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PubMed1993

Unilateral congenital ptosis: compensatory head posturing and amblyopia.

Patients with unilateral congenital ptosis often adopt chin elevation to maintain fusion. This compensatory head posturing has been considered a sign of fusion, thus indicating a low risk for amblyopia. To evaluate this sign, we reviewed the charts of 11 preverbal children with unilateral congenital ptosis who had straight eyes and appropriate compensatory head posturing to maintain binocular vision. Four additional patients with unilateral ptosis and no compensatory head posturing were tested for comparison. All patients had undergone an examination and had been tested by pattern Visual Evoked Potential (VEP) under chloral hydrate sedation. Five of the 11 patients with compensatory head posturing were found to be amblyopic, three moderately so and two severely affected. The four patients without compensatory head posturing were amblyopic. It is our hypothesis that compensatory head posturing allows peripheral fusion even when significant amblyopia is present. Additionally, the clinical sign of a compensatory head turn to maintain binocular vision does not rule out the presence of significant amblyopia.

Amblyopia↗
PubMed1995

The prevalence and significance of post-exercise (postural) hypotension in ultramarathon runners.

A consistent finding in exercise-associated collapse is a marked postural fall in the systolic blood pressure associated with a tachycardia. The prevalence and significance of these post-exercise (postural) changes in blood pressure among noncollapsed ultradistance athletes has not been well documented. The aim of this study was to compare pre- and post-race changes in systolic and diastolic blood pressures with changes in body weight and plasma volume and with symptoms of post-exercise hypotension, including the effects of posture, among a group of 31 runners competing in an 80-km footrace. During the race, runners developed a mean (+/- SD) weight loss of 3.5 (+/- 1.2) kg and plasma volume change of 12.8% (+/- 9.1). Asymptomatic postural hypotension defined as a fall in systolic blood pressure of greater than 20 mm Hg from the supine to the erect position without syncopal symptoms was present in two runners (7%) before the race and in 21 runners (68%) afterward. The degree of postural variation in systolic blood pressure was unrelated to changes in body weight or a fall in plasma volume. We conclude that (i) all runners were dehydrated by the race activity with a range of 1% to 7% and an average of 4.6%; (ii) asymptomatic post-exercise (postural) hypotension developed in the majority (68%) of ultramarathon runners in this study; (iii) the post-exercise hypotension is likely of multifactorial origin and is not entirely related to whole body dehydration or a reduction in plasma volume; and (iv) despite marked levels of dehydration among our sample of runners, their cardiovascular status in the supine position was not greatly compromised.

Adult↗
PubMedDate not supplied

Effect of postural and load variation on the coordination of the leg muscles in concentric jumping movement.

Coordination of the lower extremity muscles was studied under different load conditions (40-110% of the body weight). Skilled male subjects performed vertical jumps with maximum effort in four body postures (105-165 degree angle of the hip joint) without any balance requirements. The maximum peak force values closely followed the variation in the body weight (p < 0.001). Furthermore, a more erect body posture reduced the force level during the first half and increased it during the second half of the jump (p < 0.001) in consequence of the force-length relationship of the thigh muscles. The shift toward an erect body posture significantly increased the activity of the rectus femoris (p < 0.001) and slightly that of the vasti muscles (n.s.). On the other hand, the gastrocnemius medialis reacted clearly (p < 0.01) and the gluteus maximus and gastrocnemius lateralis muscle slightly to the variation in body weight. Hence, the concentric jump conditions divided the agonist muscles into two categories: the posture sensitive muscles guided by the rectus femoris and the load sensitive muscles guided by the gastrocnemius medialis. The central nervous system (CNS) seems basically to favour the muscle coordination of an erect body posture through the function of two-joint muscle extending the knee joint. In addition according to the requirements of the increasing load, the CNS postpones the timing of the concentration of the activity of the hip and ankle joint agonists. But in the vertical jump as a whole, the activity pattern of the leg muscles was not essentially influenced by the different posture or load conditions (n.s.).

Adult↗
PubMedDate not supplied

A new trend in the therapy of orthostatic arterial hypotension: prevention by propranolol or metoclopramide of the excessive adrenaline release of brainstem infarct patients with postural hypotension.

