routes toward a single solution [1]. In this study, we investigated the effect of somato-motor and visual strategies upon the mental simulation of a task that involved postural adjustments. Subjects were asked to stand up on a vertical force platform and instructed either to 1) rest during 20 s (ST), 2) count mentally from 1 to 15 (CO), 3) imagine themselves executing a bilateral plantar flexion 15 times (IM), and 4) execute the same movement 15 times (EX). They were further classified as visual or somato-motor dominant, according to the strategy reported as adopted to perform IM. Mental chronometry showed that mean time spent in IM matched that of EX, differing from CO for both groups. Index of stabilometric modulation during IM was computed by reference to CO. Higher index values for area and amplitude of displacement in the antero posterior (y) axis were found for the somato-motor as compared to the visual group. The stabilometric departure found for visual and somato-motor dominant subjects suggests that each imagery mode activates a distinct subset of cortical and subcortical brain networks.
Adult↗
Transitions in Visual Proprioception: A Cross-Sectional Developmental Study of the Effect of Visual Flow on Postural Control.
In the present study, a moving room paradigm was used that characterized the developmental progression of the effects of visual perturbations on stance control in subjects (N = 39) from 5 months to 10 years of age. Kinematic (probability of recording sway, magnitude of sway response) and electromyographic (probability and patterns of muscle activation, muscle onset latencies) data were found that suggested that visual flow simulating sway activates organized postural muscle responses and results in subsequent sway in standing infants as young as 5 months of age, well before they are able to stand independently. In new walkers, there was an increase in the magnitude of the effect of the visual perturbation, suggesting a possible increase in reliance on visual information. The magnitude of sway decreased to very low levels in older children and adults. The large-amplitude responses observed in the youngest age groups may indicate an inability to switch from an unreliable to a reliable source of perceptual information or an inability to modulate the responses produced following the perturbations. With increasing age and experience, the ability to resolve the conflict increased, with adult subjects demonstrating little sway response.
Journal Article↗
Attentional demands of postural control: the ability to selectively allocate information-processing resources.
Most studies have suggested the process of recovering body stability requires information-processing resources, but whether adults have the ability to selectively allocate resources to maintain balance is not known. Using a variable priority dual-task paradigm the present experiment investigated the extent to which young adults are able to shift attention between a postural task and a visual spatial memory task. Our results demonstrated a significant difference in verbal response time dependent on instructional set (focus on visual spatial memory versus postural task) but no difference in body sway measurement, indicating the ability of young adults to modulate visual spatial memory task, but not postural task focus. This suggests the existence of a hierarchy within attentional tasks with postural stability being a priority to stabilize gaze and head position.
Adult↗
[Correlation between walking ability and postural control in sitting, crawling position in children with cerebral palsy].
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Cerebral Palsy↗
The role of tonic vestibular input for postural control in rats.
Removal of a vestibular organ deprives the ipsilateral vestibular nuclei of tonic excitatory inflow from vestibular afferents, and thus evokes a central asymmetry, that is imbalance between tonic activity of the left and right vestibular nuclear complexes. In the present study, the effect of the central asymmetry upon a function of different motor systems was investigated in the freely behaving rats subjected to unilateral or bilateral labyrinthectomy (UL or BL). In four sets of experiments the following results have been obtained. 1. Seven UL-evoked symptoms (which reflect impairment of different motor systems) were qualitatively characterized. The short-lasting symptoms were: (1) body twisting, (2) rolling, (3, 4) extension of the fore- and hindlimb contralateral to UL, and (5) circling. These symptoms disappeared in a fixed order during recovery from anesthesia. During of expression of the symptoms was very short (< 1 hour) with the Halothan anesthesia and much longer (approximately 8 hours) with the chloral hydrate anesthesia. The long-lasting symptoms were (6) spontaneous ocular nystagmus, that persisted for 3 days after UL, and (7) head roll tilt, that persisted for at least several weeks after UL. 2. In BL-animals, stimulation of one of the 8th nerves was performed (by means of an implanted electrode; pulses 0.3 ms, 50 Hz, current up to 400 microA). By increasing gradually the strength of the stimulating current, we could evoke all the UL-symptoms but generally in the order (7-->1) which was the reverse as compared to the order of disappearance of the corresponding symptoms during recovery after UL (1-->7). These findings suggest that different symptoms need different levels of the central asymmetry for their appearance, and these levels also determine the order of disappearance of the symptoms during recovery from UL. 3. In UL-animals, by stimulating the 8th nerve on UL-side with a properly adjusted current (200-400 microA) we could immediately abolish all the symptoms except (6), which was, however, considerably reduced. This finding suggests that stimulation of the 8th nerve in UL-rats restores the central symmetry, which results in a concerted disappearance of almost all symptoms. In addition to the intermediate effects, stimulation of the 8th nerve in UL-animals resulted in a long-lasting effect, that is a reduction of the head roll tilt which persisted for at least 10 days after stimulation. 4. In BL-animals bilateral stimulation of the 8th nerve resulted in restoration of the muscular tone, and in considerable improvement of the control of the head position.
