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PubMed1985

Postural sway during standing and unexpected disturbance of balance in random samples of men of different ages.

Postural sway behavior while standing and during and after an unexpected disturbance of balance was examined in men aged 31 to 35, 51 to 55, and 71 to 75 years. The groups studied were random samples of men living in the town of Jyväskylä in 1981. Postural sway while standing was more pronounced in the older age groups, whereas after a disturbance of balance postural sway was nearly the same in all age groups. The functioning of the postural control system was correlated with the vibratory threshold on the ankles, grip strength, as well as with aerobic and anaerobic capacity within the age groups. Further, in the youngest age group the functioning of the postural control system was poorer among those who had been subject to noise at their work. The correlation between health status and postural sway was negligible. The results may indicate the partly parallel and similar effects of aging, poor physical fitness, and harmful environmental factors on the functioning of the postural control system.

Adult↗

PubMed1988

Development of prone extension postures in healthy infants.

The purposes of this study were to 1) investigate the sequence of development of head, upper extremity, and lower extremity extension in the prone extension posture in healthy infants; 2) identify the variations in the sequence; and 3) compare these postures within the sequence with the development of prone-on-elbows and prone-on-hands postures. Twenty healthy, full-term infants were observed longitudinally from 8 to 28 weeks of age. Two of the infants could not complete the study, and two infants never used the prone extension posture. The data from 16 of the infants, therefore, were analyzed. The results indicate that the sequence of development of the prone extension posture consists of head extension, followed by lower extremity extension, and then upper extremity extension. The results also indicate that upper extremity extension in the prone extension posture does not appear to be a prerequisite for the prone-on-elbows or prone-on-hands postures. These findings suggest that infants may use different strategies for developing motor control in the head and lower extremities than in the upper extremities. This information adds to our knowledge of the normal developmental process and may have significance in the planning of physical therapy programs.

Arm↗

PubMed1992

Incidence of common postural abnormalities in the cervical, shoulder, and thoracic regions and their association with pain in two age groups of healthy subjects.

The purposes of this study were to identify the incidence of postural abnormalities of the thoracic, cervical, and shoulder regions in two age groups of healthy subjects and to explore whether these abnormalities were associated with pain. Eighty-eight healthy subjects, aged 20 to 50 years, were asked to answer a pain questionnaire and to stand by a plumb line for postural assessment of forward head, rounded shoulders, and kyphosis. Subjects were divided into two age groups: a 20- to 35-year-old group (mean = 25, SD = 63) and a 36- to 50-year-old group (mean = 47, SD = 2.6). Interrater and intrarater reliability (Cohen's Kappa coefficients) for postural assessment were established at .611 and .825, respectively. Frequency counts revealed postural abnormalities were prevalent (forward head = 66%, kyphosis = 38%, right rounded shoulder = 73%, left rounded shoulder = 66%). No relationship was found between the severity of postural abnormality and the severity and frequency of pain. Subjects with more severe postural abnormalities, however, had a significantly increased incidence of pain, as determined by chi-square analysis (critical chi 2 = 6, df = 2, P less than .05). Subjects with kyphosis and rounded shoulders had an increased incidence of interscapular pain, and those with a forward-head posture had an increased incidence of cervical, interscapular, and headache pain.

Adult↗

PubMed2002

Upright posture reduces thermogenesis and augments core hypothermia.

