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At least 883 records · Page 49Linked to original sources
PubMed1975

Sequential responses of the renin-angiotensin-aldosterone axis to acute postural change: effect of dietary sodium.

The simultaneous levels of plasma renin activity (PRA), angiotensin II (A II), and aldosterone (PA) were frequently assessed in 13 normal subjects following acute postural change (assumption of upright posture or returning to the supine position) on low (10 mEq.) and high (200 mEq.) sodium (Na+) intakes. The rate of response of aldosterone secretion was also correlated with changes in the metabolic clearance rate (MCR) of aldosterone. Significant increments of PRA and A II on either sodium intake occurred within 5 to 20 minutes; the peak values occurred within 90 minutes and tended to plateau until the end of the study (240 minutes). The mean absolute peak levels were approximately 2 to 3.5-fold greater than control. Increments of PA were initially delayed 20 to 30 minutes, but peak levels also were achieved by 90 minutes. The secretion rate of aldosterone increased 4-fold on the 10 mEq. Na+ and 2-fold on the 200 mEq. Na+ intake even though MCR declined 30 to 40 per cent in the upright posture. Sodium restriction enhanced the rate and magnitude of response of all parameters. Specifically, the slope of the regression relationship between PRA and PA was more than 4-fold steeper in the sodium-restricted than sodium-loaded subjects. From the rate of decline in PRA following resumption of supine posture, the half-life of PRA was estimated to be 14 to 15 minutes. The present study demonstrates that acute changes in posture are associated with closely correlated changes in PRA or A II. To varying degrees, it appeared that sympathetic activity, intravascular volume, diurnal secretion, and the sodium ion play a role in the sequential responses of these parameters to acute postural alterations.

Adult↗
PubMedDate not supplied

[State of the art: posture and occlusion].

The Authors of this work propose to give an evaluation about actual relationship between posture and occlusion, trying of to give some indications about posture's meaning, organizing the relation about five points: Posture's definition Posture's history Posture's models of study Occlusal support en posture Diagnostic procedures.

Biomechanical Phenomena↗
PubMedDate not supplied

Postural changes in dental hygienists. Four-year longitudinal study.

Numerous surveys identify the occurrence of musculoskeletal complaints as a concern in dentistry. However, no longitudinal data exist to indicate whether postural changes occur as a result of practicing dental hygiene. The purpose of this preliminary, four-year longitudinal study was to investigate whether any postural changes developed during the hygienists' clinical education and/or during subsequent dental hygiene practice after one and/or two years. It was anticipated that the awkward positions and intense physical demands placed on hygienists might initiate musculoskeletal problems, but that no postural changes would occur over this short period of time. Nine of 10 dental hygienists in the graduating class of 1987 were surveyed for existing musculoskeletal complaints, and the subjects were photographed for a measurement of postural change. Responses from participants indicated an increase in musculoskeletal-related complaints in each of the six areas investigated. The photographic findings indicated that one of the nine hygienists showed an increase in forward head posture, a postural change.

Adolescent↗
PubMed1992

[Relationship between developmental prognosis and changing picture of postural findings in early infancy among early treated children].

We followed 93 infants prospectively who were treated because of moderate and severe grades of cerebral coordination disturbances since less than 6 months of age. They were divided into 3 groups according to developmental prognosis at 4 years of age; normal 44, mental retardation 18, and cerebral palsy 31. We compared the postural findings in supine and prone position, and 7 postural reactions at the first examination with those at discharge about 50 days after the first examination. We assessed the changing pictures of postural findings as improved, not changed or worsened. We analyzed the relationship between the changing pictures of postural findings during the short period in early infancy and the developmental prognosis among the 3 groups. The normal group showed improvement in a larger number of items than the other two groups. The findings of cerebral palsied children showed poor improvement, and more postural reactions changed to be more pathologic than those in the other two groups. Among the cerebral palsied children, ambulatory cases showed better improvement than those who could not crawl. But we found no significant difference between ambulatory and crawling children. This study demonstrated that assessment of changing pictures of postural findings in early infancy was helpful to predict developmental prognosis.

Age Factors↗
PubMedDate not supplied

Effects of posture change on the hemodynamics of the liver.