Anesthetics, Inhalation↗
Effect of 6-month whole body vibration training on hip density, muscle strength, and postural control in postmenopausal women: a randomized controlled pilot study.
UNLABELLED: High-frequency mechanical strain seems to stimulate bone strength in animals. In this randomized controlled trial, hip BMD was measured in postmenopausal women after a 24-week whole body vibration (WBV) training program. Vibration training significantly increased BMD of the hip. These findings suggest that WBV training might be useful in the prevention of osteoporosis. INTRODUCTION: High-frequency mechanical strain has been shown to stimulate bone strength in different animal models. However, the effects of vibration exercise on the human skeleton have rarely been studied. Particularly in postmenopausal women-who are most at risk of developing osteoporosis-randomized controlled data on the safety and efficacy of vibration loading are lacking. The aim of this randomized controlled trial was to assess the musculoskeletal effects of high-frequency loading by means of whole body vibration (WBV) in postmenopausal women. MATERIALS AND METHODS: Seventy volunteers (age, 58-74 years) were randomly assigned to a whole body vibration training group (WBV, n = 25), a resistance training group (RES, n = 22), or a control group (CON, n = 23). The WBV group and the RES group trained three times weekly for 24 weeks. The WBV group performed static and dynamic knee-extensor exercises on a vibration platform (35-40 Hz, 2.28-5.09g), which mechanically loaded the bone and evoked reflexive muscle contractions. The RES group trained knee extensors by dynamic leg press and leg extension exercises, increasing from low (20 RM) to high (8 RM) resistance. The CON group did not participate in any training. Hip bone density was measured using DXA at baseline and after the 6-month intervention. Isometric and dynamic strength were measured by means of a motor-driven dynamometer. Data were analyzed by means of repeated measures ANOVA. RESULTS: No vibration-related side effects were observed. Vibration training improved isometric and dynamic muscle strength (+15% and + 16%, respectively; p < 0.01) and also significantly increased BMD of the hip (+0.93%, p < 0.05). No changes in hip BMD were observed in women participating in resistance training or age-matched controls (-0.60% and -0.62%, respectively; not significant). Serum markers of bone turnover did not change in any of the groups. CONCLUSION: These findings suggest that WBV training may be a feasible and effective way to modify well-recognized risk factors for falls and fractures in older women and support the need for further human studies.
Aged↗
Quality of reaching and postural control in young preterm infants is related to neuromotor outcome at 6 years.
A substantial proportion of the "apparently normal" preterm infants exhibit minor and moderate dysfunctions in neuromotor outcome as they grow older. Birth characteristics, minor abnormalities on the neonatal ultrasound scan of the brain, and motor milestones have only limited value in the early detection of these children. The aim of the present study was to investigate whether nonoptimal reaching and relatively immobile postural behavior at an early age are associated with dysfunctional neuromotor and behavioural development at school age. The preterm children and full-term children of the present follow-up study participated in a previous study on the characteristics of reaching kinematics and the kinetics of posture at 4 and 6 mo corrected age. At the age of 6 y, the children were re-assessed by means of the Touwen neurologic assessment, the Movement ABC, and the Child Behavior Check List. The results demonstrated that in preterm children without cerebral palsy, a lack of successful reaching at 4 mo and a nonoptimal quality of reaching at 6 mo are related to the development of a complex form of minor neurologic dysfunction (MND) and fine manipulative disability at 6 y. Thus, these early signs indicate the presence of clinically significant brain dysfunction. A relatively immobile postural behavior at 4 mo was associated with simple MND, coordination problems, and at 6 mo with a worse score on the Movement ABC and internalizing behavior. This suggests that a relatively immobile postural behavior points to a mild form of brain dysfunction.
Brain↗
Postural control in children. Coupling to dynamic somatosensory information.
