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PubMed1985

Urinary electrolyte excretion and orthostatic response of blood pressure and plasma renin activity in children with postural hypotension before and after treatment with Dihydergot.

Na and K metabolism, and orthostatic response of blood pressure and plasma renin activity (PRA) were studied in six children, aged 10 to 15 years, with postural hypotension before and after treatment with Dihydergot (DHE). All abnormal findings which we had already observed in children with postural hypotension (i.e. low fractional excretion of filtered Na in spite of low PRA, extremely high PRA on fainting, great postural fall in blood pressure, and so on) improved on treatment with DHE. This suggests that these abnormal physiological findings found in children with postural hypotension may result from increased venous pooling which can be reduced by DHE. Consequently, DHE seems an excellent drug to treat postural hypotension from the physiological point of view.

Adolescent↗

PubMed2004

Blood flow response to a postural challenge in older men and women.

BACKGROUND: The purpose of this study was to measure blood flow in the carotid and femoral arteries, heart rate and blood pressure in response to postural challenge in older adults. A second purpose was to determine if older men and women have different cardiovascular responses to a postural challenge such as tilt. METHODS: Thirty-seven healthy elderly men and women participated in this study (69-82 years old). All subjects had similar physical activity levels. Postural challenge was induced by a 60 degrees tilt at the level of the waist. Continuous carotid blood flow and femoral blood flow was measured with Doppler ultrasound. RESULTS: Carotid blood flow was significantly reduced 17% in both men and women immediately after tilt (p < 0.001), and by 3.2% two minutes after tilt (p < 0.001). Femoral blood flow decreased 59.4% in men and 61% in women immediately after tilt (p < 0.001), and remained significantly decreased two minutes after tilt by 21% (p <0.001). Heart rate increased by 15% in men (p < 0.001), and 26% in women immediately after the tilt (p < 0.001). Heart rate returned to resting values within two minutes in both men and women. Response to tilt was not significantly related to self-report physical activity levels or to six-minute walk time. CONCLUSION: A postural challenge induced larger changes in the femoral artery compared to the carotid artery. There were no differences between men and women to a tilt table test except for differences in heart rate response. There was no difference in the blood flow responses to postural challenge with physical activity level or between healthy older men and women.

Journal Article↗

PubMed2003

Effect of posture on oxygenation, lung volume, and respiratory mechanics in premature infants studied before discharge.

OBJECTIVES: To determine if the prone versus the supine posture was associated with higher oxygenation levels in prematurely born infants before discharge, whether any such effect was explained by alterations in lung volume or respiratory mechanics, and if the changes were greater in oxygen-dependent infants. PATIENTS: Twenty infants (10 oxygen-dependent), median gestational age 30 (range: 27-32) weeks, were studied at a median postconceptional age of 35 weeks (range: 32-38 weeks). METHODS: On 2 successive days, infants were studied both supine and prone; each posture was maintained for 3 hours. Oxygen saturation was continuously monitored and at the end of each 3-hour period; compliance and resistance of the respiratory system and functional residual capacity (FRC) were measured. RESULTS: Overall, the median oxygen saturation and FRC were significantly higher in the prone position; compliance of the respiratory system and resistance of the respiratory system were not significantly affected by posture. Differences in oxygen saturation and FRC were significantly higher in the prone posture in the oxygen-dependent, but not the nonoxygen-dependent infants. CONCLUSIONS: Superior oxygenation in the prone posture in oxygen-dependent premature infants studied before discharge could be explained by higher lung volumes.

Functional Residual Capacity↗

PubMed1982

Note on criteria for writing posture used to test Levy and Reid's cerebral organization hypotheses.

Apparent ambiguities in Levy and Reid's writing posture criteria and dissimilar criteria used by other investigators are discussed. Classification of inverted writing postures by a diagram which, as Levy and Reid indicated in 1976, depicts typical writing positions is questioned because their 1978 paper suggests that these diagrammed positions were only an intermediary stage in the classification of some inverters. Results of studies using dissimilar criteria for writing posture appear to be difficult to compare because subjects who may differ in cerebral organization might be placed in the same category. Some of these studies introduced another possible source of confounding because different tasks were used to test lateralization of function. Since different tasks seem to study distinctive facets of language, lateralization of one function in sinistrals, thought to be less lateralized than dextrals, does not predict lateralization of any other function. These considerations suggest that an adequate test of Levy and Reid's ideas concerning the relationship among handedness, hand posture during writing, sex, and cerebral organization requires the development of a standard set of valid criteria for writing posture.

