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Journal of the American Heart... Jul 2023Background An elegant bedside provocation test has been shown to aid the diagnosis of long-QT syndrome (LQTS) in a retrospective cohort by evaluation of QT intervals and...
Background An elegant bedside provocation test has been shown to aid the diagnosis of long-QT syndrome (LQTS) in a retrospective cohort by evaluation of QT intervals and T-wave morphology changes resulting from the brief tachycardia provoked by standing. We aimed to prospectively determine the potential diagnostic value of the standing test for LQTS. Methods and Results In adults suspected for LQTS who had a standing test, the QT interval was assessed manually and automated. In addition, T-wave morphology changes were determined. A total of 167 controls and 131 genetically confirmed patients with LQTS were included. A prolonged heart rate-corrected QT interval (QTc) (men ≥430 ms, women ≥450 ms) at baseline before standing yielded a sensitivity of 61% (95% CI, 47-74) in men and 54% (95% CI, 42-66) in women, with a specificity of 90% (95% CI, 80-96) and 89% (95% CI, 81-95), respectively. In both men and women, QTc≥460 ms after standing increased sensitivity (89% [95% CI, 83-94]) but decreased specificity (49% [95% CI, 41-57]). Sensitivity further increased (<0.01) when a prolonged baseline QTc was accompanied by a QTc≥460 ms after standing in both men (93% [95% CI, 84-98]) and women (90% [95% CI, 81-96]). However, the area under the curve did not improve. T-wave abnormalities after standing did not further increase the sensitivity or the area under the curve significantly. Conclusions Despite earlier retrospective studies, a baseline ECG and the standing test in a prospective evaluation displayed a different diagnostic profile for congenital LQTS but no unequivocal synergism or advantage. This suggests that there is markedly reduced penetrance and incomplete expression in genetically confirmed LQTS with retention of repolarization reserve in response to the brief tachycardia provoked by standing.
Topics: Male; Humans; Adult; Female; Retrospective Studies; Electrocardiography; Long QT Syndrome; Tachycardia; Standing Position
PubMed: 37421262
DOI: 10.1161/JAHA.122.026419 -
Scientific Reports Nov 2023Changes in perceived eye height influence visually perceived object size in both the real world and in virtual reality. In virtual reality, conflicts can arise between...
Changes in perceived eye height influence visually perceived object size in both the real world and in virtual reality. In virtual reality, conflicts can arise between the eye height in the real world and the eye height simulated in a VR application. We hypothesized that participants would be influenced more by variation in simulated eye height when they had a clear expectation about their eye height in the real world such as when sitting or standing, and less so when they did not have a clear estimate of the distance between their eyes and the real-life ground plane, e.g., when lying supine. Using virtual reality, 40 participants compared the height of a red square simulated at three different distances (6, 12, and 18 m) against the length of a physical stick (38.1 cm) held in their hands. They completed this task in all combinations of four real-life postures (supine, sitting, standing, standing on a table) and three simulated eye heights that corresponded to each participant's real-world eye height (123cm sitting; 161cm standing; 201cm on table; on average). Confirming previous results, the square's perceived size varied inversely with simulated eye height. Variations in simulated eye height affected participants' perception of size significantly more when sitting than in the other postures (supine, standing, standing on a table). This shows that real-life posture can influence the perception of size in VR. However, since simulated eye height did not affect size estimates less in the lying supine than in the standing position, our hypothesis that humans would be more influenced by variations in eye height when they had a reliable estimate of the distance between their eyes and the ground plane in the real world was not fully confirmed.
Topics: Humans; Size Perception; Posture; Standing Position; Eye; Sitting Position
PubMed: 37974023
DOI: 10.1038/s41598-023-47364-6 -
International Journal of Environmental... Feb 2020The purpose of this study was to investigate if measurements of foot morphology in sitting and standing positions can predict foot muscle strength. Twenty-six healthy...
