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At least 613 records · Page 34Linked to original sources

PubMed2006

Postural control in nurses with and without low back pain.

BACKGROUND: Low back pain (LBP) is common in nurses, but it is unclear if the pain is associated with measurements of postural control. Objective measurements of function might be useful in the evaluation of patients with LBP in order to evaluate and predict disability, and in the study of the pathophysiology of chronic LBP. METHODS: In a cross-sectional study, we measured the number of postural adjustments, and degree of posterior-lateral sway in 81 nurses, using a computerized postural sway four-platter measurement system. RESULTS: There were 41 (56.6%) nurses who complained of LBP at the time of testing, and another 12 (14.8%) with a past history of LBP. Nurses with LBP consistently used more postural adjustments to keep their balance (p<0.003), and in some positions postural adjustments were positively associated with the degree of past and present pain. LBP was not significantly associated with the degree of lateral sway. CONCLUSIONS: Nurses either with present or a past history of LBP use an increased number of postural adjustments to maintain balance. Studies are warranted to determine if postural testing can predict the development of LBP or aid in determining appropriate preventive measures.

Adult↗

PubMed2006

The association between head and cervical posture and temporomandibular disorders: a systematic review.

AIMS: To carry out a systematic review to assess the evidence concerning the association between head and cervical posture and temporomandibular disorders (TMD). METHODS: A search of Medline, Pubmed, Embase, Web of Science, Lilacs, and Cochrane Library databases was conducted in all languages with the help of a health sciences librarian. Key words used in the search were posture, head posture, cervical spine or neck, vertebrae, cervical lordosis, craniomandibular disorders or temporomandibular disorders, temporomandibular disorders, and orofacial pain or facial pain. Abstracts which appeared to fulfill the initial selection criteria were selected by consensus. The original articles were retrieved and evaluated to ensure they met the inclusion criteria. A methodological checklist was used to evaluate the quality of the selected articles and their references were hand-searched for possible missing articles. RESULTS: Twelve studies met all inclusion criteria and were analyzed in detail for their methodology and information quality. Nine articles that analyzed the association between head posture and TMD included patients with mixed TMD diagnosis; 1 article differentiated among muscular, articular, and mixed symptomatology; and 3 articles analyzed information from patients with only articular problems. Finally, 2 studies evaluated the association between head posture and TMD in patients with muscular TMD. Several methodological defects were noted in the 12 studies. CONCLUSION: Since most of the studies included in this systematic review were of poor methodological quality, the findings of the studies should be interpreted with caution. The association between intra-articular and muscular TMD and head and cervical posture is still unclear, and better controlled studies with comprehensive TMD diagnoses, greater sample sizes, and objective posture evaluation are necessary.

Head↗

PubMed2006

Resting position variables at the shoulder: evidence to support a posture-impairment association.

BACKGROUND AND PURPOSE: A relationship between posture and impairment at the shoulder is theorized, but not supported by evidence. It is proposed that posture and impairment are not directly related, but linked by movement dysfunction. The purpose of this analysis was to explore the relationships among posture, pectoralis minor muscle length, and movement alterations at the shoulder. SUBJECTS: Subjects who were asymptomatic for shoulder pathology were divided into 2 groups of 25 subjects each based on normalized pectoralis minor muscle resting length. METHODS: Scapula orientation, thoracic kyphosis, and pectoralis minor muscle lengths were measured, and ratios and indexes of postural variables were calculated. All variables were analyzed for correlations and group differences. RESULTS: Significant group differences were demonstrated for several posture variables, including thoracic spine kyphosis and scapular internal rotation. The distance from the sternal notch to the coracoid process demonstrated the highest correlation with pectoralis minor muscle length. DISCUSSION AND CONCLUSION: The findings indicate a relationship between posture and pectoralis minor muscle length and support a proposed model linking posture, an anatomical variable, movement dysfunction, and impairment.

