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Age-related hearing loss is a risk factor for mobility problems and falls, possibly due to poor access to spatial sounds or the higher allocation of attention required to listen, thereby reducing cognitive resources to support mobility. Introducing stabilizing spatial sounds or reducing cognitive load through hearing aids could possibly improve balance performance; however, evidence is mixed. Few studies have evaluated the effects of hearing aids and spatial sounds on balance during realistic, multisensory, dual-tasking conditions. This study used virtual reality to simulate a listening-while-balancing task in 22 older adults with normal hearing and 22 hearing aid users, tested with their aids on versus off. Participants performed a competing digits listening task (two, four digits) and a standing postural task, alone and in combination (dual task) under different visual, postural, and acoustical loads. Listening accuracy and postural outcomes (centre of pressure mean velocity, anterior–posterior standard deviation, medial–lateral standard deviation) were collected. With respect to listening accuracy, as expected, normal hearing adults had higher listening accuracy than those with hearing loss (aided better than unaided) and both groups performed better with eyes closed (vs. open) and under lower postural loads (firm vs. compliant). With respect to postural performance, hearing aids did not remarkably improve balance overall, with no effects on dual-task costs to posture. Other factors related to the complexity of the conditions (i.e., listening, visual, postural demands) differently influenced dual-task costs to posture in individuals with and without hearing loss. Overall, these results contribute to our understanding of how age-related hearing loss and hearing aids affect balance-related outcomes under realistic, complex, multisensory, multitasking conditions. [ABSTRACT FROM AUTHOR]

Whole-body vestibular-evoked balance responses decrease following ~ 55 min of normobaric hypoxia. It is unclear how longer durations of hypoxia affect the vestibular control of balance at the muscle and whole-body levels. This study examined how four hours of normobaric hypoxia influenced the vestibular control of balance. Fifteen participants (4 females; 11 males) stood on a force plate with vision occluded and head rotated rightward while subjected to three blocks of binaural, bipolar stochastic electrical vestibular stimulation (EVS; 0–25 Hz, root mean square amplitude = 1.1 mA) consisting of two, 90-s trials. The relationship between EVS and anteroposterior (AP) forces or medial gastrocnemius (MG) electromyography (EMG) was estimated in the time and frequency domains at baseline (BL; 0.21 fraction of inspired oxygen—FIO2) and following two (H2) and four (H4) hours of normobaric hypoxia (0.11 FIO2). The EVS-MG EMG short-latency peak and peak-to-peak amplitudes were smaller than BL at H2 and H4, but the medium-latency peak amplitude was only lower at H4. The EVS-AP force medium-latency peak amplitude was lower than BL at H4, but the short-latency peak and peak-to-amplitudes were unchanged. The EVS-MG EMG coherence and gain were reduced compared to BL at H2 and H4 across multiple frequencies ≥ 7 Hz, whereas EVS-AP force coherence was blunted at H4 (≤ 4 Hz), but gain was unaffected. Overall, the central nervous system's response to vestibular-driven signals during quiet standing was decreased for up to four hours of normobaric hypoxia, and vestibular-evoked responses recorded within postural muscles may be more sensitive than the whole-body response. [ABSTRACT FROM AUTHOR]

Abstract Age-related hearing loss is a risk factor for mobility problems and falls, possibly due to poor access to spatial sounds or the higher allocation of attention required to listen, thereby reducing cognitive resources to support mobility. Introducing stabilizing spatial sounds or reducing cognitive load through hearing aids could possibly improve balance performance; however, evidence is mixed. Few studies have evaluated the effects of hearing aids and spatial sounds on balance during realistic, multisensory, dual-tasking conditions. This study used virtual reality to simulate a listening-while-balancing task in 22 older adults with normal hearing and 22 hearing aid users, tested with their aids on versus off. Participants performed a competing digits listening task (two, four digits) and a standing postural task, alone and in combination (dual task) under different visual, postural, and acoustical loads. Listening accuracy and postural outcomes (centre of pressure mean velocity, anterior–posterior standard deviation, medial–lateral standard deviation) were collected. With respect to listening accuracy, as expected, normal hearing adults had higher listening accuracy than those with hearing loss (aided better than unaided) and both groups performed better with eyes closed (vs. open) and under lower postural loads (firm vs. compliant). With respect to postural performance, hearing aids did not remarkably improve balance overall, with no effects on dual-task costs to posture. Other factors related to the complexity of the conditions (i.e., listening, visual, postural demands) differently influenced dual-task costs to posture in individuals with and without hearing loss. Overall, these results contribute to our understanding of how age-related hearing loss and hearing aids affect balance-related outcomes under realistic, complex, multisensory, multitasking conditions.

Concern about falling is reportedly related to mobility and balance in older adults. While increased concern about falling may be directly related to balance deficits, establishing a causal relationship remains limited. This study aimed to investigate whether concern about falling affects threat-induced changes in emotions and postural control in older adults. How does concern about falling affect threat-induced changes in emotions and postural control among older adults? Sixty-two older adults (age; 78.8 ± 5.7 years, height; 152.7 ± 6.3 cm) were exposed to height-related fear while standing, leaning forward, and leaning backward on the floor and a higher surface. The mean position, root mean square, and mean velocity of the center of pressure (COP) displacement were measured during the standing task, as well as the forward and backward limits of stability (LOS) tasks. The degree of self-reported fear of falling (FoF) was also obtained during the standing and LOS tasks. The participants were categorized into lower and higher concerns about falling based on the short form of the Falls Efficacy Scale International (FESI). Lower and higher concern about falling groups scored 10.2 ± 2.2 and 17.3 ± 3.3 in the short FESI. Both groups experienced increased FoF during the standing and forward LOS tasks on a higher surface. Leaning away from the edge of the surface resulted in increased COP velocity, decreased COP amplitude while standing, and decreased forward LOS. Participants with higher concern about falling had increased FoF during the backward LOS task and decreased backward LOS on a higher surface, while those with lower concern about falling did not. Concern about falling can directly affect emotions and balance control owing to the occurrence of threat-related changes. • We examined concern about falling on threat-induced changes in postural control. • Older adults changed postural control during standing and leaning forward when standing on a higher surface. • Higher concern about falling in older adults caused additional changes in backward leaning. • Concern about falling affects balance control because of threat-induced changes. [ABSTRACT FROM AUTHOR]

Study Design. Longitudinal observational cohort. Objectives. The purpose of this study was to evaluate the utility of Quantitative Romberg measurements as pre-op and post-op balance outcome measures. Summary of Background Data. Cervical spondylotic myelopathy (CSM) is characterized by balance deficiencies produced by impaired proprioception. Evaluation is subjective, and binary physical exam findings lack the precision to assess postoperative outcome improvement. Methods. CSM patients were prospectively enrolled to undergo preoperative and postoperative Quantitative Romberg tests on a force plate to record center of pressure (COP) motion for 30 seconds with eyes open followed by eyes closed. Revision cases were excluded. Kinematics of COP movement parameters were compared between preoperative and postoperative state for each patient. Results. Twenty-seven CSM patients were enrolled and completed both pre/post-testing. The mean age was 60.0 years, with 13 (48%) males and 9 (33%) smokers. Mean number of surgical levels was 2.48. The minimum mean follow-up was six months. There was a statistically significant improvement in eyes closed after surgery compared with preoperative for total COP motion (523.44 vs. 387.00 cm, P<0.001), average sway speed (17.41 vs. 13.00 cm/s, P< 0.001), and total lateral COP motion (253.44 vs. 186.70 cm, P<0.001). There was no statistically significant improvement in the modified Japanese Orthopaedic Association (13.29 vs. 14.29, P=0.28). Conclusions. CSM balance findings on Quantitative Romberg testing significantly improve postoperatively in patients with CSM. These findings support this testing as representative of proprioceptive balance deficiencies seen in CSM. Quantitative Romberg may be used as an objective measure of clinical outcome and assist in stratification of surgical interventions, surgery timing, and technique. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of acute normobaric hypoxia on standing balance under single and dual-task conditions, both with and without visual input. Methods: 20 participants (7 female, 20–31 years old) stood on a force plate for 16, 90-s trials across four balance conditions: single-task (quiet stance) or dual-task (auditory Stroop test), with eyes open or closed. Trials were divided into four oxygen conditions where the fraction of inspired oxygen (FIO2) was manipulated (normoxia: 0.21 and normobaric hypoxia: 0.16, 0.145 and 0.13 FIO2) to simulate altitudes of 1100, 3,400, 4300, and 5200 m. Participants breathed each FIO2 for ~ 3 min before testing, which lasted an additional 7–8 min per oxygen condition. Cardiorespiratory measures included heart rate, peripheral blood oxygen saturation, and pressure of end tidal (PET) CO2 and O2. Center of pressure measures included total path length, 95% ellipse area, and anteroposterior and mediolateral velocity. Auditory Stroop test performance was measured as response accuracy and latency. Results: Significant decreases in oxygen saturation and PETO2, and increased heart rate were observed between normoxia and normobaric hypoxia (P < 0.0001). Total path length was higher at 0.13 compared to 0.21 FIO2 for the eyes closed no Stoop test condition (P = 0.0197). No other significant differences were observed. Conclusion: These findings suggest that acute normobaric hypoxia has a minimal impact on standing balance and does not influence auditory Stroop test or dual-task performance. Further investigation with longer exposure is required to understand the impact and time course of normobaric hypoxia on standing balance. [ABSTRACT FROM AUTHOR]