The purpose of this study was to investigate if measurements of foot morphology in sitting and standing positions can predict foot muscle strength. Twenty-six healthy male adults were recruited, and their foot morphology and foot muscle strength were measured. Foot morphological variables, toe flexor strength, and metatarsophalangeal joint flexor strength were measured by using a digital caliper, Ailitech-AFG500 dynameter and metatarsophalangeal joint flexor strength tester, respectively. Partial correlation and multivariate stepwise regression were used to explore the relationships between foot morphology and toe/metatarsophalangeal joint strength. Results adjusted by age and body mass index were as follows: (1) truncated foot length in sitting and standing positions and foot width in standing position were positively correlated with the flexor strength of the first toe; (2) foot length, foot width, and truncated foot length in both positions were positively related to the flexor strength of the other toes; (3) arch height index in sitting position and differences in navicular height were negatively associated with the flexor strength of the other toes; (4) differences in foot width were negatively associated with metatarsophalangeal joint flexor strength; and (5) the multivariate stepwise regression model showed that truncated foot length in sitting position, navicular height in standing position, differences in navicular height, foot width in sitting position, and differences in foot width were significantly correlated with toe/metatarsophalangeal joint flexor strength. Simple measurements of foot morphological characteristics can effectively predict foot muscle strength. Preliminary findings provided practical implications for the improvement of the foot ability by making specific foot muscle training sessions in professional sports and by compensating the predicted muscle strength defects to prevent foot injury.
Topics: Adult; Foot; Humans; Male; Muscle Strength; Muscle, Skeletal; Standing Position; Toes
PubMed: 32079188
DOI: 10.3390/ijerph17041274 -
Respiration; International Review of... 2022Correlations between upright CT and pulmonary function test (PFT) measurements, and differences in lung/lobe/airway volumes between supine and standing positions in... (Randomized Controlled Trial)
Randomized Controlled Trial
Comparison of Lung, Lobe, and Airway Volumes between Supine and Upright Computed Tomography and Their Correlation with Pulmonary Function Test in Patients with Chronic Obstructive Pulmonary Disease.
BACKGROUND
Correlations between upright CT and pulmonary function test (PFT) measurements, and differences in lung/lobe/airway volumes between supine and standing positions in patients with chronic obstructive pulmonary disease (COPD) remain unknown.
OBJECTIVES
The study aimed to evaluate correlations between lung/airway volumes on both supine and upright CT and PFT measurements in patients with COPD, and compare CT-based inspiratory/expiratory lung/lobe/airway volumes between the two positions.
METHODS
Forty-eight patients with COPD underwent both conventional supine and upright CT in a randomized order during inspiration and expiration breath-holds, and PFTs within 2 h. We measured the lung/lobe/airway volumes on both CT.
RESULTS
The correlation coefficients between total lung volumes on inspiratory CT in supine/standing position and PFT total lung capacity and vital capacity were 0.887/0.920 and 0.711/0.781, respectively; between total lung volumes on expiratory CT in supine/standing position and PFT functional residual capacity and residual volume, 0.676/0.744 and 0.713/0.739, respectively; and between airway volume on inspiratory CT in supine/standing position and PFT forced expiratory volume in 1 s, 0.471/0.524, respectively. Inspiratory/expiratory bilateral upper and right lower lobe, bilateral lung, and airway volumes were significantly higher in the standing than supine position (3.6-21.2% increases, all p < 0.05); however, inspiratory/expiratory right middle lobe volumes were significantly lower in the standing position (4.6%/15.9% decreases, respectively, both p < 0.001).
CONCLUSIONS
Upright CT-based volumes were more correlated with PFT measurements than supine CT-based volumes in patients with COPD. Unlike other lobes and airway, inspiratory/expiratory right middle lobe volumes were significantly lower in the standing than supine position.
Topics: Humans; Lung; Pulmonary Disease, Chronic Obstructive; Respiratory Function Tests; Standing Position; Tomography, X-Ray Computed
PubMed: 36353776
DOI: 10.1159/000527067 -
Journal of Oral Rehabilitation Oct 2021The purpose of this study was to compare the natural head position (NHP) in the sitting position to the NHP in a standing position using inertial measurement unit (IMU)...
AIMS
The purpose of this study was to compare the natural head position (NHP) in the sitting position to the NHP in a standing position using inertial measurement unit (IMU) and lateral photographs.
MATIERIALS & METHODS
Twenty healthy young adult volunteers were asked to look at a mirror located at 1 metre in front of their eyes while being recorded with the IMU system. Lateral photographs were also taken. This procedure was undertaken for the standing and sitting positions, on two separate occasions within a one-week interval.
RESULTS
A strong correlation was found between the IMU system and the lateral photographs (r > .99) with regard to the pitch axis, the absolute mean difference was 0.4 ± 0.5 (p = .99) for both standing and sitting positions. We found that in the sitting position the head was elevated by 2.5 ± 2.4 (p < .05) more than in the standing position, but no significant differences were observed for the other two axes (roll and yaw).