Adult↗

PubMedDate not supplied

The effects of weight load and joint immobilization on reorganization of postural tremor.

To investigate change in coordinative strategies due to wrist immobilization and index loading, postural tremors from the index, hand, and forearm were recorded during different postural holding tasks. The wrist joint was immobilized with a thermoplastic splint in the constrained condition, and a copper mass of 100 grams was applied to the index finger in the loaded condition. The structures of the postural tremors of all upper limb segments among the unloaded-unconstrained, unloaded-constrained, loaded-unconstrained, and loaded-constrained conditions were compared. Index loading exaggerated index/forearm postural tremor, while the load-induced tremor enhancement was no longer evident for wrist immobilization. In the unloaded condition, wrist immobilization resulted specifically in enhancement of carpal postural tremor, rather than in the index and forearm. Index loading induced a marked tremor peak and relative power in the range of 5-8 Hz. Wrist immobilization potentiated the carpal tremor peak of 1-4 Hz in association with enhancement of carpal-forearm mechanical coupling. In light of structural changes in postural tremor, our data suggest that (1) a wrist splint is effective to counteract load-induced enhancement of postural tremor, and (2) freezing of the wrist joint might facilitate compensatory strategies to minimize passive fluctuation transmission from the carpal to index.

Adolescent↗

PubMed2006

Neck muscle activation and head postures in common high performance aerial combat maneuvers.

INTRODUCTION: Neck injuries are common in high performance combat pilots and have been attributed to high gravitational forces and the non-neutral head postures adopted during aerial combat maneuvers. There is still little known about the pathomechanics of these injuries. METHODS: Six Royal Australian Air Force Hawk pilots flew a sortie that included combinations of three +Gz levels (1, 3, and 5) and four head postures (Neutral, Turn, Extension, and Check-6). Surface electromyography from neck and shoulder muscles was recorded in flight. Three-dimensional measures of head postures adopted in flight were estimated postflight with respect to end-range of the cervical spine using an electromagnetic tracking device. RESULTS: Mean muscle activation increased significantly with both increasing +Gz and non-neutral head postures. Check-6 at +5 Gz (mean activation of all muscles = 51% MVIC) elicited significantly greater muscle activation in most muscles when compared with Neutral, Extension, and Turn head postures. High levels of muscle co-contraction were evident in high acceleration and non-neutral head postures. Head kinematics showed Check-6 was closest to end-range in any movement plane (86% ROM in rotation) and produced the greatest magnitude of rotation in other planes. Turn and Extension showed a large magnitude of rotation with reference to end-range in the primary plane of motion but displayed smaller rotations in other planes. DISCUSSION: High levels of neck muscle activation and co-contraction due to high +Gz and head postures close to end range were evident in this study, suggesting the major influence of these factors on the pathomechanics of neck injuries in high performance combat pilots.

Adult↗

PubMed2006

Relations of the morphological characteristic latent structure and body posture indicators in children aged seven to nine years.

With the aim of determining the connection between the indicators of body posture and latent structure of morphological variables in children aged 7 and 8 years, first and second grade of primary school, a set of 17 morphological measures and 12 body posture indicators were longitudinally applied to a sample of 110 boys and 114 girls. The latent structure of morphological variables in both sexes was defined by three factors but at a different order of significance: in boys, the order was longitudinal dimensionality, voluminosity, mass and subcutaneous fat tissue and transverse dimensionality, whereas in girls the order was voluminosity, mass and subcutaneous fat tissue, longitudinal dimensionality and transverse dimensionality. The latent structure of torax body posture indicator was defined by two factors, the status of body posture of the rear part of the thorax, and status of the body posture of the front part of the thorax. The results obtained by canonical correlation analysis between predictive variables, morphological latent structure and criterion variables, latent structure of thorax body posture indicators with two posture indicators of the chest and one of the foot status, showed two important pairs of canonical roots on each measurement, suggesting a significant association between these two sets of parameters.