The catecholamine (CA) response to upright posture was studied in 30 brainstem infarct patients with orthostatic arterial hypotension; the investigation was made before and after 10 days propranolol therapy (in 15 cases) and before and after 10 days metoclopramide therapy (in other 15 cases). Before treatment almost all patients responded to posture by a rise in adrenaline (A) excretion and by a depression in noradrenaline (NA) excretion. Propranolol therapy prevented the excessive A release produced by standing and normalized their NA response to posture. Metoclopramide administration also prevented the post-orthostatic A discharge but had no significant influence on NA response to posture. Both drugs exerted a favourable influence on postural hypotension of investigated patients. As post-orthostatic A discharge observed in patients with postural hypotension is involved in the pathogeny of this syndrome and both metoclopramide and propranolol are able to correct this disorder one may maintain that the clinical favourable results obtained with these drugs are ascribable at least partly to their blocking effect on A release.

Antiemetics↗
PubMed1996

A radiographic comparison of neutral cervical posture with cervical flexion and extension ranges of motion.

OBJECTIVE: To radiographically assess, using a pilot study, the relationship between the neutral cervical curve and cervical segmental ranges of motion (ROM) for flexion and extension in asymptomatic subjects. DESIGN: Survey. SETTING: Chiropractic college student health center and private practice. PATIENTS: Sixteen asymptomatic adult students with no radiographic evidence of degenerative changes. INTERVENTION: No therapeutic intervention. MAIN OUTCOME MEASURES: Neutral segmental alignment and flexion and extension segmental ranges of motion for C2-C6 evaluated relative to the subjacent segment. RESULTS: Correlations between neutral posture variables (segmental tilt and global posture) and their corresponding ROMs (segmental and global) were computed. A strong correlation was found for flexion at C4 (r = -.76, p = .0006) and at C5 (r = -.84, p = .0001). Correlations were not as strong at other vertebral levels for flexion and at all levels for extension (r = .01 to r = .52). The error in prediction of motion from neutral posture is given by the standard error of the estimate (SEE). The SEE for flexion ROM ranged from 2.6 degrees at C5 to 3.9 degrees at C6, and the SEE for extension ranged from 3.8 degrees at C4 to 6.5 degrees at C2. CONCLUSION: Correlation between neutral cervical posture and flexion or extension ranges of motion was only strong at the C4 and C5 vertebral levels. Generally, there was not good predictability of ROM from neutral posture as indicated by the R2 values and the standard errors of estimate. Further investigation is needed to determine if other variables, such as angle of the facet joints, may be influential in these postural-functional relationships.

Adult↗
PubMed1998

Personal perspective: in search of an optimum cycling posture.

Correct cycling posture improves performance and may prevent injuries. This article addresses the most important variables that determine cycling posture of road racing cyclists. It focuses not only on 'posture height' but also on 'posture length', an aspect that has as yet received little attention. In order to help cyclists find their optimum posture, reliable anthropometric measuring is of utmost importance. The relevant measurements and the necessary measuring instruments are considered. Special attention is given to gender related posture aspects.

Ankle Joint↗
PubMedDate not supplied

The relationship between posture and curvature of the cervical spine.

OBJECTIVE: To study the relationship between posture and curvature of the cervical spine in healthy subjects. SUBJECTS: The study was composed of 54 healthy students (25 men and 29 women) aged 20-31 yr with a mean age of 24.7 yr. METHODS: Lateral radiographs were taken of the head and cervical spine of the subjects while standing in a neutral position. Cervical spine posture was quantified by the angle of a reference line, composed of reference points of the upper six cervical vertebrae, with the horizontal axis. The curvature of the cervical spine was classified visually as lordotic, straight or reversed. RESULTS: A relationship was found between posture and curvature of the cervical spine (p = .006); a more forward posture of the cervical spine was related to a partly reversed curvature; and a more upright posture was related to a lordotic curvature. Moreover, men more often exhibited a straight curvature, and women more often exhibited a partly reversed curvature. CONCLUSION: The curvature of the cervical spine is related to the subject's posture and gender.

