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Annual International Conference of the... Jul 2019Standing from a seated position is an activity of daily living and a common clinical test of strength and balance. While this action is well-studied biomechanically,...
Standing from a seated position is an activity of daily living and a common clinical test of strength and balance. While this action is well-studied biomechanically, there remains a need for a clear modelling method for appropriately capturing performance and discriminating between standing strategies. This paper presents a simple framework for representing the rise from a chair as a set of splines. This formulation is inherently differentiable, defines a clear start and end point of the motion, and allows for secondary analysis of dynamic and energetic effects. This method is tested on two healthy subjects performing four different standing strategies. The spline method was found to accurately capture the standing action, with mean absolute errors of 1-2 cm for joint position, and 2-3 degrees angular error across the different standing strategies. Analysis of the spline trajectories revealed strategy-specific differences in kinematic, kinetic, and dynamic bio-markers. This suggests that low order splines can be used to accurately capture variations in sit-to-stand actions.
Topics: Biomechanical Phenomena; Humans; Models, Biological; Movement; Sitting Position; Standing Position
PubMed: 31946772
DOI: 10.1109/EMBC.2019.8857429 -
Journal of Biomechanics May 2023Ballet training is being increasingly used to improve physical functions in older adults. Our previous work showed that ballet dancers react to a novel standing-slip...
Ballet training is being increasingly used to improve physical functions in older adults. Our previous work showed that ballet dancers react to a novel standing-slip more effectively than their non-dancer counterparts through better control of the recovery step and trunk movement. The purpose of this study was to test if and to what extent ballet dancers adapt differently to repeated standing-slips relative to non-dancers. Protected by a harness, twenty young adults (10 professional ballet dancers and 10 age/sex-matched non-dancers) experienced five repeated and standardized standing-slips on a treadmill. Changes from the first slip (S1) to the fifth slip (S5) in dynamic gait stability (primary outcome) and other variables, including the center of mass position and velocity, step latency, slip distance, ankle angle, and trunk angle (secondary outcomes) were compared between groups. Results revealed that both groups adopted similar proactive controls to improve dynamic gait stability by using the ankle and hip strategies. However, dancers showed a better reactive improvement in stability after the repeated slips than non-dancers. From S1 to S5, dancers reactively improved their dynamic gait stability more than non-dancers at the recovery step liftoff (p = 0.003). Dancers decreased their recovery step latency (p = 0.004) and shortened the slip distance (p = 0.004) significantly more than non-dancers from S1 to S5. These findings suggest that ballet dancers could facilitate the adaptation to repeated slips, which may be attributed to their ballet practice experience. This finding augments our understanding of the underlying mechanisms of ballet practice reducing falls.
Topics: Dancing; Standing Position; Adaptation, Physiological; Humans; Male; Female; Young Adult; Exercise Test; Accidental Falls
PubMed: 37027960
DOI: 10.1016/j.jbiomech.2023.111572 -
Medical Engineering & Physics Aug 2022We studied the Shannon entropy of center of pressure (COP) trajectories under different sensory feedback conditions and analyzed the interrelations between...
We studied the Shannon entropy of center of pressure (COP) trajectories under different sensory feedback conditions and analyzed the interrelations between medial-lateral (ML), anterior-posterior (AP) and joint (ML and AP) sway entropy. Static balance was assessed on a force platform under different visual and proprioceptive feedback conditions: Standing on firm support with eyes open (condition 1) or closed (condition 2) and standing on foam with eyes closed (condition 3). Postural sway was analyzed by means of linear and nonlinear, information theoretic metrics (entropy of ML and AP sway, joint ML and AP entropy). ML entropy, AP entropy and joint ML and AP entropy remained stable from condition 1 through condition 3. The values of ML and AP entropies were practically at their theoretical maximum in all conditions. On the other hand, joint ML and AP entropies were clearly submaximal. Decreasing the reliability of visual and proprioceptive input does not alter the Shannon entropy of body sway, although it does increase the magnitude of conventional linear sway metrics. Importantly, individual ML and AP sway entropies tend towards absolute randomness, whereas the joint, ML and AP, sway entropy exhibits a higher degree of regularity, suggesting its role as the actual controlled variable.
Topics: Entropy; Postural Balance; Reproducibility of Results; Standing Position
PubMed: 35926955
DOI: 10.1016/j.medengphy.2022.103842 -
Scientific Reports Nov 2022No clinical study has compared lung or lobe volumes on computed tomography (CT) between the supine and standing positions in patients with idiopathic lung fibrosis...
No clinical study has compared lung or lobe volumes on computed tomography (CT) between the supine and standing positions in patients with idiopathic lung fibrosis (IPF). This study aimed to compare lung and lobe volumes between the supine and standing positions and evaluate the correlations between the supine/standing lung volumes on CT and pulmonary function in patients with IPF. Twenty-three patients with IPF underwent a pulmonary function test and both low-dose conventional (supine position) and upright CT (standing position) during inspiration breath-holds. The volumes of the total lungs and lobes were larger in the standing than in the supine position in patients with IPF (all p < 0.05). Spearman's correlation coefficients between total lung volumes on chest CT in supine/standing positions and vital capacity (VC) or forced VC (FVC) were 0.61/0.79 or 0.64/0.80, respectively. CT-based volumes on upright CT were better correlated with VC and FVC than those on supine CT. Lung and lobe volumes in the standing position may be useful biomarkers to assess disease severity or therapeutic effect in patients with IPF.