Body Weights and Measures↗

PubMed1989

Quantitative assessment of head and shoulder posture.

Posture of the head, neck, and shoulders has long been recognized as a factor contributing to the onset and perpetuation of cervical pain dysfunction syndromes. Treatment regimens frequently include exercises and instruction for postural correction. Clinical assessment of posture, however, tends to be subjective in nature. The purpose of this study was to determine the reliability of a new objective technique of posture measurement and to establish normal standards for the technique. This study used a computer-assisted slide digitizing system called Postural Analysis Digitizing System (PADS) to determine characteristic values for head and shoulder girdle posture and characteristic range of motion for head protraction-retraction and shoulder protraction-retraction in a sample of able-bodied young men. PADS is a modification of a two-dimensional slide digitizing system developed for measuring trunk range of motion. Twenty male subjects were photographed in a neutral position, the maximally protracted position, and the maximally retracted position of the head and scapula. Ten subjects were evaluated once, and ten were evaluated twice. The slide photographs were analyzed using a computer-assisted digitizing system. Well-defined anatomic landmarks were used to determine angular relationships in the head, neck, and shoulders. The reliability of the system was tested by calculating an intraclass correlation coefficient, student t-test, and the percent error for each position. The positions were considered reproducible, and reliability of the system was considered adequate for postural analysis. Mean values for the positions were 28.48 degrees, 51.97 degrees, and 62.09 degrees for head protraction, the neutral position, and head retraction, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Postural disequilibrium quantification in children with chronic lead exposure: a pilot study.

Previous studies reported that some children who survive acute lead encephalopathy suffer from ataxia and have difficulties maintaining postural equilibrium. More recent studies have failed to quantify postural imbalance in association with lower levels of lead exposures, perhaps due to the insensitivity of the clinical measure. In our study, we noninvasively measured postural disequilibrium with a microprocessor-based force platform. The test provides a real time quantification of the body's center of gravity movement pattern. Measurements were made in a cohort of 33 inner city children (mean age: six years +/- 0.4 SD) with well documented blood lead histories. The average maximum blood lead of these children during their first six years of life was 23.5 micrograms/dl (range = 8.5 to 49.4). The children performed four postural tests [i.e., standing eyes open (EO) and closed (EC), on firm surface and standing on a compliant foam surface with eyes open (FO) and closed (FC)]. The results indicated that the maximum blood lead incurred during the second year of life was significantly positively related to postural sway, and the body balance was most affected in the EC test where visual cues were eliminated and proprioceptive feedback was not modified. Fetal Pb exposure levels as well as Pb exposures during the first year of life were not correlated with postural sway of six year olds. However, the maximum blood lead concentration beyond two years of life was significantly associated with the postural sway at six years of age.

Child↗

PubMedDate not supplied

Effect of posture on heart rate and cardiac axis of mice.

Effect of change in body posture on cardiac electrical axis has not been well documented. Hence the present work was undertaken to study the effect of passive head-up and head-down postures on ventricular QRS axis and heart rate of anesthetised mice. During head-up posture, there was a statistically significant (P less than 0.02) increase in heart rate whereas during head-down posture, the heart rate decreased insignificantly. These changes in heart rate can be explained on the basis of synus and aortic nerve mediated baroreceptor reflexes. Ventricular QRS axis showed a significant increase (P less than 0.02) during head-up posture and an insignificant decrease during head-down posture. A change in the posture is likely to produce a change in anatomical orientation of heart within the thorax resulting in alteration of electrical axis of the heart.

Anesthesia↗

PubMed1986

[Postural effects in the jugular phlebogram in patients with complete absence of the left pericardium].