Adult↗
PubMed1998

[Contemporary postural and segmental modification of forced voice].

The forced voice corresponds with increased peri-laryngeal tension during phonation caused by inappropriate muscle action. It is usually accompanied by a characteristic posture (the face thrust forwards, tension in the neck muscles etc...). This posture may cause dysfunction of the cords themselves, leading to dysphonia, and perhaps requiring laryngeal microsurgery. Our project aimed to put forward and validate a system of objective, non-invasive measurements of the postural features of the forced voice, in order to improve the management of these patients. The study was prospective, comparing a control group with no previous vocal problems with a group of patients with problems of laryngeal dysfunction. We carried out a number of simultaneous measurements of postural and segmental activity during phonation, using in parallel an accelerometer, a method of cine-analysis, and a postural platform. Recordings were made during phonation, but only analysed during the resting phase. It turned out that the speed of displacement of the centre of gravity was the most useful discriminating factor. The mean value was 0.07 (displacement type 0.126) for the control group, and 0.32 (displacement type 0.211) for the patient group. The discrimination between these two groups was significant (p < 0.001, Mann-Whitney test). The reliability of this measurement allows us to envisage the inclusion into the clinical investigation package of measurements of the postural and segmental changes in the forced voice.

Adolescent↗
PubMed1998

The effect of changes in head posture on the patterns of muscle activity in cervical dystonia (CD).

Twelve patients with cervical dystonia (CD) and predominant rotation were studied to determine the effects of changes in head posture on the specific patterns of cervical muscle activity. Turns analysis was used to quantify muscle activity underlying head rotation, recorded simultaneously from the agonist and antagonist muscle pairs bilaterally (sternocleidomastoid [SCM] and splenius [SPL]). Muscle activity was compared between the uncompensated dystonic posture and during the maintenance of midposition. In addition, patients were separated into two groups (geste = 6; no geste = 6) based on whether they had a clinically efficacious geste to determine the effect of geste on patterns of cervical muscle activity. Muscle activity was measured during the maintenance of midposition with and without a clinical or simulated geste. Differences in muscle activity between the groups and postures were compared using repeated measure analysis of variance (ANOVA) analyses. The four muscles tested showed a significant difference in muscle activity in the uncompensated dystonic posture as a result of the increased activity in the agonist muscle pair (SCM and SPL responsible for the dystonic posture) (EMG amplitude: F[1,11] = 18.81, p = 0.0012; EMG frequency: F[1,11] = 32.07, p = 0.0001). Maintaining the head in the midposition was associated with a significant reduction in muscle activity compared with the uncompensated dystonic posture (EMG amplitude: F[1,9] = 6.36, p < 0.033; EMG frequency: F[1,9] = 10.96, p < 0.0091). This reduction in midposition muscle activity was significantly greater in the agonist muscle pair (EMG amplitude: F[1,10] = 19.70, p = 0.0013; EMG frequency: F[1,10] = 44.67, p < 0.0001). In the patients with clinically effective geste, there was no additional reduction in muscle activity observed in the midposition when they performed their geste (EMG amplitude: F[1,9] = 4.63, p = 0.060; EMG frequency: F[1,9] = 1.22, p = 0.298). These findings suggest that CD with rotation is characterized by predominantly increased agonist muscle activation. Patients with CD retain the ability to modulate this involuntary agonist muscle activity to maintain the head in the midposition. The maintenance of the midposition does not seem to be facilitated by geste.

Adult↗
PubMed1994

Ambulatory monitoring of left ventricular function in patients with Parkinson's disease and postural hypotension.