CONCLUSION
The IMU system is comparable to lateral photographs for pitch assessment. Except for a slight elevation of the head in the sitting position, no clinical differences were observed for the NHP when comparing the standing and sitting positions.
Topics: Head; Healthy Volunteers; Humans; Sitting Position; Standing Position; Young Adult
PubMed: 34293214
DOI: 10.1111/joor.13233 -
Skeletal Radiology Aug 2024Distances and angles measured from long-leg radiographs (LLR) are important for surgical decision-making. However, projectional radiography suffers from distortion,... (Comparative Study)
Comparative Study
OBJECTIVE
Distances and angles measured from long-leg radiographs (LLR) are important for surgical decision-making. However, projectional radiography suffers from distortion, potentially generating differences between measurement and true anatomical dimension. These phenomena are not uniform between conventional radiography (CR) digital radiography (DR) and fan-beam technology (EOS). We aimed to identify differences between these modalities in an experimental setup.
MATERIALS AND METHODS
A hemiskeleton was stabilized using an external fixator in neutral, valgus and varus knee alignment. Ten images were acquired for each alignment and each modality: one CR setup, two different DR systems, and an EOS. A total of 1680 measurements were acquired and analyzed.
RESULTS
We observed great differences for dimensions and angles between the 4 modalities. Femoral head diameter measurements varied in the range of > 5 mm depending on the modality, with EOS being the closest to the true anatomical dimension. With functional leg length, a difference of 8.7% was observed between CR and EOS and with the EOS system being precise in the vertical dimension on physical-technical grounds, this demonstrates significant projectional magnification with CR-LLR. The horizontal distance between the medial malleoli varied by 20 mm between CR and DR, equating to 21% of the mean.
CONCLUSIONS
Projectional distortion resulting in variations approaching 21% of the mean indicate, that our confidence on measurements from standing LLR may not be justified. It appears likely that among the tested equipment, EOS-generated images are closest to the true anatomical situation most of the time.
Topics: Humans; Radiographic Image Enhancement; Standing Position; Leg; Patient Positioning
PubMed: 38378861
DOI: 10.1007/s00256-024-04592-9 -
Scientific Reports Mar 2021Currently, no three-dimensional reference data exist for the normal coccyx in the standing position on computed tomography (CT); however, this information could have...
Currently, no three-dimensional reference data exist for the normal coccyx in the standing position on computed tomography (CT); however, this information could have utility for evaluating patients with coccydynia and pelvic floor dysfunction. Thus, we aimed to compare coccygeal parameters in the standing versus supine positions using upright and supine CT and evaluate the effects of sex, age, and body mass index (BMI) on coccygeal movement. Thirty-two healthy volunteers underwent both upright (standing position) and conventional (supine position) CT examinations. In the standing position, the coccyx became significantly longer and straighter, with the tip of the coccyx moving backward and downward (all p < 0.001). Additionally, the coccygeal straight length (standing/supine, 37.8 ± 7.1/35.7 ± 7.0 mm) and sacrococcygeal straight length (standing/supine, 131.7 ± 11.2/125.0 ± 10.7 mm) were significantly longer in the standing position. The sacrococcygeal angle (standing/supine, 115.0 ± 10.6/105.0 ± 12.5°) was significantly larger, while the lumbosacral angle (standing/supine, 21.1 ± 5.9/25.0 ± 4.9°) was significantly smaller. The migration length of the tip of the coccyx (mean, 7.9 mm) exhibited a moderate correlation with BMI (r = 0.42, p = 0.0163). Our results may provide important clues regarding the pathogenesis of coccydynia and pelvic floor dysfunction.
Topics: Adult; Aged; Coccyx; Female; Follow-Up Studies; Humans; Imaging, Three-Dimensional; Male; Middle Aged; Prospective Studies; Standing Position; Supine Position; Tomography, X-Ray Computed
PubMed: 33767271
DOI: 10.1038/s41598-021-86312-0 -
International Journal of Environmental... Jun 2020Sit-stand workstations have shown to reduce sitting time in office workers on a group level. However, movement behaviour patterns might differ between subgroups of...