To elucidate the function of the pericardium, alterations in jugular phlebograms, intracardiac pressures and cardiac volumes induced by postural changes were examined in seven patients with complete absence of the left pericardium. Ten patients with ischemic heart disease were studied as controls. Jugular phlebograms in patients with complete absence of the left pericardium showed decreased depths of the x descent and the tall v waves followed by the deep y descents (M-shaped pattern) in the supine position. These jugular abnormalities were exaggerated in the left lateral decubitus position. By contrast, the jugular phlebograms tended to return to normal, but remained abnormal in the right lateral decubitus position. Right atrial pressure curves showed similar postural effects. However, the jugular phlebograms and right atrial pressure curves in patients with ischemic heart disease were not altered by postural changes. The characteristic alterations of the jugular phlebograms are useful indicators for diagnosing complete absence of the left pericardium. The lack of a prompt decrease in pericardial pressure during ventricular ejection due to the absence of the pericardium is one of the causes of a decreased depth of the x descent in pericardial defect. However, this cannot explain the postural alteration of the jugular phlebogram. Another possible mechanism is the decreased excursion of the tricuspid ring during systole. As indicated in our previous report, there is anterior movement of the cardiac apex during systole in cases of pericardial defect, which is exaggerated in the left lateral decubitus position and decreased in the right lateral decubitus position due to the lack of normal pericardial support. This anterior swinging motion may inhibit the descent of the tricuspid ring toward the apex, resulting in a decreased depth of the x descent of the jugular phlebogram and the right atrial pressure curve and their postural alterations. The right ventricular volume as calculated from cardiac computerized tomography and the right ventricular end-diastolic pressure were not altered significantly by postural changes in the control cases. These indices increased to a greater extent in the left lateral decubitus position than in other postures in cases with pericardial defects.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMedDate not supplied

[Conditioned posture changes in dogs after systemic administration of dopaminergic agents].

Influence of systemic injection of some dopaminergic drugs on conditioned postural rearrangement prior to instrumental movement realization and on other motor components of instrumental reaction as well as on the performance of the instrumental task itself--was studied in chronic experiments in 5 dogs on a model of instrumental defensive reflexes connected with maintenance of a certain posture. Drugs were used influencing the nigrostriate dopaminergic system, i.e. dopamine agonist L-DOPA and haloperidol blocking dopamine striate receptors. All the motor components of the instrumental reaction and first of all conditioned postural rearrangement were modified by systemic haloperidol injection. Initial components of the postural rearrangement were modified to the greatest extent, in particular the period of preparation of the animal to the posture change increased. On the contrary, the latency of initiation of postural rearrangement was sharply shortened by systemic injection of L-DOPA. On the other hand, the main component of the postural change, i.e. redistribution of body mass among the bearing limbs (the values of which significantly increased after preliminary stimulation of the head of the caudate nucleus) changed insignificantly during modulation of the striatum dopamine level.

Animals↗

PubMed1984

Cellular mechanisms for modulation of posture by octopamine and serotonin in the lobster.

Injection of the monoamines octopamine and serotonin into the hemolymph of lobsters causes them to assume opposing static postures: octopamine causes a tonic extension of all extremities, while serotonin induces a tonic flexion. These amines have been shown previously to act as circulating neurohormones and to cause contraction of isolated exoskeletal muscles. The opposing postures elicited by amine injection do not appear to arise from peripheral actions, however, since serotonin and octopamine have similar effects on both flexor and extensor muscles. Instead, the amines are present within the central nervous system where they are probably released synaptically to activate coordinated patterns of tonic motor activity generating the observed postures. These motor patterns have been recorded from abdominal ganglia and involve the synchronized activation and inhibition of multiple excitatory and inhibitory motoneurons innervating the postural flexor and extensor muscles. These effects can be observed in an isolated abdominal ganglion. To begin a search for the cellular targets of amine action within the central nervous system, we recorded from identified postural motoneurons in abdominal ganglia. In two motoneurons that act to produce postural extension, octopamine reduced and serotonin raised the apparent threshold for action potential generation recorded in the somata. The amines do not significantly affect the resting potential or input resistance of the motoneurons measured in the cell bodies. Although the amine effect on motoneuron excitability could be due to actions directly on the motoneurons, our evidence suggests that at least part of the effect results from activation or inhibition of premotor interneurons: (1) an increase in EPSP frequency is observed in the motoneurons during octopamine superfusion, while a small decrease is observed during serotonin superfusion; (2) the amine effects on action potential threshold are abolished by cobalt ion. These results suggest that octopamine and serotonin have dual effects on posture: within the central nervous system, they act specifically to generate coordinated motor patterns for flexion or extension; as circulating neurohormones, they act nonspecifically to enhance the responses of exoskeletal muscles to motoneuronal activation.

