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Results for “Postural Balance”

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At least 109 records · Page 6Linked to original sources

PubMed1995

The influence of head rotation on human upright posture during balanced bilateral vibration.

During a balanced bilateral vibration of tensor fasciae latae muscles evoking no evident postural changes in a standing human the slow head turns resulted in a pronounced lateral common gravity centre displacements to the 'occipital' side. Neck influences were most prominent at intermediate tonic background and were lacking both during very weak and strong vibratory stimulation in contrast to usual tonic vibratory reflex which becomes stronger with the increase of frequency. Body sway was induced not only by actual head turns but also by illusory ones evoked by neck muscle vibration. The neck influences on standing posture are therefore present in healthy adults, but they require a definite level of tonic readiness for their manifestation and are incorporated in the whole system of body scheme mechanisms.

Electric Stimulation↗

PubMed2003

An investigation of stability limits while holding a load.

The objective of this study was to investigate the effects of load height and foot placement on the functional base of support (FBOS) limits and the postures that participants used when they reached their FBOS limits. Twelve young male participants were tested while holding a 12-kg load at reach (above their heads), at shoulder and knuckle height, and unladen under both wide and narrow foot placements. The FBOS limits and the centre of pressure (COP) excursion length were calculated based on data from a force platform. Postural angles when participants reached their FBOS limits were calculated from records of a 2-D motion analysis system. The results showed that the load height had greater effect on the posterior FBOS limit. As the load height decreased, the COP excursion length decreased. Participants were prone to using a hip strategy to maintain postural balance when reaching their FBOS limits. Quantitative data of FBOS limits and postural control while participants hold a load at various heights when reaching their FBOS limits is of value for designing a safe materials handling workplace.

Adolescent↗

PubMed2006

[Role of the Neurocom Balance Master in assessment of gait problems and risk of falling in elderly people].

INTRODUCTION: Falls in elderly people is currently a health service problem because of the multiple consequences. Numerous teams have been interested in predicting the risk of falling with clinical and instrumental tests. Our study investigated instrumental evaluation by use of the Neurocom Balance Master in the global assessment of gait problems and risk of falling in elderly people. PATIENTS AND METHODS: Transverse study concerning 60 subjects older than 65 years distributed in 2 groups of 30 subjects each according to the existence or not of falling incidents during the past year. Evaluation by the Balance Master involved the following items: 1) the modified Clinical Test for the Sensory Interaction on Balance (CTSIB), which estimates balance by measuring the speed of oscillation of the center of pressure (CP) with open then closed eyes and firm then mossy ground; 2) support monopodal 5" to the left then to the right, eyes open then closed in moderated speeds of oscillation of the CP; 3) passage from standing to sitting, in moderated speeds of oscillation of the CP; 4) limits of stability: the possibilities of moving the CP towards a predetermined target without moving the feet in moderated time and speed; 5) study of the step: determine length and width of the step as well as speed; 6) most about-turn: measure of speed of oscillation of the CP during the right then left about-turn; 7) clearing: the force of the impact and the oscillations of the CP during the clearing of an obstacle 10 cm high to measure leverage. RESULTS: The oscillation speed of the CP in the 2 groups during modified CTSIB, support monopodal 5", passage from standing to sitting, about-turn and clearing were significantly improved the group of the patients with falls (P < 0.05). The step, length and speed of these patients were significantly reduced, with no difference in width of the step between the 2 groups. In the evaluation of the limits of stability, only time necessary to reach the target was significantly increased in the group with falls. Finally, the indication of leverage and the force of impact on the ground measured by the test of clearing were more important in the group of fallers than in non-fallers. CONCLUSION: The Neurocom Balance Master estimates not only postural balance, but also the vestibulary system and reproduces the physiological conditions of daily life. It has a certain role in the early assessment of gait problems and the risk of falling. This system also allows for rehabilitation of the impaired balance and offers a profit with the biofeedback.

Accidental Falls↗

PubMedDate not supplied

Evaluation of nonlinear dynamics in postural steadiness time series.