UNLABELLED: We recently reported that baroreceptor-mediated reflexes modulate thermoregulatory vasoconstriction during lower abdominal surgery. Accordingly, we examined the hypothesis that postural differences and the related alterations in baroreceptor loading similarly modulate the thermogenic (i.e., shivering) response to hypothermia in humans. In healthy humans (n = 7), cold saline was infused IV (30 mL/kg at 4 degrees C) for 30 min to decrease core temperature. Each participant was studied on 2 separate days, once lying supine and once sitting upright. Tympanic membrane temperature and oxygen consumption were monitored for 40 min after each saline infusion. The decrease in core temperature upon completion of the infusion in the upright posture position was 1.24 degrees C +/- 0.07 degrees C, which was significantly greater than the 1.02 degrees C +/- 0.06 degrees C seen in the supine position. The core temperature was reduced by 0.59 degrees C +/- 0.07 degrees C in the upright position but only by 0.37 degrees C +/- 0.05 degrees C in the supine position when the increase in oxygen consumption signaling thermogenic shivering occurred. Thus, the threshold temperature for thermogenesis was significantly less in the upright than the supine position. The gain of the thermogenic response did not differ significantly between the positions (363 +/- 69 mL. min(-1). degrees C(-1) for upright and 480 +/- 80 mL. min(-1). degrees C(-1) for supine). The skin temperature gradient was significantly larger in the upright than in the supine posture, suggesting that the peripheral vasoconstriction was augmented by upright posture. Plasma norepinephrine concentrations increased in response to cold saline infusion under both conditions, but the increase was significantly larger in the upright than in the supine posture. Baroreceptor unloading thus augments the peripheral vasoconstrictor and catecholamine response to core hypothermia but simultaneously reduces thermogenesis, which consequently aggravated the core temperature decrease in the upright posture. IMPLICATIONS: Upright posture attenuates the thermogenic response to core hypothermia but augments peripheral vasoconstriction. This divergent result suggests that input from the baroreceptor modifies the individual thermoregulatory efferent pathway at a site distal to the common thermoregulatory center or neural pathway.

Adult↗

PubMed1983

Postural variations in pulmonary resistance, dynamic compliance, and esophageal pressure in neonates.

In order to determine effect of posture and to assess the reliability of the esophageal balloon method for measuring esophageal pressure changes (delta Pes) under clinical conditions, lung mechanics were measured in 13 term and preterm babies in each of 3 postures: supine, right, and left lateral. The pulmonary resistance (Rp) was significantly lower and the dynamic compliance (Cdyn) higher in the right lateral than in the supine position. Judged by the occlusion test, delta Pes was recorded accurately in each posture. The mean end-expiratory esophageal balloon pressure (PesEE) was higher in preterm infants and in the supine posture. It is concluded that the (right) lateral posture is mechanically less demanding than the supine posture and that delta Pes can be measured accurately in the supine posture. Absolute values of PesEE have no physiologic meaning and should not be used for patient management or for the calculation of lung mechanics.

Airway Resistance↗

PubMed1990

How does posture influence the haemodynamic assessment of a cardiovascular drug? Experience with nicardipine.

The extent to which posture altered the haemodynamic response to slow calcium channel blocker nicardipine was evaluated in 22 male patients with angiographically confirmed coronary artery disease. Patients were randomly allocated to supine or upright posture and an otherwise identical protocol performed in each group. At rest, following a control saline period, four doses of the drug (log cumulative dosage: 1.25, 2.5, 5.0, and 10.0 mg) were administered by i.v. infusion over a total period of 40 min; haemodynamic indices were recorded during the 3-5 min following each 5 min infusion. The exercise effects of the drug, in each posture, were determined by comparison of a control predrug exercise with observations at the same workload following the maximal cumulative dose. Nicardipine reduced resting mean blood pressure (MBP) and systemic vascular resistance index (SVRI) in both postures, the decrease being more pronounced when upright (MBP, -12%, -18%; p less than 0.01: SVRI, -30%, -46%; p less than 0.01). The increases in cardiac index (CI) and stroke volume index (SVI) were higher when upright (29 and 54% vs. 10 and 27%; p less than 0.01). Pulmonary artery occluded pressure (PAOP) increased by 29% when upright, without change when supine. On exercise, the effects for HR, MBP, CI, SI, and SVRI responses were independent of posture; however, a qualitative difference was apparent for PAOP (-17% vs. +14%; p less than 0.05). Thus, although the actions of nicardipine were qualitatively similar, quantitative differences related to posture were confirmed. These differences appeared to relate to posture-related baseline haemodynamic differences between the groups but with similar postnicardipine absolute values.

Adult↗

PubMed1999

The associations between adolescent head-on-neck posture, backpack weight, and anthropometric features.

