-
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 -
Journal of Bodywork and Movement... Apr 2021The purpose of this study was to investigate the surface electromyographic (EMG) activity of the medial (GM) and lateral (GL) heads of the gastrocnemius muscle during...
OBJECTIVE
The purpose of this study was to investigate the surface electromyographic (EMG) activity of the medial (GM) and lateral (GL) heads of the gastrocnemius muscle during plantar flexion performed in standing or seated positions, and with a neutral or dorsiflexed ankle.
INTRODUCTION
The tríceps surae (gastrocnemius and soleus) is an essential muscle group that promotes propulsion during walking, running and tasks of daily living.
METHODS
Ten male volunteers (24.5 ± 3.6 years, weight: 75.8 ± 10 kg; height: 1.74 ± 0.07 m) performed ten repetitions of plantar flexion under four different conditions: a) standing position (SP); b) standing position with passive stretch of the gastrocnemius muscle (SPS); c) seated with the knee flexed (KF); d) seated with the knee flexed and a passive stretch of the gastrocnemius (KFS).
RESULTS
The muscle activity expressed as the root mean square (RMS) was significantly higher for the GL in the SPS versus the SP condition, while there was no difference for the GM between conditions. However, for the KF condition, GM activity was significantly higher versus the KFS condition, which was not verified for the GL.
CONCLUSIONS
Therefore, the standing position with passive stretching of the triceps surae may be more efficient in increasing the myoelectric activity of the GL. However, the sitting position without passive stretching promoted greater GM muscle recruitment. The length/tension relationship of gastrocnemius could be used as a prescription variable during rehabilitation or conditioning programs.
Topics: Ankle; Electromyography; Humans; Male; Muscle, Skeletal; Pilot Projects; Sitting Position; Standing Position; Walking
PubMed: 33992275
DOI: 10.1016/j.jbmt.2020.09.003 -
International Urogynecology Journal Sep 2022Clinical assessment of the pelvic floor muscles (PFMs) in a standing position may provide a more valid representation of PFM function experienced by patients in daily...
INTRODUCTION AND HYPOTHESIS
Clinical assessment of the pelvic floor muscles (PFMs) in a standing position may provide a more valid representation of PFM function experienced by patients in daily life than assessment in the lying position. The primary aim of this study was to examine PFM function in a standing versus a lying position in parous women with any type of urinary incontinence and/or pelvic organ prolapse.
METHODS
In this exploratory cross-sectional study, participant symptom status was determined using the Australian Pelvic Floor Questionnaire. Pelvic floor muscle function was assessed in standing and lying positions with a randomised order of testing. The primary outcome measure was vaginal squeeze pressure (VSP) using intra-vaginal manometry. Secondary outcomes included vaginal resting pressure, total PFM work and digital muscle testing. The difference between PFM function in a standing position compared with a lying position was analysed using paired t test or Wilcoxon's signed rank test.
RESULTS
Vaginal squeeze pressure assessed with manometry was higher in a standing than in a lying position (p = 0.001): standing (mean [SD]) 24.90 [12.67], lying 21.15 [14.65]. In contrast, PFM strength on digital muscle testing was lower in a standing position than in a lying position.
CONCLUSIONS
This study has demonstrated that PFM function in a standing position is different from that in a lying position in women with pelvic floor dysfunction. Whether the higher VSP observed in a standing position reflects a true difference in strength between positions, or a higher pressure reading due to incorrect PFM contraction technique in a standing position is uncertain. Further research with larger cohorts and a measurement tool that can accurately distinguish a rise in intra-vaginal pressure from PFM contraction rather than increasing intra-abdominal pressure is required to confirm this difference, and the clinical significance of any difference.
Topics: Australia; Cross-Sectional Studies; Female; Humans; Muscle Contraction; Muscle Strength; Pelvic Floor; Standing Position
PubMed: 34825921
DOI: 10.1007/s00192-021-05003-6 -
Journal of Motor Behavior 2024We tested twenty-one 6- to 10-month-old infants with a wide range of sitting experience in forward and rightward reaching during unsupported sitting on the floor....
We tested twenty-one 6- to 10-month-old infants with a wide range of sitting experience in forward and rightward reaching during unsupported sitting on the floor. Sessions were video-recorded for further behavioral and machine learning-based kinematic analyses. All infants, including novice sitters, successfully touched and grasped toys in both directions. Infant falls, hand support, and base of support changes were rare. Infants with more sitting experience showed better upright posture than novice sitters. However, we found no differences in trunk displacement or reaching kinematics between directions or across sitting experience. Thus, multi-directional reaching is functional in both novice and experienced infant sitters. We suggest that trunk and arm stability in sagittal and frontal planes is integral to learning to sit.
Topics: Infant; Humans; Posture; Hand; Standing Position; Biomechanical Phenomena; Postural Balance
PubMed: 37751896
DOI: 10.1080/00222895.2023.2262428 -
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 -
Applied Ergonomics Oct 2022Visuospatial attention during walking has been associated with pedestrian safety and fall risks. However, visuospatial attention measures during walking remained...
Visuospatial attention during walking has been associated with pedestrian safety and fall risks. However, visuospatial attention measures during walking remained under-explored. Current studies introduced a newly-developed Standing and Walking Visual Attention Field (SWAVF) task to assess visuospatial attention during walking and examined its reliability, validity, and stability. Thirty young adults completed a traditional computerized Attention Visual Field (AVF) task while sitting, and the SWAVF task under walking and standing settings. Nine participants also performed the SWAVF task under additional distraction conditions. Results showed good split-half reliability during standing (r = 0.70) and walking (r = 0.69), moderate concurrent validity with the sitting AVF task (r = 0.42), moderate convergent validity between the standing and walking settings (r = 0.69), good construct validity, and moderate rank-order stability (r = 0.53). Overall, the SWAVF task showed good psychometric properties. Potential applications to the evaluation of prosthetic and other exoskeleton devices, smart glasses, and ground-level traffic lights or signs were discussed.
