Sensory reweighting for balance in people living with Parkinson's Disease: Postural adaptation, muscle co-contraction, and perceptual delays.

Background: Postural instability is common in people with Parkinson's Disease (PwPD), increasing their risk of injurious falls. Evidence suggests a sensory reweighting deficit in PwPD, along with compensatory muscle co-contraction in response to postural challenges. During balance tasks requiring sensory reweighting, older adults exhibit elevated postural sway and muscle co-contraction, as well as longer perceptual delays, compared to young adults.

Association of 30-s Sit-to-Stand Power Test Outcome With Body Balance in Physically Active Older Adults.

Amount of serial sitting and standing movements has been employed in clinical and research settings to assess legs' muscular strength. In this cross-sectional study, we aimed to test the correlation between the 30-s sit-to-stand power test (30STSp) outcome and body balance in older adults. We evaluated physically active male and female (n = 51) individuals with an age range of 60-80 years (M = 69.

Cortical activity in body balance tasks as a function of motor and cognitive demands: A systematic review.

Technological tools, like electroencephalography and functional near-infrared spectroscopy, have deepened our understanding of cortical regions involved in balance control. In this systematic literature review, we aimed to identify the prevalent cortical areas activated during balance tasks with specific motor or cognitive demands. Our search strategy encompassed terms related to balance control and cortical activity, yielding 2250 results across five databases.

Increasing Movement Amplitude in Speeded Hitting Enhances Contact Velocity Without Affecting Directional Accuracy or Movement Variability.

Performance of sport-related ballistic motor skills, like ball hitting in golf and baseball, requires wide movements to produce highly fast and spatially accurate movements. In this study, we assessed the effect of movement amplitude on directional accuracy in a ballistic hitting task. Participants performed the task of moving a manual handle over a flat surface to hit with high speed a moveable disc, aiming to propel it towards a frontal target.

Perceptual training with implicit and explicit learning improves the prediction of ball direction in soccer penalty kicks.

Perceptual training enhances the ability to anticipate crucial information for decision-making, for example, a soccer goalkeeper predicting penalty kick direction. However, it remains unclear whether perceptual practice alone (implicit method) is sufficient for optimal decision-making improvement, or whether emphasising pertinent details during practice (explicit method) could yield better results. This study compared implicit and explicit methods of learning ball direction prediction during soccer penalties, involving both goalkeepers and non-soccer players (novices).

Reciprocal Inhibition and Coactivation of Ankle Muscles in Low- and High-Velocity Forward and Backward Perturbations.

Reciprocal inhibition and coactivation are strategies of the central nervous system used to perform various daily tasks. In automatic postural responses (APR), coactivation is widely investigated in the ankle joint muscles, however reciprocal inhibition, although clear in manipulative motor actions, has not been investigated in the context of APRs. The aim was to identify whether reciprocal inhibition can be observed as a strategy in the recruitment of gastrocnemius Medialis (GM), Soleus (So) and Tibialis Anterior (TA) muscles in low- and high-velocity forward and backward perturbations.

Validation of the Equidyn protocol for evaluation of dynamic balance in older adults through a smartphone application.

Background: Different tasks and proxy measurements have been employed to evaluate dynamic balance in older individuals. However, due to inherent limitations, results from most evaluations could hardly be taken as valid measurements of dynamic balance.

Research Question: Is the Equidyn smartphone application-based protocol valid and sensitive for assessment of dynamic balance in older adults?

Methods: Dynamic balance was evaluated in 52 physically active individuals, age range 60-80 years (M = 69.

Mesencephalic Locomotor Region and Presynaptic Inhibition during Anticipatory Postural Adjustments in People with Parkinson's Disease.

Individuals with Parkinson's disease (PD) and freezing of gait (FOG) have a loss of presynaptic inhibition (PSI) during anticipatory postural adjustments (APAs) for step initiation. The mesencephalic locomotor region (MLR) has connections to the reticulospinal tract that mediates inhibitory interneurons responsible for modulating PSI and APAs. Here, we hypothesized that MLR activity during step initiation would explain the loss of PSI during APAs for step initiation in FOG (freezers).

