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At least 1,279 records · Page 71Linked to original sources
PubMed2004

Postural control mechanisms during quiet standing in patients with diabetic sensory neuropathy.

OBJECTIVE: The objective of the present study was to compare postural mechanisms identified by using dual force platform in healthy elderly community-dwelling subjects and diabetic sensory neuropathy (DSN) patients under different visual conditions. RESEARCH DESIGN AND METHODS: The presence and the severity of the sensory neuropathy was evaluated with a clinical scale. Postural mechanisms and motor strategies of the ankle and hip joints were quantified by testing subjects in quiet stance on a dual force platform under two visual conditions (eyes open and eyes closed). Root mean square (RMS) values of the center of pressure (COP) time-varying signals and normalized cross-correlation function were used to estimate the contribution and the interdependence of postural control mechanisms. RESULTS: DSN patients show larger RMS values of the COP(net) displacement in both anteroposterior and mediolateral (ML) directions. Motor strategies at the ankle joints are altered in DSN patients compared with healthy elderly subjects particularly in the ML direction. CONCLUSIONS: This experiment is the first to highlight that even with vision, postural mechanisms at the ankle joints are impaired in DSN patients during quiet standing. Our results point out the importance of focusing on postural control instability in ML of DSN patients.

Aged↗
PubMed1977

Relationship of field-dependence--independence to posture and judgment of time duration.

Relationships between 84 field-dependent subjects and 84 field-independent subjects, posture, and judgment of duration of time were examined. An analysis of variance yielded no significant difference between the two groups of subjects in the judgment of a 40-sec. interval while in the standing, sitting or horizontal postures or in the comparison of the three postures. Mean judgments of durations became larger from standing to sitting to horizontal postures and over trials for the three postures. It was suggested that the lengthening of the judgment of the 40-sec. interval could be related to a decrease in kinesthetic stimulation with a resultant increase in muscular relaxation which led to a decrease in vigilance.

Adolescent↗
PubMed1993

Development of a system for analyzing working postures.

In order to assist in the analysis of working postures which might cause lumbago in the field of industrial health, a system was developed for the synchronous recording and analyzing of postures, work content and physiological data. The system is composed of a portable unit for recording 3 channels of goniometers, 1 channel of inclinometer and 1 channel of surface electromyogram, a video camera for recording work content, a host computer and some peripheral devices for analyzing the data from the portable unit and video camera. In this system, postures are automatically classified from data on joint angles and upper body inclination angle by using a discriminant function. The joint angles are measured by the goniometers using rubber optical fibers. The angle of upper body inclination is obtained by the inclinometer using a magnetic resistance sensor. In addition to the work content and video images, the postures and the electromyogram can be analyzed and confirmed by simultaneous display of the data on the host computer screen. Based on the trial use of this system in a work model of manual baggage handling, it was proved useful for evaluating in detail the workload caused by working postures.

Electromyography↗
PubMed1993

Effect of the aircast on unilateral postural control: amplitude and frequency variables.

Little objective data exist regarding the effect of the Aircast Air-Stirrup on motor performance. Thus, the effect of the Aircast on the amplitude and frequency of postural sway during unilateral stance was evaluated for 15 uninjured male subjects. Postural sway during static and dynamic tests was measured using the Chattecx Balance System. Use of the Aircast improved unilateral postural control as evidenced by decreases in some of the components of postural sway. Previously, a link was made between a large amplitude of unilateral sway and a high probability of ankle injury (14). Thus, since Aircast use was found to decrease the amplitude of unilateral sway, it may also be beneficial in reducing the probability of injury. Although the scope of this study did not allow for differentiation among the complex systems involved in postural control, the possibility of the Aircast enhancing afferent feedback was proposed. The restricted inversion-eversion range of motion associated with the Aircast, in conjunction with the present observation that unilateral stability was enhanced with its use, suggests that the Aircast may provide a valuable prophylactic role in helping to reduce the incidence of ankle injuries.