BACKGROUND: In individuals with transfemoral amputation (TFA), adaptations caused by prosthesis use may adversely affect contractile/noncontractile structures. OBJECTIVE: To investigate the immediate effect of the thoracolumbar fascia (TLF) kinesiology taping (KT) on the tone and stiffness of the fascia, low back pain (LBP) and standing balance in individuals with TFA. METHODS: Syrian male participants with TFA were enrolled in the prospective, single-blind, randomised controlled trial. Participants were divided into two groups: Experimental (EG with KT, n = 15) and Control (CG with sham KT, n = 14). A 6-minute walk test (6MWT) was performed, after which KT was applied. Measurements were taken at baseline, immediately after the 6MWT and 30 minutes after KT. RESULTS: Although pain decreased below baseline in both groups at 30 minutes post intervention (p < 0.001), the rate of pain reduction was significantly higher in the EG (p = 0.016). Anterior-posterior sway with eyes open improved significantly 30 minutes after KT application only in the EG (p = 0.010). In the eyes closed condition, anterior-posterior and medio-lateral sway decreased significantly compared to baseline 30 minutes after taping in the EG (p = 0.010 - 0.032). CONCLUSION: KT can be used as an effective method to support standing balance and reduce LBP in individuals with TFA. [ABSTRACT FROM AUTHOR]

To determine the effectiveness of Kinesio taping along with routine physical therapy on improving gross motor function in sitting and standing among spastic diplegic Cerebral Palsy children. Randomized controlled trial. University Teaching Hospital University of Lahore, Lahore. 53 participants with diagnosed spastic diplegic cerebral palsy were randomly allocated in control and experimental groups. 26 Participants were treated by kinesio taping which was applied in a criss-cross manner along with routine physical therapy program while the control group (n = 27) received NDT exercise program that comprises of stretching, functional reaching, weight-bearing exercises and walking. Gross motor function was assessed using 2 components of Gross Motor Function Classification System (GMFCS-88), i.e., sitting as well as standing at the base line and after every 3rd week for 12 weeks follow up. In study and control group the mean score of gross motor function for sitting at baseline was 33.96 ± 3.11 and 31.50 ± 3.32 respectively. After intervention, it changed to 47.70 ± 5.46 and 43.46 ± 1.81 respectively. Mean score for Gross Motor Function calculated at base line in study and control group for standing was 27.37 ± 1.14 and 26 ± 3.01 respectively. At the end of intervention, the score improved to 36.55 ± 4.27 and 33.69 ± 2.46 respectively. In comparison to control group, significant increase in gross motor function of intervention group was seen after the 12 weeks of intervention. In this way, over back muscles the application of kinesio tape in a Criss-Cross manner may be helpful. Also it can be used as an additional approach along with routine physical therapy to improve standing and sitting in spastic diplegic children. [ABSTRACT FROM AUTHOR]

Standing balance disorder in stroke refers to the difficulty a patient experiences in maintaining static and dynamic balance while standing, including standing instability, swaying, and a higher risk of falling. It seriously affects the patient's ability of walking and activities of daily living. Physical therapy and traditional Chinese treatment are effective rehabilitation methods for improving standing balance function in stroke patients. For standardized assessment and application of physical therapy and traditional Chinese treatment on standing balance, an expert panel compiled a draft of clinical practice guidelines for standing balance impairment rehabilitation in stroke based on the Delphi method of summarizing consensus opinions, and was modified and formulated to guideline after consensus conference. This guideline covers the technical scope of practice, normative reference documents, terms and definitions (balance, base of support, center of mass, center of gravity, limits of stability, proprioception, vestibular function, visual sense, vestibulo-ocular reflex, standing balance function, standing balance disorder, core stability, balance strategy), rehabilitation assessments (clinical manifestation, clinical evaluations, special assessments related to balance function, visual and coordination function assessment), rehabilitation treatments (vestibular function training, sensory function training, visual function training, motor function training, coordination and dystaxia training, psychotherapy, kinesitherapy, dual task training, virtual reality technique, non-invasive neural regulation technology, rehabilitation robot, hydrotherapy, visual feedback balance training，traditional rehabilitation therapy and medical gymnastics) and evaluations of therapeutic efficiency. This guideline can provide standardized diagnosis and treatment procedures for rehabilitation treatment of standing balance disorder in stroke patients and evidence reference for clinical decision-making practice, with good clinical applicability and practicability.

Acute exposure to hypoxia increases postural sway, but the underlying neurophysiological factors are unclear. Golgi tendon organs (GTOs), located within the musculotendinous junction (MTJ), provide inhibitory signals to plantar flexor muscles that are important for balance control; however, it is uncertain if GTO function is influenced by hypoxia. The aim of this study was to determine how normobaric hypoxia influences lower limb tendon-evoked inhibitory reflexes during upright stance. We hypothesized that tendon-evoked reflex area and duration would decrease during hypoxia, indicating less inhibition of postural muscles compared with normoxia. At baseline (BL; 0.21 fraction of inspired oxygen, FIO2) and at ∼2 (H2) and 4 (H4) h of normobaric hypoxia (0.11 FIO2) in a normobaric hypoxic chamber, 16 healthy participants received electrical musculotendinous stimulation (MTstim) to the MTJ of the left Achilles tendon. The MTstim was delivered as two sets of 50 stimuli while the participant stood on a force plate with their feet together. Tendon-evoked inhibitory reflexes were recorded from the surface electromyogram of the ipsilateral medial gastrocnemius, and center of pressure (CoP) variables were recorded from the force plate. Normobaric hypoxia increased CoP velocity (P ≤ 0.002) but not CoP standard deviation (P ≥ 0.12). Compared with BL, normobaric hypoxia reduced tendon-evoked inhibitory reflex area by 45% at H2 and 53% at H4 (P ≤ 0.002). In contrast, reflex duration was unchanged during hypoxia. The reduced inhibitory feedback from the GTO pathway could likely play a role in the increased postural sway observed during acute exposure to hypoxia. NEW & NOTEWORTHY: The Ib pathway arising from the Golgi tendon organ provides inhibitory signals onto motor neuron pools that modifies force and, hence, postural control. Although hypoxia influences standing balance (increases sway), the underlying mechanisms have yet to be unraveled. Our study identified that tendon-evoked inhibition onto a plantar flexor motoneuron pool is reduced by acute exposure to normobaric hypoxia. This reduction of inhibition may contribute to the hypoxia-related increase in postural sway. [ABSTRACT FROM AUTHOR]