BACKGROUND/AIMS: According to our experience, blood flow in the portal vein may alter according to body posture. It is reported that decreased portal venous flow immediately gives rise to significantly increased blood flow in the hepatic artery. To gain further insight into blood flow changes affected by posture, we examined blood flows in the portal vein, hepatic artery and hepatic vein at different postures. METHODOLOGY: Using a Doppler ultrasound system, the hemodynamics of the portal vein, right hepatic artery, and hepatic vein were examined in 35 patients at supine and left decubitus positions. RESULTS: Portal vein blood flow volumes were significantly lower in the left decubitus position than in the supine. In the right hepatic artery, the left decubitus position gave significantly higher blood flow velocity values than the supine. CONCLUSIONS: Our results indicated that upon change of posture from the supine to left decubitus position, portal vein flow velocity was reduced and hepatic artery flow velocity increased. Changes in portal and hepatic arterial flows by changing posture may be explained by decreased portal flow as a direct result of changed posture, leading to increased hepatic arterial flow to maintain total hepatic blood inflow.

Aged↗
PubMed2004

[A biomechanical study on cervical spinal posture and prior loading history affecting spinal compressive strength].

OBJECTIVE: The purpose of this study is to investigate the effect of cervical spinal posture and prior loading history on spinal compressive strength. METHODS: Twelve human cadaver cervical spines were harvested and dissected into 24 motion segments containing 2 vertebrae and the intervertebral discs (C3,4 and C5,6). Compressive loads were applied on so that the effects of 2 loading conditions (dehydrated, superhydrated) and 2 postures (neutral trunk, flexed) could be examined. Dissection techniques and X-rays were used to determine the tissue injuries. RESULTS: Specimens had a lower ultimate compressive strength (P <0.001) in flexed posture than in neutral trunk posture. Under the injury loading in neutral trunk posture, superhydrated specimens had a lower strength (29%, P <0.01) than dehydrated specimens did. CONCLUSION: The spine may be more prone to injury early in the morning when the discs are at highest level of hydration and the cervical spine is in fully flexed posture.

Biomechanical Phenomena↗
PubMed2005

[Primary prevention program of the Hungarian Spine Society--part I. Scientific background of the posture correction exercise scheme].

The primary prevention program of the Hungarian Spine Society aims to increase awareness of the need to develop and automatically maintain a biomechanically correct posture for all school children. The biomechanically correct posture is a dynamic balance based on a correct middle position of the pelvis and on muscle balance. In this position three important anatomical points--the left and right anterior superior iliac spines and the upper medial point of the pubic bone--form one frontal plane. From side-view the imaginary weight median of the body crosses the 2nd to 5th lumbar and the 2nd to 5th cervical vertebral bodies. When the muscles involved in posture are in balance, their strength and flexibility are just appropriate for the almost continuous work required against gravity. In case of static and/or dynamic under- or overload tonic muscles become shortened, and phasic muscles become stretched, and are no longer able to work optimally. Since many muscles and muscle parts that are involved in normal posture maintenance are not satisfactorily challenged in regular physical exercises and sport activities, the preventive exercise scheme of the Hungarian Spine Society aimed to involve these rarely used muscles in special strengthening and stretching exercises. The scheme is based on 12 test exercises that assess the strength and flexibility of postural muscles. A person who is able to do all test exercises correctly has no problem with his or her muscle balance. In order to counteract the harm caused by sedentary lifestyle already in childhood, regular use of this posture correction scheme in physical education starting from preschool throughout the school-years is recommended for all children.

Biomechanical Phenomena↗
PubMed1992

The effect of arm exercise and ocular massage on postural hand tremor.

In this pilot study, the effect of exertion on hand tremor was investigated. Postural head tremor was measured in eight ophthalmology residents before and after lifting a barbell and before and after massaging a phantom eye. All subjects showed an increase in postural hand tremor after lifting a barbell for five minutes (mean, 79% +/- 59%). Postural hand tremor increased 38% +/- 79% after ocular massage, which was not statistically significant (P greater than .5). The peak pressures generated during ocular massage ranged from 25 to 265 mmHg (mean, 134 +/- 80.4 mmHg). There was also no correlation between change in postural hand tremor and the pressure generated by ocular massage (P greater than .2). The authors conclude that strenuous arm exercise, such as lifting a barbell, increases postural hand tremor and should be avoided before doing microsurgery; ocular massage is not sufficient exercise to affect postural hand tremor adversely.

Arm↗
PubMed1990

Postural hypotension in chronically medicated schizophrenics.