The purpose of this investigation was to determine whether the coupling between dynamic somatosensory information and body sway is similar in children and adults. Thirty children (4-, 6-, and 8-year-olds) and 10 adults stood upright, with feet parallel, and lightly contacting the fingertip to a rigid metal plate that moved rhythmically at 0.2, 0.5, and 0.8 Hz. Light touch to the moving contact surface induced postural sway in all participants. The somatosensory stimulus produced a broadband frequency response in children, while the adult response was primarily at the driving frequency. Gain, as a function of frequency, was qualitatively the same in children and adults. Phase decreased less in 4-year-olds than other age groups, suggesting a weaker coupling to position information in the sensory stimulus. Postural sway variability was larger in children than adults. These findings suggest that, even as young as age 6, children show well-developed coupling to the sensory stimulus. However, unlike adults, this coupling is not well focused at the frequency specified by the somatosensory signal. Children may be unable to uncouple from sensory information that is less relevant to the task, resulting in a broadband response in their frequency spectrum. Moreover, higher sway variability may not result from the sensory feedback process, but rather from the children's underdeveloped ability to estimate an internal model of body orientation.
Adult↗
Endogenous vasopressin affects postural control of blood pressure in man.
1. Six healthy volunteers received intravenous infusions of isotonic (0.9% NaCl) and hypertonic (3% NaCl) saline on separate days. There were no significant changes in blood pressure or forearm blood flow, despite an increase in plasma arginine vasopressin (AVP) during hypertonic saline. 2. Immediately and 10 min after passive tilting to 50 degrees, mean forearm blood flow fell by 17.1 and 14.3% compared with the values in the supine position during isotonic saline and by 40.3 and 43.3% during hypertonic saline. Forearm vascular resistance rose by 23.6 and 17.8% with isotonic saline and by 80.2 and 88.2% with hypertonic saline for the two readings in the tilted compared with the supine position. 3. Tilting was associated with a 14.9 and 12.1% rise in diastolic blood pressure immediately and 10 min after assuming this position during hypertonic saline, and a rise of 6.4% in mean arterial pressure. 4. The results from this study are similar to those obtained previously, when small amounts of AVP were infused. They provide further evidence that AVP may have a physiological role in the postural regulation of blood pressure.
Adult↗
Effects of visual center of pressure feedback on postural control in young and elderly healthy adults and in stroke patients.
The goal of this study was to compare young and elderly healthy individuals and elderly stroke patients in their capacity to use visual CP feedback (VF) in controlling both quiet standing and weight shifting and to assess their sensory re-weighing when this VF is withdrawn. A total of 40 participants were involved in this study. Participants were asked to either quietly stand on a force platform for a period of 45 s with eyes open (EO), using visual feedback (VF) or without visual feedback (No VF) or to perform a dynamic weight shifting task while using VF or No VF. During the quiet standing trials with VF, only the young (YO) were able to decrease the amplitude and increase the frequency of their sway in either plane. Removal of the VF resulted in a 'destabilizing' effect in both healthy elderly (EL) and stroke patients (ST) in the sagittal plane. With regard to the dynamic task, both the YO and EL were generally more successful at weight shifting in terms of speed and control when compared to the ST. Yet, when VF was removed, only the YO were able to largely maintain speed and precision of control. Hence, providing or removing visual CP feedback during quiet standing or removing VF during visually controlled weight shifting can discriminate healthy young participants from healthy elderly, but does not clearly discriminate healthy elderly from stroke patients in the same age group. Results revealed that sagittal plane imbalance in healthy elderly and stroke patients may be largely due to the effects of aging, whereas frontal plane imbalance is much more specific for the postural problems associated with stroke.
Adult↗
Foot placement alters the mechanisms of postural control while standing and reaching.
This study investigated the effects of altering foot placement on the strategies used by able-bodied subjects to perform reaching tasks while standing. The motivation for this study was to consider the results in the context of a person with a spinal cord injury using a functional neuromuscular stimulation (FNS) system to stand while reaching. Three foot placement conditions were compared as subjects reached to the left, right, and center. Centers of pressure (COP), joint angles, and joint moments were calculated as postural parameters using force platform and video marker data. Side-by-side and wide foot placements resulted in similar postural parameters. In contrast, the modified tandem stance (feet spaced at pelvic width with one foot shifted forward) resulted in anterior/posterior COP excursions that were larger in magnitude and more consistent across reach directions when compared to the other foot placement conditions. Furthermore, the movement patterns used during the tandem stance were more consistent and may be more readily achievable with FNS than the movement patterns utilized with the side-by-side and wide stances. These results suggest that the modified tandem stance may enhance the functionality of FNS standing systems and may also be useful in other standing rehabilitation programs.
Adaptation, Physiological↗
Ontogenetic development of postural control in man: adaptation to altered support and visual conditions during stance.
