Lower Quarter Y Balance Test performance: Reference values for healthy youth aged 10 to 17 years

BackgroundThe Lower Quarter Y Balance Test (YBT-LQ) has been widely used to register dynamic balance performance in children and adolescents. However, studies evaluating age- and sex-specific normative data to assess and classify YBT-LQ performance for these age-cohorts are missing.ObjectiveThus, we investigated YBT-LQ performance in healthy youth to provide age- and sex-specific reference values.MethodsSix-hundred and sixty-nine individuals (286 female, 383 male) aged 10–17 years performed the YBT-LQ with their left and right leg. Normalized maximal reach distances (% leg length) for all three directions (i.e., anterior, posterolateral, posteromedial) and the composite score were calculated. Further, age- and sex-specific percentile values (i.e., 10th to 90th percentile) were computed and plotted.ResultsIn boys, the oldest age group (16−17 years) performed better than the younger ones (14−15, 12−13, and 10−11 years). In girls, the youngest age group (10−11 years) often achieved better values compared to the 12−13-year olds. Further, 16−17-year old boys compared to the same aged girls showed better YBT-LQ performance in all but one measure (except left leg reach in posterolateral direction). For both sexes, curvilinear shaped curves were detected for percentile values across the reach directions.ConclusionsThe generated age- and sex-specific reference values for the YBT-LQ can be used by practitioners to evaluate dynamic balance performance in healthy youth aged 10–17 years.     

An external focus of attention compared to an internal focus of attention improves anticipatory postural adjustments among people post-stroke

BackgroundPeople after stroke often have postural impairments that can increase their risk of falling. Anticipatory postural adjustments (APAs) are changes in the activity of postural muscles prior to a voluntary movement in order to maintain vertical equilibrium. Previous research suggests that improving APAs leads to better postural control and reduces the risk of falls. Despite the importance of APAs and their impairment among people post-stroke, studies that aim to investigate methods for improving APAs are limited. Consistent evidence supports that an external focus of attention compared to an internal focus of attention, yields superior performance of motor skills that include postural control.Research questionWhat are the effects of adopting different foci of attention on measures of APAs and movement parameters when performing a lower extremity Fitts’ task among people post-stroke?MethodsTwelve individuals post-stroke performed a lower extremity stepping movement (Fitts’ task) while adopting an external focus or an internal focus of attention in a within-subject design. A motion capture system was used to record participants’ movement data. Custom software derived movement time (MT), peak velocity (PV), time to peak velocity (ttPV) and variability at endpoint (SD_T). Electromyography was used to measure muscle activity and determine APAs onset and magnitude. For all dependent variables separate repeated measures ANOVAs were conducted to compare performance between foci of attention.ResultsThe results showed that an external focus of attention yielded significantly better performance on all outcome measures. The improvement in performance was seen in shorter MT, higher PV, shorter ttPV, smaller SD_T, earlier APAs onset and more efficient APAs magnitude.SignificanceThe changes in outcome measures suggest that adopting an external focus of attention during postural tasks could be an effective strategy for improving balance control among people post-stroke.     

Dyslexic children suffer from less informative visual cues to control posture

The goal of this study was to investigate the effects of manipulation of the characteristics of visual stimulus on postural control in dyslexic children. A total of 18 dyslexic and 18 non-dyslexic children stood upright inside a moving room, as still as possible, and looked at a target at different conditions of distance between the participant and a moving room frontal wall (25–150 cm) and vision (full and central). The first trial was performed without vision (baseline). Then four trials were performed in which the room remained stationary and eight trials with the room moving, lasting 60 s each. Mean sway amplitude, coherence, relative phase, and angular deviation were calculated. The results revealed that dyslexic children swayed with larger magnitude in both stationary and moving conditions. When the room remained stationary, all children showed larger body sway magnitude at 150 cm distance. Dyslexic children showed larger body sway magnitude in central compared to full vision condition. In the moving condition, body sway magnitude was similar between dyslexic and non-dyslexic children but the coupling between visual information and body sway was weaker in dyslexic children. Moreover, in the absence of peripheral visual cues, induced body sway in dyslexic children was temporally delayed regarding visual stimulus. Taken together, these results indicate that poor postural control performance in dyslexic children is related to how sensory information is acquired from the environment and used to produce postural responses. In conditions in which sensory cues are less informative, dyslexic children take longer to process sensory stimuli in order to obtain precise information, which leads to performance deterioration.     

Attention modulates step initiation postural adjustments in Parkinson freezers

BackgroundIn view of freezing of gait's circumstances of occurrence in Parkinson's disease, attentional resources appear to be involved in step initiation failure. Anticipatory postural adjustments (APAs) are essential because they allow unloading of the stepping leg and so create the conditions required for progression.Our main objective was to establish whether or not a change in attentional load during step initiation modulates APAs differently in patients with vs. without freezing of gait.MethodsThree groups of 15 subjects were recruited: elderly people and parkinsonian patients with or without freezing of gait. Attention was modulated before step execution by means of an auditory oddball discrimination task with event-related potential recording. The primary endpoint was the occurrence of inappropriate APAs following the attentional task, i.e. APAs not followed by a step after an intercurrent auditory stimulus.ResultsIn parkinsonian patients with freezing of gait, inappropriate APAs were recorded in 63% of the trials and were observed more frequently than in patients without freezing of gait (51%) and elderly controls (48%). Furthermore, inappropriate APAs in freezers were longer and more ample than in parkinsonian non-freezers and controls. Lastly, postural preparation was impaired in the parkinsonian patients.ConclusionOur results indicate that allocation of attentional resources during step preparation influences the release of APAs differently in freezers and non-freezers. Modulating attentional load is partly responsible for triggering an inappropriate motor program. This difficulty in focusing attention or resisting interference may contribute (at least in part) to the gait initiation failure observed in parkinsonian freezers.     