Dominance, Cerebral↗

PubMed2006

Comparison of different structural foot types for measures of standing postural control.

STUDY DESIGN: Matched group comparison of 3 subject groups with 3 different foot structures for force plate and clinical measures of postural control. OBJECTIVES: To determine if subjects with different weight-bearing foot structure would demonstrate differences in static standing postural control, and to determine the reliability of study procedures. BACKGROUND: Weight-bearing foot structure may influence postural control either because of a decreased base of support (supinated foot structure) or because of passive instability of the joints of the foot (pronated foot structure). METHODS AND MEASURES: Young adults were categorized based on weight-bearing foot structure into neutral, pronated, or supinated groups (15 subjects per group). Postural control in single-limb stance with eyes closed was assessed using force plate measures and by measuring duration of single-limb stance on a firm floor and on a balance pad. Force plate measures were normalized center-of-pressure average speed; and standard deviation and maximum displacement in the anterior-posterior and medial-lateral directions. RESULTS: Individuals in the supinated group had significantly greater center-of-pressure average speed, greater maximum displacement in the anterior-posterior direction, and greater SD and maximum displacement in the medial-lateral direction than individuals in the neutral group. The individuals in the pronated group had significantly greater SD and maximum displacement in the anterior-posterior direction, used more trials to complete force plate testing, and had shorter single-limb stance duration than those in the neutral group. CONCLUSION: Individuals with pronated feet or supinated feet have poorer postural control than individuals with neutral feet, but perhaps through different mechanisms.

Adolescent↗

PubMedDate not supplied

Use of the longitudinal arch angle to predict dynamic foot posture in walking.

To determine whether differences exist in the longitudinal arch angle based on sex or extremity, the longitudinal arch angle was assessed in 21 men and 21 women using a digital image of the medial aspect of each subject's feet. The image was obtained with the subject in relaxed standing posture and in maximum internal rotation of the lower leg. To determine whether the longitudinal arch angle could be used to predict dynamic foot posture during walking, 50 different subjects were asked to walk across a 6-m walkway while the medial aspect of each foot was videotaped. The longitudinal arch angle was digitized from digital images obtained at midstance for three walking trials. No differences in the longitudinal arch angle were found based on sex or extremity. The longitudinal arch angles obtained in the static positions of relaxed standing posture and maximum internal rotation were highly predictive of dynamic foot posture at midstance during walking. Relaxed standing posture and maximum internal rotation significantly contributed to explaining more than 90% of the variance associated with the longitudinal arch angle position at midstance during walking. These results validate use of the longitudinal arch angle as part of the foot and ankle physical examination.

Adult↗

PubMedDate not supplied

Effects of 2 ankle fatigue models on the duration of postural stability dysfunction.

