The effects of postural balancing on tracking efficiency of blind subjects: a pilot study.
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Adolescent↗
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[A plea for the adoption of a neutral balanced posture for the registration of centric relation].
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Dental Occlusion, Centric↗
Postural sway analysis of a teenager with childhood lead intoxication--a case study.
We had an opportunity to study a 15-year-old boy, evaluating the long-term effect of early childhood lead (Pb) poisoning on the maturation of postural balance. Postural balance (or sway) was quantified using a microprocessor-based Force Platform System along with four postural tasks specifically designed to indirectly challenge and/or minimize the effect of vision, proprioception and vestibular systems relevant for postural stability. The Pb-intoxicated patient showed increased postural sway compared to those of non-poisoned young adults and a 14-year-old boy for postural tasks requiring input from higher centers. A review of historical information and results of the physical and neurological examinations did not reveal an alternative explanation for this patient's postural sway abnormalities. These responses are also comparable to those noted in younger children with chronic Pb-exposure histories. In summary, this case study gives suggestive evidence that early excessive exposure to Pb can have long-term, detrimental neurological effects as reflected by postural stability. Measurement of postural balance appears to be a sensitive research methodology to assess subclinical neurological effects of remote lead intoxication.
Adolescent↗
The effects of an attentional demand tasks on standing posture control.
The present study sought to determine if the postural sway of a subject required to grasp a tray (motor task) holding a cup filled with water and prevent spilling (mental task), would be reduced by consciously redirecting attention to maintain the tray in a horizontal position. We hypothesized the mental task would increase the stabilization of standing postural balance. Postural sway was measured in 17 normal subjects under the following conditions: 1) holding a 100 g weight in each hand (total 200 g; no mental task), 2) holding with both hands a tray on which 200 g was placed (tray-holding task), and 3) holding with both hands a tray on which a cup filled with water weighing 200 g was placed in the center (mental task). Postural sway was significantly reduced during the mental task versus other tasks. Standing posture balance was stabilized when a mental task was added. Thus, we concluded that higher brain functions such as attention and consciousness exerted a significant influence over the control of standing posture.
Adult↗
Posture and balance responses to a sensory challenge are related to anxiety in mice.
Anxiety disorders and balance disorders share common clinical features related to perception such as spatial disorientation or dizziness. The search for the mechanism underlying this core of symptoms led us to investigate impairments in multisensory integration. In mice, the 'rotating beam test' allows analysis of changes in balance control and posture in response to a multisensory challenge. We used the BALB/c and C57BL/6 inbred strains of mice, known for their contrasted anxiety-related behavior. The level of anxiety was also manipulated using anxiolytic and anxiogenic pharmacological compounds. Despite equal sensori-motor abilities, anxious mice were more prone to fall off the rotating beam and showed more imbalance than non-anxious mice. Striking inter-strain differences in posture were also observed. Diazepam and beta-CCM reversed these strain-specific responses in opposite directions. We demonstrated that balance and postural strategies developed in response to a multisensory challenge vary as a function of the level of anxiety in mice.
Animals↗
Modelling of the biomechanics of posture and balance.
A technique for studying the relationship of posture to balance has been developed. To investigate this relationship quantitatively, the human body was treated as consisting of 11 rigid body segments, each with six degrees of freedom. A bilateral Selspot II/TRACK data acquisition system provides position and orientation kinematic data for estimation of the trajectories of the individual body segment centers of gravity. From these, the whole body center of gravity is estimated and compared to concurrent force plate center of force data. Center of gravity and center of force excursions agree where dynamics are not significant. The technique may be employed to study quiet stance, response to postural disturbances, or the initiation and coordination of complex movements such as gait.
Adolescent↗
Changes in posture and balance with age.
Changes in posture with age are of concern because of their association with impaired mobility and the possibility of falls. In this study alignment of the joint centers and balance of body segments were measured in 41 women, aged 65 and older, and correlated with weight, age, change in height, and activity. Balance was assessed by calculating the whole-body center of gravity, and the partial centers of gravity above the knee and hip. Compared to a younger reference population, the older subjects had greater kyphosis, a more posterior hip position, and leaned forward more from the hips (more anterior center of gravity above the hips). Among the 41 elderly subjects, larger kyphoses correlated with greater decrease in height. Elderly subjects who were inactive tended to learn more, but forward lean was not correlated to other variables. These findings suggest two separate sets of changes: an osteoporosis-related stooping, and also a forward lean that may relate to muscular weakness or to fear of instability. Posture among the elderly was quite varied and did not follow any one pattern of change.