Left ventricular (LV) function was continuously monitored using a radionuclide detector (VEST) after intravenous injection of 25 mCi technetium-99m labelled red blood cells in nine patients with Parkinson's disease and postural hypotension (group 1) and ten patients with Parkinson's disease but without postural hypotension (group 2). LV function and blood pressure were monitored in the supine position for 15 min (period A), upon changing posture from the supine to the upright position for 10 min (period B), and upon returning to the supine position for 10 min (period C). In group 1, the passage from period A to period B induced a significant decrease in end-diastolic volume, end-systolic volume and ejection fraction (all P < 0.01). In group 2, ejection fraction increased (P < 0.05) upon changing posture from the supine to the upright position. Ejection fraction (F = 33, P < 0.01), end-diastolic volume (F = 9, P < 0.05) and end-systolic volume (F = 10, P < 0.05) were significantly different between the two groups. In group 1, stroke volume, cardiac output and vascular peripheral resistance decreased from period A to period B (all P < 0.001). In group 2, no changes in stroke volume, cardiac output and vascular peripheral resistance were observed from period A to period B. All parameters were similar in the two groups during the periods A and C. Upon changing posture from the supine to the upright position, patients with Parkinson's disease and postural hypotension showed marked changes in parameters of LV function induced by vascular abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography, Ambulatory↗
PubMed2000

Management of postural hypotension.

Several mechanisms counteract the gravitational forces on blood and maintain systemic arterial pressure and cerebral perfusion upon assumption of the upright posture. Failure of these mechanisms can lead to a postural decrease in blood pressure. Postural hypotension is defined as a reduction of at least 20 mm Hg in systolic blood pressure or at least a 10 mm Hg decrease in diastolic blood pressure. Acute postural hypotension is usually due to fluid or blood loss and responds well to fluid repletion. Chronic postural hypotension is due to drugs or endocrine or neurogenic disorders. A functional classification based on severity of symptoms is useful in monitoring the patient's condition and documenting improvement with treatment. Whenever possible, the reversible causes of chronic postural hypotension should be treated. For symptomatic treatment, a stepped approach starting with nonpharmacologic measures is recommended. Fludrocortisone, midodrine, indomethacin, and atrial tachypacing are recommended, in that order, for patients in whom nonpharmacologic measures prove insufficient. Other drugs can be added if necessary. The goal of treatment is to make the patient as ambulatory and symptom-free as possible without causing supine hypertension.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1980

The effects and measurement of working postures.

Postures are a necessary result of undertaking working activities but the constraints the impose on these activities are not overtly recognised. The forms which these constraints can take are discussed, as well as the likely outcomes for a worker arising from long held or frequently adopted postures. Methods for the recording and evaluation of postures and their effects are described. Research into the relationships between the extent of and holding times for postures and the effects of various recovery times are discussed. Where a maximal postural effort has a recovery period of twelve times the length of the time the posture was held, only about 80% of the initial performance can be expected. Full recovery requires rest periods in excess of 1200% of working time.

Journal Article↗
PubMed1991

Factors related to working posture and its assessment among keyboard operators.

Video analysis of 15 keyboard operators was conducted over two four-hour periods to determine the effects of symptoms of over-use injury, the adjustability of the workstation, the type of keyboard, time of day and sex on working posture. The only factor which significantly affected posture was the type of keyboard, with operators at typewriters adopting a more extended shoulder position, reduced elbow flexion and increased wrist flexion, than those working at a VDU terminal. Analysis of the components of variance associated with repeated observations revealed that to minimise the variance associated with recording the posture of these subjects, and therefore obtain a representative mean posture, required at least nine observations for wrist angle, four for elbow angle, six for shoulder angle and three for trunk incline. The mean posture adopted by this group of operators was similar to the 'right angles' posture, with the trunk reclined 4 degrees , shoulder extended 1 degrees , elbow 92 degrees and wrist extended 7 degrees .

Journal Article↗
PubMed1991

The effect on sitting posture of a desk with a ten-degree inclination using an adjustable chair and table.