STUDY DESIGN: A Cross-sectional, observational study, examining the effects of backpack weight on adolescent posture. OBJECTIVES: To investigate the response of the craniovertebral angle to backpack load. SUMMARY OF BACKGROUND DATA: There is a widely held belief that repeated carrying of heavy loads, such as school backpacks, places additional stress on rapidly growing adolescent spinal structures, making them prone to postural change. METHODS: Ten volunteer state high schools in metropolitan Adelaide, South Australia, provided 985 students, aged 12 to 18 years and from five different high school years, for this study. Students' posture was measured with and without their school backpack. All data analyses were undertaken per school year level to account for specific load-carrying requirements and spinal development associated with the age group. RESULTS: A significant change in craniovertebral angle was found at every year level, when comparing standing posture with no backpack with posture when carrying a backpack. The change was greatest for the youngest students. Incremental change in craniovertebral angle was not strongly associated with backpack loads. The association became stronger for the oldest girls when controlled for body mass index and for weight. CONCLUSION: The results support a differential postural response per gender and per level of spinal development but also suggest that the craniovertebral angle may not be the most sensitive measure of head-on-neck postural change for adolescents.

Adolescent↗

PubMed1999

Measuring postural changes in blood pressure in the healthy elderly.

BACKGROUND: Background The reproducibility of postural changes in blood pressure of a healthy elderly population determined using standard clinical measurements is not known. OBJECTIVE: To assess the differences in reproducibility of postural changes in blood pressure in healthy elderly subjects 1 and 3 min after standing within a day and between visits spaced 6 weeks apart. METHODS: Casual readings of blood pressures of supine and standing subjects were measured twice during the day by the same observer on two occasions 6 weeks apart using a semi-automatic syphgmomanometer. Twenty-two subjects with no known risk factors for orthostatic hypotension (13 men) aged 69+/-3 years (mean+/-SD) with a mean initial screening supine blood pressure of 153+/-19/88+/-11 mmHg were recruited. RESULTS: There were significant differences(P<0.001) between the postural changes both for systolic and for diastolic blood pressure between 1 and 3 min of standing, the largest falls occurring after 1 min of standing, though we found no variation between morning and afternoon measurements and between visits. The coefficients of reproducibility between visits for the postural changes in blood pressure after 1 and 3 min of standing were large both for systolic and for diastolic blood pressure, ranging from 9.8 to 29.3 mmHg. CONCLUSIONS: There was a consistent and significant difference between the postural changes in blood pressure after 1 and 3 min of standing for this healthy elderly population, but there was no significant difference between the postural changes in morning and afternoon measurements and between visits. This marked variability in the postural change in blood pressure with duration of standing must be taken into account when assessing the prevalence of orthostatic hypotension and the effects of treatment in patients with orthostatic falls in blood pressure.

Aged↗

PubMed2003

Reposition sense of lumbar curvature with flexed and asymmetric lifting postures.

STUDY DESIGN: Reposition sense of lumbar curvature was assessed as a function of trunk flexion, trunk asymmetry, and target lumbar curvature using a repeated-measures design and an active-active proprioception paradigm. OBJECTIVE: The objectives of the research were to measure the ability of the subjects to sense and control the lumbar curvature in different lifting postures and to see if error in the lumbar curvature would increase in high-risk postures. SUMMARY OF BACKGROUND DATA: The risk of low back disorders (LBDs) is related to trunk posture, with greater risk reported in flexed and asymmetric trunk positions. Spinal posture, including trunk position and lumbar lordosis, influences spinal stability. Hence, the ability to accurately sense and control spinal curvature may be an important factor in the control of LBD risk. METHODS: Eleven subjects were trained to assume specified lumbar curvatures using visual feedback. The ability of the subjects to reproduce this curvature without feedback was then assessed. This procedure was repeated for different trunk postures, including flexion and asymmetry, and with different target lumbar curvatures. RESULTS: These measurements demonstrated reposition error was increased in flexed trunk positions but was unchanged with trunk asymmetry. This increase in reposition error with flexion was diminished when the target posture and lumbar curvature were highly flexed and kyphotic. CONCLUSIONS: This research suggests that it may be difficult to control spinal curvature in flexed positions, leading to an increased risk of injury. For jobs in which flexed working postures are unavoidable, therefore, it is important to minimize potentially unstable events such as slipping or shifting loads to avoid injury.

Adult↗

PubMed1997

Early recognition of postural disorders in multiple sclerosis through movement analysis: a modeling study.