Topics: Humans; Standing Position; Idiopathic Pulmonary Fibrosis; Respiratory Function Tests; Lung; Tomography, X-Ray Computed
PubMed: 36371537
DOI: 10.1038/s41598-022-24157-x -
Radiography (London, England : 1995) Feb 2022
Topics: Humans; Radiography; Standing Position
PubMed: 35012751
DOI: 10.1016/j.radi.2021.12.012 -
Military Medicine Jul 2023Transitioning between the ground and standing is a required activity for many professions including skilled trades, law enforcement, and military service. However,...
INTRODUCTION
Transitioning between the ground and standing is a required activity for many professions including skilled trades, law enforcement, and military service. However, available assessments are limited and focus primarily on quality of movement. Thus, we developed two novel assessments of functional mobility specific for ground-to-standing transitions: Stand-Prone-Standx2 (SPS2) and Stand-Kneel-Standx2 (SKS2-L/R) tests. The purpose of this study was to determine the psychometrics of these two new measures in able-bodied (AB) service members and in service members with unilateral lower extremity injury (LEI).
MATERIALS AND METHODS
A total of 57 AB service members and 31 service members with a traumatic unilateral LEI wearing a custom carbon-fiber ankle-foot orthosis participated in this study. In total, 36 AB and 18 LEI participants returned for a second session to assess intersession reliability. Intraclass correlation coefficients were calculated for intersession and inter-rater comparisons (two-way random model for consistency and single measure). Additionally, performance was compared between legs and groups.
RESULTS
The SPS2 and SKS2 assessments demonstrated excellent inter-rater and intersession reliability in both the AB and LEI groups with all intraclass correlation coefficient values greater than 0.8. Further, the tests were responsive to deficits associated with LEI, with the LEI group having significantly longer times on all assessments compared to the AB group.
CONCLUSIONS
The SPS2 and SKS2 performance measures were found to have excellent inter-rater and intersession reliability in both AB participants and participants with LEI. Further, participants with LEI performed significantly slower than the AB participants. Excellent reliability and responsiveness to deficits associated with LEI support the use of the SPS2 and SKS2 to assess mobility in individuals with LEI. Transitions between the ground and standing occur in many occupational and daily tasks. These reliable performance measures that assess ground-to-stand transitions can be applied widely, in many populations beyond highly functioning service members with LEI.
Topics: Humans; Male; Female; Adult; Reproducibility of Results; Psychometrics; Standing Position
PubMed: 35869886
DOI: 10.1093/milmed/usac228 -
Journal of Biomechanics Dec 2023This study investigated the inter- and intramuscular variability of plantar flexors stiffness during prone and standing positions at different muscle lengths in healthy...
This study investigated the inter- and intramuscular variability of plantar flexors stiffness during prone and standing positions at different muscle lengths in healthy and paretic individuals. To access tissue stiffness, shear wave elastography (SWE) measurements were carried out on two groups: control group (CG; n=14; age 43.9±9.6 years; body mass index [BMI]=24.5±2.5 kg/m) and stroke survivor group (SSG; n=14; age 43.9±9.6 years; BMI=24.5±2.5 kg/m). Shear Modulus (μ, kPa) within three plantar flexors (the gastrocnemius medialis [GM], gastrocnemius lateralis [GL], and soleus [SOL]) was obtained during two conditions: prone and standing position, at different angles of dorsiflexion (0°, 10°, and 20°). Measurements were also performed in different proximo-distal regions of each muscle. Muscle activation of the GM, GL, SOL, and tibialis anterior were evaluated during the two conditions. Results showed a high spatial stiffness variability between and within plantar flexors during dorsiflexion. The highest stiffness was observed in the GM, especially in the distal region at 20° in healthy and paretic muscles. In the prone position, the paretic muscle exhibits greater stiffness compared to the healthy muscle (p < 0.05). In contrast, in the standing position, an increase of stiffness in the healthy muscle compared to the paretic muscle was observed (p < 0.05). Thus, mechanical properties are differently affected by stroke depending on active and passive states of ankle muscles during dorsiflexion. In addition, the modification of ankle muscle state change stiffness distribution between and within plantar flexors.
Topics: Humans; Adult; Middle Aged; Standing Position; Muscle, Skeletal; Ankle; Ankle Joint; Elasticity Imaging Techniques; Stroke
PubMed: 37922613
DOI: 10.1016/j.jbiomech.2023.111838 -
International Journal of Environmental... Aug 2021Public health guidelines for physical activity now include recommendations to break up prolonged sitting with light-intensity activities. Concurrently, interventions to...
