SEARCH · PubMed Health

Results for “Postural control”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources

PubMed1984

Mathematical modeling and simulation of the postural control loop. Part III.

The engineering analysis and modeling of the neuromuscular system is an exciting and challenging area of research where we may learn something about the principles of controlling large, complex systems. This review is limited to the most peripheral subsystem: the postural control loop. In the first part, we reviewed the input-output properties of the motoneuron pool, modeling of the motor unit action potential, and analysis of the interference electromyographic activity. Aslo included were the engineering techniques to quantitatively study electromyographic activity and its relationship to muscle force. The second part of this review focuses on the biomechanical models of the muscle based on Hill's work as well as the modern sliding filament theory. This section also includes models of the proprioceptive receptors: the muscle spindle organ and the Golgi tendon organ. In this final paper we discuss various models and simulations of the peripheral loop and their applications to study physiological system behavior such as tremor.

Afferent Pathways↗

PubMed2005

[Immediate effects of physiotherapy session of lower limb by balneotherapy on postural control].

OBJECTIVE: The aim of this study was to compare the immediate effects of standard physiotherapy (S) and balneotherapy (B) on the postural capacity of subjects with lower-limb injuries. METHODS: The postural sway of 12 voluntary subjects was evaluated before (REF1 and REF2) and after two different physiotherapy sessions performed in the swimming pool (B) or under (S). The centre of pressure (CP) trajectory was recorded by use of a force platform. CP displacements in the mediolateral and anteroposterior axes were then separated into two elementary superimposed components: the horizontal motion of the centre of gravity (CG) and the difference between the CP and the vertical projection of the CG (CP-CG). The amplitude of the latter component (CP-CG) is thought to express neuromuscular activity. All trajectories were then analysed in terms of classical and frequency parameters. RESULTS: Postural sway did not differ before and after the physiotherapy sessions. Following both sessions, the mean CG velocity decreased significantly (P<0.5). The area of CP-CG trajectory was diminished solely by the aquatic exercise (P<0.5) and was associated with decreased amplitude of motion along the anteroposterior axis (P<0.05), which suggests decreased neuromuscular activity to maintain posture. CONCLUSION: Interestingly, decreased motion was observed along the anteroposterior axis, which corresponds to ankle movements. Exercising lower-limb muscles under water could reinforce proprioceptive input, resulting in a better postural control.

Adolescent↗

PubMed1992

[Study in predictive posture control during the performance of actions].

In order to maintain an ordinary upright posture, the body's center of gravity must be predicted and controlled on the supporting surface based on synthesis of multiple-sensory inputs. In order to evaluate the accuracy of predictive (feedforward) posture control during the performance of actions, we measured maximal shifts in the body's center of gravity using a force platform in 6 normal adults under two visual conditions (with eyes open and closed) and four standing conditions (one-legged; heel to toe posture; and both legs together or apart). Subjects were asked to perform five kinds of voluntary actions (static standing; head tilting forward, backward and laterally; head turning; bending forward; and maximal inclinations to the anterior, posterior and lateral directions). The smaller the supporting surface, the more markedly displacement of the body's center of gravity was increased upon closing the eyes. This finding suggests that the accuracy of predictive posture control decreases as a result of the reduction in the number of multisensory inputs which determine spatial orientation. Assessing purposive shifts in center of gravity during voluntary actions, we can conclude that the body's center of gravity is accurately controlled even in the presence of head movements under ordinary standing conditions. To evaluate balance during the performance of routine actions, we must devise a better method of discriminating purposive shifts in center of gravity from control disorder errors as well as a method of quantifying the accuracy of feedforward regulation.

Adult↗

PubMed1984

Mathematical modeling and simulation of the postural control loop--Part II.

The engineering analysis and modeling of the neuromuscular system is an exciting and challenging area of research where we may learn something about the principles of controlling large, complex systems. This review is limited to the most peripheral subsystem: the postural control loop. In the first part, we reviewed the input-output properties of the motoneuron pool, modeling of the motor unit action potential and analysis of the interference electromyographic activity. Also included were the engineering techniques to quantitatively study electromyographic activity and its relationship to muscle force. The second part of this review focuses on the biomechanical models of the muscle based on Hill's work as well as the modern sliding filament theory. This section will also include models of the proprioceptive receptors: the muscle spindle organ and the Golgi tendon organ. In the final paper we will discuss various models and simulations of the peripheral loop and their applications to study physiological system behavior such as tremor.