CONTEXT: Muscle fatigue is generally categorized in 2 ways: that caused by peripheral weakness (peripheral fatigue) and that caused by a progressive failure of voluntary neural drive (central fatigue). Numerous variables have been studied in conjunction with fatigue protocols, including postural stability, maximum voluntary contraction force, and reaction time. When torque recordings fall below 50% of a maximum voluntary contraction, the muscle is described as fatigued, but whether this value is a good indicator of fatigue has not been studied. OBJECTIVE: To compare the effects of 2 ankle musculature fatigue protocols (30% and 50%) on the duration of postural stability dysfunction. DESIGN: To assess differences between the 30% and 50% fatigue protocols, we calculated a 1 between-groups factor (subjects) and 2 within-groups factors (fatigue, test) analysis of variance. SETTING: E.J. Nutter Athletic Training Facility. PATIENTS OR OTHER PARTICIPANTS: Twenty subjects (10 men, 10 women; age = 21.15 +/- 2.23 years; height = 172.97 +/- 9.86 cm; mass = 70.62 +/- 14.60 kg) volunteered for this study. Subjects had no history of lower extremity injury, vestibular or balance disorders, functional ankle instability, or head injury in the past 6 months. INTERVENTION(S): On separate days, subjects performed isokinetic fatiguing contractions of the plantar flexors and dorsiflexors in a 30% protocol (70% decrease in strength) and a 50% protocol (50% decrease in strength). MAIN OUTCOME MEASURE(S): Baseline and postfatigue postural stability scores were determined before and after the isokinetic fatiguing contractions. Plantar-flexion peak-torque measurements were obtained for the 2 fatiguing protocols. Three prefatigue and 12 postfatigue postural stability trials were recorded. Velocities for testing were 60 degrees /s for plantar flexion and 120 degrees /s for dorsiflexion. RESULTS: Sway velocity was significantly greater when the ankle was fatigued to 30% (1.56 degrees /s) than in the 50% condition (1.36 degrees /s). For the 30% protocol, sway was significantly impaired when the pretest condition (1.19 degrees /s) was compared with posttest trial 1 (2.34 degrees /s), trial 2 (2.37 degrees /s), and trial 3 (1.71 degrees /s). For the 50% protocol, sway was significantly impaired when the pretest condition (1.27 degrees /s) was compared with posttest trial 1 (2.02 degrees /s). CONCLUSIONS: The 30% fatigue protocol resulted in significantly longer impairment of postural stability than the 50% protocol. Because the 30% protocol resulted in a greater effect but was relatively short-lived (approximately 75 to 90 s), it is more useful for research purposes.

Journal Article↗

PubMed1996

Effect of mild head injury on postural stability in athletes.

OBJECTIVE: Athletic trainers and team physicians are often faced with the dilemma of when to return athletes to participation following mild head injury. Unfortunately, clinicians rarely have quantitative information on which to base their decisions. The purpose of this investigation was to identify postural stability changes in athletes with acute mild head injury. DESIGN AND SETTING: High school and college male athletes were prescreened for postural stability before the start of their season. Subjects suffering injury during the season returned for testing on days 1, 3, 5, and 10 following injury, and 1 month postseason. Control subjects were selected for comparisons. SUBJECTS: Ten prescreened subjects (age = 17.4 +/- 2.2 yr; ht = 183.8 + 8.1 cm; wt = 87.7 + 17.3 kg) returned for testing following an injury. Ten matched control subjects (age = 18.6 +/- 2.6 yr; ht = 185.7 +/- 6.7 cm; wt = 84.5 +/- 19.5 kg) were selected for comparisons. Additionally, nine subjects (eight male and one female) (age = 19.9 +/- 4.2 yr; ht = 182.3 + 10.9 cm; wt = 89.6 +/- 25.2 kg) who had sustained a mild head injury from other varsity sports teams were recruited. Nine matched controls (age = 22.1 +/- 3.3 yr; ht = 181.0 +/- 9.9 cm; wt = 84.9 +/- 25.6 kg) were again utilized. MEASUREMENTS: Sway index and center of balance were measured using the Chattecx Balance System during three eye conditions and three surface conditions for all subjects. RESULTS: Repeated measures analyses of variance (ANOVA) for each prescreened subject's sway index revealed significant differences between injured subjects and control subjects on day 1 postinjury as compared with the prescreening and/or subsequent tests. The analysis for sway index and center of balance inclusive of all 19 subjects with mild head injury and all 19 control subjects demonstrated increased postural sway compared with control subjects on day 1 postinjury during all plafform conditions, and on day 3 during the foam platform condition. The analysis for center of balance using the same subjects revealed that injured subjects maintained their center of balance farther away on day 1 postinjury compared with subsequent tests (p < .05). CONCLUSIONS: These findings suggest that computerized dynamic posturography is a useful tool in objectively assessing postural stability in subjects with mild head injuries. Subjects with mild head injury appear to demonstrate impaired postural stability 1 to 3 days following injury. This information should aid clinicians in determining when an athlete can safely return to participation.

Journal Article↗

PubMedDate not supplied

Dynamic postural stability in subjects with braced, functionally unstable ankles.