By means of continuous recording of the positions of the trunk and head, an investigation was carried out to examine the effect of the Erasmus office-desk - a desk with a 10 degrees inclination - on sitting posture whilst reading and writing, sitting in an adjustable chair at an adjustable table. The posture assumed by a person who is doing mixed reading and writing work at a table with the Erasmus office-desk is more upright than the posture of the same person doing the same work without the desk. This applies for both the head and the trunk. The average position of the trunk was changed from 26.0 degrees to 18.2 degrees when working with the desk placed on the table. The moment of force caused by gravity is proportional to the sine of the angle. Therefore the change of angle results in a decrease of the average moment of force on the back at L5-S1 of 29%. The largest individual decrease found was 86%. The average change of the position of the head was changed from 38.5 degrees to 29.6 degrees , resulting in an average decrease of the moment of force, on C7-T1, of 21%. The largest individual decrease was 51%. Lateroflexion of the back was less often assumed when the subjects were using the desk. The posture assumed by the subjects when they were doing writing work only was generally more upright when working at a desk with a 10 degrees inclination than when working at a flat desk. Marked differences were found between the postures of the subjects. The change of posture while using the desk also showed marked differences for each subject individually.

Journal Article↗
PubMed1992

Working postures and activities of lorry drivers: a reliability study of on-site observation and recording on a pocket computer.

Poor working postures are associated with the development of musculoskeletal disorders. Many different observation methods have been developed to analyse working posture and activity. TRAC (Task Recording and Analysis on Computer) enables the observer to choose and define the variables and the categories within variables to be recorded at the workplace and analysed afterwards. In this study, inter-observer reliabilities were determined for the variables that were essential to ensure accurate recording of both working posture and activity of lorry drivers. The pre-set standard for observer reliability was not reached before the number of variables was decreased: the variables concerning activities and load handled were omitted in favour of those concerning body posture. As a result of this reliability study an improved application of TRAC is proposed. For the purpose of recording all selected variables a second observer is introduced, so that two observers work simultaneously at the working site. The first observer pays attention only to working postures and the second observer records, among other things, activities. An additional program has been written to combine the variables of both observers for subsequent analysis. This enables us to investigate the relation between activity, appliances or goods being handled, and the corresponding working postures. The second observer records on a real-time basis and provides accurate information on the duration and sequence of activities. It is considered that this twofold application of TRAC is an important contribution to the accurate analysis of workplaces.

Journal Article↗
PubMed1993

Two-dimensional photographic posture recording and description: a validity study.

Posture recording and description is necessary to yield data by which postural load can be assessed. In this paper an inexpensive and simple method to gather these data is described, ie two-dimensional (2-D) posture recording and description by means of photography. A disadvantage of this method, perspective error, is discussed and guidelines are given to reduce it. The validity of the method was experimentally tested for a situation slightly conflicting with some guidelines, ie recording of the whole body, with a small distance between camera and subject. For this purpose posture recording with 2-D photography was compared with posture recording by means of a three-dimensional optoelectronic system (Vicon). In general, 2-D photographic posture recording and description is a valid method as long as some guidelines for reduction of perspective error are followed.

Journal Article↗
PubMed1995

Factors affecting posture for machine sewing tasks: the need for changes in sewing machine design.

Sewing machinists suffer from musculoskeletal problems, which have been attributed to poor working postures as well as to the repetitive hand and arm movements. Their posture is constrained by both the visual and the manual aspects of the task, and the design of the sewing machine and table have a considerable influence on the posture adopted. The potential for improvement of industrial sewing machines was investigated in a study of the effects of two design parameters (table inclination and view of the needle). It was shown that both trunk posture and head/neck flexion could be improved significantly by altering these design parameters. Trunk posture was found to be strongly related to the manual aspects of the task, and could be improved by altering the working positions for the arm. Head posture was most influenced by the view of the task/needle and could be improved by improving the visual condition for the task.

Journal Article↗
PubMed1994

Postural stress analysis in industry.

Both observational and instrumentation-based techniques have been used to conduct postural stress analysis in industry. As observational methods are more widespread than instrumentation-based techniques and can be used as a practical tool in the workplace, this study reviews and assesses the scientific literature on observational techniques. Techniques are classified into macropostural, micropostural and postural-work activity. The basis for each classification is outlined and evaluated. Postural recording is performed either continuously or intermittently. Intermittent postural recording procedures lack the criteria for determining the optimum number of observations for low and high repetitive jobs. Research is warranted to examine the sources and magnitudes of errors associated with postural classification. Such information is required to train job analysts in the ergonomics of working postures.

Journal Article↗