Action Potentials↗

PubMed2006

Assessment of seated postural control in children: comparison of a force platform versus a pressure mapping system.

OBJECTIVE: To establish the validity and reliability of a pressure mapping system to measure seated postural control in children. DESIGN: A concurrent validity and reliability study. SETTING: Gait and posture laboratory of a rehabilitation center. PARTICIPANTS: Thirteen able-bodied children volunteers. INTERVENTION: Measurements were taken on a seating simulator in quiet sitting and while reaching. The localization of the center of pressure (COP) in the anteroposterior and mediolateral directions was measured simultaneously by means of a pressure mapping system and a force platform. MAIN OUTCOME MEASURES: Concurrent validity was first assessed by Pearson and Spearman correlation coefficients and then by Student paired t tests and Wilcoxon signed-rank test (P<.05) on the range and root mean square (RMS) amplitudes of COP. Reliability was evaluated using intraclass correlation coefficients and coefficients of variation. RESULTS: The COP signals were significantly correlated between both instruments for the RMS and range in both tasks and directions (mean r> or =.87) and for the time series while reaching (r> or =.99), as well as during quiet sitting (r> or =65). Both instruments showed generally fair to good reliability in quiet sitting and excellent reliability when reaching. CONCLUSIONS: The pressure mapping system can detect the COP displacement as effectively as the force platform. In a clinical context, it could help in the evaluation of seated stability and also help in evaluating the efficacy of seating components for wheelchair users.

Adolescent↗

PubMed1983

Descriptive analysis of static postural control in 4, 6, and 8 year old normal and motorically awkward children.

The purpose of the study was to analyze static postural control in 4, 6, and 8 year old normally and slowly developing children using qualitative electromyographic (EMG) techniques. Fourteen normally developing and six motorically awkward children performed seven different static balance tasks; twelve different muscle groups were monitored electromyographically. Results indicated that average amplitude of EMG activity involved in static postural task performance decreased with increasing age for normally developing children. Motorically awkward children displayed greater amounts of muscular activity in task performance than did normal children of similar chronological ages. Muscle activity profiles of motorically awkward children were clearly unlike those of normally developing children. The suggestion is made that one of the important characteristics of neuromuscular development in normal children is a gradual refinement of both localization and level of muscle activity.

Action Potentials↗

PubMed2004

Impaired postural control in patients affected by tension-type headache.

Sixteen subjects, affected by chronic tension-type headache (TTH) accordingly to the International Headache Society Classification (1988) criteria, in presence of tenderness in pericranial muscles,with a mean age of 37+/-11.8 years, and ten healthy volunteer subjects, age and sex matched, were submitted to postural analysis by Static Posturography (S.Ve.P. Amplaid). Aim of the study was to evaluate whether patients with TTH have disturbed postural control, as compared to normal subjects. Postural analysis considered all posturographic variables but focused on spectral frequency analysis of body sway. In both open (OE) and closed eyes (CE) condition, spectral frequency analysis showed a significantly increased body sway at low (OE= p < or = 0.01; CE= p < or = 0.01) and middle (OE= p < or = 0.01; CE= p < or = 0.01) frequencies on the antero-posterior (y) plane and at low frequencies (OE= p < or = 0.05; CE= p < or = 0.05) on the lateral (x) plane. Statistical analysis was performed using the Student's t test for unpaired data, p value 0.05 defined significant. The proprioceptive input seems to be predominant at middle and high frequencies in maintaining posture, our results seem then to suggest a proprioceptive disturbance in TTH patients. The disturbance is likely related to chronic pericranial muscle contraction and tenderness. Posturography and spectral analysis may help not only in the diagnosis of a postural disturbance but even more in the follow-up of TTH patients, during and after a medical and/or a rehabilitative treatment.

Adult↗

PubMed2004

Can Tai Chi improve vestibulopathic postural control?