Blood pressure readings at rest and on standing in 196 chronic schizophrenic patients on stable long-term antipsychotic treatment were compared with those in unmedicated healthy controls. Patients recorded significantly lower resting blood pressure and significantly higher prevalence of postural hypotension than controls. The prevalence of postural hypotension in patients was 77% at 1 minute and 16.8% at 3 minutes after standing compared with absence of postural hypotension in controls at both time points. Prevalence of postural hypotension was unaffected by age or sex and was poorly correlated with drug dose, except in young patients. alpha 1-Receptor binding affinity of antipsychotic drugs was not predictive of postural hypotension. The possible significance of such persistent postural hypotension in chronically medicated patients is discussed.

Administration, Oral↗
PubMed1990

Enlarged tonsils and the effect of tonsillectomy. Characteristics of the dentition and facial skeleton. Posture of the head, hyoid bone and tongue. Mode of breathing.

Associations between craniofacial morphology, its development and growth on the one hand and functional factors on the other hand have been eagerly debated in the literature during the last 20 years. The aim of the present thesis, based on five publications, was to evaluate the effect of enlarged tonsils and tonsillectomy on the dento-facial morphology, the posture of the head, the position of the hyoid bone and tongue, and on the mode of breathing. The material comprised 146 Swedish children (66 boys and 80 girls), 5.3-17.3 years old, with a mean age of 10.1 years. Of these children 73 were judged by one otolaryngologist to have enlarged tonsils and were, on this criterion, selected for the investigation. The remaining 73 children comprised the control group and matched the tonsil group for sex and age. The controls were nosebreathers and had no history or symptoms of Ear-Nose-and-Throat-problems. During the investigation 18 of the tonsil children underwent tonsillectomy and 29 remained unoperated. Comparisons between the groups were based on anamnestic and clinical records, measurements on plaster study models and lateral skull radiographs. The results indicate that the children with enlarged tonsils, when compared with the control children, had retroclined lower incisors, protruded upper incisors, shorter lower dental arch, smaller overbite, larger overjet and a greater incidence of lateral crossbites. Furthermore they had retrognathic, posteriorly inclined mandibles, larger anterior lower facial height and skeletal open bite. They also displayed extended headpostures, low posture of the hyoid bone, anterio-inferior posture of the tongue and large oro-pharyngeal depth. 62.5% of the children in the tonsil group were mouthbreathers during the day and 84.7% during the night. The effect of tonsillectomy was mainly associated with a dorsal reposturing of the base of the tongue, change in hyoid bone posture cranially and change to nosebreathing during the night. Furthermore, a decrease in lower inter-molar width and in the tendency to lateral crossbite, as well as a slight increase in the posterior lower facial height had occurred postoperatively. Associations between postural and functional changes mutually, as well as between these changes and morphological changes were found. Enlarged tonsils thus seem to be associated with a characteristic postural and functional pattern, which in its turn seems to have had some influence on the dentition and craniofacial morphology.

Adolescent↗
PubMed1989

Effects of posture on upper and lower limb peripheral resistance following submaximal cycling.

The purpose of this study was to determine postural effects on upper and lower limb peripheral resistance (PR) after submaximal exercise. Twelve subjects (six men and six women) completed submaximal cycle ergometer tests (60% age-predicted maximum heart rate) in the supine and upright seated positions. Each test included 20 minutes of rest, 20 minutes of cycling, and 15 minutes of recovery. Stroke volume and heart rate were determined by impedance cardiography, and blood pressure was measured by auscultation during rest, immediately after exercise, and at minutes 1-5, 7.5, 10, 12.5, and 15 of recovery. Peripheral resistance was calculated from values of mean arterial pressure and cardiac output. No significant (p less than 0.05) postural differences in PR were noted during rest for either limb. Immediately after exercise, PR decreased (55% to 61%) from resting levels in both limbs, independent of posture. Recovery ankle PR values were significantly different between postures. Upright ankle PR returned to 92% of the resting level within four minutes of recovery, compared to 76% of the resting level after 15 minutes in the supine posture. Peripheral resistance values in the supine and upright arm were not affected by posture and demonstrated a gradual pattern of recovery similar to the supine ankle recovery response (85% to 88% of rest within 15 minutes). The accelerated recovery rate of PR after upright exercise may result from local vasoconstriction mediated by a central regulatory response to stimulation from gravitational pressure on lower body circulation.

