Research Ann Hallemans

Abstract

Falls among older adults represent a pressing public health concern, and often result from the interaction of intrinsic capacities, e.g. decreased visual abilities, with complex environments, e.g. busy streets. These environments demand individuals to effectively track moving objects using their gaze for safe navigation. In this project, I propose that a better understanding of gaze control, its contributing factors, and its role in fall risk, is crucial for the development of more accurate fall prediction models. Current research on fall prediction occurs in controlled laboratory settings and employs simple tasks without ecological validity that neglect the role of gaze control in real-life navigation. Despite the link between gaze control and known fall risk factors (e.g. sensory and cognitive deficits and decreased postural control), the integration of these functions for ensuring gaze control remains unknown. In this project I position gaze control as a proxy to understanding sensory, cognitive, and motor functioning in relation to falls in older adults. Additionally, I hypothesize that by integrating gaze control in current fall prediction models, we can more accurately predict the likelihood of falls. My study represents an inventive yet challenging paradigm that significantly advances prior methodologies, overcoming technological limitations by leveraging Augmented Reality tools to simulate realistic but standardized tasks while concurrently tracking gaze control.

Researcher(s)

• Promoter: Hallemans Ann
• Co-promoter: De Hertogh Willem
• Fellow: Embrechts Elissa

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

Worldwide, cerebral palsy (CP) is the major cause of motor disorders in children. Deficits in balance during standing and walking are crucial problems in the daily life of children with CP. Although balance deficits are increasingly recognised the past decades, the fundamental understanding of the underlying causes of poor balance remain understood, resulting in mixed results in the effects of different balance training paradigms. Centrally, a lesion in the developing brain induces negative effects down the systems underlying balance control. Although the sensory system, especially lower limb proprioception, is known to be a key factor of adequate balance control, it is relatively ignored in CP. Peripherally, prolonged physical activity can increase balance difficulties by the accumulation of muscle fatigue. Given the likelihood of muscle fatigue symptoms in CP, balance difficulties can occur as a consequence of physical exertion. Therefore, the main aim of this project is to understand both these understudied, but likely highly relevant, central and peripheral factors underlying poor balance control in children with CP by studying balance performance in relation with central nervous system dysfunctions (proprioception, brain lesion characteristics) and physical activity (muscle fatigue). The novelty of this study lies in the synergistic approach of combining neuromechanics, brain imaging and functional assessments.

Researcher(s)

• Promoter: Hallemans Ann
• Fellow: Jacobs Nina

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

During the next five years I will be focussing on the following research goals: • To study human walking, considering this mode of locomotion as an outcome measurement of the underlying motor control processes governed by the principles of neuromechanics. • To study the effects of development (in children) and ageing (in elderly) on postural balance control and gait stability to better understand the changes occurring during the lifespan • To study the effects of peripheral sensory loss (e.g. proprioception, vestibular function) on postural balance control to better understand the mechanisms of sensorimotor control and identify potential central compensation mechanisms

Researcher(s)

• Promoter: Hallemans Ann
• Fellow: Hallemans Ann

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

Worldwide, Developmental Coordination Disorder (DCD) accounts for 5-6% of the school-aged children showing a motor delay early in childhood. Poor balance control is the most significant motor problem occurring in 73-87% of the children with DCD. These balance deficits severely affect everyday functioning, but underlying control mechanisms are still poorly understood. Therefore, the main aim of this project is understanding the heterogeneity of DCD by studying balance performance, its control mechanisms and its impact on motor performance. Based on functional performance and neuroimaging data it is hypothesized that balance performance and control of children with DCD can be situated on a continuum between cerebral palsy (CP) and typically developing children (TDC). As such a case-control study will be performed comparing balance performance, motor performance, cortical brain activity and muscular activation patterns in children with DCD to children with CP and TDC. The novelty of this study lies in the synergistic approach of combining functional assessments with brain imaging and neuromechanical analysis. This approach is a major step forward in unraveling the interplay between the control system (brain and the rest of the nervous system) and the effector system (musculoskeletal system). It can provide groundbreaking insights into the heterogeneity of DCD as well as a better understanding of the relationship between balance and motor performance.