Animals↗

PubMed1980

[Standing ataxia in cerebellar lesions. Differential diagnosis and pathophysiology of disorders of postural control].

Several forms of postural ataxia can be distinguished in cerebellar lesions by quantitative analysis of stance, a paleocerebellar, a vestibulocerebellar and a neocerebellar syndrome, for each of which a different underlying pathomechanism was found. The pathognomonic anterior-posterior 3 Hz postural tremor in the paleocerebellar syndrome is caused by delayed and enhanced long latency reflexes, which result in an oscillation of the posture control system. In the beginning disease this oscillation can be provoked by rapid tilt or electrical stimulation of the tibial nerves. The oscillation frequency correlates inversely with the severity of the disease. In contrast to that, postural ataxia in the vestibulocerebellar syndrome is caused by a loss of intersegmental reflex patterns and a loss of the systems set value. Patients with the neocerebellar syndrome show remarkably less instability. Disturbances are often only provoked by voluntary postural movements as in tracking experiments, which suggests a defect in the interfacing of postural and voluntary motor activity. These cerebellar atactic syndromes may be separated from several forms of postural ataxias of extracerebellar origin.

Cerebellar Ataxia↗

PubMed1996

The effect of wrist and arm postures on peak pinch strength.

This paper examines the effect of various arm postures on peak pinch strength. Twenty (20) able-bodied, male subjects volunteered to participate in a set of two experiments. The first experiment examined the effect of shoulder and elbow posture on peak pinch strength. The second experiment examined the effect of forearm posture, wrist posture, and pinch type on peak pinch strength. Results from the first experiment indicated that elbow posture had a significant effect on pinch strength. It was documented that extreme elbow flexion decreased pinch strength by up to 9%. Results from the second experiment indicated that deviated wrist postures, forearm postures, and pinch type significantly decreased pinch strength as much as 33%. Ergonomic guidelines which utilize the above factors as significant modifiers of pinch strength capacity may assist ergonomists to reduce the risk of injury and development of cumulative trauma disorders in the workplace.

Adult↗

PubMed1991

Opposite effects of agonist and inverse agonist ligands of benzodiazepine receptor on self-defensive and submissive postures in the rat.

The effects of benzodiazepine receptor ligands on different types of defensive behaviours were examined in intruder male rats confronted with offensive residents. Chronic administration, via a subcutaneous silastic pellet, of a full agonist (diazepam) for 15 days increased self-defensive postures as well as social and non-social behaviour whereas submissive postures and flight were reduced. Acute administration of a partial agonist (ZK 91296) resulted in a similar increase in self-defensive postures and a decrease of submission and non-social elements. Acute administration of a partial inverse agonist (FG 7142) reduced defensive postures and social behaviour whereas submissive postures were increased. These results show that activation of benzodiazepine receptors by full or partial agonists increased self-defensive responses to attacks by a conspecific, while decreasing submissive postures. On the contrary, "inverse activation" of these receptors by an inverse agonist increased submissive postures while decreasing self-defensive responses. These data suggest that benzodiazepine receptors are involved in the control of the animal's strategy to respond to an attack of another rat.

Aggression↗

PubMed1993

Analysis of working postures in hammering tasks on building construction sites using the computerized OWAS method.

