Standing Data Disproves Biomechanical Mechanism for Balance-Based Torso-Weighting

An important aspect of motor control is the ability to perform tasks with the upper limbs while maintaining whole body balance. However, little is known about the coordination of upper limb voluntary and whole body postural control after mechanical disturbances that require both upper limb motor corrections to attain a behavioral goal and lower limb motor responses to maintain whole body balance. The present study identified the temporal organization of muscle responses and center of pressure (COP) changes following mechanical perturbations during reaching. Our results demonstrate that muscle responses in the upper limb are evoked first (∼50 ms), with lower limb muscle activity occurring immediately after, in as little as ∼60 ms after perturbation. Hand motion was immediately altered by the load, while COP changes occurred after ∼100 ms, when lower limb muscle activity was already present. Our secondary findings showed that both muscle activity and COP changes were influenced by behavioral context (by altering target shape, circle vs. rectangle). Voluntary and postural actions initially directed the hand toward the center of both target types, but after the perturbation upper limb and postural responses redirected the hand toward different spatial locations along the rectangle. Muscle activity was increased for both upper and lower limbs when correcting to the circle vs. the rectangle, and these differences emerged as early as the long-latency epoch (∼75-120 ms). Our results demonstrate that postural responses are rapidly and flexibly altered to consider the behavioral goal of the upper limb.NEW & NOTEWORTHY The present work establishes that, when reaching to a target while standing, perturbations applied to the upper limb elicit a rapid response in lower limb muscles. Unlike voluntary movements, postural responses do not occur before corrections of the upper limb. We show the first evidence that corrective postural adjustments are modulated by upper limb behavioral context (target shape). Importantly, this indicates that postural responses take into account upper limb feedback for online control.

102. An introductory investigation of standing postural control ‘error’ and its relation to balance in adult spinal deformity surgery patients

The objective of this study was to analyse the upper urinary tract (UT) function in a group of consecutive multiple sclerosis (MS) patients, who had not previously been treated by urologist. Ninety-two MS patients suffering from lower UT dysfunction were included in the study. The group of patients consisted of 69 women and 23 men. The average Expanded Disability Status Scale (EDSS) score in our group was 4.29 (0-8.5). Functional examination of the kidneys using assessment of creatinine clearance and morphological examination of the kidneys using ultrasound was performed in all patients. Analysis of the upper UT function is presented. The average serum creatinine clearance in our group was 132.84 ml/min/1.73 m(2) (46.8-510). Lower levels than normal were found in three patients (3.3%). Abnormal ultrasound findings were recorded in five patients (5.4%). The creatinine clearance was correlated with the clinical subtype of MS, the severity expressed by EDSS, the urodynamic parameters, the duration of the disease, the duration of the symptoms of lower UT and the EDSS score. We did not find a statistically significant correlation for any of these parameters. Our results suggest that impairment of the upper UT function is exceptional in MS patients.

The effect of acute respiratory demand on postural control: A systematic review

The aim of this article was to develop a center of pressure (COP) measurement device and application to evaluate the fall risk among the elderly. The approach was designed to measure changes in COP in a standing position to assess balance, an important risk factor in falling. The developed approach consisted of both hardware and software; the hardware's function was to measure the sway in COP while the software controlled the device, displayed the results, and stored the data. Data was transmitted from device to tablet or smartphone via Bluetooth. This approach to COP measurement was configured as a dedicated application, making it easier for the elderly to measure their own COP for evaluating balance and fall risks using the measurement data. In conclusion, this device is easy and convenient for the elderly to use in their daily life and could help with fall management and prevention.

Physical and hormonal modifications occuring during the pregnancy, can lead to an increase in postural instability and to a higher risk of falls during gait. The first objective was to describe the center of pressure (COP) during late pregnancy at different gait velocity. Comparison of nulliparous women with postpartum women were conducted in order to investigate the effects of pregnancy. The second objective was to analyse COP variability between pregnant and non-pregnant women in order to investigate the effects of pregnancy on gait variability. Fifty-eight pregnant women in the last four months of pregnancy, nine postpartum women and twenty-three healthy non-pregnant women performed gait trials at three different speeds: preferred, slow and fast. In the last four months of pregnancy gait velocity decreased. During the pregnancy, gait velocity decreased by 22%, stopover time increased by 6-12%, COP excursion XY decreased by 5% and COP velocity decreased by 16% and 20% along the anteroposterior and transverse axes, respectively. After delivery, gait velocity increased by 3% but remained a lower compared to non-pregnant women (-12%). Intra-individual variability was greater for non-pregnant than pregnant women. COP parameters were influenced by pregnancy. This suggests that pregnant women establish very specific and individual strategies with the aim of maintaining stability during gait.