Sit-stand workstations have shown to reduce sitting time in office workers on a group level. However, movement behaviour patterns might differ between subgroups of workers. Therefore, the objective of this study was to examine sitting, standing and stepping outcomes between habitual users and non-users of sit-stand workstations. From an international office population based in the Netherlands, 24 users and 25 non-users of sit-stand workstations were included (all had long-term access to these workstations). Using the ActivPAL, sitting, standing and stepping were objectively measured during and outside working hours. Differences in outcomes between users and non-users were analysed using linear regression. During working hours, users sat less (-1.64; 95% IC= -2.27--1.01 hour/8 hour workday) and stood more (1.51; 95% IC= 0.92-2.10 hour/8 hour workday) than non-users. Attenuated but similar differences were also found for total sitting time over the whole week. Furthermore, time in static standing bouts was relatively high for users during working hours (median= 0.56; IQR = 0.19-1.08 hour/8 hour workday). During non-working hours on workdays and during non-working days, no differences were found between users and non-users. During working hours, habitual users of their sit-stand workstation sat substantially less and stood proportionally more than non-users. No differences were observed outside working hours, leading to attenuated but similar differences in total sitting and standing time between users and non-users for total days. This indicated that the users of sit-stand workstations reduced their sitting time at work, but this seemed not to be accompanied by major carry-over or compensatory effects outside working hours.
Topics: Humans; Male; Netherlands; Occupational Health; Posture; Sitting Position; Standing Position; Workplace
PubMed: 32521625
DOI: 10.3390/ijerph17114075 -
PloS One 2022A simple and inexpensive method to evaluate slip resistance that can be readily introduced into the workplace is required. In the present study, we investigated the...
A simple and inexpensive method to evaluate slip resistance that can be readily introduced into the workplace is required. In the present study, we investigated the relationship between a simple sensory evaluation of anti-slipperiness by foot rubbing in standing and sitting positions and the actual friction properties obtained with in situ measurements at slip onset and during sliding. We also verified the possibility of identifying a hazardous area with a high slip-induced fall risk by the sensory evaluation scores. At the foot rubbing tests, more than half of the 15 participants in experiments could adequately perceive the slip resistance using the proposed method without any education on its perception. Furthermore, hazard detection scores, where a friction coefficient of 0.2 was detected as hazardous area, were obtained from optimal cut-off points of receiver operatorating characteristic curves for the participants with friction perception capability. The scores were 28.7, 20.7, 24.7, and 52.3/100 for the slip onset while standing, sliding while standing, slip onset while sitting, and sliding while sitting, respectively. From the viewpoint of hazard detection accuracies, the standing position was a better way than the sitting although limited to participants with the capability of perceiving friction. Based on the analysis of how to apply forces, the participants who showed a small movement of the center of pressure while standing or an increase in the vertical load while sitting had the capability of perceiving friction.
Topics: Foot; Friction; Humans; Lower Extremity; Shoes; Standing Position
PubMed: 36174046
DOI: 10.1371/journal.pone.0275385 -
Journal of Visualized Experiments : JoVE Jul 2021Transcranial magnetic stimulation (TMS) is a common tool used to measure the behavior of motor circuits in healthy and neurologically impaired populations. TMS is used...
Transcranial magnetic stimulation (TMS) is a common tool used to measure the behavior of motor circuits in healthy and neurologically impaired populations. TMS is used extensively to study motor control and the response to neurorehabilitation of the upper extremities. However, TMS has been less utilized in the study of lower extremity postural and walking-specific motor control. The limited use and the additional methodological challenges of lower extremity TMS assessments have contributed to the lack of consistency in lower extremity TMS procedures within the literature. Inspired by the decreased ability to record lower extremity TMS motor evoked potentials (MEP), this methodological report details steps to enable post-stroke TMS assessments in a standing posture. The standing posture allows for the activation of the neuromuscular system, reflecting a state more akin to the system's state during postural and walking tasks. Using dual-top force plates, we instructed participants to equally distribute their weight between their paretic and non-paretic legs. Visual feedback of the participants' weight distribution was provided. Using image guidance software, we delivered single TMS pulses via a double-cone coil to the participants' lesioned and non-lesioned hemispheres and measured the corticomotor response of the paretic and non-paretic tibialis anterior and soleus muscles. Performing assessments in the standing position increased the TMS response rate and allowed for the use of the lower stimulation intensities compared to the standard sitting/resting position. Utilization of this TMS protocol can provide a common approach to assess the lower extremity corticomotor response post-stroke when the neurorehabilitation of postural and gait impairments are of interest.
Topics: Evoked Potentials, Motor; Humans; Lower Extremity; Motor Cortex; Muscle, Skeletal; Standing Position; Stroke; Transcranial Magnetic Stimulation
PubMed: 34369926
DOI: 10.3791/62601