In the present study, spontaneous postural behavior has been analyzed in freely standing multiple sclerosis (MS) patients, exhibiting no clinically assessable abnormalities of postural control. This population has been compared with two other groups, healthy people and hemiparetic patients. This latter group represents a situation where the central nervous system (CNS) lesion is precisely localized in one anatomical site and no signal-conduction disorders are present; i.e., it has an opposite anatomical character with respect to the MS at a preclinical stage. The hypothesis underlying the modeling study is the presence of a controller block working in a feedback posture control system. This controller block receives the body sway as input, and produces the corresponding ankle torque stabilizing the body, the latter being modeled as an inverted pendulum. The CNS damage, caused by MS, is supposed to be reflected in some detectable change in the structure of the controller of the posture control system. The identification of the controller has been performed by means of a parametric estimation procedure which employed as input sequences, data recorded by means of a movement-analysis (MA) system. Reported findings show a structural changes of the model of the controller block in the posture control system. This result may suggest the presence of an MS-specific reorganization of the posture control system. Some speculation is finally made on the black-box approach in comparison with traditional posturography, to arrive at hypothesizing a progression path for postural disorders.

Adult↗

PubMed1994

Postural stimulation test in patients with aldosterone producing adenomas.

OBJECTIVE: The purpose of this study was to evaluate the postural stimulation test before and after surgical treatment in patients with aldosterone-producing adenomas. DESIGN: The retrospective study was made on patients with aldosterone producing adenomas. PATIENTS: The postural stimulation test was analysed in 60 patients with surgically proven aldosterone producing adenoma and in 15 healthy volunteers. MEASUREMENTS: The postural stimulation test was based on measurements of plasma aldosterone, cortisol and renin activity (PRA) at 0800 h and at noon after 4 hours ambulation. RESULTS: The patients were divided into two groups according to the individual pattern of plasma aldosterone concentration following the postural test. Plasma aldosterone concentration decreased or did not change after 4 hours of standing in 42 patients (group 1, 70% of total) and increased in 18 patients (group 2, 30% of total). Mean plasma aldosterone was significantly higher in group 1 than in group 2 (1325 +/- 164 pmol/l (mean +/- SE) and 538 +/- 53 pmol/l, respectively). Mean plasma cortisol concentration after 4 hours of upright posture in both groups remained low (242 +/- 35 vs 401 +/- 63 nmol/l (group 1) and 317 +/- 46 vs 367 +/- 43 nmol/l (group 2)). Mean PRA in both groups was suppressed after 4 hours of upright posture (0.2 +/- 0.04 vs 0.2 +/- 0.04 pmol/l/s and 0.3 +/- 0.06 vs 0.1 +/- 0.02 pmol/l/s, respectively). CONCLUSION: Diverse changes in plasma aldosterone and cortisol found in response to the postural test may indicate pathogenetic heterogeneity amongst patients with aldosterone producing adenomas and should be considered during diagnosis of primary aldosteronism.

Adenoma↗

PubMed1993

Postural effects on diastolic blood pressure are differently recorded by a non-invasive ambulatory blood pressure monitor and a standard auscultatory device.

The aim of this study was to determine the influence of change of posture on blood pressure as recorded with an automatic ambulatory blood pressure monitor and a standard auscultatory device. The blood pressure difference between sitting and supine and between standing and supine posture was 1.1/3.9 and 6.5/6.3 mmHg, respectively, for the monitor recordings, and 0.7/6.7 and 7.9/14.8 mmHg, respectively, for the standard recordings. All differences were significant, except the systolic blood pressure difference between sitting and supine posture. There were no significant differences in systolic blood pressure between monitor and standard recordings in any posture. The corresponding differences in diastolic blood pressure were significant in sitting (-4.6 mmHg) and standing postures (-10.3 mmHg), but not in supine posture (-1.8 mmHg). It is concluded that a change of posture contributes to blood pressure variability, and agreement between diastolic blood pressure in supine subjects, as recorded by an ambulatory monitor and a standard device, does not necessarily mean agreement in standing (or sitting) subjects.

Adult↗

PubMed2006

Evaluation of time-to-contact measures for assessing postural stability.