CONTEXT: Research concerning prophylactic ankle stabilizers (PASs) has focused on healthy subjects, and the results cannot be generalized to the functional ankle instability (FAI) population, a population that has an increased risk of reinjury and is likely to wear PASs. OBJECTIVE: To determine whether PASs improve dynamic postural stability in FAI subjects as compared with a control (no-brace) condition. DESIGN: A crossover design was used to determine the effects of PASs on dynamic postural stability and vertical ground reaction forces. SETTING: Biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-eight subjects with unilateral FAI, 13 men (age = 21.5 +/- 1.2 years, height = 181.5 +/- 10.5 cm, mass = 77.6 +/- 17.2 kg) and 15 women (age = 20.5 +/- 1.1 years, height = 169.4 +/- 8.2 cm, mass = 67.9 +/- 8.8 kg). INTERVENTION(S): A jump protocol required subjects to perform a 2-legged jump to a height equivalent to 50% of their maximum vertical leap and land on a single leg. MAIN OUTCOME MEASURE(S): The dynamic postural stability index, the directional components (medial-lateral, anterior-posterior, and vertical), and vertical ground reaction force after a jump landing. RESULTS: Compared with the control condition, only the vertical component score was reduced (improved) with the application of a soft or semirigid PAS (P < .01). CONCLUSIONS: Soft and semirigid PASs did not improve dynamic postural stability as measured by the Dynamic Postural Stability Index. However, PASs may help with the attenuation of vertical forces.

Journal Article↗

PubMed1995

Constrained and unconstrained postures of the mandible--a break with tradition?

Evaluation of detailed electrognathographic recordings of various movements of the mandible (and points on it) suggested interpretations at variance with some traditional concepts. Data previously accumulated from several sources were subjected to critical analysis. An objective was to assess the manner in which two rotations of the mandible influenced its postures during trials of mastication and deliberate lateral excursions. Rotations about a vertical and an antero-posterior axis appear to facilitate a greater functional posturing potential of the mandible than has previously been reported. In most instances the influence of the rotations upon mandibular posture is considerably greater than the size of the recorded angles would suggest. Some of the resulting postures seem to challenge concepts derived strictly from cadaverine anatomy. For example, during mastication the condyle does not simply glide forward and backward relative to the eminence but may be distracted downward away from it for a part of the time. Furthermore, the ability of a subject to effect a considerable variety of mandibular postures challenges traditional reliance upon constrained mandibular movements as a means of evaluating function.

Humans↗

PubMed2003

Effect of cognitive and motor tasks on postural stability in Parkinson's disease: a posturographic study.

To analyse the effect of concomitant cognitive or motor task performance on balance control in Parkinson's disease (PD), we performed a posturographic study in 24 PD patients and in 20 sex- and age-matched control subjects. Postural sway was measured with eyes open (EO) and eyes closed (EC) during quiet stance and during performance of calculation or motor sequence of thumb opposition to the other fingers. No difference of centre of foot pressure (COP) parameters was observed during quiet standing (either EO or EC) between patients and controls, but visual deprivation induced in both groups a worsening of postural stability. COP area was significantly increased in PD patients during dual task performance, whereas no difference of COP path and x-y axes was observed. The effects induced by the performance of cognitive or motor task were significantly more evident in PD patients with clinical evidence of postural instability (presence of prior falls in the history). This study demonstrates that dual task interference on postural control can be observed in PD patients during performance of cognitive as well as motor tasks. The balance deterioration during dual task performance was significantly enhanced in patients with history of prior falls. These findings have some implications for the strategies to be used in reducing the risk of fall in PD.

Accidental Falls↗

PubMed2003

Forceplate and accelerometer measures for evaluating the effect of muscle fatigue on postural control during one-legged stance.