Researcher(s)

• Promoter: Hallemans Ann
• Co-promoter: Verbecque Evi
• Fellow: Johnson Charlotte

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

Worldwide, cerebral palsy (CP) is the major cause of motor disorders in children. Deficits in balance during standing and walking are crucial problems in the daily life of children with CP. Although balance deficits are increasingly recognised the past decades, the fundamental understanding of the underlying causes of poor balance remain understood, resulting in mixed results in the effects of different balance training paradigms. Centrally, a lesion in the developing brain induces negative effects down the systems underlying balance control. Although the sensory system, especially lower limb proprioception, is known to be a key factor of adequate balance control, it is relatively ignored in CP. Peripherally, prolonged physical activity can increase balance difficulties by the accumulation of muscle fatigue. Given the likelihood of muscle fatigue symptoms in CP, balance difficulties can occur as a consequence of physical exertion. Therefore, the main aim of this project is to understand both these understudied, but likely highly relevant, central and peripheral factors underlying poor balance control in children with CP by studying balance performance in relation with central nervous system dysfunctions (proprioception, brain lesion characteristics) and physical activity (muscle fatigue). The novelty of this study lies in the synergistic approach of combining neuromechanics, brain imaging and functional assessments.

Researcher(s)

• Promoter: Hallemans Ann
• Fellow: Jacobs Nina

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

Worldwide, developmental coordination disorder (DCD) accounts for 5-6% of the school-aged children showing a motor delay with an onset early in childhood that often persists in adolescence. Poor balance control is the most significant motor problem occurring in 73-87% of the cases of children with DCD. These balance deficits severely affect everyday functioning but underlying control mechanisms are still poorly understood. Therefore, the main aim of this project is understanding the heterogeneity of DCD by studying balance control, its impact on motor performance and its control mechanisms. Based on functional performance and neuroimaging data it is hypothesized that both performance and motor control of children with DCD can be situated on the continuum of balance performance between children with cerebral palsy (CP) and their typically developing (TD) peers. As such a cross-sectional case-control study will be performed comparing balance performance, motor performance, cortical brain activity and muscular activation patterns in children with DCD to children with CP and their TD peers. This synergistic approach of combining functional assessments with brain imaging and neuromechanical analysis will provide a major step forward in unravelling the interplay between the control system (brain and the rest of the nervous system) and the effector system (musculoskeletal system) when specific balance tasks are performed. The expected outcomes of this project are new balance profiles in children with DCD as well as a better understanding of the relation between balance and motor performance. These profiles can add insights in the heterogeneity of DCD and the debate whether DCD represents pathological development or a delayed development, which would be a scientific breakthrough. Furthermore, the novelty of this study lies in the synergistic approach of combining functional assessments with brain imaging and neuromechanical analysis. This approach can provide groundbreaking insights into control mechanisms of balance and, when succesful, might serve as a gold standard for future research. Ultimately, the insights obtained in this project could enhance adequate physiotherapeutic treatment planning, improve motor potential and result in better execution of everyday activities for children with DCD.

Researcher(s)