Fractal and correlation dimensions have been computed for time series obtained from tests of balance (postural steadiness). Although these measures appear to be reliable and differentiate subject groups, it has become clear that random (noise) time series may have finite dimensions and appear to demonstrate dynamics characteristic of nonlinear systems. Consequently, it is necessary to apply a test to distinguish a time series with putative nonlinear dynamics from random noise. A simple predictor was utilized to compare center of pressure (COP) time series with surrogate data constructed to have similar time and frequency domain characteristics. It was found that the original time series was more predictable than the surrogate data, suggesting that the COP data is derived from a nonlinear system.

Adult↗

PubMed2001

The influence of moving auditory stimuli on standing balance in healthy young adults and the elderly.

The maintenance of postural balance depends on effective and efficient feedback from various sensory inputs. The importance of auditory inputs in this respect is not, as yet, fully understood. The purpose of this study was to analyse how the moving auditory stimuli could affect the standing balance in healthy adults of different ages. The participants of the study were 12 healthy volunteers, who were divided into two age categories: the young group (mean = 21.9 years) and the elderly group (mean = 68.9 years). The instrument used for evaluation of standing balance was a force plate for measuring body sway parameters. The toe pressure was measured using the F-scan Tactile Sensor System. The moving auditory stimulus produced a white-noise sound and binaural cue using the Beachtron Affordable 3D Audio system. The moving auditory stimulus conditions were employed by having the sound come from the right to left or vice versa at the height of the participant's ears. Participants were asked to stand on the force plate in the Romberg position for 20 s with either eyes opened or eyes closed for analysing the effect of visual input. Simultaneously, all participants tried to remain in the standing position with and without auditory stimulation that the participants heard from the headphone. In addition, the variables of body sway were measured under four conditions for analysing the effect of decreased tactile sensation of toes and feet soles: standing on the normal surface (NS) or soft surface (SS) with and without auditory stimulation. The participants were asked to stand in a total of eight conditions. The results showed that the lateral body sway of the elderly group was more influenced than that of the young group by the lateral moving auditory stimulation. The analysis of toe pressure indicated that all participants used their left feet more than their right feet to maintain balance. Moreover, the elderly had the tendency to be stabilized mainly by use of their heels. The young group were mainly stabilized by the toes of their feet. The results suggest that the elderly may need a more appropriate stimulus of tactile and auditory sense as a feedback system than the young for maintaining and control of their standing postures.

Acoustic Stimulation↗

PubMed2006

Total sleep deprivation can increase vestibulo-ocular responses.

The effect of sleep deprivation on the vestibular function is largely unknown. Some studies have found that postural balance or vestibular reflexes are decreased in sleep-deprived subjects while others found no change. The aim of this study was to evaluate the effect of sleep deprivation on the vestibulo-ocular reflex (VOR). Horizontal eye movements were recorded in healthy subjects during earth vertical axis rotation in darkness once after an ordinary night sleep and once after 26-29 h of sleep deprivation. In the first experiment (n = 8), for which rotation was a 60 degrees s(-1) velocity step, sleep deprivation induced a significant increase in VOR gain. In the second experiment (n = 12), for which rotation was sinusoidal (0.2 Hz +/- 25 degrees s(-1)), sleep deprivation induced no significant modification in VOR gain. The difference between the two studies was the abrupt onset of the step stimulation in comparison with the sinusoidal rotation. Because of its unexpected onset and the potential threat to postural balance, the step stimulation may activate the system specialized in reorienting attention towards salient or behaviourally relevant events. This system includes the right temporoparietal cortex, an area also involved in VOR control. A number of studies have found that sleep deprivation alters the activity of this cortical area during attentional tasks. It is therefore our hypothesis that the difference between the effects of these two vestibular stimulations results from a sleep deprivation-induced modulation of the right temporoparietal cortex.

Adult↗

PubMed2006

Postural equilibrium during pregnancy: decreased stability with an increased reliance on visual cues.