BACKGROUND AND PURPOSE: The control of balance is vital in many sporting activities as well as in activities of daily life. In order to treat deficiencies properly valid and reliable methods are needed to evaluate different aspects of stability. Muscle fatigue has been proposed to cause a change in postural control strategy, and the use of different tools and variables might therefore elucidate these changes. The aims of the present study were: to investigate if forceplate and accelerometer measurements about postural control during one-legged stance indicate changes in postural control strategy after fatiguing exercise; and to investigate the correlation between forceplate and accelerometer measurements obtained before and after fatiguing exercise. METHOD: The study used an experimental design. Twenty-three healthy women (mean age 26.8 years; range 20-34 years) were studied. Forceplate and accelerometer data were obtained simultaneously and consisted of measures of centre of pressure movements and horizontal trunk acceleration in medio-lateral and antero-posterior directions. The calf muscles of the right leg were fatigued by repeated heel rises. RESULTS: The average amplitude of centre of pressure movements and trunk acceleration increased, whereas the average velocity of centre of pressure movements decreased during fatigue. These changes indicate a change of movement strategy. Moderate correlation between trunk acceleration and centre of pressure movements was seen, confirming the link between the variables, but indicating that different aspects of the ability to control balance were measured. CONCLUSIONS: Calf muscle fatigue has a short-lasting effect on body balance, with measurements indicating a change in postural control strategy. Different tools and variables are needed to identify different balance control strategies. The procedures used in the present study may be modified to identify subjects with inadequate capacity to choose between balance control strategies; they are also applicable in clinical settings outside a laboratory environment.

Acceleration↗

PubMed2026

Effect of Global Postural Re-Education in Individuals With Text Neck Syndrome: A Randomized Controlled Trial.

BACKGROUND AND PURPOSE: This study investigated the effect of Global Postural Re-Education (GPR) versus conventional physical therapy in text neck syndrome (TNS). A prospective, single-blinded, parallel-group randomized controlled trial design was used. METHODS: Sixty participants with TNS (aged 18-40 years) were randomly assigned to either conventional treatment or GPR plus conventional treatment. Both groups received supervised therapy for three sessions per week over 4 weeks. Outcome measures included craniovertebral and shoulder angles assessed by photogrammetry, pain intensity via Visual Analog Scale, and Cervical Range of Motion via a smartphone application (Clinometer). Measured before and after the intervention. RESULTS: Within-group analyses showed significant improvements in pain and CROM in both groups (p < 0.001). However, the between-group analysis revealed no superiority of GPR for pain or CROM (p > 0.05). In contrast, GPR demonstrated statistically significant superiority in postural correction, with greater improvements in craniovertebral angle (MD: 2.14°; 95% CI: 0.69-3.59; p = 0.005) and shoulder angle (MD: 3.2°; 95% CI: 0.33-6.07; p = 0.03), exceeding MCID thresholds and indicating clinically meaningful benefits. However, these findings should be interpreted with caution because of the longer session duration in the GPR group. DISCUSSION: Incorporating Global Postural Reeducation (GPR) into conventional treatment provided significant additional benefits for postural parameters (craniovertebral and shoulder angles) in individuals with text neck syndrome. However, GPR demonstrated no added superiority over conventional treatment alone regarding pain intensity and cervical range of motion outcomes.

Humans↗

PubMed2002

Vestibulospinal control of posture.

To better understand the role of the vestibular system in postural coordination, we compared the ability of subjects with complete, bilateral loss of vestibular function and age-matched control subjects to maintain equilibrium and postural orientation during sinusoidal displacements of the support surface at a variety of frequencies. We also examined the ability of visual or somatosensory-light touch information to substitute for missing vestibular information in dynamic postural coordination. The results suggest that vestibular information is used as a gravitational reference frame to prevent slow drift of the trunk in space during complex postural tasks. Furthermore, visual information or somatosensory information from light touch of a finger on a stable reference can significantly substitute for loss of vestibular function.

Gravitation↗

PubMed2006

Postural activity of the pelvic floor muscles is delayed during rapid arm movements in women with stress urinary incontinence.

The aim of this study was to determine whether postural activity of the pelvic floor (PF) and abdominal muscles differs between continent and incontinent women during rapid arm movements that present a postural challenge to the trunk. A further aim was to study the effect of bladder filling. Electromyographic activity (EMG) of the PF, abdominal, erector spinae (ES), and deltoid muscles was recorded with surface electrodes. During rapid shoulder flexion and extension, PF EMG increased before that of the deltoid in continent women, but after the deltoid in incontinent women (p = 0.002). In many incontinent women, PF EMG decreased before the postural activation. Although delayed, postural PF EMG amplitude was greater in women with incontinence (p = 0.010). In both groups, PF EMG decreased and abdominal and ES EMG increased when the bladder was moderately full. These findings would be expected to have negative consequences for continence and lumbopelvic stability in women with incontinence.