Introduction: Tai Chi has proved to be an effective therapy for balance performance and cognition. However, non-consistency exists in the results of the effect of Tai Chi training on standing balance control in older adults. This study aimed to use traditional and non-traditional methods to investigate the effect of Tai Chi on standing balance in older adults. Methods: Thirty-six Tai Chi practitioners (TC group) and thirty-six older adults with no Tai Chi practice (control group) were recruited in this study. A Nintendo Wii Balance Board was used to record the center of pressure (COP) during standing balance over 20 s in the condition of eyes closed with three repetitions. The wavelet analysis, multiscale entropy, recurrence quantification analysis, and traditional methods were used to evaluate the standing balance control in the anterior-posterior (AP) and mediolateral (ML) directions. Results: (1) Greater sway mean velocity in the AP direction and sway Path length were found in the TC group compared with the control group; (2) lower Very-low frequency band (0.10-0.39Hz) and higher Moderate frequency band (1.56-6.25Hz) in the AP andML directions were found in the TC group compared with the control group; (3) greater complexity index (CI) and lower determinism (DET) in the AP and ML directions were observed in the TC group compared with control group; (4) greater path length linked with smaller Very-low frequency band in the AP and ML directions and higher Moderate frequency band in the AP direction in both groups; (5) greater path length linked with lower DET and higher CI in the AP direction only in the TC group. Conclusion: Long-term Tai Chi practice improved sensory reweighting (more reliance on the proprioception systemand less reliance on the vestibular system) and complexity of standing balance control in older adults. In addition, greater sway velocity may be as an exploratory role in standing balance control of TC older adults, which correlated with greater complexity, but no such significant relationship in the control group. Therefore, the effects of Tai Chi practice on standing balance control in older adults may be attributed to the improvement of sensory reweighting and complexity rather than reduced sway velocity or amplitude. [ABSTRACT FROM AUTHOR]

Introduction: Modular prosthetic ankle components have been shown to improve walking in transtibial prosthesis users, but they may reduce stability during standing. Therefore, the stiffness of the prosthetic foot-ankle components may need to be appropriately tuned to provide a balance between walking mobility and standing balance. The present research investigates both concepts to improve our knowledge about how prosthetic ankle stiffness influences standing and walking performance. Methods: Ten individuals with unilateral transtibial amputation and categorized as minimum K3-level ambulators participated. Standing balance and gait analyses at three self-selected speeds were performed at three different levels of ankle dorsiflexion stiffness (Soft, Medium, and Firm) using the College Park Venture foot (College Park Industries, Warren, MI, USA). Repeated-measures analyses of variance (ANOVAs) were performed on relevant standing balance, gait spatiotemporal, and roll-over shape (ROS) outcomes. Gait kinetic and kinematic data were analyzed using a one-dimension statistical parametric analysis. Results: Ankle dorsiflexion stiffness influenced balance and gait. Overall, the Firm dorsiflexion stiffness provided a smaller body sway on standing balance, a ROS radius close to the one of able-bodied individuals, and reduced step length asymmetry while walking. Furthermore, walking speed had an influence on ROS radii, resulting in a larger radius for slow walking speeds and a smaller one for fast walking speeds. Discussion: The Firm stiffness appeared to offer the most advantages for balance and gait. The radius of ROS under the Firm condition, close to the radius of able-bodied individuals, could have caused the improvement in step length symmetry by a greater progression of the center of pressure, resulting in further progression of the prosthetic side. This information, in addition to the observed walking speed effect on ROS radii, encourages us to develop studies to examine the effect of walking speed on foot performance and improve prosthetic foot design to maintain the same gait characteristics under different walking speeds. Clinical Relevance: These results improve our understanding of how a specific prosthetic ankle dorsiflexion stiffness affects standing balance and gait, which supports the prosthetist's evaluation process to determine specific individual stiffness for each prosthesis user. [ABSTRACT FROM AUTHOR]

Introduction: Plantar cutaneous augmentation is a promising approach in balance rehabilitation by enhancing motion-dependent sensory feedback. The effect of plantar cutaneous augmentation on balance has been mainly investigated in its passive form (e.g., textured insole) or on lower-limb amputees. In this study, we tested the effect of plantar cutaneous augmentation on balance in its active form (i.e., electrical stimulation) for individuals with intact limbs. Methods: Ten healthy subjects participated in the study and were instructed to maintain their balance as long as possible on the balance board, with or without electrotactile feedback evoked on the medial side of the heel, synched with the lateral board sway. Electrotactile feedback was given in two different modes: 1) Discretemode E-stim as the stimulation on/off by a predefined threshold of lateral board sway and 2) Proportional-mode E-stim as the stimulation frequency proportional to the amount of lateral board sway. All subjects were distracted from the balancing task by the n-back counting task, to test subjects' balancing capability with minimal cognitive involvement. Results: Proportional-mode E-stim, along with the n-back counting task, increased the balance time from 1.86 ± 0.03 s to 1.98 ± 0.04 s (p = 0.010). However, discrete-mode E-stim did not change the balance time (p = 0.669). Proportional-mode E-stim also increased the time duration per each swayed state (p = 0.035) while discrete-mode E-stim did not (p = 0.053). Discussion: These results suggest that proportional-mode E-stim is more effective than discrete-mode E-stim on improving standing balance. It is perhaps because the proportional electrotactile feedback better mimics the natural tactile sensation of foot pressure than its discrete counterpart. [ABSTRACT FROM AUTHOR]

Abstract Individuals with incomplete spinal-cord injury/disease are at an increased risk of falling due to their impaired ability to maintain balance. Our research group has developed a closed-loop visual-feedback balance training (VFBT) system coupled with functional electrical stimulation (FES) for rehabilitation of standing balance (FES + VFBT system); however, clinical usage of this system is limited by the use of force plates, which are expensive and not easily accessible. This study aimed to investigate the feasibility of a more affordable and accessible sensor such as a depth camera or pressure mat in place of the force plate. Ten able-bodied participants (7 males, 3 females) performed three sets of four different standing balance exercises using the FES + VFBT system with the force plate. A depth camera and pressure mat collected centre of mass and centre of pressure data passively, respectively. The depth camera showed higher Pearson's correlation (r > 98) and lower root mean squared error (RMSE 0.82; RMSE

Abstract Background Balance parameters derived from wearable sensor measurements during postural sway have been shown to be sensitive to experimental variables such as test duration, sensor number, and sensor location that influence the magnitude and frequency-related properties of measured center-of-mass (COM) and center-of-pressure (COP) excursions. In this study, we investigated the effects of test duration, the number of sensors, and sensor location on the reliability of standing balance parameters derived using body-mounted accelerometers. Methods Twelve volunteers without any prior history of balance disorders were enrolled in the study. They were asked to perform two 2-min quiet standing tests with two different testing conditions (eyes open and eyes closed). Five inertial measurement units (IMUs) were employed to capture postural sway data from each participant. IMUs were attached to the participants’ right legs, the second sacral vertebra, sternum, and the left mastoid processes. Balance parameters of interest were calculated for the single head, sternum, and sacrum accelerometers, as well as, a three-sensor combination (leg, sacrum, and sternum). Accelerometer data were used to estimate COP-based and COM-based balance parameters during quiet standing. To examine the effect of test duration and sensor location, each 120-s recording from different sensor locations was segmented into 20-, 30-, 40-, 50-, 60-, 70-, 80-, 90-, 100-, and 110-s intervals. For each of these time intervals, time- and frequency-domain balance parameters were calculated for all sensor locations. Results Most COM-based and COP-based balance parameters could be derived reliably for clinical applications (Intraclass-Correlation Coefficient, ICC ≥ 0.90) with a minimum test duration of 70 and 110 s, respectively. The exceptions were COP-based parameters obtained using a sacrum-mounted sensor, especially in the eyes-closed condition, which could not be reliably used for clinical applications even with a 120-s test duration. Conclusions Most standing balance parameters can be reliably measured using a single head- or sternum-mounted sensor within a 120-s test duration. For other sensor locations, the minimum test duration may be longer and may depend on the specific test conditions.