Topics: Humans; Reproducibility of Results; Sitting Position; Standing Position; Visual Fields; Walking; Young Adult
PubMed: 35635940
DOI: 10.1016/j.apergo.2022.103804 -
Gait & Posture Mar 2022An exact definition is lacking for the term "weight-bearing" or different standing modalities when implementing foot radiographs for children and adults; moreover, only...
BACKGROUND
An exact definition is lacking for the term "weight-bearing" or different standing modalities when implementing foot radiographs for children and adults; moreover, only few studies have investigated the relationship between radiographic and pedobarographic measurements.
RESEARCH QUESTION
We hypothesized that the method of weight-bearing in single-leg and both-leg standing positions could influence the measurement results in radiographs and the distribution of foot pressure.
METHODS
This prospective study evaluated 33 children (66 feet) with flexible flatfoot deformities scheduled for subtalar screw arthroereisis surgery. Radiographs in the lateral and anteroposterior (AP) views were assessed independently in the single-leg and both-leg standing positions. Static pedobarography was performed as that for measuring weight-bearing. Standardized radiographic angles and pedobarographic data were analysed and correlated.
RESULTS
There were differences in radiographic measurements between the single-leg and both-leg standing positions, including the AP talocalcaneal angle (p = 0.032), AP talus-first metatarsal base angle (p = 0.003), AP talus-first metatarsal angle (p = 0.003), lateral calcaneal pitch angle (p = 0.001), talus-first metatarsal index (p = 0.004), and talocalcaneal index (p = 0.029). Moreover, differences between these two standing modalities were found in most of the static pedobarographic data, including the contact area (p = 0001), maximal force (p = 0.001), and peak pressure (p = 0.007). Overall, medial foot pressure increased more in both-leg standing than in the single-leg standing position, whereas radiographic measurements showed a more pronounced flatfoot deformity in the single-leg standing position. The AP talus-first metatarsal angle was the only angle or index with a significant association to some pedobarographic measurements in both standing modalities.
SIGNIFICANCE
As there are significant differences between single-leg standing and both-leg standing radiographic and static pedobarographic values, observers have to be precise in the definition of "weight-bearing" to gain reproducible and comparable study values in children and adults. We recommend acquiring both-leg standing foot radiographs because children with flexible flatfeet can stand more steadily in this position than in the single-leg standing position.
Topics: Adult; Child; Flatfoot; Humans; Leg; Prospective Studies; Standing Position; Weight-Bearing
PubMed: 35149243
DOI: 10.1016/j.gaitpost.2022.01.009 -
Gait & Posture Mar 2022Fear of falling (FOF) is a psychological condition that can lead to increased morbidity and mortality in the elderly population. However, the subjective and...
BACKGROUND
Fear of falling (FOF) is a psychological condition that can lead to increased morbidity and mortality in the elderly population. However, the subjective and multidimensional nature of FOF results in limitations of existing FOF measurement tools, which could influence the generalization of the findings from various studies. An objective measure of FOF could address those limitations. The present study aimed to identify the feasibility of using center of pressure (COP) parameters to quantify FOF.
RESEARCH QUESTION
(1) Are 360º roller coaster videos effective to induce FOF? And (2) Which COP parameter(s) is/are feasible to quantify FOF?
METHODS
Nineteen young, healthy adults (24 ± 2.47 years) were recruited in the present study. Subjects were required to watch three 360º videos: one control video and two roller coaster videos, through virtual reality goggles during standing and sitting. Six trials (3 during standing and 3 during sitting) with video were performed. Subjects were required to rate their FOF on a visual analogue scale after watching each video. COP mean power frequency, COP root mean square, and COP range were measured. The Friedman test was used to assess differences in COP parameters under different video conditions, and Spearman's correlation analysis was used to assess the relationship between FOF and COP parameters.
RESULTS
Similar COP changes were observed in sitting and standing conditions. With increased FOF, participants demonstrated decreased COP mean power frequency and increased COP root mean square in the medial-lateral direction during both sitting and standing.
SIGNIFICANCE
Our study provided evidence that 360º roller coaster videos are effective tools to induce FOF and change in COP parameters. The relationship between FOF and COP parameters suggests that the measurement of body sway may be an objective way to quantify FOF. More research are needed to solidify the evidence.
Topics: Aged; Fear; Humans; Sitting Position; Standing Position; Virtual Reality
PubMed: 35180684
DOI: 10.1016/j.gaitpost.2022.02.006 -
Journal of Equine Veterinary Science Jan 2020Mules are hybrids bred from the mating of a jack donkey and a horse mare, known for their strength and resistance and still used to work in agriculture. Although they...
Mules are hybrids bred from the mating of a jack donkey and a horse mare, known for their strength and resistance and still used to work in agriculture. Although they have been for long considered sterile, evidence of estrus cycle has been demonstrated together with abnormal behavior related to ovarian activity. In this study, a bilateral standing laparoscopic ovariectomy technique using the LigaSure technology was applied in 10 mare mules for treating unwanted behavioral patterns. The technique was effectively performed on these animals avoiding the risk of general anesthesia, and the use of the LigaSure technology allowed good hemostasis and reduced surgical time. Owners declared to be satisfied with the resolution of the behavior.
Topics: Animals; Equidae; Estrus; Female; Horses; Laparoscopy; Ovariectomy; Standing Position
PubMed: 31864467
DOI: 10.1016/j.jevs.2019.102857