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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 -
Clinical Neurophysiology : Official... Sep 2023The vestibular cortex is a multisensory associative region that, in neuroimaging investigations, is activated by slow-frequency (1-2 Hz) galvanic stimulation of... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
The vestibular cortex is a multisensory associative region that, in neuroimaging investigations, is activated by slow-frequency (1-2 Hz) galvanic stimulation of peripheral receptors. We aimed to directly activate the vestibular cortex with biophysically modeled transcranial oscillatory current stimulation (tACS) in the same frequency range.
METHODS
Thirty healthy subjects and one rare patient with chronic bilateral vestibular deafferentation underwent, in a randomized, double-blind, controlled trial, to tACS at slow (1 or 2 Hz) or higher (10 Hz) frequency and sham stimulations, over the Parieto-Insular Vestibular Cortex (PIVC), while standing on a stabilometric platform. Subjective symptoms of motion sickness were scored by Simulator Sickness Questionnaire and subjects' postural sways were monitored on the platform.
RESULTS
tACS at 1 and 2 Hz induced symptoms of motion sickness, oscillopsia and postural instability, that were supported by posturographic sway recordings. Both 10 Hz-tACS and sham stimulation on the vestibular cortex did not affect vestibular function. As these effects persisted in a rare patient with bilateral peripheral vestibular areflexia documented by the absence of the Vestibular-Ocular Reflex, the possibility of a current spread toward peripheral afferents is unlikely. Conversely, the 10 Hz-tACS significantly reduced his chronic vestibular symptoms in this patient.
CONCLUSIONS
Weak electrical oscillations in a frequency range corresponding to the physiological cortical activity of the vestibular system may generate motion sickness and postural sways, both in healthy subjects and in the case of bilateral vestibular deafferentation.
SIGNIFICANCE
This should be taken into account as a new side effect of tACS in future studies addressing cognitive functions. Higher frequencies of stimulation applied to the vestibular cortex may represent a new interventional option to reduce motion sickness in different scenarios.
Topics: Humans; Vestibule, Labyrinth; Cognition; Neuroimaging; Standing Position; Double-Blind Method; Transcranial Direct Current Stimulation
PubMed: 37481873
DOI: 10.1016/j.clinph.2023.06.013 -
BMC Nephrology Mar 2022As hemodialysis is administered with the patient lying down, the distribution of body fluid is stable in the lying position, which is why this position is recommended...
BACKGROUND
As hemodialysis is administered with the patient lying down, the distribution of body fluid is stable in the lying position, which is why this position is recommended for bioimpedance analysis (BIA). Although the InBody S10 is widely used for hemodialysis patients in the lying position, clinicians must make the measurements in person. In contrast, patients can use the InBody 770 to obtain measurements by themselves in the standing position, which may be more convenient. Therefore, this study compared the measurements of hemodialysis patients' estimated target weight and ECW/TBW obtained lying down using the S10 to those obtained in the standing position using the 770.
METHODS
This study was conducted among maintenance hemodialysis patients at Chuncheon Sacred Heart Hospital in October 2020. Measurements from 56 patients before and after hemodialysis were obtained using the 2 machines. Each (S10 or 770) estimated target weight, both pre- and post-hemodialysis, was considered ideal when the ECW/TBW ratio was 0.380. R was calculated and the Bland-Altman test was performed.
RESULTS
The patients' median age was 64 years old, and 51% were men. The actual ultrafiltration was 2 kg, and the mean TBW change measured using the InBody devices was 1.5 L (R = 0.718) for the S10 and 1.7 L (R = 0.616) for the 770. The estimated target weight at pre- and post-hemodialysis showed a remarkably high correlation with the patients' actual pre- and post-hemodialysis weight (R > 0.095). The correlation between these measurements (lying vs. standing) before and after hemodialysis was also very close (R = 1.0000). In addition, ECW/TBW had a good correlation (R2 ≥ 0.970) The Bland-Altman test of dry weight and ECW/TBW yielded similar results.
CONCLUSIONS
This study showed that patients' estimated target weights in the lying position using the InBody S10 device and in the standing position using the InBody 770 device were consistent in both pre- and post-hemodialysis states.