Abstract Background Visuospatial neglect (VSN) has been suggested to limit standing balance improvement post-stroke. However, studies investigating this association longitudinally by means of repeated within-subject measurements early post-stroke are lacking. This prospective longitudinal cohort study evaluates the longitudinal association of egocentric and allocentric VSN severity with 1) standing balance independence and 2) postural control and weight-bearing asymmetry (WBA) during quiet standing, in the first 12 weeks post-stroke. Methods Thirty-six hemiplegic individuals after a first-ever unilateral stroke were evaluated at weeks 3, 5, 8 and 12 post-stroke. Egocentric and allocentric VSN severity were evaluated using the Broken Hearts Test. The standing unperturbed item of the Berg Balance Scale (BBS-s) was used to clinically evaluate standing independence. Posturographic measures included measures of postural control (mediolateral (ML)/anteroposterior (AP) net center-of-pressure velocities (COPvel)) and WBA during quiet standing. A linear mixed model was used to examine longitudinal associations between egocentric and allocentric VSN, and BBS-s, COPvel-ML, COPvel-AP and WBA within the first 12 weeks post-stroke. Results Egocentric (β = -0.08, 95%CI[-0.15;-0.01], P = .029) and allocentric VSN severity (β = -0.09, 95%CI[-0.15; -0.04], P = .002) were significant independent factors for BBS-s scores in the first 12 weeks post-stroke. Egocentric and allocentric VSN were no significant independent factors for COPvel-ML, COPvel-AP and WBA in the first 12 weeks post-stroke. Conclusions Allocentric and egocentric VSN severity were significantly associated with decreased standing independence, but not impaired postural control or greater asymmetric weight-bearing, in the early subacute post-stroke phase. This may involve traditional VSN measures being not sensitive enough to detect fine-grained VSN deficits due to a ceiling effect between 5 and 8 weeks post-stroke, once the individual regains standing ability. Future studies may require more sensitive VSN measurements to detect such deficits. Trial registration Clinicaltrials.gov. unique identifier NCT05060458.

Background: Visuospatial neglect (VSN) has been suggested to limit standing balance improvement post-stroke. However, studies investigating this association longitudinally by means of repeated within-subject measurements early post-stroke are lacking. This prospective longitudinal cohort study evaluates the longitudinal association of egocentric and allocentric VSN severity with 1) standing balance independence and 2) postural control and weight-bearing asymmetry (WBA) during quiet standing, in the first 12 weeks post-stroke. Methods: Thirty-six hemiplegic individuals after a first-ever unilateral stroke were evaluated at weeks 3, 5, 8 and 12 post-stroke. Egocentric and allocentric VSN severity were evaluated using the Broken Hearts Test. The standing unperturbed item of the Berg Balance Scale (BBS-s) was used to clinically evaluate standing independence. Posturographic measures included measures of postural control (mediolateral (ML)/anteroposterior (AP) net center-of-pressure velocities (COPvel)) and WBA during quiet standing. A linear mixed model was used to examine longitudinal associations between egocentric and allocentric VSN, and BBS-s, COPvel-ML, COPvel-AP and WBA within the first 12 weeks post-stroke. Results: Egocentric (β = -0.08, 95%CI[-0.15;-0.01], P =.029) and allocentric VSN severity (β = -0.09, 95%CI[-0.15; -0.04], P =.002) were significant independent factors for BBS-s scores in the first 12 weeks post-stroke. Egocentric and allocentric VSN were no significant independent factors for COPvel-ML, COPvel-AP and WBA in the first 12 weeks post-stroke. Conclusions: Allocentric and egocentric VSN severity were significantly associated with decreased standing independence, but not impaired postural control or greater asymmetric weight-bearing, in the early subacute post-stroke phase. This may involve traditional VSN measures being not sensitive enough to detect fine-grained VSN deficits due to a ceiling effect between 5 and 8 weeks post-stroke, once the individual regains standing ability. Future studies may require more sensitive VSN measurements to detect such deficits. Trial registration Clinicaltrials.gov. unique identifier NCT05060458. [ABSTRACT FROM AUTHOR]

Maintaining standing balance is essential for people to engage in productive activities in daily life. However, the process of interaction between the cortex and the muscles during balance regulation is understudied. Four balance paradigms of different difficulty were designed by closing eyes and laying sponge pad under feet. Ten healthy subjects were recruited to stand for ten 15 s trials in each paradigm. This study used simultaneously acquired electroencephalography (EEG) and electromyography (EMG) to investigate changes in the human cortico-muscular coupling relationship and functional brain network characteristics during balance control. The coherence and causality of EEG and EMG signals were calculated by magnitude-squared coherence (MSC) and transfer entropy (TE). It was found that changes in balance strategies may lead to a shift in cortico-muscular coherence (CMC) from the beta band to the gamma band when the difficulty of balance increased. As subjects performed the four standing balance paradigms, the causality of the beta band and the gamma band was stronger in the descending neural pathway than that in the ascending neural pathway. A multi-rhythmic functional brain network with 19 EEG channels was constructed and analyzed based on graph theory, showing that its topology also changed with changes in balance difficulty. These results show an active adjustment of the sensorimotor system under different balance paradigms and provide new insights into the endogenous physiological mechanisms underlying the control of standing balance. [ABSTRACT FROM AUTHOR]

While several studies have explored the impacts of smartphone usage on postural balance, their tasks are limited to texting or calling, and the studies were performed on rigid ground. 1. How does modern smartphone usage, specifically taking selfies or posting statuses on social media, affect balance? 2. How does their interaction with challenging ground conditions affect balance? Sixteen healthy young adults were recruited to perform two smartphone tasks: taking selfies and posting statuses on social media; participants were standing on four different grounds: rigid, foam-based compliant, robot-simulated compliant, and robot-simulated oscillatory grounds. The center-of-pressure (CoP) under each foot was recorded via force plates and the net CoP was calculated. Temporal, spatial, and control aspects of postural balance were analyzed by virtual time-to-contact (VTC), CoP path length (PL) and sway area (SA), and switching rate (SR), respectively. Two-way repeated measures analysis of variance (ANOVA) tests were performed for each dependent variable to compare the mean differences between smartphone tasks and ground conditions and their interaction effect. Paired t-tests with Bonferroni correction were used to determine significant differences in post-hoc analyses. VTC decreased significantly whereas CoP PL and SA increased significantly during smartphone usage (all p-values <0.001). Interaction effects between task and ground condition (all p-values <0.001) were observed in all measures but SR, implying that the effect of smartphone usage on postural balance can significantly change depending on the ground condition. These results highlight the potential fall risks due to the impact of modern smartphone usage on standing balance. Understanding the effect of smartphone usage on standing balance and the interaction effect with various ground conditions opens the door for potential balance assistive devices and mobile phone applications to minimize falls. • Modern smartphone usage has a negative impact on standing postural balance. • Smartphone's effect on balance changes significantly with different ground conditions. • The effect is less evident as the ground condition becomes more challenging. • Temporal and spatial aspects of standing balance are sensitive to smartphone use. [ABSTRACT FROM AUTHOR]

Introduction: Degenerative lumbar disease (DLD) is a prevalent disorder that predominantly affects the elderly population, especially female. Extensive research has demonstrated that overweight individuals (categorized by body fat distribution) have a higher susceptibility to developing DLD and an increased risk of falling. However, there is limited research available on the standing balance and functional performance of overweight females with DLD.Aims: To determine the impact of body fat distribution on standing balance and functional performance in overweight females with DLD.Methods: This cross-sectional study evaluated thirty females with DLD were categorized into three types of body fat distribution based on body mass index (BMI) and waist-hip ratio, specifically as android-type, gynoid-type, and normal weight groups. In addition, a control group of ten age-matched females with normal weight was recruited. The Visual Analogue Scale, Roland Morris Disability Questionnaire, Cobb angle (Determined using x-ray), and body composition (Determined using the InBody S10), were conducted only on the DLD groups. All participants were assessed standing balance in the anteroposterior and mediolateral directions. The functional assessments included timed-up-and-go and 5-times-sit-to-stand tests.Results: There were 10 people in each group. Android-type (Age = 65.00 ± 6.34 years; BMI = 26.87 ± 2.05 kg/m2), Gynoid-type (Age = 65.60 ± 4.99 years; BMI = 26.60 ± 1.75 kg/m2), Normal weight (Age = 65.70 ± 5.92 years; BMI = 22.35 ± 1.26 kg/m2), and Control (Age = 65.00 ± 5.23 years; BMI = 22.60 ± 1.12 kg/m2). The android-type group had higher body fat, visceral fat, and lower muscle mass (p < 0.05), along with an increased Cobb angle (p < 0.05). They showed greater ellipse area, total excursion, and mean distance in the anteroposterior direction (p < 0.05). During the functional performance assessments, the android-type group had longer durations in both the 5-times-sit-to-stand and timed-up-and-go tasks (p < 0.05).Conclusion: Our study found that android-type overweight individuals showed postural instability, reduced functional performance, and insufficient lower limb muscle strength and mass. These findings might help physical therapists in planning interventions, as they imply that patients with DLD may require specific types of standing balance training and lower extremities muscle-strengthening based on their body fat distribution.Clinical Trial Registration:ClinicalTrials.gov, identifier NCT05375201