Adult↗
PubMed1988

On neck muscle activity and load reduction in sitting postures. An electromyographic and biomechanical study with applications in ergonomics and rehabilitation.

In this study of the biomechanics and muscular function of the cervical spine, skilled women workers simulated standardized electromechanical assembly work in eight sitting postures. Normalized electromyography was used to quantify activity in neck-and-shoulder muscles. With the whole spine flexed, muscle activity in the cervical erector spinae, trapezius and thoracic erector spinae muscles was higher than when the whole spine was straight and vertical. The posture with the trunk slightly inclined backward and neck vertical gave the lowest activity levels. Flexed neck compared to vertical neck gave higher activity in the cervical erector spinae. Work with abducted arm gave high neck muscle activity. Work postures can thus be optimized to diminish neck muscle load. Two ergonomic acids were studied during the work cycle. Elbow support reduced the activity in the trapezius and thoracic erector spinae/rhomboids muscles in the posture with the whole spine flexed and in the posture with the whole spine vertical. Arm suspension gave mainly similar reduction in these postures, and also a reduction in the cervical erector spinae. In the position with the trunk slightly inclined backward, arm suspension gave a reduction in the trapezius. These findings indicate that arm support or arm suspension can be used to reduce neck muscle load. Three methodological studies related to neck muscle load and normalization were included. 1) Examination of the effect of different isometric maximum test contractions on neck muscles showed that all contractions activated all muscles studied, including those on the contralateral side, to some extent and at various levels. The highest frequency of attained maximum levels was: for neck extension, in cervical erector spinae; for cervical spinae lateral flexion, in splenius and levator scapulae; for arm abduction, in trapezius, and, for shoulder elevation and scapular retraction/elevation, in thoracic erector spinae/rhomboids. Proximal resistance gave higher activity than distal. 2) The relationship between EMG activity and muscular moment was studied in women during submaximal and maximum isometric neck extension. The relationship found was non-linear, with greater increase in activity at high moments in the posterior neck muscles studied. The slightly flexed cervical spine position induced a higher level of activity in erector spinae cervicalis than did the neutral position for a given relative muscular moment. 3) Muscular activity was related to cervical spine position during maximum isometric neck extension. Peak activity in the cervical erector spinae was found in the slightly flexed lower-cervical spine position.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMedDate not supplied

Excretion of urinary amino acids in children with postural proteinuria.

The urinary excretion of free amino acids was studied in urine specimens from 12 subjects with postural proteinuria in recumbent posture and after a period of upright lordotic posture. The lordotic posture produced an increased urinary excretion of total amino acid and 12 amino acids, particularly of taurine, glutamic acid, a-amino adipic acid, valine, leucine, ethanolamine and arginine. However, 90 min after the lordotic posture, all amino acids returned to the initial values. Although, many factors must be considered in the evaluation of the urinary excretion of amino acids, an increased urinary excretion of amino acids occurring after the lordotic posture may be the result of reabsorption disturbance of the renal tubules.

Adolescent↗
PubMed1980

Low back pain related to bowing posture of greenhouse farmers.

Farming by means of greenhouses has spread in different parts of Japan during the past 20 years. Low back pain, an important health problem for farmers, affects those working inside a greenhouse as a result of their taking up particular postures. In order to analyze ergonomic problems of greenhouse farming relevant to low back pain, localized fatigue complaints and parts of the body where fatigue was felt during fruit picking were studied among 49 female farmers engaged in greenhouse strawberry culture and 53 female farmers engaged in greenhouse eggplant culture. Furthermore, the bowing posture for strawberry picking was compared with that of eggplant picking using newly devised posture-pattern recording equipment. More than 50% of strawberry or eggplant farmers complained of fatigue in the lower back and shoulders. The prevalence of low back pain was significantly higher among strawberry farmers than among eggplant farmers, probably due to the deep bowing posture of the farmer during picking work. The new posture-pattern recording equipment proved useful for investigating changes of work postures.

Adult↗
PubMed1983

Universe of finger postures and finger dynamography. A conceptual methodological tool for assessing and recording the motor capacity of the finger.