Adult↗
PubMed1993

Reliability of measuring forward head posture in a clinical setting.

We believe there is a need to identify a practical method for determining objective measurement of forward head posture. In our study, we determined the within-tester and between-tester reliabilities for clinical measurements of static, sitting, forward head posture using the cervical range of motion (CROM) instrument. Repeated measurements were made using a standardized protocol on 40 patients seated in a standardized position. The seven testers had from 1 to 8 years of clinical experience. All measurements were recorded by the same investigator. The intraclass correlation coefficient (ICC[1,1]) was used to quantitate within-tester and between-tester reliability. Measurements of forward head position performed by the same physical therapist had high reliability (ICC = 0.93). Good reliability (ICC = 0.83) was demonstrated when different physical therapists measured the forward head posture of the same patient. We concluded that measurements of forward head posture made by physical therapists trained in the correct use of the CROM instrument are reliable. This reliability is important for determining the effectiveness of treatment programs. On the basis of our data, the CROM instrument will assist clinicians in the objective evaluation and reassessment of the patient population demonstrating forward head posture.

Adult↗
PubMed1995

Posture in patients with shoulder overuse injuries and healthy individuals.

Assessment of posture is an integral component of patient evaluation with shoulder overuse injuries. However, the professional literature contains relatively few studies that have assessed the relationship between posture, function, and injury. The purpose of this study was to determine the relationship and differences in postural variables within and between subjects with overuse injuries to the shoulder of healthy subjects. Thirty patient subjects and 30 healthy subjects matched for age and gender were recruited. Scapular protraction and rotation, forward head position, midthoracic curvature, and passive humeral elevation in the plane of the scapula were measured randomly in standing. All measurement techniques were standardized and validated. Intrarater and interrater reliability for all clinical measures were established before data collection. Forward head position was significantly greater (p < .001) in the patient group than the healthy group; humeral elevation was significantly greater (p < .001) in the healthy group than in the patient group and in the uninvolved shoulders (p < .01) than the involved shoulders within the patient group. Scapular protraction, rotation, midthoracic curvature, and scapular symmetry were not significantly different between groups. Scapula protraction and rotation were significantly related (p < .05) in the patient group. No other postural variables were related. Conclusions regarding the influence of posture to shoulder injury are inconclusive based on several confounding variables that may have affected the outcome.

Adolescent↗
PubMed1975

Postural behavior and motion sickness.

(1) An interesting style of acting was demonstrated on a stage of a Kyogen, a classic comedy of Japan, titled "Funawatashimuko", i.e., "A boatman and a bridgegroom in a boat". Antagonistic postures which move toward the opposite direction were displayed by a boatman who is pulling an oar and a passenger who is being moved by the rolling of a boat. (2) Why doesn't one suffer from motion sickness when he drives a car but may suffer from it when he is a passenger? This question was answered, from the standpoint of human postures, by observing the antagonistic postures exhibited by a bus-driver and a passenger, and also by the findings in postrotatory eye nystagmus (an indication of artificial motion sickness) which was varied according to the three different positions of the head. (3) Learning postural adjustment against motion sickness, developing through repetitively traveling in vehicles, was also objectively shown in a posture of an experienced lady bus-conductor whose body inclined in the same direction as that of the driver. Its similarity to the establishment of a kinetic labyrinthine reflex in chickens was explained.

Animals↗
PubMed1992

The effect of posture on three objective audiological measures.

This study examines the effect of posture on click evoked otoacoustic emissions, tympanic membrane displacement, and travelling wave velocity obtained using the auditory brainstem response. Statistically significant changes with posture were observed for each technique. The changes in evoked emission and tympanic membrane displacement measurements were comparable with those reported by previous experiments. Travelling wave velocity measurements were shown to be sensitive to inferred posturally-induced changes in labyrinthine fluid pressure of around 150 mm saline. There was no statistically significant correlation between posturally-induced changes measured by the three techniques. It is suggested that different mechanisms are responsible for the posturally-induced changes observed for the three techniques.