Adult↗
A multi-purpose rehabilitation frame: an apparatus for experimental investigations of human balance and postural control.
Moving and rotating platforms are often used in experimental investigations of human balance and postural control. These devices are not well suited for testing elderly and neurologically impaired individuals, because of inherent risk of injury to the experimental subject due to a potential fall. This paper describes a novel mechanical apparatus that generates perturbations to a standing subject by applying pushing forces at the level of the pelvis and can also provide restoring forces in the case of destabilization. The device has two degrees of freedom, which are actuated by hydraulic servo systems, and can deliver a perturbation in any direction comprised within anterio-posterior and medio-lateral postural space. The accuracy and repeatability of the perturbations elicited in eight different directions was evaluated. The results, showing a high degree of correlation between the trajectories in both degrees of freedom of the apparatus, demonstrate that accurate and repeatable perturbations can be imposed on the subjects tested.
Biomechanical Phenomena↗
Learning to coordinate redundant degrees of freedom in a dynamic balance task.
The present study investigated Bernstein's [The co-ordination and regulation of movements, 1967] proposal regarding the three stages of learning in the changing coordination and control of redundant joint-space degrees of freedom. Six participants practiced maintaining balance on a moving platform that was sinusoidally translated in the anterior-posterior direction for 30 trials on day 1 and 10 trials on day 2. At the beginning of practice, the motion of the torso and limb segments was less coherent in the attempt to compensate for the movement of the support surface in retaining a balanced posture. However, with practice, the organization of a compensatory postural coordination mode became highly coherent and also progressively utilized the passive, inertial forces generated by the movement of the support surface. The findings support the propositions that: (a) the pathway of change over time in the coordination pattern of the torso and joint motions depends on the task goal and constraints to action and (b) the changes in limb and torso motion are in support of the learning of a global body center of mass/platform dynamic.
Adult↗
Effects of isokinetic ankle fatigue on the maintenance of balance and postural limits.
OBJECTIVE: To quantify changes in balance parameters and ranges of postural control at the ankle after isokinetic fatigue. DESIGN: Before-after trials, with a 5 x 6 repeated-measures design. SETTING: General community. PARTICIPANTS: Twenty-four men (age, 24.9 +/- 3.92y; height, 177.79 +/- 6.36cm; weight, 80.78 +/- 13.22kg) without ankle trauma within 2 years. INTERVENTIONS: Fatigue of the plantarflexors and dorsiflexors was induced by isokinetic contractions. Balance was assessed by using a unilateral test (15-s quiet stance, 10-s lean test) on a force platform immediately before and at 0 (T0), 10 (T10), 20 (T20), and 30 (T30) minutes postfatigue. MAIN OUTCOME MEASURE: Mediolateral (ML) and fore-aft (FA) sway as well as ML and FA displacement were analyzed by analysis of variance with repeated measures for time (alpha =.05). RESULTS: In quiet stance, ML sway was greater at T0, whereas total sway increased at all time points postfatigue (P < .05). For the lean test, FA sway increased at T0 and T10, and total sway increased at all time points (P < .05). Both ML and FA displacement significantly differed at T0 (P < .05). All sway parameters returned to baseline within 20 minutes. CONCLUSIONS: Isokinetic fatigue of ankle plantarflexors and dorsiflexors significantly influences sway parameters and ranges of postural control in healthy young men. These perturbations are transient, and recovery occurs within 20 minutes.
Adult↗
A clinical model for the assessment of posture and balance in people with stroke.
PURPOSE: The lack of models to define and describe rehabilitation processes have often been identified as limiting research and the development of clinical practice. This study describes the development of a clinical model to address a key aspect of stroke physiotherapy--the assessment of posture and balance. METHOD: Twenty seven experienced neurological physiotherapists (PT) in six focus groups were used. Participants were shown photographs of a typical stroke patient in sitting and standing positions and were asked 'What would you note if you were assessing the posture and balance of this patient?' Answers were displayed on flip charts to allow immediate feedback about the accuracy and completeness of data. Thematic content analysis was then used. RESULTS: A complex reasoning process emerged to answer three main questions: What can the patient do? How does s/he do it? Why does s/he do it that way? To answer these questions physiotherapists established balance disability (by observing the patient's ability to perform a series of increasingly demanding balance tasks), identified postural and movement impairments (by observing alignment and movement of body segments relative to each other and to the expected norm for that patient) and assessed muscle activity (by observation and palpation). CONCLUSIONS: Focus groups have been used to elicit a clinical model for the assessment of posture and balance, the content of which will be used to inform a new outcome measure.