Although standing plantar perception training (SPPT) may improve standing postural stability, the underlying neural mechanisms remain unclear. The authors investigated the relationship between regional cortical responses to SPPT using a balance pad and training outcomes in 32 older participants (mean ± SD:72.2 ± 6.0, range:60–87). Regional cortical activity was measured in the bilateral supplementary motor area, primary sensorimotor area, and parietal association area using near-infrared spectroscopy. Postural sway changes were compared before and after SPPT. Changes in two-point plantar discrimination and regional cortical activity during SPPT, associated with standing postural stability improvements, were examined using multiple regression and indicated improved standing postural stability after SPPT (p <.0001). Changes in right parietal association area activity were associated with standing postural stability improvements while barefoot. Overall, the results suggest that right parietal association area activation during SPPT plays a crucial role in regulating standing postural stability and may help develop strategies to prevent older adults from falling. [ABSTRACT FROM AUTHOR]

IntroductionPlantar cutaneous augmentation is a promising approach in balance rehabilitation by enhancing motion-dependent sensory feedback. The effect of plantar cutaneous augmentation on balance has been mainly investigated in its passive form (e.g., textured insole) or on lower-limb amputees. In this study, we tested the effect of plantar cutaneous augmentation on balance in its active form (i.e., electrical stimulation) for individuals with intact limbs.MethodsTen healthy subjects participated in the study and were instructed to maintain their balance as long as possible on the balance board, with or without electrotactile feedback evoked on the medial side of the heel, synched with the lateral board sway. Electrotactile feedback was given in two different modes: 1) Discrete-mode E-stim as the stimulation on/off by a predefined threshold of lateral board sway and 2) Proportional-mode E-stim as the stimulation frequency proportional to the amount of lateral board sway. All subjects were distracted from the balancing task by the n-back counting task, to test subjects’ balancing capability with minimal cognitive involvement.ResultsProportional-mode E-stim, along with the n-back counting task, increased the balance time from 1.86 ± 0.03 s to 1.98 ± 0.04 s (p = 0.010). However, discrete-mode E-stim did not change the balance time (p = 0.669). Proportional-mode E-stim also increased the time duration per each swayed state (p = 0.035) while discrete-mode E-stim did not (p = 0.053).DiscussionThese results suggest that proportional-mode E-stim is more effective than discrete-mode E-stim on improving standing balance. It is perhaps because the proportional electrotactile feedback better mimics the natural tactile sensation of foot pressure than its discrete counterpart.

Hypoxia increases postural sway compared to normoxia, but the underlying sensorimotor factors remain unclear. An important contributor to balance control is cutaneous feedback arising from the feet, which can be partially characterized by electrically evoking a reflex from a purely cutaneous nerve (i.e., sural) and sampling the subsequent motor activity of a muscle. The purpose of the present study was to determine how normobaric hypoxia influences sural nerve reflex parameters during a standing posture. It was hypothesized that normobaric hypoxia would reduce cutaneous reflex area compared to normoxia. Participants (n = 16; 5 females, 11 males) stood with their feet together while receiving two trials of 50 sural nerve stimulations (200-Hz, 5-pulse train, presented randomly every 3–6 s) at baseline (BL; normoxia), and at 2 (H2) and 4 (H4) h of normobaric hypoxia (~ 0.11 fraction of inspired oxygen in a hypoxic chamber). The sural nerve reflex was recorded using surface electromyography from the left medial gastrocnemius, and characterized by area and duration of the initial positive and negative peaks of the response. When normalized to pre-stimulus electromyography, the area of the peak-to-peak cutaneous reflex was not different than BL (p ≥ 0.14) for up to 4 h of normobaric hypoxia (BL: 0.26 ± 0.22, H2: 0.19 ± 0.19, H4: 0.22 ± 0.20 A.U.). Furthermore, the duration of the response was not different during hypoxia (BL: 73.2 ± 42.4; H2: 75.2 ± 47.0; H4: 77.6 ± 54.6 ms; p ≥ 0.13) than BL. Thus, reflexes arising from cutaneous afferents of the lateral border of the foot are resilient to at least 4 h of normobaric hypoxia. [ABSTRACT FROM AUTHOR]

We examined effects of a visual search task (VST) in virtual reality (VR) with a moving background on spatial cognition and standing balance in left hemiparetic strokes. The VST with background deviation was allocated to Case A. In Case B, the VST without the deviation was performed. As a results, in Case A, the reaction time of VST was shortened in the paretic space and ability of weight-shift to the paretic side was improved. In conclusion, the VST in the VR with a spatial manipulation may improve spatial cognition and standing balance in left hemiparetic strokes. [ABSTRACT FROM AUTHOR]

Balance control can be quantified with measurements from force plates or wearable accelerometers. The purposes of our study were (1) to assess the explanatory power of accelerometer measures to predict center-ofpressure (CoP) sway-area rate across four standing balance tests, (2) to provide expanded Romberg quotient (RQ) reference ranges for older adults, and (3) to perform an agreement analysis between RQs derived from accelerometer measures with those from CoP sway-area rate. Twenty-six healthy older adults completed four 30-s balance tests standing on rigid and foam surfaces with eyes opened and closed on two occasions. Tests were performed on a force plate (1 variable) while wearing accelerometers (5 variables). The outcomes were assessed with linear mixed-effects models, RQs, and agreement analyses. CoP sway-area rate could be significantly predicted by different combinations of accelerometer variables for each balance condition (R²≥0.45). Despite some accelerometer RQs not being significantly different (p≥0.12) from corresponding CoP sway-area rate RQs, there was low agreement between these RQs as determined by intraclass correlation coefficients, Bland-Altman plots, and mountain plots. Clinicians with access to wearable accelerometers but not force plates can use our models to estimate CoP sway-area rate for each standardized test of standing balance. The expanded RQ reference ranges provide information about potential sensory impairments that can influence balance control in older adults. [ABSTRACT FROM AUTHOR]

The purpose of the study was to investigate the effects of ankle angular position and standing surface type on static upright balance. Ten young adults stood on a force platform or on a firm wedge that induced 15° of either dorsiflexion or plantarflexion. In addition, a piece of foam was placed on top of the force platform and on the wedge. The center of pressure distance and velocity in the anteroposterior and mediolateral directions were calculated. Significantly larger magnitudes in most of the investigated variables were seen while standing with ankles in the dorsiflexion when compared with standing with the ankle joints in a natural position (p < .05). Plantarflexion increased the center of pressure anteroposterior velocity by 87% when compared with a natural stance (p < .05). Standing on the foam surfaces resulted in increases in all of the center of pressure measures by an average of 38% in all of the ankle conditions. [ABSTRACT FROM AUTHOR]

BackgroundWhile standing upright, the brain must accurately accommodate for delays between sensory feedback and self-generated motor commands. Natural aging may limit adaptation to sensorimotor delays due to age-related decline in sensory acuity, neuromuscular capacity and cognitive function. This study examined balance learning in young and older adults as they stood with robot-induced sensorimotor delays.MethodsA cohort of community dwelling young (mean = 23.6 years, N = 20) and older adults (mean = 70.1 years, N = 20) participated in this balance learning study. Participants stood on a robotic balance simulator which was used to artificially impose a 250 ms delay into their control of standing. Young and older adults practiced to balance with the imposed delay either with or without visual feedback (i.e., eyes open or closed), resulting in four training groups. We assessed their balance behavior and performance (i.e., variability in postural sway and ability to maintain upright posture) before, during and after training. We further evaluated whether training benefits gained in one visual condition transferred to the untrained condition.ResultsAll participants, regardless of age or visual training condition, improved their balance performance through training to stand with the imposed delay. Compared to young adults, however, older adults had larger postural oscillations at all stages of the experiments, exhibited less relative learning to balance with the delay and had slower rates of balance improvement. Visual feedback was not required to learn to stand with the imposed delay, but it had a modest effect on the amount of time participants could remain upright. For all groups, balance improvements gained from training in one visual condition transferred to the untrained visual condition.ConclusionOur study reveals that while advanced age partially impairs balance learning, the older nervous system maintains the ability to recalibrate motor control to stand with initially destabilizing sensorimotor delays under differing visual feedback conditions.