OBJECTIVE: The purpose of this study was to determine whether there are changes in postural equilibrium during pregnancy and to examine whether the incidence of falls increases during pregnancy. STUDY DESIGN: Static postural balance measures were collected from 12 pregnant women at 11 to 14, 19 to 22, and 36 to 39 weeks gestation and at 6 to 8 weeks after delivery and from 12 nulligravid control subjects who were matched for age, height, weight, and body mass index. Subjects were asked to stand quietly on a stable force platform for 30 seconds with eyes open and closed. Path length and average radial displacement were computed on the basis of the average of 3 trials for each condition. The women were asked at each session if they had sustained a fall in the previous 3 months. RESULTS: Postural stability remained relatively stable during the first trimester; however, second and third trimester and postpartum values for path length and average radial displacement with eyes open and closed were increased significantly compared with the control subjects, which indicates diminished postural balance. The difference between the eyes open and closed values of path length increased as pregnancy progressed. Although 25% of pregnant women sustained falls, none of the control subjects had fallen in the past year. CONCLUSION: These data suggest that postural stability declines during pregnancy and remains diminished at 6 to 8 weeks after delivery. The study also indicates that there is an increased reliance on visual cues to maintain balance during pregnancy.

Accidental Falls↗

PubMed1999

Specificity of the monocular crescents of the visual field in postural control.

Postural reactions elicited by monocular visual stimulation in the temporal crescent of the visual field were studied in adult subjects in dynamic balance on a rocking platform. Circular translation of a visual scene was induced in the temporal crescent by the rotation of membrane prisms placed laterally to the stimulated eye. In anteroposterior balance, postural reactions are identical whichever eyes is stimulated: ventral extension of the body when the visual scene moves upwards and dorsal extension when it moves downwards. In lateral balance, postural reactions vary with the stimulated eye: extension of the right side of the body when the right eye is stimulated by an upward displacement of the visual scene, extension of the left side when the left eye is stimulated. This difference, which contrasts with the similarity of reactions elicited by the stimulation of either para-foveal fields, suggests that the most peripheral part of the nasal retina has a specific role in head and body stabilisation.

Adult↗

PubMed1999

The role of vision on postural strategy evaluated in patients affected by congenital nystagmus as an experimental model.

The role of vision in postural control is crucial and is strictly related to the characteristics of the visual stimulus and to the performance of the visual system. The purpose of this investigation was to evaluate the effects of chronically reduced visual cues upon postural control in patients affected by Congenital Nystagmus (CN). These patients have developed since birth a postural strategy mainly based on vestibular and somatosensorial cues. Fifteen patients affected by CN and 15 normal controls (NC) were enrolled in the study and evaluated by means of dynamic posturography. The overall postural control in CN patients was impaired as demonstrated by the equilibrium score and by the changes of the postural strategy. This impairment was even more enhanced in CN than in NC group when somatosensorial cues were experimentally reduced. An aspecific pattern of visual impairment and a pathological composite score were also present. Our data outline that in patients affected by CN an impairment of the postural balance is present especially when the postural control relies mainly on visual cues. Moreover, a decrease in accuracy of the somatosensory cues has a proportionally greater effect on balance than it has on normal subjects.

Adult↗

PubMed1998

Postural control in benign paroxysmal positional vertigo before and after recovery.

Thirty-two patients affected by idiopathic benign paroxysmal positional vertigo (BPPV) of the posterior semicircular canal were studied before, 3 days and I month after a resolutive Semont manoeuvre by means of dynamic posturography. The overall postural control in BPPV patients was shown to be impaired, as demonstrated by the pathological equilibrium scores. Data obtained before treatment showed a specific pattern of vestibular involvement and a pathological composite score. After the liberatory manoeuvre the Sensory Organization Test indicated a significant improvement in the pathological composite and vestibular scores. However, significant differences from controls were still detected 3 days and 1 month after clinical recovery from BPPV. The results clearly show that, in BPPV patients, there is an impairment of the vestibular system, which seems unable to maintain a normal postural balance. This deficit can be particularly detected when dynamic posturography evaluates the vestibular cues. After the liberatory manoeuvre a consistent improvement in the overall postural control has been observed but the residual differences from controls seem to suggest that damage to the otoconial maculae influences postural control, even when there is significant improvement in the clinical signs.