Adult↗
PubMed1995

Postural control and vestibulospinal function in patients selected for cochlear implantation.

Postural control, vestibular and eye motor function were evaluated in seven postlingually deaf patients before cochlear implantation and were compared with 21 control subjects. Vibration to the calf muscles or galvanic electrical stimulation of the vestibular nerves, perturbed stance and body sway velocity, statistical variance of antero-posterior body sway and identification of characteristic parameters of postural dynamics were all evaluated. Vibration-induced body sway was increased among the patients compared with the normal subjects and there were differences in characteristic parameters of postural dynamics, indicating decreased postural control. Galvanic stimulation induced a body sway not significantly different from the control group suggesting that the patients selected for cochlear implantation, and with an otherwise reduced postural control, are sensitive to electrical stimulation of the vestibular nerve. Thus, postlingually deaf subjects who perceive a sensation of sound at electrical promontorial stimulation also respond with increased body sway to electrical stimulation aimed at the vestibular nerves. This finding may contribute an additional hypothesis to the causes of dizziness among cochlear implant patients, complementary to the that of wrongly placed electrodes and peroperative vestibular lesions.

Adult↗
PubMed1991

Dissociation of plasma atrial natriuretic peptide responses to upright posture and furosemide administration in patients with normal-, low renin essential hypertension and primary aldosteronism.

Plasma levels of atrial natriuretic peptide (ANP) were measured in patients with normal renin essential hypertension (n = 12), low renin essential hypertension (n = 11) and primary aldosteronism due to aldosterone producing adenoma (APA, n = 8) and idiopathic hyperaldosteronism (IHA, n = 3) after overnight rest in the supine position and after 4 h upright posture and furosemide administration. Plasma renin activity (PRA) and aldosterone (Aldo) levels were also determined. Compared to normal renin essential hypertension (33.6 +/- 2.2 pg/ml), basal plasma ANP was significantly higher in low renin essential hypertension (66.8 +/- 6 pg/ml), IHA (54.1 +/- 6.3 pg/ml) and APA before (62.4 +/- 4.9 pg/ml) but not after adrenal surgery (22 +/- 3 pg/ml). After upright posture and furosemide administration plasma ANP was decreased (p less than 0.01) in patients with low renin and, less markedly, with normal renin essential hypertension, however not in IHA and APA. In about half of the patients with low renin essential hypertension, unchanged PRA after upright posture and furosemide administration was associated with increased plasma Aldo and decreased ANP levels. We conclude that (i) the relatively high basal plasma ANP levels in low renin essential hypertension, IHA and APA may reflect the presence of volume expansion in these patients; (ii) the hormonal responses to upright posture and furosemide administration in patients with normal and low renin essential hypertension may indicate a counterregulatory role of ANP during activation of the renin-angiotensin-aldosterone system; (iii) the high plasma ANP, which is unresponsive to upright posture and furosemide administration, in patients with APA and IHA may be a potentially interesting new finding whose pathophysiological significance remains to be established.

Adult↗
PubMed1979

Postural effects on nystagmus response during caloric labyrinthine stimulation in patients with adolescent idiopathic scoliosis. II. An electro-nystagmographic study.

An electro-nystagmographic study of postural effects on the nystagmus response has been performed in 40 patients with adolescent idiopathic scoliosis aged from 10 to 16 years. The control group comprised 29 healthy children of the same age. Caloric labyrinthine stimulation was done in the supine and erect position. The results were analysed with the aim of finding out whether an increased scoliotic deformity might influence the labyrinthine response. For comparison of the nystagmus response in the two different positions a quotient of the values (degrees/second) obtained from cold water stimulation in the erect and supine position was calculated. In the control children the labyrinthine response in erect posture was half of the response in supine posture. In erect posture the scoliotic deformity increased. This obvious change in the spine did not increase the caloric response from the convex side labyrinth. The predominance of the convex side labyrinth observed in the supine position was thus not seen in the erect position. The results of this study did not support the assumption that a postural deformity in the spine can influence a calorically induced labyrinthine response.