Normal young children ranging in age from 1 1/2 to 10 years were assessed in a number of experimental paradigms testing the ability to adapt quickly their strategy of control to altered support surface and visual conditions. The experimental protocols, using a movable platform and visual surround, and the analytic techniques, using EMGs and measures of reaction forces and body motions, were identical to those employed in a complementary study in this issue (Nashner, L. M., F. O. Black, and C. Wall, III (1982) J. Neurosci. 2: 536-544). The structure of automatic postural adjustments in young children was, with the exception of greater variability, similar to that of adult subjects studied previously. However, young children below the age of 7 1/2 years were unable to suppress systematically the influence of inputs derived from the support surface or from vision when these provided inappropriate orientation information due to the motion of these surfaces. The discussion emphasizes that the automatic postural adjustments and the context-dependent reweighting of support surface, vestibular, and visual inputs are organizationally separate processes and that the hierarchically lower level automatic process matures before the higher level adaptive processes.
Acclimatization↗
Effects of loratadine on postural control.
The effects of classical sedating antihistamines on cognitive and perceptual functions are well known. Loratadine is a new antihistamine without sedative effects. In this study, loratadine 10 and 40 mg daily, clemastine 2 mg twice daily and placebo were evaluated in 8 healthy subjects in terms of effects on equilibrium as measured with dynamic posturography. Dynamic posturography comprises a sensory organization part in which the support surface and visual surround are either stable or referenced to the patient's sway, with eyes open or closed. In a movement coordination part, the platform makes active movements. Analysis of variance showed no effects on equilibrium attributable to loratadine. Comparing substances pairwise, however, a significant difference between loratadine and clemastine was displayed in 2 out of 6 sensory test conditions. In conclusion, loratadine can be considered safe regarding balance functions.
Adult↗
Posture control after prolonged exercise.
The perturbations of equilibrium after prolonged exercise were investigated by dynamic posturography on nine well-trained subjects (four athletes and five triathletes). A sensory organization test, where the platform and visual surround were either stable or referenced to the subject's sway with eyes open or closed, was performed before and after a 25-km run (average time 1 h 44 min) by the nine subjects. In addition, the same test was performed on the five triathletes only, before and after ergocycle exercise of identical duration (i.e. ergocycle time = running time). The results showed that the ability to maintain postural stability during conflicting sensory conditions decreased after exercise, with some differences depending on the kind of exercise. Sensory analysis revealed that the subjects made less effective use of vestibular inputs after running than after cycling (P < 0.05). Adaptation to prolonged stimulation of proprioceptive, vestibular and visual inputs had probably occurred in the integrating centres during exercise. This adaptation was maintained during the recovery period and could explain the postexercise balance disorders. Other mechanisms such as impairment of motor efferents or haemodynamic changes should not be excluded.
Adult↗
Current concepts of the vestibular system reviewed: 1. The role of the vestibulospinal system in postural control.
This paper reviews the research findings that support the presence of vestibulospinal reflexes in corrections for head and body instability. Studies of the importance of labyrinthine inputs to the central nervous system organization of eye, head, and body movements demonstrate that the vestibular nuclei are more than a simple relay station for labyrinthine activity. At all levels of the vestibular system beyond the primary vestibular afferents, parallel processing of labyrinthine signals occurs with input from other sensory systems. Thus, output of the vestibular nuclear complex (VNC) is not equivalent to the labyrinthine input. It is the VNC output that influences motor behavior. Various sensory inputs are available to the nervous system to detect and correct postural instability. Most notably, vestibular, visual, and proprioceptive signals contribute significantly to the stabilizing responses in humans. The intent of this paper is to review experimental results rather than to discuss treatment interventions. Wherever possible, conclusions are drawn as to the clinical implications of current research findings.
Ear, Inner↗
Gravistatic postural control in simpler systems.
Most types of human and animal motor behaviour are spatially oriented. Studies of the fish gravity orientation system are proving particularly valuable for understanding the functional organization of this system in higher animals. In particular, the development of in vitro central nervous system preparations with gravity sensory organs that exhibit a 'fictive' space orientation behaviour has led to some important new discoveries.
Animals↗
Improvement of postural control in patients with peripheral vestibulopathy.
We present here the results of a short-term prospective study on a group of 37 patients with persistent unsteadiness. The treatment of these patients was customized according to the results of the Sensory Organization Test carried out using computerized dynamic posturography. A 5-week period of instrumental rehabilitation was established involving visual biofeedback-based computerized balance intervention that manipulated the individuals' capacities, the goals of the tasks and the environmental context. Exercises were performed twice weekly. This adaptation of the treatment was based on the hypothesis that it would reduce the level of disability and handicap associated with the unsteadiness suffered by these patients. Of the patients, 73% improved their status according to the DHI results. Furthermore, in the group of patients that showed an improvement in the DHI, their SOT composite score increased significantly, their reaction time reduced and their sway velocity, endpoint excursion, maximum excursion and directional control all increased. However, for those patients who did not experience a significant improvement or who recorded an increase in the total DHI score, the modifications in the SOT and LOS tests were not significant.
Adult↗