The sum total of all postures actively possible at a joint constitutes its "universe of postures". This universe can be identified by its limits. The universe of a biarticular system like the finger can be mapped out visually, by identifying the limiting postures, plotting them as points in a graph sheet in which the postures of the MP joint are represented in the horizontal axis and the postures of the PIP joint are represented in the vertical axis, and connecting the points serially. The closed figure thus obtained represents the universe of postures of the finger and shows at a glance the motor deficits of the finger as a whole. It also remains as an objective record of the universe, available for comparison after treatment. This method of evaluation of the finger has been found to be particularly useful in assessing fingers with paralytic problems. Such a visual representation of the universe, called "dynamogram" here, can also be used for kinesiological studies.

Biomechanical Phenomena↗
PubMed1981

Changing fetal position through maternal posturing.

Two completed studies and a study in progress have addressed the question whether maternal posturing can produce the rotation of a fetus from a posterior or transverse position to the optimal anterior position. There are clinical problems associated with a malposition and also with the therapeutic procedures used to correct the malposition. Maternal posturing is considered safe, simple, economic, and noninvasive. There is a sound rationale for the choice of the hands and knees posture and the variations used to facilitate fetal rotation. Two studies indicate the effectiveness of maternal posturing. The physical theories of gravity, buoyancy, and friction are used to explain the postures, the fetus, and fetal rotation. The results of the second study are explained with the same physical theories. A current study about maternal postures and fetal position is in progress.

Biophysical Phenomena↗
PubMed1994

The Bergen Blood Pressure Study. Estimated prevalence of postural hypotension is influenced by the alerting reaction to blood pressure measurement.

The prevalence of postural hypotension, defined as a > or = 20 mmHg decline in SBP from the sitting to the standing position, was studied in 430 subjects aged 67.2 +/- 6.8 years (mean +/- SD). Before the subjects assumed the upright position, three sitting measurements were performed. The difference between the first sitting and standing recording revealed a postural hypotension prevalence of 18.9%. However, when the mean of the two last sitting recordings was used as baseline, only 4.9% of the subjects experienced a > or = 20 mmHg drop in SBP on standing. It is well documented that the alerting reaction to conventional sphygmomanometry causes the BP to rise and that BP decreases spontaneously with repeated measurements. When postural hypotension is based on the difference between the first sitting and the standing recording, the change in BP is not caused by the change in posture alone but reflects the effect of repeated measurements and the regression-towards-the-mean-phenomenon as well. Consequently, the prevalence of postural hypotension is overestimated. Repeated baseline recordings are encouraged in the assessment of postural hypotension.

Aged↗
PubMed1993

Compartmentalized cerebellar functions upon the stabilization of body posture.

This paper reviews the features and topodiagnostical meaning of pathological body posture in cerebellar disorders and presents knowledge as to the physiology and pathophysiology of postural disturbances attributed to the cerebellum. Lesions of the spinocerebellar (upper vermal and intermediate) part of the anterior lobe lead to spontaneous anterior-posterior body sway, with a frequency of about 3 Hz with mild or absent ataxia of the upper limbs, but prominent ataxia of the lower limbs. The tremor is provoked by eye closure and by body displacement. Increased gain and poor cerebellar control of the duration and gain of stabilizing reflexes may be the mechanisms of this oscillation. Lesions of the lower (vestibulocerebellar) vermis cause postural ataxia of the head and trunk while sitting, standing, and walking. Postural ataxia is omnidirectional, sometimes of excessive amplitude and contains frequency components below 1 Hz. Dysmetria of the upper and lower limbs is not prominent. Visual stabilization is less than in the other groups of cerebellar patients. Lesions of the cerebellar hemispheres alone, do not cause an increase of postural sway. Lesions of spinocerebellar afferents (Friedreich's disease) lead to a low frequency large amplitude lateral sway with the most of its power below 1.1 Hz. Visual stabilization is preserved. Latencies of early and late EMG responses to sudden displacements are normal in patients with cerebellar disorders. The cerebellum is, therefore, unlikely to be the primary generator of these reflexive responses. On the other hand, the temporal composition of the orderly time sequence of a complex motor program--be it a voluntary act or its postural balancing--is deranged in cerebellar lesions. It is hypothesized that the cerebellum helps to coordinate the timing not only within but also between the single components involved in each subunit of a complex movement in three-dimensional space and that is scales the size and duration of each muscular action. The cerebellum possibly specifies the cortical movement command and sends it back to the motor cortex. The basic structure of a motor program, however, does not seem to be generated within the cerebellum.

Cerebellar Diseases↗