Public health guidelines for physical activity now include recommendations to break up prolonged sitting with light-intensity activities. Concurrently, interventions to increase standing have emerged, especially within the workplace in the form of sit-stand or standing workstations. Moreover, in short-duration studies, breaking up prolonged sitting with standing has been associated improved cardiometabolic outcomes. Publicly available estimates of the intensity of standing range from 1.5 to 2.3 metabolic equivalents (METs), neatly classifying standing as a light-intensity activity (>1.5 to <3.0 METs). Further delineation between 'active' and 'passive' standing has been proposed, with corresponding METs of >2.0 METs and ≤2.0 METs, respectively. However, this study reviews data suggesting that some standing (e.g., while performing deskwork) is substantially below the minimum light intensity activity threshold of 1.5 METs. These data bring into question whether standing should be universally classified as a light-intensity behavior. The objectives of this study are to (i) highlight discrepancies in classifying standing behavior in the human movement spectrum continuum, and (ii) to propose a realignment of the 'active' vs. 'passive' standing threshold to match the light intensity threshold to help provide a clearer research framework and subsequent public health messaging for the expected health benefits from standing.
Topics: Exercise; Humans; Sedentary Behavior; Standing Position; Time Factors; Workplace
PubMed: 34444209
DOI: 10.3390/ijerph18168460 -
Multiple Sclerosis and Related Disorders Jul 2021Widespread demyelination in the central nervous system can lead to progressive sensorimotor impairments following multiple sclerosis, with compromised postural stability...
BACKGROUND
Widespread demyelination in the central nervous system can lead to progressive sensorimotor impairments following multiple sclerosis, with compromised postural stability during standing being a common consequence. As such, clinical strategies are needed to improve postural stability following multiple sclerosis. The objective of this study was therefore to investigate the effect of non-invasive transcutaneous spinal stimulation on postural stability during upright standing in individuals with multiple sclerosis.
METHODS
Center of pressure displacement and electromyograms from the soleus and tibialis anterior were recorded in seven individuals with multiple sclerosis during standing without and with transcutaneous spinal stimulation. Center of pressure and muscle activity measures were calculated and compared between no stimulation and transcutaneous spinal stimulation conditions. The relationship between the center of pressure displacement and electromyograms was quantified using cross-correlation analysis.
RESULTS
For transcutaneous spinal stimulation, postural stability was significantly improved during standing with eyes closed: the time- and frequency-domain measures obtained from the anterior-posterior center of pressure fluctuation decreased and increased, respectively, and the tibialis anterior activity was lower compared to no stimulation. Conversely, no differences were found between no stimulation and transcutaneous spinal stimulation when standing with eyes open.
CONCLUSION
Following multiple sclerosis, transcutaneous spinal stimulation improved postural stability during standing with eyes closed, presumably by catalyzing proprioceptive function. Future work should confirm underlying mechanisms and explore the clinical value of transcutaneous spinal stimulation for individuals with multiple sclerosis.
Topics: Electromyography; Humans; Multiple Sclerosis; Muscle, Skeletal; Postural Balance; Spinal Cord; Spinal Cord Stimulation; Standing Position
PubMed: 34023772
DOI: 10.1016/j.msard.2021.103009 -
European Spine Journal : Official... Mar 2020To investigate the characteristics of standing and sitting spinopelvic sagittal alignment among Chinese healthy population with different age groups.
PURPOSE
To investigate the characteristics of standing and sitting spinopelvic sagittal alignment among Chinese healthy population with different age groups.
METHOD
This cross-sectional, prospective study included a total of 235 volunteers aged 19 to 71 years. Volunteers were divided into two groups: group A (age ≤ 40 years; n = 140) and group B (age > 40 years, n = 95). Student's t test was performed to compare the sagittal parameters including sagittal vertical axis (SVA), T1 pelvic angle (TPA), cervical lordosis (CL), thoracic kyphosis (TK), lumbar lordosis (LL) and pelvic tilt (PT) between standing and sitting positions of two groups. Multiple regression was performed to explore the influence factors of differences between two positions.
RESULTS
In the standing position, group B had larger SVA, TK, PT and TPA than group A. When moving from standing to sitting position, increased SVA and PT were found in both groups, accompanied by decreased LL and TK. However, despite similar change in SVA, group B presented with lesser changes in LL, PT and TPA than group A in sitting position. Age and gender independently influenced the difference in PT and LL.
CONCLUSION
In the standing position, the older volunteers showed larger SVA, TPA, TK, CL and PT than young population. Both groups showed similar changes when moving from standing to sitting, but the differences between the positions were smaller in older population. These characteristics in the standing and sitting positions of different age groups should be considered when planning surgical reconstruction of sagittal alignment. These slides can be retrieved under Electronic Supplementary Material.
Topics: Adult; Aged; Aged, 80 and over; Asian People; China; Cross-Sectional Studies; Female; Humans; Male; Middle Aged; Pelvis; Posture; Sitting Position; Spine; Standing Position; Young Adult
PubMed: 31630266
DOI: 10.1007/s00586-019-06185-w