Inventories of Human Lateral Preference: A Systematic Review.

There are a variety of inventories available to evaluate human lateral preference, but no previous review has systematically analyzed and compared them. We conducted a systematic literature review to identify these inventories and describe their characteristics (e.g.

Prediction of ball direction in soccer penalty through kinematic analysis of the kicker.

The penalty kick is a crucial opportunity to score and determine the outcome of a soccer match or championship. Anticipating the direction of the ball is key for goalkeepers to enhance their defensive capabilities, considering the ball's swift travel time. However, it remains unclear which kinematic cues from the kicker can predict the ball's direction.

Control of interjoint coordination in the performance of manual circular movements can explain lateral specialization.

Between-arm performance asymmetry can be seen in different arm movements requiring specific interjoint coordination to generate the desired hand trajectory. In the current investigation, we assessed between-arm asymmetry of shoulder-elbow coordination and its stability in the performance of circular movements. Participants were 16 healthy right-handed university students.

Perturbation-based balance training leads to improved reactive postural responses in individuals with Parkinson's disease and freezing of gait.

Perturbation-based balance training (PBT) exposes individuals to a series of sudden upright balance perturbations to improve their reactive postural responses. In this study, we aimed to evaluate the effect of a short PBT program on body balance recovery following a perturbation in individuals with freezing of gait due to Parkinson's disease. Volunteers (mean age = 64 years, SD = 10.

Cognitive and emotional factors influence specific domains of postural control in individuals with moderate-to-severe Parkinson's disease.

Introduction: Cognition and emotional state are domains that highly interfere with postural control in individuals with Parkinson's disease (PD). This study aims to find associations between executive function, anxiety, depression, and reactive and anticipatory postural control domains in individuals with moderate-to-severe Parkinson's disease.

Methods: In this study, 34 individuals with PD while on medication were thoroughly assessed for postural control in perturbed, quiet standing and stepping.

Freezing of gait, gait initiation, and gait automaticity share a similar neural substrate in Parkinson's disease.

Individuals with Parkinson's disease (PD) and freezing of gait (FOG) have difficulty initiating and maintaining a healthy gait pattern; however, the relationship among FOG severity, gait initiation, and gait automaticity, in addition to the neural substrate of this relationship has not been investigated. This study investigated the association among FOG severity during turning (FOG-ratio), gait initiation (anticipatory postural adjustment [APA]), and gait automaticity (dual-task cost [DTC]), and the neural substrates of these associations. Thirty-four individuals with FOG of PD were assessed in the ON-medication state.

Between-leg asymmetry in automatic postural responses to stance perturbations in people with Parkinson's disease.

Background: People with Parkinson's disease (PwPD) showed impairments of balance control which can be aggravated by the presence of higher interlateral postural asymmetry caused by a distinct dopaminergic loss in the substantia nigra between cerebral hemispheres.

Research Question: We evaluate asymmetries between the more and the less affected leg in PwPD in responses to unanticipated stance perturbations.

Methods: Sixteen 16 PwPD participated in the experiment that consisted of recovering a stable upright stance, keeping the feet in place, in response to a perturbation caused by a sudden release of a load equivalent to 7 % of the participant's body mass.

Use of accelerometry to investigate standing and dynamic body balance in people with cerebral palsy: A systematic review.

Background: People with cerebral palsy (CP) often have difficulties related to maintaining body balance in their daily living activities. Accelerometers are low-cost wearable devices with potential use to objectively assess balance.

Research Question: What are the main characteristics and findings from protocols used in research aiming to investigate standing or dynamic body balance stability through trunk accelerometry in people with CP?

Method: We searched in December 2021 seven databases, Pubmed, Embase, Cochrane, Science Direct, Scopus, PEDro, and Lilacs, with descriptors related to cerebral palsy, accelerometer, and balance.

Judokas Show Increased Resilience to Unpredictable Stance Perturbations.