Analysis of Variance↗

PubMed1983

Compensation of vestibular symptoms in hemilabyrinthectomized guinea pigs. Role of the sensorimotor activation.

The effect of sensorimotor activation on compensatory rate of vestibular asymmetries after unilateral labyrinthectomy was analyzed in guinea pigs. An intensified sensorimotor activation was obtained by putting in water the animals immediately after the appearance of hemilabyrinthectomy (HL) symptoms. The water-maintained group exhibited a faster dampening of vestibular disturbances in comparison with control animals. Both ocular and postural asymmetries declined to about 50% of peak values after 2-3 h from HL, while in control group the same extent of recovery was achieved in 4-6 h from HL. It is concluded that the generalized activation of the ascending spinal pathways carrying exteroceptive and proprioceptive information to the vestibular nuclei represents a favourable condition for the regainment of ocular and postural balance impaired by HL.

Animals↗

PubMed2003

Understanding and treating "pusher syndrome".

"Pusher syndrome" is a clinical disorder following left or right brain damage in which patients actively push away from the nonhemiparetic side, leading to a loss of postural balance. The mechanism underlying this disorder and its related anatomy have only recently been identified. Investigation of patients with severe pushing behavior has shown that perception of body posture in relation to gravity is altered. The patients experience their body as oriented "upright" when the body actually is tilted to the side of the brain lesion (to the ipsilesional side). In contrast, patients with pusher syndrome show no disturbed processing of visual and vestibular inputs determining visual vertical. These new insights have allowed the authors to suggest a new physical therapy approach for patients with pusher syndrome where the visual control of vertical upright orientation, which is undisturbed in these patients, is the central element of intervention.

Accidental Falls↗

PubMed2002

Adapted physical activity in old age: effects of a low-intensity training program on isokinetic power and fatigability.

BACKGROUND AND AIMS: This pilot study measured the effects of an original low-intensity training program, called "posture-balancing-mobility" (PBM), on muscular function. METHODS: Nine non-disabled, elderly (74.3 +/- 6 years) subjects were trained with the PBM technique for 11 weeks (2 sessions per week). Mean power and fatigue index parameters were measured using an isokinetic dynamometer before and after training and compared with those recorded in another group of 9 elderly (71.1 +/- 4.3 years) subjects, who had performed aquatic exercises during the same period and with the same frequency. RESULTS: The mean power of the knee extension muscles increased slightly but significantly on the dominant (15.6%, p<0.05) and non-dominant sides (13.4%, p<0.05) in the PBM group, with no significant fatigue index variation. None of the parameters changed significantly for the aquatic group, and comparison of variations obtained in the two groups showed no significant difference between their respective effects. CONCLUSIONS: Although the results showed slightly enhanced strength production in the PBM group, the low statistical power does not allow conclusions about the impact of this type of training intervention in its current form. Nevertheless, this pilot study provides some indication of the benefits that can be obtained from such an individualized approach. Its efficiency would most likely be improved by further exploration of the minimal threshold of intensity required for strength exercises and by measurement of its effect on functions involving neuromuscular parameters, such as balance or gait.

Aged↗

PubMed2001

Automatic postural response systems in individuals with congenital total blindness.