Postural stability has traditionally been examined through spatial measures of the center of mass (CoM) or center of pressure (CoP), where larger amounts of CoM or CoP movements are considered signs of postural instability. However, for stabilization, the postural control system may utilize additional information about the CoM or CoP such as velocity, acceleration, and the temporal margin to a stability boundary. Postural time-to-contact (TtC) is a variable that can take into account this additional information about the CoM or CoP. Postural TtC is the time it would take the CoM or CoP, given its instantaneous trajectory, to contact a stability boundary. This is essentially the time the system has to reverse any perturbation before stance is threatened. Although this measure shows promise in assessing postural stability, the TtC values derived between studies are highly ambiguous due to major differences in how they are calculated. In this study, various methodologies used to assess postural TtC were compared during quiet stance and induced-sway conditions. The effects of the different methodologies on TtC values will be assessed, and issues regarding the interpretation of TtC data will also be discussed.

Adult↗

PubMed2001

Static postural sway, proprioception, and maximal voluntary quadriceps contraction in patients with knee osteoarthritis and normal control subjects.

OBJECTIVES: To investigate whether subjects with knee osteoarthritis (OA) have reduced static postural control, knee proprioceptive acuity, and maximal voluntary contraction (MVC) of the quadriceps compared with normal controls, and to determine possible independent predictors of static postural sway. METHODS: 77 subjects with symptomatic and radiographic knee OA (58 women, 19 men; mean age 63.4 years, range 36-82) and 63 controls with asymptomatic and clinically normal knees (45 women, 18 men; mean age 63 years, range 46-85) underwent assessment of static postural sway. 108 subjects (59 patients, 49 controls) also underwent assessment of knee proprioceptive activity and MVC (including calculation of quadriceps activation). In patients with knee OA knee pain, stiffness, and functional disability were assessed using the WOMAC Index. The height (m) and weight (kg) of all subjects was assessed. RESULTS: Compared with controls, patients with knee OA were heavier (mean difference 15.3 kg, p<0.001), had increased postural lateral sway (controls: median 2.3, interquartile (IQ) range 1.8-2.9; patients: median 4.7, IQ range 1.9-4.7, p<0.001), reduced proprioceptive acuity (controls: mean 7.9, 95% CI 6.9 to 8.9; patients: mean 12.0, 95% CI 10.5 to 13.6, p<0.001), weaker quadriceps strength (controls: mean 22.5, 95% CI 19.9 to 24.6; patients: mean 14.7, 95% CI 12.5 to 16.9, p<0.001), and less percentage activation of quadriceps (controls: mean 87.4, 95% CI 80.7 to 94.2; patients: mean 66.0, 95% CI 58.8 to 73.2, p<0.001). The significant predictors of postural sway were knee pain and the ratio of MVC/body weight. CONCLUSIONS: Compared with age and sex matched controls, subjects with symptomatic knee OA have quadriceps weakness, reduced knee proprioception, and increased postural sway. Pain and muscle strength may particularly influence postural sway. The interaction between physiological, structural, and functional abnormalities in knee OA deserves further study.

Adult↗

PubMed1993

Flexibility and posture assessment in relation to hamstring injury.

Posture and flexibility were assessed in 34 athletes. Subjects were divided into two groups: (1) a noninjured group that did not have a history of hamstring strain injury within the previous 12 months; (2) an injured group that had a history of hamstring strain within the previous 12 months. Ten postural components were assessed: head erectness; shoulder symmetry; spinal curvature; hip symmetry; foot and ankle alignment; knee hyperextension; upper back roundness; trunk erectness; abdomen protrusion; and lumbar lordosis. Hamstring flexibility was assessed in both legs. Results indicated no difference (P > 0.05) in flexibility between groups (mean(s.d.) of both legs was: noninjured = 77.1(9.3) degrees, injured = 77.8(9.2) degrees. Also no difference (P > 0.05) was observed between the injured limb and the noninjured limb for injured subjects (injured limb = 78.1(11.1) degrees, noninjured limb = 77.5(8.1) degrees. A significant difference (P < 0.01) between groups occurred in low back posture (lumbar lordosis). No other difference occurred in the remaining nine posture components between groups. Intercorrelation coefficients among posture components indicated that at best only 53% of common variance existed between any two components (head and shoulder components: r = 0.73, P < 0.01). All other correlations indicated less than 40% common variance between components. The results of the study indicate that while differences in hamstring flexibility are not evident between injured and noninjured groups poorer low back posture was found in the injured group. Regular monitoring of posture in athletes is recommended.