Adolescent↗
PubMed2004

Variations of tool and task characteristics reveal that tool-use postures are anticipated.

The authors examined anticipation in tool use, focusing on tool length and tool-use posture. Adults (9 women and 9 men in each experiment) held a rod (length 0.4-0.8 m), with the tip upward; walked toward a cube; chose a place to stop; and displaced the cube with the rod's tip. In 2 experiments, rod length, mass, and mass distribution, and the size of the cube were manipulated. Chosen distance depended on rod length and cube size. Because effects of cube size on distance resulted only from postural changes related to required control, distance anticipated displacement posture. A postural synergy comprising legs and trunk provided a stable platform for the displacement. An arm synergy was less extended for small cubes, longer rods, and handle-weighted rods. Selected distance anticipated those postures.

Adult↗
PubMed2005

Postural stability and hand preference as constraints on one-handed catching performance in children.

Effects of postural state and hand preference as constraints on 1-handed catching performance were investigated in different ability groups of children aged 9-10 years. On the basis of pretest data, the authors classified 48 participants into groups of good, intermediate, and poor catchers (n = 16 in each) and asked them to perform 1-handed catches with their preferred and nonpreferred hands while standing and sitting. The good catchers' performance was not affected by the imposed postural constraints but did improve when they used the preferred hand. A similar effect of hand preference was evident in the intermediate and poor catchers, but there was also an effect of postural constraint. Independent of hand preference, intermediate catchers' performance while seated improved significantly compared with that during standing. For poor catchers, there was an interaction between hand preference and posture; significant improvement was evident only when they used the preferred hand in the sitting condition. The finding that manipulation of posture and hand preference affected performance outcomes indicates that perceptual skill is not the only influence on catching performance in children. Manipulation of those key constraints may facilitate the acquisition of catching skill, but more research is needed to determine the permanence of those effects.

Aptitude↗
PubMed2002

Visuo-tactile links in covert exogenous spatial attention remap across changes in unseen hand posture.

We investigated the effect of unseen hand posture on cross-modal, visuo-tactile links in covert spatial attention. In Experiment 1, a spatially nonpredictive visual cue was presented to the left or right hemifield shortly before a tactile target on either hand. To examine the spatial coordinates of any cross-modal cuing, the unseen hands were either uncrossed or crossed so that the left hand lay to the right and vice versa. Tactile up/down (i.e., index finger/thumb) judgments were better on the same side of external space as the visual cue, for both crossed and uncrossed postures. Thus, which hand was advantaged by a visual cue in a particular hemifield reversed across the different unseen postures. In Experiment 2, nonpredictive tactile cues now preceded visual targets. Up/down judgments for the latter were better on the same side of external space as the tactile cue, again for both postures. These results demonstrate cross-modal links between vision and touch in exogenous covert spatial attention that remap across changes in unseen hand posture, suggesting a modulatory role for proprioception.

Adolescent↗
PubMed2002

Influences of hand posture and hand position on compatibility effects for up-down stimuli mapped to left-right responses: evidence for a hand referent hypothesis.

Unimanual left-right responses to up-down stimuli show a stimulus-response compatibility (SRC) effect for which the preferred mapping varies as a function of response eccentricity. Responses made in the right hemispace and, to a lesser extent, at a midline position, are faster with the up-right/down-left mapping than with the up-left/down-right mapping, but responses made in the left hemispace are faster with the up-left/down-right mapping. Also, for responses at the midline position, the preferred mapping switches when the hand is placed in a supine posture instead of the more usual prone posture. The response eccentricity effect can be explained in terms of correspondence of asymmetrically coded stimulus and response features, but it is not obvious whether the hand posture effect can be explained in a similar manner. The present study tested the implications of a hypothesis that the body of the hand provides a frame of reference with respect to which the response switch is coded as left or right. As was predicted by this hand referent hypothesis, Experiment 1 showed that the influence of hand posture (prone and supine) on orthogonal SRC was additive with that of response location. In Experiment 2, the location of the switch relative to the hand was varied by having subjects use either a normal grip in which the switch was held between the thumb and the index finger or a grip in which it was held between the little and the ring fingers. The magnitudes of the mapping preferences varied as a function of the grip and hand posture in a manner consistent with the hand referent hypothesis.