This study examined the effects of the absence of vision from birth on automatic postural responses to platform displacements during stance. Postural responses were induced by producing randomly four types of perturbations which consisted of forward and backward translations, and toe up and down rotations. Nine congenitally totally blind and nine sighted adults served as subjects. EMG signals were recorded from four muscles in the right leg, and reaction time to somatosensory stimuli generated by platform displacements was measured by pushing a hand-held button. To assess the ability to control postural balance, the root mean square (RMS) values for lateral and antero-posterior sway before, during, and after perturbations were calculated. The EMG amplitude in the gastrocnemius muscle of a blind subject was smaller than that of a sighted subject with eyes closed. No significant differences were found between blind and sighted subjects in EMG latencies of the lower extremity muscles in response to perturbations. The blind subjects had significantly faster reaction times to somatosensory stimuli triggered by platform displacements, but in toe down rotations no significant difference was found between blind and sighted subjects. The difference in the EMG latencies and reaction times between the two groups suggests that blindness from birth may not affect the spinal stretch reflex, but may affect a volitional act mediated through the motor cortex. There were also no significant differences in the RMS values for postural sway between blind and sighted subjects with eyes open or closed, although blind subjects swayed more after backward translations than did sighted subjects with eyes open. Results suggest that the ability to control postural balance during perturbations was not affected by vision loss from birth. Our findings suggest that the automatic postural response systems of humans are unaffected by the absence of vision from birth and are rather hard wired.

Adaptation, Physiological↗

PubMed2004

The effect of anxiety on postural control in humans depends on visual information processing.

To examine the possibility that anxiety affects the control of postural balance, state anxiety, and body sway during orthostatic standing were measured twice in college students with an interval of 1 month. Correlations between the changes in state anxiety and the parameters of body sway were examined by Pearson's correlation analysis. The changes in the enveloped area of body sway and in the maximum length of the antero-posterior body sway showed a positive correlation with the changes in state anxiety (r = 0.543 and 0.659, respectively). The data showed that an increase in anxiety caused instability in the control of postural balance. These correlations were abolished when the eyes were closed. In conclusion, anxiety affects the processing of visual input and influences the net performance of postural control.

Adult↗

PubMed1975

Biomechanical appraisal of some skeletal features associated with head balance and posture in the Hominoidea.

The condylar position index, condylar angle and the area of insertion of the nuchal musculature corrected for condylar position, direction of muscle pull and skull size were determined in Homo sapiens, Gorilla, Pan and the casts of two Neanderthal and two australopithecine crania. In all three attributes, the values of H. sapiens exceeded, by statistically significant amounts, those for the ape genera. The greater value for the condylar position index indicates a better balance of the head, that for the condylar angle reflects the more vertical orientation of the vertebral column while that for the corrected nuchal area suggests a less effective nuchal musculature in H. sapiens as compared to the apes. In the casts of the Neanderthal crania, the values all came within, or close to, the ranges for H. sapiens. In the australopithecine casts, the condylar angle cane within the ranges for H. sapiens while the condylar position index and the corrected nuchal area were intermediate in value between H. sapiens and the extant apes. These findings are consistent with observations from other skeletal regions that while Australopithecus had an upright posture, this creature was, in the complex of posturally significant morphological features, distinct from extant hominoids.

Animals↗

PubMed2001

Anxiety affects the postural sway of the antero-posterior axis in college students.

To examine whether the postural balance is influenced by the degree of anxiety, body sway during orthostatic standing while gazing at a visual target was examined in college students. Students, physically and mentally healthy, were divided into two groups according to the degree of state anxiety; high anxiety group (HA) and low anxiety group (LA). A fast Fourier transform analysis of the postural sway in antero-posterior axis showed that frequency components of 0.02-0.21 Hz, reflecting vestibular inputs, were 16% greater and those of 2.02-10.0 Hz, reflecting somatosensory inputs, were 24% smaller in HA. These differences between HA and LA were abolished when the eyes were closed. It is concluded that the interactions of visual inputs with vestibular and somatosensory inputs are influenced by anxiety.

Adolescent↗

PubMed1979

Height vertigo and human posture.

A theory is presented supporting a geometrical explanation for physiological height vertigo being a distance vertigo through visual destabilization of postural balance when the distance between the eyes and visible stationary contrasts becomes critically large. Physiological and posturographic data obtained under natural height vertigo conditions are consistent with this hypothesis.

Humans↗