OBJECTIVES: To evaluate the rationale and scientific support for Tai Chi as an intervention for vestibulopathy and to offer recommendations for future studies. DATA SOURCES: A computer-aided search, including MEDLINE and Science Citation Index, to identify original Tai Chi studies published in English; relevant references cited in the retrieved articles were also included. STUDY SELECTION: A preliminary screening selected all randomized controlled trials (RCTs), non-RCTs, case-control studies, and case series that included Tai Chi as an intervention and had at least 1 outcome variable relevant to postural stability. DATA EXTRACTION: Authors critically reviewed studies and summarized study designs and outcomes in a summary table. DATA SYNTHESIS: Twenty-four Tai Chi studies met screening criteria. No studies specifically studying Tai Chi for vestibulopathy were found. Collectively, the 24 studies provide sometimes contradictory but generally supportive evidence that Tai Chi may have beneficial effects for balance and postural impairments, especially those associated with aging. Ten RCTs were found, of which 8 provide support that Tai Chi practiced alone, or in combination with other therapies, can reduce risk of falls, and/or impact factors associated with postural control, including improved balance and dynamic stability, increased musculoskeletal strength and flexibility, improved performance of activities of daily living (ADLs), reduced fear of falling, and general improvement in psychologic well-being. Studies using other designs support the results observed in RCTs. CONCLUSIONS: At present, few data exist to support the contention that Tai Chi specifically targets the impairments, functional limitations, disability, and quality of life associated with peripheral vestibulopathy. There are, however, compelling reasons to further investigate Tai Chi for vestibulopathy, in part because Tai Chi appears useful for a variety of nonvestibulopathy etiologic balance disorders, and is safe. Especially needed are studies that integrate measures of balance relevant to ADLs with other psychologic and cognitive measures; these might help identify specific mechanisms whereby Tai Chi can remedy balance disorders.

Humans↗

PubMed2000

Effects of back extensor strength training versus balance training on postural control.

PURPOSE: Aim of this study was to investigate effects of 1) regular back extensor strength training as opposed to balance training, and 2) the influence of the sequence of both training types on postural control, force, and muscle efficiency. METHODS: Twenty-six young, healthy subjects were investigated at baseline, 1 month and 2 months later. At each examination, subjects completed a posturographic, balance skill, and isometric maximum voluntary (MVC) back extension testing, including surface electromyographic (SEMG) recordings. After baseline evaluation, subjects were assigned to either daily strength training or balance training. After 1 month, the type of training was exchanged between groups. RESULTS: After 1 month, back extensor strengthening led to decreased postural stability on hard surface, whereas there were no change after balance skill training. Analysis of the low- and high-frequency components of the sway signal revealed that strength training increased control efforts as indicated by an increased high-frequency component in order to maintain postural stability and unchanged low-frequency component. Balance skill training, however, increased postural stability as indicated by a decreased low-frequency component. The control effort remained unchanged. After completing either sequence of training, all postural parameters remained unchanged in both groups. Muscular efficiency as measured by SEMG root mean square during a standardized motor skill task revealed improved muscle economy regardless of the type of training. Back extension torque improved in both groups. CONCLUSION: To avoid reduction of postural stability in rehabilitation processes, we recommend to include antagonist muscles in a comprehensive strength training regime or balance skill training.

Adult↗

PubMed2002

The Spectral Qualities of Postural Control are Unaffected by 4 Days of Ankle-Brace Application.

OBJECTIVE: To determine if the spectral qualities of medial-lateral (ML) and anterior-posterior (AP) center of pressure during a 1-legged stance are affected by 4 days of ankle-brace application. DESIGN AND SETTING: The study, which consisted of a pretest-posttest randomized group design, took place in the Sports Injury Research Laboratory at Indiana State University. SUBJECTS: Twenty-eight Indiana State University students, who had not suffered from any ankle injuries within the past 2 years and were free of any neurologic or vestibular disorders, participated in the study. MEASUREMENTS: The effects of 3 independent variables on mean frequency amplitude for both ML and AP center of pressure were examined: (1) treatment (brace, control), (2) frequency bin (0%-20%, 20%-40%, 40%-60%, 60%-80%, and 80%-100% of area), and (3) time (pretest, immediately after brace application, and after 1, 2, 3, or 4 days of brace wear). RESULTS: We detected no difference (P >.05) for the ML or AP mean frequency when comparing the brace and control groups. CONCLUSIONS: Application of an ankle brace may not require modifications in the postural-control strategies during a 1-legged stance in subjects with healthy ankles.