Topics: Body Composition; Body Water; Electric Impedance; Female; Humans; Male; Middle Aged; Renal Dialysis; Standing Position; Ultrafiltration
PubMed: 35300597
DOI: 10.1186/s12882-022-02737-3 -
Sensors (Basel, Switzerland) Oct 2022Few standards and guidelines to prevent health problems have been associated with tablet use. We estimated the effects of posture and tablet tilt angle on muscle...
Few standards and guidelines to prevent health problems have been associated with tablet use. We estimated the effects of posture and tablet tilt angle on muscle activity and posture in healthy young adults. Seventeen healthy young adults (age: 20.5 ± 3 years) performed a cognitive task using a tablet in two posture (sitting and standing) and tablet tilt angle (0 degrees and 45 deg) conditions. Segment and joint kinematics were evaluated using 16 inertial measurement unit sensors. Neck, trunk, and upper limb electromyography (EMG) activities were monitored using 12 EMG sensors. Perceived discomfort, kinematics, and EMG activities were compared between conditions using the Friedman test. The perceived discomfort in the standing-0 deg condition was significantly higher than in the remaining three conditions. Standing posture and tablet inclination significantly reduced the sagittal segment and joint angles of the spine, compared with sitting and flat tablet conditions. Similarly, standing posture and tablet inclination significantly reduced EMG activities of the dorsal neck, upper, and lower trunk muscles, while increasing EMG activity of shoulder flexors. Standing posture and tablet inclination reduced the sagittal flexion angle, and dorsal neck, upper, and lower trunk muscle activities, while potentially increasing the muscle activity of arm flexors.
Topics: Young Adult; Humans; Adolescent; Adult; Sitting Position; Standing Position; Posture; Biomechanical Phenomena; Electromyography; Muscle, Skeletal
PubMed: 36365931
DOI: 10.3390/s22218237 -
Tomography (Ann Arbor, Mich.) Feb 2022An important factor for the development of spinal degeneration, pain and the outcome of spinal surgery is known to be the balance of the spine. It must be analyzed in an...
An important factor for the development of spinal degeneration, pain and the outcome of spinal surgery is known to be the balance of the spine. It must be analyzed in an upright, standing position to ensure physiological loading conditions and visualize load-dependent deformations. Despite the complex 3D shape of the spine, this analysis is currently performed using 2D radiographs, as all frequently used 3D imaging techniques require the patient to be scanned in a prone position. To overcome this limitation, we propose a deep neural network to reconstruct the 3D spinal pose in an upright standing position, loaded naturally. Specifically, we propose a novel neural network architecture, which takes orthogonal 2D radiographs and infers the spine's 3D posture using vertebral shape priors. In this work, we define vertebral shape priors using an atlas and a spine shape prior, incorporating both into our proposed network architecture. We validate our architecture on digitally reconstructed radiographs, achieving a 3D reconstruction Dice of 0.95, indicating an almost perfect 2D-to-3D domain translation. Validating the reconstruction accuracy of a 3D standing spine on real data is infeasible due to the lack of a valid ground truth. Hence, we design a novel experiment for this purpose, using an orientation invariant distance metric, to evaluate our model's ability to synthesize full-3D, upright, and patient-specific spine models. We compare the synthesized spine shapes from clinical upright standing radiographs to the same patient's 3D spinal posture in the prone position from CT.
Topics: Humans; Imaging, Three-Dimensional; Posture; Radiography; Spine; Standing Position
PubMed: 35202204
DOI: 10.3390/tomography8010039 -
The Journal of Spinal Cord Medicine Nov 2023Assessed feasibility and potential effectiveness of using a novel robotic upright stand trainer (RobUST) to deliver postural perturbations or provide...
CONTEXT/OBJECTIVE
Assessed feasibility and potential effectiveness of using a novel robotic upright stand trainer (RobUST) to deliver postural perturbations or provide assistance-as-needed at the trunk while individuals with spinal cord injury (SCI) performed stable standing and self-initiated trunk movements. These tasks were assessed with research participants' hands on handlebars for self-balance assistance (hands on) and with hands off (free hands).
DESIGN
Proof of concept study.
PARTICIPANTS
Four individuals with motor complete (n = 3) or incomplete (n = 1) SCI who were not able to achieve independent standing and presented a neurological lesion level ranging from cervical 4 to thoracic 2.
OUTCOME MEASURES
Ground reaction forces, trunk displacement, and electromyography activity of trunk and lower limb muscles.