Standing centre of pressure alters the vibration transmissibility response of the foot

Objective: To investigate whether the changes in the corticospinal excitability contribute to the anticipatory postural adjustments (APAs) in the lower limb muscles when performing the ballistic upper limb movement of the dart throwing.Methods: We examined the primary motor cortex (M1) excitability of the lower limb muscles [tibialis anterior (TA) and soleus (SOL) muscles] during the APA phase by using transcranial magnetic stimulation (TMS) in the healthy volunteers. The surface electromyography (EMG) of anterior deltoid, triceps brachii, biceps brachii, TA, and SOL muscles was recorded and the motor evoked potential (MEP) to TMS was recorded in the TA muscle along with the SOL muscle. TMS at the hotspot of the TA muscle was applied at the timings immediately prior to the TA onset. The kinematic parameters including the three-dimensional motion analysis and center of pressure (COP) during the dart throwing were also assessed.Results: The changes in COP and EMG of the TA muscle occurred preceding the dart throwing, which involved a slight elbow flexion followed by an extension. The correlation analysis revealed that the onset of the TA muscle was related to the COP change and the elbow joint flexion. The MEP amplitude in the TA muscle, but not that in the SOL muscle, significantly increased immediately prior to the EMG burst (100, 50, and 0 ms prior to the TA onset).Conclusion: Our findings demonstrate that the corticospinal excitability of the TA muscle increases prior to the ballistic upper limb movement of the dart throwing, suggesting that the corticospinal pathway contributes to the APA in the lower limb in a muscle-specific manner.

This pilot study investigated the potential of using trunk acceleration feedback control of center of pressure (COP) against postural disturbances with a standing neuroprosthesis following paralysis. Artificial neural networks (ANNs) were trained to use three-dimensional trunk acceleration as input to predict changes in COP for able-bodied subjects undergoing perturbations during bipedal stance. Correlation coefficients between ANN predictions and actual COP ranged from 0.67 to 0.77. An ANN trained across all subject-normalized data was used to drive feedback control of ankle muscle excitation levels for a computer model representing a standing neuroprosthesis user. Feedback control reduced average upper-body loading during perturbation onset and recovery by 42% and peak loading by 29% compared with optimal, constant excitation.

It is important to improve caregiving skills to help reduce the strain on inexperienced caregivers. Previous studies on quantifying caregiving skills have predominantly relied on expensive equipment, such as motion-capture systems with multiple infrared cameras or acceleration sensors. To overcome the cost and space limitations of existing systems, we developed a simple evaluation system for transfer care skills that uses capacitive sensors composed of conductive embroidery fibers. The proposed system can be developed with a few thousand US dollars. The developed evaluation system was used to compare the seating position and velocity of a care recipient during transfers from a nursing-care bed to a wheelchair between groups of inexperienced and expert caregivers. To validate the proposed system, we compare the motion data measured by our system and the data obtained from a conventional three-dimensional motion-capture system and force plate. We analyze the relationship between changes in the center of pressure (CoP) recorded by the force plate and the center of gravity (CoG) obtained by the developed system. Evidently, the changes in CoP have a relation with the CoG. We show that the actual seating speed ([Formula: see text] measured by the motion-capture system is related to the speed coefficient calculated from our sensor output. A significant difference exists in [Formula: see text] between the inexperienced group and the physical therapists/occupational therapists' group. The proposed system can effectively estimate a caregiver's skill level in transferring patients from a bed to a wheelchair in terms of the seating position and velocity.