Journal Article↗

PubMedDate not supplied

[Gait disorders and falls from the neurologic viewpoint. 1. Basic principles: postural control in the aged].

In the framework of gait, disturbances in old age falls of neurologic origin are either due to pareses of the lower extremities or to postural dyscontrol. The latter shows, either alone or in combination, age-associated alterations in its afferent, efferent, and central-integrative components. Considering gait in the elderly as the flexible maintenance of dynamic equilibrium this overview describes the age-associated alterations of postural control.

Accidental Falls↗

PubMed1993

Postural control of fish related to gravity input.

The disappearance of gravity input during space flight causes many functional disorders in animal and human postural control system. On the other hand, it has been shown that these functional deficits reduce or disappear with time and adapt to weightlessness. Unusual fish behavior was reported during the first few days of orbit flight and also during postflight recovery in Skylab 3 experiment. Similar fish behavior was observed in microgravity obtained during the parabolic flight of airplane. These results suggest that fish might provide a good model for investigating adaptation of sensory-motor interaction in microgravity. The fish generally show a "dorsal light response (DLR)" indicating how these postural mechanisms concern with the environment. That is, when a light is presented laterally, a fish rolls its dorsal surface toward the light an equilibrium point between the gravity vector and the light source vector. In addition, the DLR after bilaterally labyrinthectomy or changes of the DLR in microgravity show the involvement of other factors related to the changes of gravity. In this investigation, the behavioral changes of bilaterally labyrinthectomized (BL) and unilaterally labyrinthectomized (UL) fish adapted for more than 3 months on the ground postoperatively were used to analyze whether buoyancy was affected by injecting of a contrast medium into the swimming bladder.

Adaptation, Physiological↗

PubMed1997

Analysis of the posture control system under fixed and sway-referenced support conditions.

To delineate the relative roles of each of the feedback sensors in the posture control system such as the visual, vestibular, and proprioceptive sensors, an identification technique was applied to measurements of antero-posterior sway angeles of the body and ankle moments under the following conditions: standing on a fixed support with eyes open (ox), standing on a fixed support with eyes closed (cx), standing on a sway-referenced support with eyes open (os), and standing on a sway-referenced support with eyes closed (cs). Frequency response functions from the sway angle to the ankle moment were calculated. Gain and phase characteristics for conditions (os) and (cs) were similar to those of Nashner's vestibular model in the high-frequency range, which shows that the vestibular system may be dominant. The gain was higher under condition (cx) than under (ox). Judging from the phase characteristics, this was probably due to increased weighting of the proprioceptive sensor over the vestibular sensor. There was a tendency for gain to increase as balance tasks became more demanding.

Adult↗

PubMed1996

Postural control in the older adult.

Age-related changes in the neural, sensory, and musculoskeletal systems can lead to balance impairments that have a tremendous impact on the ability to move about safely. The many complex substrates of the posture control system subserve a common functional goal: regulation of the relationship between the center of mass and the base of support. Traditional approaches, which have focused on the control of the center-of-mass displacement, have documented age-related changes in "feet-in-place" responses: during quiet standing, during volitional movement, or in response to applied perturbation. Recently, increasing attention has been directed toward the control of the base of support, that is, compensatory leg and arm movement, as an important element of the postural repertoire, and early results suggest profound age-related impairment in the control of compensatory stepping movements. For both feet-in-place and stepping responses, control of lateral stability appears to be a major problem associated with increased risk of falling. In view of age-related differences in ability to adapt postural responses under predictable task conditions, future work will likely benefit by mimicking, as much as possible, the varied and unpredictable nature of the events that often precipitate falls in daily life, in order to draw connections between the laboratory or clinic and "real-life" stability.

Accidental Falls↗

PubMed2005

Ankle joint proprioception and postural control in basketball players with bilateral ankle sprains.