Evaluation Studies as Topic↗
The effect of backpack weight on the standing posture and balance of schoolgirls with adolescent idiopathic scoliosis and normal controls.
Concerns have been raised regarding the effect of carrying a backpack on adolescent posture and balance, but the effect of backpack loading combined with other factors affecting balance, such as adolescent idiopathic scoliosis (AIS), has not been determined. This study examines the effects of backpack load on the posture and balance of schoolgirls with AIS and normal controls. The standing posture of 26 schoolgirls with mild AIS (mean age 13, Cobb angle 10-25 degrees ) and 20 age-matched normal schoolgirls were recorded without a backpack and while carrying a standard dual-strap backpack loaded at 7.5%, 10%, 12.5% and 15% of the subject's bodyweight (BW). Kinematics of the pelvis, trunk and head were recorded using a motion analysis system and centre of pressure (COP) data were recorded using a force platform. Reliable COP data could only be derived for 13 of the subjects with AIS. Increasing backpack load causes a significantly increased flexion of the trunk in relation to the pelvis and extension of the head in relation to the trunk, as well as increased antero-posterior range of COP motion. While backpack load appears to affect balance predominantly in the antero-posterior direction, differences between groups were more evident in the medio-lateral direction, with AIS subjects showing poor balance in this direction. Overall, carrying a backpack causes similar sagittal plane changes in posture and balance in both normal and AIS groups. Load size or subject group did not influence balance, but the additive effect of backpack carrying and AIS on postural control alters the risk of fall in this population. Therefore, load limit recommendations based on normal subjects should not be applicable to subjects with AIS.
Adolescent↗
An integrated EMG/biomechanical model of upper body balance and posture during human gait.
Full scale biomechanical and EMG analyses of the balance during human gait are required to understand the neural control of locomotion. The purpose of this paper was to develop an inverted pendulum model of upper body balance in both the plane of progression and the frontal plane, and a medical/lateral balance model of the total body. EMG evidence was also recorded to reinforce the conclusions from the moment of force analyses. The kinematics and kinetics for up to ten natural walking trials on each of four subjects and EMG records from walking trials on eleven subjects were investigated. The results support the following conclusions. (1) The hip extensors/flexors have an over-powering role in maintaining dynamic balance of the head, arms and trunk (HAT) in the plane of progression. Because of the lack of suitable neurological and biomechanical delays between the small head acceleration, presumably exciting vestibular afferents, and the hip moment patterns, the vestibular system appears not to be involved as a feedback sensor in the balance control during gait. (2) In the frontal plane, the hip abductors are dominant in countering the large medial-lateral (M/L) imbalance of HAT during single support but are assisted by the medial acceleration of the hip joint. (3) the total body M/L balance is achieved by the M/L placement of the foot with some opposition and some assistance by the M/L acceleration of the subtalar joint. The subtalar invertors/evertors play an insignificant role during single stance.(ABSTRACT TRUNCATED AT 250 WORDS)
Arm↗
Balance and strength of elderly Chinese men and women.
The purpose of this study was to examine whether there was a difference between Chinese men and women in postural balance, and muscular strength and endurance; and the effect of participation and non-participation in regular exercise by these elderly Chinese adults on postural balance, and muscular strength and endurance. Chinese men (n = 328) and women (n = 210), age 65 to 80 years, were recruited as subjects (n=538). They were grouped by age: 65-69 (G1), 70-74 (G2), and 75-80 (G3) years old, and classified by exercise status as participation (E) and non-participation in regular exercise (NE). All subjects underwent the following tests: one-leg standing balance with eyes open (OEB) and eyes closed (CEB), timed sit-to-stand from a chair (STS), and repeated sit-to-stand from a chair for 30 sec (STS30). Analysis of covariance (2 x 2 ANCOVA) with weight, height and body mass index as covariates revealed that there were differences (p<0.05) between genders, age, and exercise status for the OEB and CEB tests. The OEB & CEB tests performance declined with advancing age in both E & NE groups. For the STS test, no difference was detected between genders, but there was a difference between age and exercise status. For the STS30 test, there was a difference between genders, age, and exercise status. Based on the present results, it was concluded that: 1) the 75-80 yr old elderly Chinese men and women showed greater decline in postural balance, and muscular strength and endurance compared to the younger (age 65-70 yr) elderly persons, 2) elderly Chinese women were poorer in postural balance, and in muscular strength and endurance relative to men, 3) participation in regular exercise helped in the retainment of postural balance, and of muscular strength and endurance compared to the non-exercisers.