RESULTS
Research participants received continuous pelvic assistance via RobUST, and manual trainer assistance at the knees to maintain standing. Participants were able to attempt all tasks. Free hands trunk perturbations resulted in greater load bearing-related sensory information (73% ipsilateral vertical loading), trunk displacement (57%), and muscle activation compared to hands on. Similarly, free hands stable standing with RobUST assistance-as-needed resulted in 8.5% larger bodyweight bearing, 112% larger trunk movement velocity, and higher trunk muscles activation compared to standing with hands on. Self-initiated trunk movements controlled by hands on showed 116% greater trunk displacement, 10% greater vertical ground reaction force, and greater ankle muscle activation compared to free hands.
CONCLUSION
RobUST established a safe and challenging standing environment for individuals with SCI and has the potential to improve training paradigms and assessments of standing postural control.
Topics: Humans; Spinal Cord Injuries; Robotic Surgical Procedures; Torso; Standing Position; Muscle, Skeletal; Postural Balance
PubMed: 35532324
DOI: 10.1080/10790268.2022.2069532 -
Rheumatology (Oxford, England) Oct 2021The aims of this study were to examine the longitudinal and bi-directional associations of pain and fatigue with sedentary, standing and stepping time in RA.
OBJECTIVES
The aims of this study were to examine the longitudinal and bi-directional associations of pain and fatigue with sedentary, standing and stepping time in RA.
METHODS
People living with RA undertook identical assessments at baseline (T1, n = 104) and 6-month follow-up (T2, n = 54). Participants completed physical measures (e.g. height, weight, BMI) and routine clinical assessments to characterize RA disease activity (DAS-28). Participants also completed questionnaires to assess physical function (HAQ), pain (McGill Pain Questionnaire) and fatigue (Multidimensional Assessment of Fatigue Scale). Participants' free-living sedentary, standing and stepping time (min/day) were assessed over 7 days using the activPAL3µ™. For the statistical analysis, hierarchical regression analysis was employed to inform the construction of path models, which were subsequently used to examine bi-directional associations of pain and fatigue with sedentary, standing and stepping time. Specifically, where significant associations were observed in longitudinal regression analysis, the bi-directionality of these associations was further investigated via path analysis. For regression analysis, bootstrapping was applied to regression models to account for non-normally distributed data, with significance confirmed using 95% CIs. Where variables were normally distributed, parametric, non-bootstrapped statistics were also examined (significance confirmed via β coefficients, with P < 0.05) to ensure all plausible bi-directional associations were examined in path analysis.
RESULTS
Longitudinal bootstrapped regression analysis indicated that from T1 to T2, change in pain, but not fatigue, was positively associated with change in sedentary time. In addition, change in pain and fatigue were negatively related to change in standing time. Longitudinal non-bootstrapped regression analysis demonstrated a significant positive association between change in fatigue with change in sedentary time. Path analysis supported the hypothesized bi-directionality of associations between change in pain and fatigue with change in sedentary time (pain, β = 0.38; fatigue, β = 0.44) and standing time (pain, β = -0.39; fatigue, β = -0.50).
CONCLUSION
Findings suggest pain and fatigue are longitudinally and bi-directionally associated with sedentary and standing time in RA.
Topics: Aged; Arthritis, Rheumatoid; Exercise; Fatigue; Female; Humans; Longitudinal Studies; Male; Middle Aged; Pain; Pain Measurement; Regression Analysis; Sedentary Behavior; Severity of Illness Index; Standing Position; Time Factors; Walking
PubMed: 33493311
DOI: 10.1093/rheumatology/keab029 -
International Journal of Environmental... Apr 2022Prior investigations have been primarily conducted in a laboratory to examine the effects of the smartphone use on the neck and head positions, whether these results are...
Prior investigations have been primarily conducted in a laboratory to examine the effects of the smartphone use on the neck and head positions, whether these results are applicable to actual conditions is still unknown. This field survey thus analyzed the neck flexion (NF), head flexion (HF), gaze angle (GA), and viewing distance (VD) of smartphone users in public areas in Taipei, Taiwan. Six hundred smartphone users (300 men and 300 women) were photographed sagittally in standing, supported sitting, or unsupported sitting postures while using a smartphone. Results showed that women had significantly less NF and HF and shorter VDs than male users. Regardless of gender, higher NF was observed for standing than for sitting. Women had similar NF and HF while sitting supported and unsupported, but both were significantly lower than those while standing. By contrast, male users had higher NF and HF during unsupported sitting than during supported sitting. The NF (45°-50°) was much greater than the recommended maximum safe NF of 15°. Women may be at higher risk of visual strain because of shorter VD.