Athletic Injuries↗

PubMed1995

Anticipatory postural adjustments during self inflicted and predictable perturbations in Parkinson's disease.

This study investigated the relation between impaired anticipatory postural adjustments and bradykinesia in Parkinson's disease. Patients with Parkinson's disease and age matched controls stood on a platform. In one series of experiments, they performed fast, discrete shoulder flexion or extension movements. In another series, they were required to press a trigger with the right thumb and thus to release a load that was suspended from a bar which they were holding in front of them in extended arms. One more series included catching a load on the same bar. Anticipatory changes in the activity of postural muscles before fast voluntary movements occurred in patients and controls although the patients showed higher variability of anticipatory patterns. During load dropping and catching, control subjects had reproducible, although smaller, anticipatory changes in postural muscle activity. Such changes were absent in all but one patient. Two sources of these postural perturbations were analysed. The anticipatory postural adjustments in different muscle groups may counteract perturbations of different origin. The distal to proximal sequencing of joint involvement in postural reactions may be related to different reference points and working points associated with these tasks compared with reaching limb movements. The deficit in anticipatory postural adjustments in Parkinson's disease is likely to be unrelated to bradykinesia and is more likely to reflect the deficits in the basic processes of preparation and initiation of a motor act.

Aged↗

PubMed2003

Effects of light fingertip touch on postural responses in subjects with diabetic neuropathy.

OBJECTIVES: To investigate the potential benefits from lightly touching an external supporting device on automatic postural responses to support surface translations, in subjects with profound sensory neuropathy in the feet due to diabetes mellitus (DM-PN). METHODS: Eight subjects with DM-PN and 10 age matched controls were tested under randomly ordered conditions of no fingertip touch (NT), light touch (LT; <1 N), and heavy touch (HT, as needed) of a stationary touch plate, during three backward translation velocities of the support surface at 10, 20, and 30 cm/s. Dependent variables included response latencies, CoP velocity, and the slope of the relation between centre of pressure (CoP) velocity and translation velocity as a measure of response scaling. RESULTS: Postural response latencies were significantly longer and scaling of initial response magnitude in proportion to translation velocity was significantly smaller in the DM-PN subjects compared to the control subjects. LT had no significant effect on response latencies of the DM-PN patients. Fingertip touch increased the slope of the scaling of postural response magnitude in both groups. However, DM-PN subjects had to use HT to improve response scaling, whereas control subjects improved scaling with LT as well as HT. LT significantly increased rightward CoP velocity towards the touch plate in all subjects. CONCLUSIONS: LT did not reduce the latency or improve the scaling of automatic postural responses in subjects with peripheral neuropathy. The major effect of LT on the automatic postural responses of the DM-PN subjects was in increasing CoP velocity towards the side of the supporting device. HT in neuropathy subjects and LT in age matched control subjects increased the sensitivity of initial postural response scaling, suggesting that somatosensory substitution from a cane in the hand could be used to improve the magnitude of medium latency postural responses to slips and trips.

Aged↗

PubMed2004

A comparison of methods for the assessment of postural load and duration of computer use.

AIM: To compare two different methods for assessment of postural load and duration of computer use in office workers. METHODS: The study population existed of 87 computer workers. Questionnaire data about exposure were compared with exposures measured by a standardised or objective method. Measuring true exposure to postural load consisted of an observation of the workstation design and posture by a trained observer. A software program was used to record individual computer use. RESULTS: Comparing the answers for each item of postural load, six of eleven items showed low agreement (kappa <0.20). For six items the sensitivity was below 50%, while for eight items the specificity was 80% or higher. Computer workers were unable to identify risk factors in their workplace and work posture. On average, computer workers overestimated their total computer use by 1.6 hours. The agreement among employees who reported a maximum of three hours of computer use per day was higher than the agreement among employees with a high duration of computer use. CONCLUSIONS: Self-report by means of this questionnaire is not a very reliable method to measure postural load and duration of computer use. This study emphasises that the challenge to develop quick and inexpensive techniques for assessing exposure to postural load and duration of computer use is still open.

Adult↗