Age Factors↗
Is balance or posture at the end of a voluntary movement programmed?
Two leg movements, differing only by the final balance conditions, were analysed to determine whether the final body posture or the equilibrium were taken into account by the motor programming. The test movement was a flexion-extension of a lower limb executed at maximal velocity. The initial body posture was bipedal, while the final one was either bipedal or unipedal. The biomechanical and electromyographic data showed significant differences between parameters of the two movements. The results indicate that the final body equilibrium is the major parameter controlled.
Biomechanical Phenomena↗
Kinematic response characteristics of the CAREN moving platform system for use in posture and balance research.
The CAREN system is a new and unique device for use in postural and balance research in clinical settings due to its ability to independently perturb the support surface in each of six degrees of freedom. Users of this system need knowledge of its technical performance which is not available. The aim of this study was to determine the technical performance of the CAREN system by defining its kinematic response characteristics to two commonly used input functions (sine and ramp) for each of its six translational and rotational axes. The translational and rotational displacement, velocity and acceleration limits of the CAREN system suggest that it is a mid-range system with regard to single degree of freedom moving platform devices reported in the literature. The maximum average displacement cross-talk was 1.5% of the viable working range in any specified direction. The maximum average velocity cross-talk was 3.3% of its maximum velocity in any specified direction. The CAREN system was able to respond to ramp input functions within its displacement and velocity limits although, for short duration ramps, there was evidence that target velocity was not reached. It is concluded that the CAREN system is an appropriate device for postural and balance research with some unique features. This specification of its technical performance should help researchers to identify the tasks for which it is most suitable.
Biomechanical Phenomena↗
An accelerometry-based system for the assessment of balance and postural sway.
The aim of this investigation was to develop an inexpensive, efficient system for the clinical assessment of static and dynamic balance and postural sway using accelerometry-based measurements. Subjects consisted of 10 young (range 18-32 years) and 10 older (range 69-86 years) individuals screened for polypharmacy and history of cardiovascular, neurological or orthopedic health conditions. A lightweight uniaxial accelerometer and general-purpose microcomputer were used to obtain measurements of postural sway. Customized software was written to acquire the data and provide a real-time display consisting of amplitude and frequency characteristics of the sway profile. Intraclass reliability coefficients greater than R = 0.75 were obtained in both eyes-open and challenging-standing balance tasks. Preliminary results demonstrate that the instrumentation can be used to discriminate among balance tasks and to differentiate healthy older adults from those with a tendency toward frequent falls. Moreover, the technique described yields a simple-to-administer, inexpensive procedure that can be conducted in the home or another natural environment. Accelerometry also allows for balance training and re-learning, using tasks that might ordinarily pose a balance challenge for the older or frail adult.
Adolescent↗
Comparison of a functional obstacle course with an index of clinical gait and balance and postural sway.
BACKGROUND: Older adults commonly experience falls because of balance and mobility problems. Better assessment methods are needed to understand and correct balance and mobility disorders. METHODS: We used a low technology, functional obstacle course (FOC) to measure balance and mobility in 352 community-dwelling elderly participants. To establish concurrent validity of the FOC, we compared performance on the FOC with two established measures of balance and mobility: performance on the Tinetti Index (TI) and postural sway area measured on a force platform. RESULTS: Bivariate correlation analyses revealed significant inverse correlations between FOC completion time, the TI balance and gait subscores, and the TI total score (r = -.73 to -.78). The FOC quality scores and TI balance and subscores gait and TI total scores (r = .76 to .82) were significantly positively correlated. FOC time had significant, but small, positive correlations with sway area with eyes open (r = .18) and closed (r = .17) and nonsignificant correlation with sway area with visual feedback. FOC quality also had significant, but smaller, inverse correlations with sway area with eyes open (r = -.024) and closed (r = -.015), and nonsignificant correlation with sway area with visual feedback. Regression analysis showed that TI gait and balance measures accounted for most of the variance found in FOC performance. CONCLUSIONS: Our findings support the position that the FOC and the TI measure dynamic balance, whereas postural sway measures a different aspect of balance. Advantages of the FOC include the evaluation of environmentally influenced falls and balance problems.
Accidental Falls↗