Maintaining standing balance is essential for people to engage in productive activities in daily life. However, the process of interaction between the cortex and the muscles during balance regulation is understudied. Four balance paradigms of different difficulty were designed by closing eyes and laying sponge pad under feet. Ten healthy subjects were recruited to stand for ten 15 s trials in each paradigm. This study used simultaneously acquired electroencephalography (EEG) and electromyography (EMG) to investigate changes in the human cortico-muscular coupling relationship and functional brain network characteristics during balance control. The coherence and causality of EEG and EMG signals were calculated by magnitude-squared coherence (MSC) and transfer entropy (TE). It was found that changes in balance strategies may lead to a shift in cortico-muscular coherence (CMC) from the beta band to the gamma band when the difficulty of balance increased. As subjects performed the four standing balance paradigms, the causality of the beta band and the gamma band was stronger in the descending neural pathway than that in the ascending neural pathway. A multi-rhythmic functional brain network with 19 EEG channels was constructed and analyzed based on graph theory, showing that its topology also changed with changes in balance difficulty. These results show an active adjustment of the sensorimotor system under different balance paradigms and provide new insights into the endogenous physiological mechanisms underlying the control of standing balance.

Abstract Background Numerous studies showed that postural balance improves through light touch on a stable surface highlighting the importance of haptic information, seemingly downplaying the mechanical contributions of the support. The present study examined the mechanical effects of canes for assisting balance in healthy individuals challenged by standing on a beam. Methods Sixteen participants supported themselves with two canes, one in each hand, and applied minimal, preferred, or maximum force onto the canes. They positioned the canes in the frontal plane or in a tripod configuration. Statistical analysis used a linear mixed model to evaluate the effects on the center of pressure and the center of mass. Results The canes significantly reduced the variability of the center of pressure and the center of mass to the same level as when standing on the ground. Increasing the exerted force beyond the preferred level yielded no further benefits, although in the preferred force condition, participants exploited the altered mechanics by resting their arms on the canes. The tripod configuration allowed for larger variability of the center of pressure in the task-irrelevant anterior–posterior dimension. High forces had a destabilizing effect on the canes: the displacement of the hand on the cane handle increased with the force. Conclusions Given this static instability, these results show that using canes can provide not only mechanical benefits but also challenges. From a control perspective, effort can be reduced by resting the arms on the canes and by channeling noise in the task-irrelevant dimensions. However, larger forces exerted onto the canes can also have destabilizing effects and the instability of the canes needs to be counteracted, possibly by arm and shoulder stiffness. Insights into the variety of mechanical effects is important for the design of canes and the instructions of how to use them.

The mechanical consequences of the motor actions used to maintain upright standing balance can be discriminated in two mechanisms: i) moving the center of pressure (CoP) within the base of support (M1); and ii) modifying the whole-body angular momentum (M2). Since the contribution of M2 to the whole-body CoM acceleration increases with postural constraints, a postural analysis focusing only on the CoP trajectory (i.e. M1) could ignore the majority of the control actions in challenging postural tasks. The objective of this study was to determine the contributions of the two postural balance mechanisms across postures with different areas of the base of support. Forty-one healthy young adults (19 females, 22.9 ± 2.9 years old) stood quietly on a forceplate, maintaining four different postures: bipedal, tandem, unipedal and unipedal on a 4-cm wooden bar; each with eyes open and for 60 s. Relative contributions of the two balance postural mechanisms were computed for each posture, in both directions of the horizontal plane. The posture impacted the mechanisms contributions, where the contribution of M1 decreased between each posture in the mediolateral direction as the area of the base of support was reduced. The contribution of M2 in the mediolateral direction was not negligible (about 1/3) in tandem and unipedal postures and became dominant (nearly 90% on average) in the most challenging unipedal posture. This suggests the contribution of M2 should not be neglected for the analysis of postural balance, and particularly in challenging standing postures. • The contributions of the two postural balance mechanisms were objectified. • CoP motion, the first mechanism, is dominant in bipedal postures. • But it only explains 12% of mediolateral CoM acceleration in a challenging posture. • Analysis of the two mechanisms is complementary and should be encouraged. [ABSTRACT FROM AUTHOR]

Background: Falls are the leading cause of injury among adults ≥ 65 years of age. Participation in physical activity (PA) is associated with improved balance, though it is impact in the middle-age population is not well understood. Aim: The purpose of the current study was to examine the influence of PA intensity on static balance in middle-aged and older aged individuals. Methods: Included were middle-aged adults (40–64 years) and older adults (≥ 65 years) from the 2003–2004 years of the National Health and Nutrition Evaluation Survey. Light physical activity (LPA) and moderate–vigorous physical activity (MVPA) were collected via accelerometer and static balance via the Romberg Test of Standing Balance. Results: No significant odds ratio relationship was found between MVPA or LPA and having good static balance in the middle-aged population; 1.04 (95% CI 0.95, 1.13) p = 0.427 and 1.05 (95% CI 0.97, 1.14) p = 0.182, respectively. Whereas, in older adults, every 60-min increase in LPA was significantly associated with 28% higher odds of good balance (95% CI 1.15, 1.41; p < 0.001), and every 10-min increase in MVPA with 25% higher odds of good balance (95% CI 1.08, 1.45; p = 0.006). Discussion: LPA and MVPA were not associated with good static balance in middle-aged adults, but in older adults LPA was significantly associated with good static balance. Conclusion: A significant relationship is found between age and fall risk, which is a major concern in the aging population. [ABSTRACT FROM AUTHOR]

Many women wearing high-heeled footwear are at high risk of falls. Past studies have examined the balance on level ground or balance during walking. We measured the standing balance on the ground and side slopes for 18 healthy women. Body sway was evaluated based on the center of pressure (COP) while participants stood on level ground on a side slope. The total locus length as well as rectangular and outer peripheral areas were then measured using a Zebris system. Measurements were compared under bare feet, normal shoe, and high-heeled shoe conditions. On level ground, there were no significant differences among the three conditions. On the side slope, the total locus length (TLL), rectangular area (RA) and outer peripheral areas (OPA) were significantly greater for the high-heeled shoes than for the bare feet and normal shoes. Standing on the side slope caused larger body sway than on the level ground, along with a higher risk of falling. In TLL, OPA, and RA, the COP moved outside substantially when participants stood on a slope in high heels than in shoes. High heels were highly unstable for standing on a slope since the ankle joint of one leg is in plantar flexion, the foot is pronated, and the other side is plantarflexed at the ankle with pronation of the foot. High-heeled shoes significantly alter a person's balance when standing on a side slope, suggesting a high risk of falling. • We compared standing balance in bare feet, normal, and high-heeled shoe condition. • Total locus length, rectangular area, and outer peripheral area were measured. • There were no significant differences among the three conditions on level ground. • High-heeled shoes were most unstable on slide slope. • Wearing high-heeled shoes on a side slope made standing balance unstable. [ABSTRACT FROM AUTHOR]