The main objectives of this study were to identify the most problematic postures in hammering tasks performed at building construction sites through application of the computerized OWAS method, and to develop recommendations for improvement of working method and workplaces. Eighteen construction workers, with mean age of 41.6, from three construction companies participated in the field study. The hammering tasks observed during the two-month period included roof boarding, concrete form preparation, clamping support braces, assembling roof frames, roof joisting, shelter form preparation, and fixing fork clamps. Three different types of hammer, including a small Fiskar's hammer, a Fiskar's construction hammer, and a Rocket hammer, were used by the workers. Of all the observations, poor working postures were observed most frequently in roof joisting (12.4% of all observations within the task), followed by concrete form preparation (8.6%), and construction of frames for the roof (7.5%). Overall, out of 593 different postures analysed, a total of 7.8% of postures adopted by the workers during various hammering tasks were classified into OWAS categories III or IV, indicating that these postures should be corrected either soon or immediately. The computerized OWAS method for postural data analysis proved to be a very useful way to reduce postural load of dynamic hammering tasks, and allowed for efficient application of the original OWAS method.

Journal Article↗

PubMed2001

Mechanisms of hypotensive effects of a posture change from seated to supine in humans.

The hypothesis tested was that the hydrostatic stimulation of carotid baroreceptors is pivotal to decrease mean arterial pressure at heart level during a posture change from seated to supine. In eight males, the cardiovascular responses to a 15-min posture change from seated to supine were compared with those of water immersion to the xiphoid process and to the neck, respectively. Left atrial diameter and cardiac output (rebreathing) increased similarly during the posture change and water immersion to the xiphoid process and further so during neck immersion. Mean arterial pressure decreased by 12 +/- 2 mmHg during the posture change, by 5 +/- 1 mmHg during xiphoid immersion, and was unchanged during neck immersion. Arterial pulse pressure increased by 12 +/- 3 mmHg during the posture change (P < 0.05) and less during xiphoid and neck immersion by 7 +/- 3 mmHg (P < 0.05). Total peripheral vascular resistance decreased similarly during the posture change and neck immersion and slightly less during xiphoid immersion (P < 0.05). In conclusion, the hydrostatic stimulation of carotid baroreceptors combined with some additional increase in arterial pulse pressure, which also stimulates aortic baroreceptors, accounts for more than half of the hypotensive response at heart level to a posture change from seated to supine.

Adult↗

PubMed2002

Comparative study of cerebral blood flow between postural tachycardia and neurocardiogenic syncope, during head-up tilt test.

We assessed the cerebral blood flow velocity response to head-up tilt test in patients with typical neurocardiogenic syncope compared with patients showing postural tachycardia. Fifty patients (21 men) with history of orthostatic intolerance, younger than 50 years (mean 27 +/- 10), participated in the study. Transcranial Doppler sonography of the middle cerebral artery, heart rate and brachial blood pressure were recorded during a head-up tilt test. According to the outcome of the test, patients were categorized in two groups: neurocardiogenic syncope (29 patients) and postural tachycardia (21 patients). The clinical history of the two groups was similar. During baseline in the supine position, no differences in haemodynamic parameters were observed. From the first min of tilt, the heart rate was higher in patients with postural tachycardia than in patients with neurocardiogenic syncope. Although, during tilt, the absolute values of the cerebral blood flow parameters were similar in the two groups, throughout tilt, continuous observation of the Doppler recording in patients with postural tachycardia showed intermittent fluctuation of the blood flow velocity, with an oscillatory pattern, which were not observed in the recordings in patients with neurocardiogenic syncope. Comparison of patients with neurocardiogenic syncope, and those with postural tachycardia also showed larger variations of the pulsatility index (P < 0.05) in the postural tachycardia group. These findings support the possibility that abnormalities within the central nervous system play a pivotal role in the pathogenesis of postural tachycardia.

Adult↗