Topics: Female; Humans; Male; Neck; Posture; Sitting Position; Smartphone; Standing Position
PubMed: 35457450
DOI: 10.3390/ijerph19084583 -
PloS One 2022Balance can be a main factor contributing to success in many disciplines, and biathlon is a representative example. A more stable posture may be a key factor for...
Balance can be a main factor contributing to success in many disciplines, and biathlon is a representative example. A more stable posture may be a key factor for shooting scores. The center of foot pressure (COP) is commonly recorded when evaluating postural control. As COP measurements are highly irregular and non-stationary, non-linear deterministic methods, such as entropy, are more appropriate for the analysis of COP displacement. The aim of our study was to investigate whether the longitudinal effects of biathlon training can elicit specific changes in postural control. Eight national-level biathletes, 15 non-athletes who prior to the experiment took part in 3 months of shooting training, and 15 non-athletes with no prior rifle shooting experience took part in our study. The data was collected with the use of a force plate. Participants performed three balance tasks in quiet standing, the shooting position (internal focus-participants concentrated on maintaining the correct body position and rifle), and aiming at the target (external focus-participants concentrated on keeping the laser beam centered on the targets). Biathletes obtained significantly lower values of sample entropy compared to the other groups during the shooting and aiming at the target trials (p<0.05). External and internal focuses influenced the process of postural control among participants who had prior rifle shooting experience and the control group; they obtained significantly higher values of sample entropy while shooting and aiming at the target compared to the quiet standing trial (p<0.05). The biathletes obtained significantly lower values of sample entropy in the aiming at the target position compared to the quiet standing trial. Specific balance training is associated with the ability to deal with a more challenging, non-specific task. The biathletes seemed to employ a different motor control strategy than the beginners and control group, creating repeating patterns (more regular signal for COP) to keep one's balance during the shooting and aiming at the target positions.
Topics: Athletes; Firearms; Humans; Postural Balance; Posture; Standing Position
PubMed: 35503761
DOI: 10.1371/journal.pone.0267105 -
Scientific Reports Dec 2022Upright computed tomography (CT) provides physiologically relevant images of daily life postures (sitting and standing). The volume of the human airway in sitting or...
Upright computed tomography (CT) provides physiologically relevant images of daily life postures (sitting and standing). The volume of the human airway in sitting or standing positions remains unclear, and no clinical study to date has compared the inspiratory and expiratory airway volumes and luminal areas among standing, sitting, and supine positions. In this prospective study, 100 asymptomatic volunteers underwent both upright (sitting and standing positions) and conventional (supine position) CT during inspiration and expiration breath-holds and the pulmonary function test (PFT) within 2 h of CT. We compared the inspiratory/expiratory airway volumes and luminal areas on CT among the three positions and evaluated the correlation between airway volumes in each position on CT and PFT measurements. The inspiratory and expiratory airway volumes were significantly higher in the sitting and standing positions than in the supine position (inspiratory, 4.6% and 2.5% increase, respectively; expiratory, 14.9% and 13.4% increase, respectively; all P < 0.001). The inspiratory and expiratory luminal areas of the trachea, bilateral main bronchi, and average third-generation airway were significantly higher in the sitting and standing positions than in the supine position (inspiratory, 4.2‒10.3% increases, all P < 0.001; expiratory, 6.4‒12.8% increases, all P < 0.0001). These results could provide important clues regarding the pathogenesis of orthopnea. Spearman's correlation coefficients between the inspiratory airway volume on CT and forced vital capacity and forced expiratory volume in 1 s on PFT were numerically higher in the standing position than in the supine position (0.673 vs. 0.659 and 0.669 vs. 0.643, respectively); however, no statistically significant differences were found. Thus, the airway volumes on upright and conventional supine CT were moderately correlated with the PFT measurements.
Topics: Humans; Prospective Studies; Standing Position; Exhalation; Tidal Volume; Tomography, X-Ray Computed
PubMed: 36494466
DOI: 10.1038/s41598-022-25865-0