Lumbar spondylosis (LS) is a common degenerative spine disease that often leads to impaired motor control, sensory changes, and imbalance. The current study aimed to compare the dynamic balance control between patients with LS and healthy controls in terms of inclination angles (IA) and the rate of change of IA (RCIA) of the center of mass relative to the center of pressure (COM–COP motion) during walking and to identify the correlation between dynamic balance and standing balance in patients with LS. Eleven patients with LS and eleven healthy controls performed level walking and static standing in a gait laboratory while their whole-body motion and ground reaction forces were measured to calculate the IA and RCIA. Gait temporal–spatial parameters were also recorded. Correlations between the COP motions during standing balance and COM–COP motions during gait were quantified using Pearson's correlation coefficients (r). In the sagittal plane, the patients increased posterior IA with decreased posterior RCIA during the double-limb support phase of gait and showed decreased anterior RCIA, with small ranges of IA and RCIA during the single-limb support phase (p < 0.05). In the frontal plane, the patients increased medial–lateral ranges of RCIA and medial IA during the double-limb support phase of gait and increased medial RCIA and ranges of IA during the single-limb support phase of gait (p < 0.05). A moderate to strong correlation was found between dynamic balance and standing balance in the patients (p < 0.05). The patients presented a conservative anterior–posterior dynamic balance control but an unstable medial–lateral dynamic balance control during walking, which may be related to the decreased gait speed. The results showed that the greater the postural sway in the patients' standing balance, the more conservative the dynamic balance control in the sagittal plane, and the greater the risk of imbalance in the frontal plane. It is thus suggested that dynamic balance control deviations during gait in patients with LS cannot be deduced solely from standing balance test data, and should thus be monitored via dynamic approaches in clinical applications. [ABSTRACT FROM AUTHOR]

Purpose: Aging and spinal disease impair standing whole body sagittal alignment (WBS alignment), which leads to stooping. When WBS alignment deteriorates, compensatory mechanisms are activated to maintain standing posture. Increase of the compensation impairs health-related quality of life (HRQOL). The purpose of this research was to determine whether postural factors, age, and sex affect HRQOL. Methods: This cross-sectional study evaluated the influence of WBS alignment, standing body sway (balance), skeletal muscle mass (SMM), aging, and sex on HRQOL in healthy volunteers (n = 150; mean age 40.9 years [20–76], 96 women). Age, sex, weight, height, and body mass index (BMI) were obtained. HRQOL was assessed with Scoliosis Research Society-22 (SRS-22r). WBS alignment and balance were measured by EOS imaging with simultaneous force plate measurement. SMM was measured using a medical body composition analyzer. Based on the bivariate analysis between the SRS-22r subtotal and all parameters, selected ten parameters were used for multivariate logistic regression analysis to identify affecting factors to SRS-22r. Results: Men had significantly higher weight, height, BMI, and SRS-22r score in all domains. The L4-S1 lumbar lordosis angle was greater in men, and pelvic tilt and knee hyperextension were greater in women. Women had a more stable standing posture, whereas men had significantly higher SMM values. Multivariate logistic regression analysis revealed that age, sex, and TPA were identified as significant factors affecting SRS-22r. Conclusions: In healthy volunteers, SRS-22r is affected by aging, sex (woman had a lower score), and sagittal malalignment. Neither Standing balance nor SMM, however, affect SRS-22r.4 [ABSTRACT FROM AUTHOR]

Connectivity of somatosensory cortex (S1) and cerebellum with the motor cortex (M1) is critical for balance control. While both S1-M1 and cerebellar-M1 connections are affected with aging, the implications of altered connectivity for balance control are not known. We investigated the relationship between S1-M1 and cerebellar-M1 connectivity and standing balance in middle-aged and older adults. Our secondary objective was to investigate how cognition affected the relationship between connectivity and balance. Our results show that greater S1-M1 and cerebellar-M1 connectivity was related to greater postural sway during standing. This may be indicative of an increase in functional recruitment of additional brain networks to maintain upright balance despite differences in network connectivity. Also, cognition moderated the relationship between S1-M1 connectivity and balance, such that those with lower cognition had a stronger relationship between connectivity and balance performance. It may be that individuals with poor cognition need increased recruitment of brain regions (compensation for cognitive declines) and in turn, higher wiring costs, which would be associated with increased functional connectivity., Competing Interests: Declaration of Competing Interest The authors have no actual or potential conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Cortical mechanism is necessary for human standing control. Previous research has demonstrated that cortical oscillations and corticospinal excitability respond flexibly to postural demands. However, it is unclear how corticocortical and corticomuscular connectivity changes dynamically during standing with spontaneous postural sway and over time. This study investigated the dynamics of sway- and time-varying connectivity using electroencephalography and electromyography. Electroencephalography and electromyography were recorded in sitting position and 3 standing postures with varying base-of-support: normal standing, one-leg standing, and standing on a piece of wood. For sway-varying connectivity, corticomuscular connectivity was calculated based on the timing of peak velocity in anteroposterior sway. For time-varying connectivity, corticocortical connectivity was measured using the sliding-window approach. This study found that corticomuscular connectivity was strengthened at the peak velocity of postural sway in the γ- and β-frequency bands. For time-varying corticocortical connectivity, the θ-connectivity in all time-epoch was classified into 7 clusters including posture-relevant component. In one of the 7 clusters, strong connectivity pairs were concentrated in the mid-central region, and the proportion of epochs under narrow-base standing conditions was significantly higher, indicating a functional role for posture balance. These findings shed light on the connectivity dynamics and cortical oscillation that govern standing balance., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Humans rely on ankle torque to maintain standing balance, particularly in the presence of small to moderate perturbations. Reductions in maximum torque (MT) production and maximum rate of torque development (MRTD) occur at the ankle with age, diminishing stability. Ankle exoskeletons are powered orthotic devices that may assist older adults by compensating for reduced torque and power production capabilities. They may also be able to assist with ankle strategies used for balance. However, the effect of such devices on standing balance in older adults is not well understood. Here, we model the effects ankle exoskeletons have on stability in physics-based models of healthy young and old adults, focusing on the potential to mitigate age-related deficits in MT and MRTD. Using backward reachability, a mathematical technique for analyzing the behavior of dynamical systems, we compute the set of stable center of mass positions and velocities for sex and age adjusted models of human standing balance with an ankle exoskeleton. We show that an ankle exoskeleton moderately reduces feasible stability boundaries in users who have full ankle strength. For individuals with age-related deficits, there is a trade-off. While exoskeletons augment stability at low center of mass velocities, they reduce stability in some high velocity conditions. Our results suggest that well-established control strategies must still be experimentally validated in older adults.

Background: Adolescent idiopathic scoliosis (AIS), the most common spinal deformity, possibly develops due to imbalanced spinal loading following asymmetric development. Since altered loading patterns may affect standing balance and gait, we investigated whether a correlation exists between balance ability, gait pattern, and the three-dimensional radiographic spinopelvic parameters in AIS patients.Methods: A cross-sectional observational study was conducted with 34 AIS patients (aged 10–18 years) and an equal number of healthy age and sex-matched teenagers (normal group). We obtained the spinopelvic three-dimensional parameters and balance parameters simultaneously through the EOS imaging system and gait and center of pressure (CoP) characteristics using a plantar pressure measurement mat. Besides determining the intergroup differences in balance and gait parameters, multiple linear regression analyses were performed to identify any correlation between the static plantar pressure and radiographic parameters.Results: Compared to the normal group, the CoPx is lower, the CoP path length and 90% confidence ellipse area were significantly higher in AIS patients (AIS: −13.7 ± 5.7 mm, 147.4 ± 58.1 mm, 150.5 ± 62.8 mm2; normal: −7.0 ± 5.4 mm, 78.8 ± 32.0 mm, 92.1 ± 41.7 mm2, respectively), correlated with apical vertebra translation, sagittal pelvic tilt, and pelvis axial rotation, respectively. Moreover, AIS patients had a shorter stance phase (61.35 ± 0.97 s vs. 62.39 ± 1.09 s), a longer swing phase (38.66 ± 0.97 s vs. 37.62 ± 1.08 s), and smaller maximum pressure peaks in the gait cycle, especially on the left foot, as compared to healthy subjects. Moreover, the CoP trajectory in AIS patients was different from the latter, and changes in the bipedal trend were not consistent.Conclusion: The standing balance and gait characteristics of AIS patients are different from those of healthy subjects, as reflected in their three-dimensional spinopelvic radiographic parameters. Trial registration: The study protocol was registered with the Chinese Clinical Trial Registry (Number ChCTR1800018310) and the Human Subject Committee of Guangzhou Sport University (Number: 2018LCLL003).