Functional Laterality↗
PubMed1991

Stimulus-response compatibilities between vertically oriented stimuli and horizontally oriented responses: the effects of hand position and posture.

Stimulus-response (S-R) compatibility effects between vertically oriented stimuli (above or below fixation) and horizontally oriented responses (left or right switch deflections by a single hand) have been shown to depend both on which hand responds (Bauer & Miller, 1982) and on the location at which the response is made (eccentricity on a frontoparallel line; Michaels, 1989). In the latter study, hand position and hand posture were confounded, so it is unclear which variable determined the compatibility effect. In Experiment 1, the importance of effector position was tested. Vertically oriented stimuli were paired with a horizontal response solicited at different locations but always involving the same hand posture. Compatibility effects emerged, and their direction depended on position. In Experiment 2, the compatibilities were not evident in a simple reaction time paradigm, so the effect was not due to differential ease of responses. In Experiment 3, a change in hand posture (palm up or palm down) at the same location (the body midline) also affected the compatibilities. It was concluded that the S-R compatibility of orthogonally oriented stimuli and responses is influenced by (1) which hand responds, (2) the location of that hand, and (3) its posture. The results imply that both postural and positional states of the action system affect S-R compatibility.

Fixation, Ocular↗
PubMed1998

Computer mouse position as a determinant of posture, muscular load and perceived exertion.

OBJECTIVES: This study concerned the influence of 6 positions of the computer mouse on the work table on posture, muscular load, and perceived exertion during text editing. METHODS: An optoelectronic 3-dimensional motion analysis system was used to register the postures of 10 men and 10 women using video display units. Muscular load was also registered (with electromyography), as was perceived exertion (with rating scales). RESULTS: A neutral posture with a relaxed and supported arm showed the least perceived exertion, and the electromyographic results showed low activity in both trapezius muscles in this position. Short operators (all women) showed a numerically higher activity in the 4 examined muscles than the tall operators (all men, except 1). This finding could be related to lower muscle force among women and to anthropometric differences, which also influence biomechanic load moments. Narrow-shouldered operators (8 women and 1 man) and short operators worked with larger outward rotation and abduction of the shoulder in a position of the mouse lateral to the keyboard than the broad-shouldered (7 men and 2 women) and tall operators did. Arm support markedly reduced muscle load in the neck-shoulder region among the operators. CONCLUSIONS: The operators using video display units in this study preferred to use the mouse on a table in a close to relaxed, neutral posture of the arm in combination with arm support. Short and narrow-shouldered operators worked in more strenuous postures of the arm when the mouse was located lateral to the keyboard.

Adult↗
PubMed1997

Age-related differences in performance of stereotype arm movements: movement and posture interaction.

Postural destabilizations in response to cyclic pull-and-push arm movements were compared in young and elderly subjects, with the goal of determining how age-related differences in postural stability influence strategies of cyclic arm movements made at different speeds, against different loads and while standing on support surfaces of different compliances. The results show that elderly subjects performed the experimental task more slowly with a lower mean movement frequency and a smaller amplitude. Despite of this fact, the elderly's upright posture was destabilized by this movement to a greater extent than in young subjects. The older adults exhibited lower damping of the disturbing torques produced by arm movements as evidenced by a higher amplitude of the center of foot pressure excursions. The results document close reciprocal motor and posture interaction and indicate that parameters of the voluntary movement task such as cyclic arm movements might be used as a sensitive measure of postural stability.

Adult↗