Adult↗

PubMed2005

Attentional demands associated with the use of a light fingertip touch for postural control during quiet standing.

The purpose of the present experiment was to investigate whether and how using a light fingertip touch for postural control during quiet standing requires additional attentional demands. Nine young healthy university students were asked to respond as rapidly as possible to an unpredictable auditory stimulus while maintaining stable seated and upright postures in three sensory conditions: vision, no-vision and no-vision/touch. Touch condition involved a gentle light touch with the right index finger on a nearby surface at waist height. Center of foot pressure (CoP) displacements were recorded using a force platform. Reaction times (RTs) values were used as an index of the attentional demand necessary for calibrating the postural system. Results showed decreased CoP displacements in both the vision and no-vision/touch conditions relative to the no-vision condition. More interestingly, a longer RT in the no-vision/touch than in the vision and no-vision conditions was observed. The present findings suggest that the ability to use a light fingertip touch as a source of sensory information to improve postural control during quiet standing is attention demanding.

Adult↗

PubMed2006

Altered timing of postural reflexes contributes to falling in persons with chronic stroke.

The purpose of this study was to determine differences in the timing of postural reflexes and changes in kinematics between those who fell (fallers) in response to standing platform translations and those who did not (non-fallers). Forty-four persons with stroke were exposed to unexpected forward and backward platform translations while standing. Surface electromyography from bilateral tibialis anterior, gastrocnemius, rectus femoris, and biceps femoris were recorded along with kinematic data. Those that fell in response to the translations were compared to those who did not fall in terms of (1) postural reflex onset latency, (2) the time interval between the activation of distal and proximal muscles (i.e. intralimb coupling), and (3) changes in joint angles and trunk motion. Approximately 85% of falls occurred in response to the forward translations. Postural reflex onset latencies were delayed and intralimb coupling durations were longer in the faller versus non-faller group. At the time that the platform completed the translating motion (300 ms), the faller group demonstrated higher trunk velocity, greater change in paretic ankle angle, and the trunk was further behind the ankle compared to the non-faller group. This study suggests that following platform translations, delays in the timing of postural reflexes and disturbed intralimb coupling result in changes in kinematics, which contribute to falls in persons with stroke.

Aged↗

PubMed2005

Postural responses triggered by multidirectional leg lifts and surface tilts.

The aim of the present study was to investigate the relationship between proactive and reactive components of postural control. We contrasted the kinematic and electromyographic (EMG) responses to multidirectional voluntary leg lifts with those elicited by unexpected surface tilts. In particular, we addressed the role of trunk stabilization following either a voluntary or forced weight shift from double to single limb support. Nine young female subjects stood with a standing posture of 45 degrees toe-out and their arms abducted to shoulder level. On the experimenter's signal, subjects either (1) lifted one leg as fast as possible in one of six directions (R/L side, R/L diagonal front, R/L diagonal back) to a height of 45 degrees or (2) maintained standing as the support surface tilted at a rate of 53 degrees /s to a height of 10 degrees in one of six directions (R/L-up, R/L diagonal toes-up, R/L diagonal toes-down). For both tasks, our results showed that the center of pressure (COP) displacement began before or in conjunction with displacement of the center of mass (COM), after which the COP oscillated about the horizontal projection of the COM. In addition, the muscles were recruited in a distal-to-proximal sequence, either in anticipation of the voluntary leg lift or in response to the sudden surface tilt. Thus, the COP was being used dynamically to control displacement of the COM. The axial postural strategy comprising head, trunk, and pelvis movements was quantified by means of principal component analysis. More than 95% of the variance in the data could be described by the first two eigenvectors, which revealed specific coordination patterns dominated by pelvis rotation in one direction and head/trunk rotation in the opposite direction. Unexpected surface tilting elicited an automatic response strategy that focused on controlling the orientation of the head and trunk with respect to the vertical gravity vector while trunk verticality was compromised for movement generation and the recovery of postural equilibrium during leg lifting. In conclusion, regardless of the type (voluntary versus involuntary) or direction of perturbation, the strategy employed by the central nervous system to control the body COM displacement concerns mainly trunk stabilization.

Adult↗