Postural stability during long duration quiet standing in post stroke hemiplegia

To investigate spinal cord and brain atrophy in neuromyelitis optica (NMO), and its relationship with other MRI measurements and clinical disability, compared with patients with multiple sclerosis (MS) and healthy controls (HC). We recruited 35 patients with NMO, 35 patients with MS, and 35 HC, who underwent both spinal cord and brain MRI. Mean upper cervical cord area (MUCCA), brain parenchymal fraction (BPF), gray matter fraction (GMF), white matter fraction (WMF), and spinal cord and brain lesion loads were measured and compared among groups. Multivariate associations between MUCCA and brain volume measurement and clinical variables were assessed by partial correlations and multiple linear regression. Patients with NMO showed smaller MUCCA than HC (p = 0.004), and patients with MS had a trend of smaller MUCCA compared to HC (p = 0.07), with no significant difference between the patient groups. Patients with NMO showed lower BPF than HC, and patients with MS had lower BPF and GMF than patients with NMO. In NMO, MUCCA was correlated with Expanded Disability Status Scale score (EDSS), number of relapses, and total spinal cord lesion length, while in MS, MUCCA was correlated with WMF and EDSS. MUCCA was the only independent variable for predicting clinical disability measured by EDSS in NMO (R(2) = 0.55, p < 0.001) and MS (R(2) = 0.17, p = 0.013). NMO showed predominately spinal cord atrophy with mild brain atrophy, while MS demonstrated more brain atrophy, especially in the gray matter. MUCCA is the main MRI-derived parameter for explaining clinical disability in NMO and MS, and may serve as a potential biomarker for further clinical trials, especially in NMO.

Body composition in ambulatory women with multiple sclerosis

This meta-analysis systematically explored predictive factors for the progression of multiple sclerosis (MS). Computerized searches were conducted in Pubmed, OVID, Web of science, Willey Library, and EMbase from inception to August 2023. Patients with MS were divided into the deterioration group, defined as those with an increase in the Expanded Disability Status Scale (EDSS) score of ≥ 1.0 for a baseline EDSS ≤ 5.5 or ≥ 0.5 for a baseline EDSS > 5.5 during the follow-up period, and the non-deterioration group, comprising patients who exhibited no significant changes in EDSS over the same period. This study analyzed the impact of specific predictors, including age at onset, sex (male), smoking status, disease duration, number of relapses, EDSS score, prodromal neurological symptoms, and the use of disease-modifying therapies (DMTs) on MS progression. Of 3647 retrieved, 14 studies were finally included. Meta-analysis showed that sex (male) [odds ratio (OR) = 1.15, 95% confidence interval (CI): 1.05-1.26, P < 0.01], smoking [OR = 1.92, 95%CI: 1.41-2.60, P < 0.01], relapses frequency [OR = 1.05, 95%CI: 1.02-1.08, P < 0.01], EDSS score [OR = 1.54, 95%CI: 1.10-2.15, P = 0.01], and DMTs use [OR = 0.38, 95%CI: 0.26-0.55, P < 0.01] significant influenced MS progression, while age at onset, disease duration, and prodromal neurological symptoms were not significant. Sex (male), smoking, a higher number of relapses, EDSS score, and DMTs are predictors of MS deterioration. Hence, particular attention should be given to these risk factors when assessing MS deterioration.

Gait disability in people with progressive multiple sclerosis (MS) is difficult to quantify using existing clinical tools. This study aims to identify reliable and objective gait-based biomarkers to monitor progressive multiple sclerosis (MS) in clinical settings. During routine clinical visits, 57 people with secondary progressive MS and 24 healthy controls walked for 6 minutes wearing three inertial motion sensors. Fifteen gait measures were computed from the sensor data and tested for between-session reliability, for differences between controls and people with moderate and severe MS disability, and for correlation with Expanded Disability Status Scale (EDSS) scores. The majority of gait measures showed good to excellent between-session reliability when assessed in a subgroup of 23 healthy controls and 25 people with MS. These measures showed that people with MS walked with significantly longer step and stride durations, reduced step and stride regularity, and experienced difficulties in controlling and maintaining a stable walk when compared to controls. These abnormalities significantly increased in people with a higher level of disability and correlated with their EDSS scores. Reliable and objective gait-based biomarkers using wearable sensors have been identified. These biomarkers may allow clinicians to quantify clinically relevant alterations in gait in people with progressive MS within the context of regular clinical visits.