BACKGROUND: Deficiencies in ankle proprioception and standing balance in basketball players with multiple ankle sprains have been reported in separate studies. However, the question of how ankle proprioceptive inputs and postural control in stance are related is still unclear. HYPOTHESIS: Ankle repositioning errors and the amount of postural sway in stance are increased in basketball players with multiple ankle sprains. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty healthy male basketball players and 19 male basketball players who had suffered bilateral ankle sprains within the past 2 years were examined. Both groups were similar in age. Passive ankle joint repositioning errors at 5 degrees of plantar flexion were used to test for ankle joint proprioception. The Sensory Organization Test was applied with dynamic posturography to assess postural sway angle under 6 sensory conditions. RESULTS: A significant increase in ankle repositioning errors was demonstrated in basketball players with bilateral ankle sprains (P < .05). The mean errors in the right and left ankles were increased from 1.0 degrees (standard deviation, 0.4 degrees ) and 0.8 degrees (standard deviation, 0.2 degrees ), respectively, in the healthy players to 1.4 degrees (standard deviation, 0.7 degrees ) and 1.1 degrees (standard deviation, 0.5 degrees ) in the injured group. A significant increase in the amount of postural sway in the injured subjects was also found in conditions 1, 2, and 5 of the Sensory Organization Test (P < .05). Furthermore, there were positive associations between averaged errors in repositioning both ankles and postural sway angles in conditions 1, 2, and 3 of the Sensory Organization Test (r = 0.39-0.54, P < .05). CONCLUSIONS: Ankle repositioning errors and postural sway in stance increased in basketball players with multiple ankle sprains. A positive relationship was found between these 2 variables. CLINICAL RELEVANCE: Such findings highlight the need for the rehabilitation of patients with multiple ankle sprains to include proprioceptive and balance training.

Adult↗

PubMed1995

An investigation into the development of early postural control.

Eighteen normal infants were studied longitudinally using video and photographic records of their levels of lying and sitting ability. A developmental sequence of postural control in lying and sitting was confirmed in the normal infants. All infants reached level 4 prone and supine lying ability before achieving level 3 sitting ability (maintaining independent sitting). 34 children with cerebral palsy in a cross-sectional study could be ascribed a level of sitting or lying ability. The relationship found in normal infants between lying and sitting was confirmed in all the children with cerebral palsy.

Adolescent↗

PubMed2005

[The relationship between visual perception and postural control in falls of the elderly living in local communities].

We have examined the relationship between visual sense information, such as perception data and postural control, and falls among elderly people aged 65 years or over living in Nishibiwajima-cho, Aichi Prefecture. Of 286 participants, 204 were enrolled and analyzed, after excluding those with a visual acuity of less than 0.3, or the activities of daily living (ADL) index of less than 11. In the analysis group, 52 people (25.2%) had already had experience of falls. Two-way analysis of variance showed that intensity of dynamic visual stimulation and the presence or absence of falls had a significant effect on body sway, although no interaction was observed. These results indicate that body sway is increased in those who have experience of falls, and that strong visual stimulation is associated with body sway. This suggests that greater dynamic visual stimulation is likely to increase the risk of falls.

Accidental Falls↗

PubMed2006

Neck muscle fatigue and postural control in patients with whiplash injury.

OBJECTIVES: To examine if patients with whiplash injury show identifiable increases in neck muscle fatigability and associated increase in postural body sway after contractions of dorsal neck muscles, and if physiotherapy treatment reduces these effects. METHODS: Sway was measured during stance in 13 patients before and after 5 min of isometric dorsal neck muscle contractions and after recovery, pre- and post-physiotherapy, using a force platform. Amplitude and median frequency of neck muscle EMG were calculated during the contracting period. After each stance trial, patients gave a subjective score of sway. RESULTS: Pre-treatment, seven patients showed EMG signs of fatigue (increases in amplitude, decreases in median frequency) and increases in sway (eyes closed) after contractions. The other patients showed neither fatigue nor increased sway. Post-treatment, no signs of fatigue or imbalance were recorded in all patients, for the same levels of muscle contraction. CONCLUSIONS: As in normal human subjects, increases in sway are associated with signs of neck muscle fatigue in some whiplash injury patients. Physiotherapy decreases the susceptibility to fatigue of neck muscles and is an effective choice of treatment of subjective instability and sway. SIGNIFICANCE: This study demonstrates a pathophysiological link between neck muscle fatigue and impaired postural control, and also that physiotherapy can relieve symptoms and signs of impaired neck muscle function by reducing muscle fatigability.

Adult↗