Background: Numerous studies showed that postural balance improves through light touch on a stable surface highlighting the importance of haptic information, seemingly downplaying the mechanical contributions of the support. The present study examined the mechanical effects of canes for assisting balance in healthy individuals challenged by standing on a beam.Methods: Sixteen participants supported themselves with two canes, one in each hand, and applied minimal, preferred, or maximum force onto the canes. They positioned the canes in the frontal plane or in a tripod configuration. Statistical analysis used a linear mixed model to evaluate the effects on the center of pressure and the center of mass.Results: The canes significantly reduced the variability of the center of pressure and the center of mass to the same level as when standing on the ground. Increasing the exerted force beyond the preferred level yielded no further benefits, although in the preferred force condition, participants exploited the altered mechanics by resting their arms on the canes. The tripod configuration allowed for larger variability of the center of pressure in the task-irrelevant anterior-posterior dimension. High forces had a destabilizing effect on the canes: the displacement of the hand on the cane handle increased with the force.Conclusions: Given this static instability, these results show that using canes can provide not only mechanical benefits but also challenges. From a control perspective, effort can be reduced by resting the arms on the canes and by channeling noise in the task-irrelevant dimensions. However, larger forces exerted onto the canes can also have destabilizing effects and the instability of the canes needs to be counteracted, possibly by arm and shoulder stiffness. Insights into the variety of mechanical effects is important for the design of canes and the instructions of how to use them. [ABSTRACT FROM AUTHOR]

Background: Postpartum women are at an increased risk of falls. Maintaining standing balance is multifactorial, involving abdominal wall/pelvic floor muscle responsivity, quick generation of intra-abdominal pressure, and glottis position. Objective: To identify whether using voicing tasks improves balance in postpartum women. Study Design: Research report. Methods: Eleven postpartum women and 10 age-matched nulliparous controls stood on a force plate when balance was perturbed to the front or back of their bodies while performing 6 different breathing and voicing tasks. Tasks modified glottis position and lung volume. Primary outcome measure was maximal displacement of center of pressure immediately following perturbation. Results: When comparing the 2 groups' responses, postpartum women showed worse balance during the "Ah" sound and "normal exhale without breath hold" (P =.049 and P =.031, respectively). When comparing all responses to each task, participants in both groups showed no significantly different response to any tasks when they were perturbed anteriorly. The nulliparous group also had no significantly different responses when perturbed posteriorly. Postpartum women showed a significant difference in response to "normal exhale without breath hold" compared with "counting" (P =.01), with better balance for "counting." Conclusion: Postpartum women showed improved balance during the "counting" task, which incorporates the glottis into the balance mechanism. Tasks that did not incorporate the glottis (exhalation) and relied more on the abdominal wall/pelvic floor produced worse balance in postpartum women. For recently postpartum women, counting may be a helpful strategy to improve balance and reduce fall risk. [ABSTRACT FROM AUTHOR]

The exoskeleton is often regarded as a tool for rehabilitation and assistance of human movement. The control schemes were conventionally implemented by developing accurate physical and kinematic models, which often lack robustness to external variational disturbing forces. This paper presents a virtual neuromuscular control for robotic ankle exoskeleton standing balance. The robustness of the proposed method was improved by applying a specific virtual neuromuscular model to estimate the desired ankle torques for ankle exoskeleton standing balance control. In specialty, the proposed control method has two key components, including musculoskeletal mechanics and neural control. A simple version of the ankle exoskeleton was designed, and three sets of comparative experiments were carried out. The experimentation results demonstrated that the proposed virtual neuromuscular control could effectively reduce the wearer's lower limb muscle activation, and improve the robustness of the different external disturbances. [ABSTRACT FROM AUTHOR]

The recovery strategies used by young adults to maintain standing balance following external force-controlled perturbations in densely populated group formations was investigated in this work. In particular, the moment of step initiation as well and the characteristics of the first recovery steps and hand-raising were studied here. The experimental data considered in this work are part of a larger dataset relying on a new experimental paradigm inspired by Feldmann and Adrian (2023). In this experiment, 20 participants (8 females, 12 males, 24. 8 ± 3. 7 y o) equipped with motion capture suits were asked to stand in tightly packed formation before receiving a force-controlled perturbation. In total, four group configurations and two interpersonal distancing conditions have been investigated here. The standing balance recovery strategies observed in this dense groups experiment were then compared with the observed behaviour of single individuals following external perturbations (Chatagnon et al., 2023). Results suggest that the moment of initiation for recovery steps was affected by the initial interpersonal distancing conditions. The first recovery steps within the studied dense groups were observed to be slower, smaller and more dispersed than those of single individuals for comparable level of perturbation intensity. However, the relationship between the average speed of first recovery steps and the length of these steps remained similar to the one of single individuals. This suggests that the first recovery step duration remained almost constant during both the dense groups experiment and the experiment with single individuals. Finally, we observed a significant occurrence of participants raising their hands, as physical interactions played an important role in this dense groups experiment. This behaviour was mainly observed to be initiated before recovery steps. • Standing balance findings in dense crowds. • Experimental paradigm to capture full body in crowds. [ABSTRACT FROM AUTHOR]

Reactive balance control following hand perturbations is important for everyday living as humans constantly encounter perturbations to the upper limb while performing functional tasks while standing. When multiple tasks are performed simultaneously, cognitive processing is increased, and performance on at least one of the tasks is often disrupted, owing to attentional resources being divided. The purpose here was to assess the effects of increased cognitive processing on whole-body balance responses to perturbations of the hand during continuous voluntary reaching. Sixteen participants (8 females; 22.9 ± 4.5 years) stood and grasped the handle of a KINARM – a robotic-controlled manipulandum paired with an augmented visual display. Participants completed 10 total trials of 100 mediolateral arm movements at a consistent speed of one reach per second, and an auditory n-back task (cognitive task). Twenty anteroposterior hand perturbations were interspersed randomly throughout the reaching trials. The arm movements with random arm perturbations were either performed simultaneously with the cognitive task (combined task) or in isolation (arm perturbation task). Peak centre of pressure (COP) displacement and velocity, time to COP displacement onset and peak, as well as hand displacement and velocity following the hand perturbation were evaluated. N-back response times were 8% slower and 11% less accurate for the combined than the cognitive task. Peak COP displacement following posterior perturbations increased by 8% during the combined compared to the arm perturbation task alone, with no other differences detected. Hand peak displacement decreased by 5% during the combined compared to the arm perturbation task. The main findings indicate that with increased cognitive processing, attentional resources were allocated from the cognitive task towards upper limb movements, while attentional resources for balance seemed unaltered. [ABSTRACT FROM AUTHOR]

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Balance control is a critical task of daily life, the ability to maintain upright posture becomes of particular concern during aging when the sensory and motor system becomes deteriorated. Falls contribute to the most deaths caused by injury within the aged population, and the mortality rate following a fall is drastically elevated. Longitudinal and reliable assessment of balance control abilities is a critical point in the prediction of increased risk of falling in an elderly population. The primary aim of the study was to evaluate the efficiency of the Homebalance test in the identification of persons being at higher risk of falling. 135 subjects (82 women and 53 men) with geriatric syndrome have been recruited and the Homebalance and the Tinetti Balance test were performed. Results of both tests strongly correlated proving the good performance of the Homebalance test. Standing balance declines with increasing body mass index in both genders. Analysis of fluctuations of the center of pressure (COP) revealed higher frequency and magnitude in mediolateral direction COP movements when compared women to men. A strong negative correlation has been found between Tinetti static balance score and the total length of the COP trajectory during the examination on Homebalance (r = -0.6, p<0.001). Although both methods revealed good performance in detecting balance impairment, Homebalance test possesses higher precision due to the continuous nature of COP-derived parameters. In conclusion, our data proved that the Homebalance test is capable to identify persons with impaired balance control and thus are at higher risk of falling. [ABSTRACT FROM AUTHOR]