Combat sports are characterized by frequent large-scale stance perturbations that may lead to falls. In the present investigation, we compared compensatory arm and leg movements in response to unpredictable stance perturbations between judokas and other athletes whose sports present reduced balance demand, relative to combat sports. Specifically, we tested judokas ( = 9), and a group of swimmers and runners ( = 11, controls) in sudden support base displacements in the mediolateral direction, generated by a movable electronic platform, in the following modes: (a) rotation, (b) translation, and (c) combined rotation-translation.

Single Leg Balance Training: A Systematic Review.

Single leg balance training promotes significant increments in balance control, but previous reviews on balance control have not analyzed this form of balance training. Accordingly, we aimed to review the single leg balance training literature to better understand the effects of applying this training to healthy individuals. We searched five databases-PubMed, EMBASE, Scopus, Lilacs, and Scielo-with the following inclusion criteria: (a) peer-reviewed articles published in English; (b) analysis of adult participants who had no musculoskeletal injuries or diseases that might impair balance control; and (c) use of methods containing at least a pre-test, exclusive single leg balance training, and a post-test assessment.

Differential activation of the plantar flexor muscles in balance control across different feet orientations on the ground.

The ankle plantar flexor muscles act synergistically to control quiet and dynamic body balance. Previous research has shown that the medial (MG) and lateral (LG) gastrocnemii, and soleus (SOL) are differentially activated as a function of motor task requirements. In the present investigation, we evaluated modulation of the plantar flexors' activation from feet orientation on the ground in an upright stance and the ensuing reactive response to a perturbation.

Vigor of reactive postural responses is set from feedback and feedforward processes.

I explore a distinct perspective from that brought in the book by arguing that in postural control our organism selects the vigor of reactive responses guided by an optimization rule considering first the required postural response for balance recovery as indicated by afferent information from a myriad of sensory receptors, and second the history of previous responses to similar perturbations.

Preserved flexibility of dynamic postural control in individuals with Parkinson's disease.

Background: Continuous oscillation of the support base requires anticipatory and reactive postural adjustments to maintain a stable balance. In this context, postural control flexibility or the ability to adjust balance mechanisms following the requirements of the environment is needed to counterbalance the predictable, continuous perturbation of body balance. Considering the inflexibility of postural responses in individuals with Parkinson's disease (PD), maintaining stability in the support base's continuous oscillations may be challenging.

Age-Related Changes in Presynaptic Inhibition During Gait Initiation.

Age-related changes in presynaptic inhibition (PSI) have not been observed during gait initiation, which requires anticipatory postural adjustment (APA). As APA is centrally modulated and is impaired in older compared to young adults, here we aimed to study the presynaptic control and co-contraction levels in the ankle muscles during gait initiation in older compared to young adults. Fifteen older (age range 65-80 years) and 15 young adults (age range 19-30 years) performed a gait initiation task on a force platform under 3 conditions: (i) without electrical stimulation; (ii) test Hoffman reflex (H-reflex); and (iii) conditioned H-reflex.

Brain networks associated with anticipatory postural adjustments in Parkinson's disease patients with freezing of gait.

Specific impairments of anticipatory postural adjustment (APA) during step initiation have been reported in patients with Parkinson's disease (PD) and freezing of gait (FoG). Although APA disruption has been associated with FoG, there is scarce knowledge about its neural correlates. We sought to better understand the neural networks involved with APA in patients with FoG by assessing the level of hemodynamic response of specific brain regions and the functional connectivity during the leg lifting task.

Compensatory control between the legs in automatic postural responses to stance perturbations under single-leg fatigue.

In response to sudden perturbations of stance stability, muscles of both legs are activated for balance recovery. In conditions that one of the legs has a reduced capacity to respond, the opposite leg is predicted to compensate by responding more powerfully to restore stable upright stance. In this investigation, we aimed to evaluate between-leg compensatory control in automatic postural responses to sudden perturbations in a situation in which plantar flexor muscles of a single leg were fatigued.