Rapid processing of haptic cues for postural control in blind subjects

ObjectivesVision and touch rapidly lead to postural stabilization in sighted subjects. Is touch-induced stabilization more rapid in blind than in sighted subjects, owing to cross-modal reorganization of function in the blind?MethodsWe estimated the time-period elapsing from onset of availability of haptic support to onset of lateral stabilization in a group of early- and late-onset blinds. Eleven blind (age 39.4 years ± 11.7 SD) and eleven sighted subjects (age 30.0 years ± 10.0 SD), standing eyes closed with feet in tandem position, touched a pad with their index finger and withdrew the finger from the pad in sequence. EMG of postural muscles and displacement of centre of foot pressure were recorded. The task was repeated fifty times, to allow statistical evaluation of the latency of EMG and sway changes following the haptic shift.ResultsSteady-state sway (with or without contact with pad, no haptic shift) did not differ between blind and sighted. On adding the haptic stimulus, EMG and sway diminished in both groups, but at an earlier latency (by about 0.5 s) in the blinds (p <0.01). Latencies were still shorter in the early-than late-blinds. When the haptic stimulus was withdrawn, both groups increased EMG and sway at equally short delays.ConclusionsBlinds are rapid in implementing adaptive postural modifications when granted an external haptic reference. Fast processing of the stabilizing haptic spatial-orientation cues may be favoured by cortical plasticity in blinds.SignificanceThese findings add new information to the field of sensory-guided dynamic control of equilibrium in man.     

Updating freeze: Aligning animal and human research

Freezing is widely used as the main outcome measure for fear in animal studies. Freezing is also getting attention more frequently in human stress research, as it is considered to play an important role in the development of psychopathology. Human models on defense behavior are largely based on animal models. Unfortunately, direct translations between animal and human studies are hampered by differences in definitions and methods. The present review therefore aims to clarify the conceptualization of freezing. Neurophysiological and neuroanatomical correlates are discussed and a translational model is proposed. We review the upcoming research on freezing in humans that aims to match animal studies by using physiological indicators of freezing (bradycardia and objective reduction in movement). Finally, we set the agenda for future research in order to optimize mutual animal–human translations and stimulate consistency and systematization in future empirical research on the freezing phenomenon.     

Structural brain plasticity in Parkinson's disease induced by balance training

We investigated morphometric brain changes in patients with Parkinson's disease (PD) that are associated with balance training. A total of 20 patients and 16 healthy matched controls learned a balance task over a period of 6 weeks. Balance testing and structural magnetic resonance imaging were performed before and after 2, 4, and 6 training weeks. Balance performance was re-evaluated after ∼20 months. Balance training resulted in performance improvements in both groups. Voxel-based morphometry revealed learning-dependent gray matter changes in the left hippocampus in healthy controls. In PD patients, performance improvements were correlated with gray matter changes in the right anterior precuneus, left inferior parietal cortex, left ventral premotor cortex, bilateral anterior cingulate cortex, and left middle temporal gyrus. Furthermore, a TIME × GROUP interaction analysis revealed time-dependent gray matter changes in the right cerebellum. Our results highlight training-induced balance improvements in PD patients that may be associated with specific patterns of structural brain plasticity. In summary, we provide novel evidence for the capacity of the human brain to undergo learning-related structural plasticity even in a pathophysiological disease state such as in PD.     

Suitability of commercial barometric pressure sensors to distinguish sitting and standing activities for wearable monitoring

Despite its medical relevance, accurate recognition of sedentary (sitting and lying) and dynamic activities (e.g. standing and walking) remains challenging using a single wearable device. Currently, trunk-worn wearable systems can differentiate sitting from standing with moderate success, as activity classifiers often rely on inertial signals at the transition period (e.g. from sitting to standing) which contains limited information. Discriminating sitting from standing thus requires additional sources of information such as elevation change.The aim of this study is to demonstrate the suitability of barometric pressure, providing an absolute estimate of elevation, for evaluating sitting and standing periods during daily activities. Three sensors were evaluated in both calm laboratory conditions and a pilot study involving seven healthy subjects performing 322 sitting and standing transitions, both indoor and outdoor, in real-world conditions.The MS5611-BA01 barometric pressure sensor (Measurement Specialties, USA) demonstrated superior performance to counterparts. It discriminates actual sitting and standing transitions from stationary postures with 99.5% accuracy and is also capable to completely dissociate Sit-to-Stand from Stand-to-Sit transitions.     

Efectividad de los ejercicios de equilibrio entre los adultos mayores en Depok,Indonesia

ObjectiveFalls are a serious problem for older adults. Balance impairment is one of the most significant reasons why adults fall from a standing position. This study aims to investigate the effect of an eight-week postural balance exercise intended to reduce the risk of falls among older adults in a community in Depok City, Indonesia.MethodThis quasi-experimental study employed a pre- and post-test design using a control group. The study involved an intervention group of 30 respondents and a control group of a further 30 respondents. The sample was selected using multistage random sampling. The data were analyzed using a t-test.ResultsThe balance exercise significantly affected the respondents’ postural balance and reduced their risk of falling. There were significant differences between the two groups (intervention group and control group) in postural balance (p < 0.001) and the risk of suffering a fall (p = 0.023).ConclusiónBalance exercises can be utilized as one of the preventive efforts to maintain postural balance and reduce the risk of falls among older adults. Future studies may consider the variation of age to more accurately determine the effectiveness of this balance exercise.