• Promoter: Hallemans Ann
• Fellow: Johnson Charlotte

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

Adequate balance control is a prerequisite to achieve postures in early life and more complex gross and fine motor skills later in childhood. Balance deficits are a common problem in children with various pathologies such as cerebral palsy, developmental coordination disorder or sensorineural hearing loss. Because of the potential impact of these balance deficits on motor development, they need to be detected early in childhood. However, balance control is complex and comprises different mechanisms such as predictive, proactive and reactive control. At present none of the available paediatric balance tests comprehend to total concept of balance control. Most tests have been focussing on balance control in static and predictable environments, ignoring the contribution of reactive balance mechanisms. This is an underrepresentation of the daily life situation involving object interactions and changing physical environments. Therefore, the aim of this project is to develop an integrated approach of assessing balance in 5 to 7 year old children covering the entire concept of balance control. A synergistic approach, combining functional assessment methods of balance performance with more in-depth neuromechanical analysis will be used. Neuromechanics focusses on the interplay between the neural processes (e.g. reaction times) and the mechanical aspects of balance control (e.g. amount of sway) unravelling balance control strategies that might otherwise remain hidden. In this way, fundamental insights will be gained into the construct of balance control and the contribution of the different mechanisms in 5 to 7 year old children. These insights will result in a validated test that allows the clinician to identify overall balance deficits as well as the specific domains of balance control that are disturbed. Identification of these domains allows for specific physiotherapeutic intervention planning. Furthermore, the better understanding of balance control mechanisms in young children will open new horizons for research regarding the contribution of balance control deficits to developmental (motor) problems in children.

Researcher(s)

• Promoter: Hallemans Ann

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

Dravet syndrome is a severe infantile onset epilepsy syndrome with a prevalence of 1/15.000 to 1/30.000. An infant with an apparently normal development presents around 6 months of age with a convulsive status epilepticus. Seizures can be triggered by fever, illness or vaccination. Because of its drug-resistance, in the past, most attention has been paid to seizure control. However, developmental and behavioural problems also become a serious concern during the second year of life. Outcome is poor, with intellectual disability and ongoing seizures. On the long term, the deterioration in gait is very characteristic. A crouch gait pattern develops that largely impacts the daily life functioning. Most children maintain the ability to walk around the house, but for longer distances they must rely on wheel-chair use, which further negatively affects their mobility. Gait analysis, when combined with physical examination, provides quantitative information to guide treatment of gait disorders and assess its outcome. The goal of this project is the development of a clinical decision framework based upon 3D gait analysis to diagnose and treat mobility problems in children with Dravet syndrome. Two major university hospitals in Flanders (UZA and UZ Leuven) are partners in this project. The parent organisation "Stichting Dravetsyndroom Nederland/Vlaanderen" will also participate, as intermediate partner to facilitate contacts between all parties being patients and their caregivers, clinical gait labs and treating physicians.

Researcher(s)

• Promoter: Hallemans Ann

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

The objective of this PhD study is to investigate dynamic balance control in a population consisting of healthy adults, patients with vestibular dysfunction and stroke patients, thereby exploring different strategies to adapt gait to reduced dynamic balance control. To do so, biomechanical measures of gait stability, will be considered as primary outcome measures. Secondary outcome measures are postural instability, falls and fear of falling, documented using the "Dizziness Handicap Inventory" (DHI) and the "Activities specific Balance Confidence scale" (ABC). Fall risk is determined using standardized clinical tests. The goal of this study is to gain further insight into the relation between variability in foot placement, measures of biomechanical stability and postural instability, risk of falling and documented falls. Different populations will be considered, consisting of community dwelling adults, patients with vestibular deficit and stroke patients. Patients with vestibular deficit are an interesting population to study gait adaptability because, despite loss of vestibular function, in unilateral vestibular deficit no increased risk of falling is observed. In stroke patients, on the other hand, up to 50 percent annually reports a fall. Differences in gait adaptability strategies in these three populations will be investigated using a case-control design. To investigate predictive ability of gait stability measures a prospective cohort study will be performed. Insight into gait adaptability strategies creates opportunities to develop guidelines for gait training and rehabilitation.

Researcher(s)

• Promoter: Hallemans Ann
• Co-promoter: Saeys Wim
• Fellow: Herssens Nolan

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

"Life is animation. To live is to move. For humans, movement is essential for our survival" Efficient movement is complex and requires an ultimate integration of balance control and movement coordination. An interesting approach to gain insight into these processes of motor control is the neuromechanical concept. This concepts stresses the interaction between the neural processes and the biomechanical laws of motion that together shape the movement patterns. The movement outcome hereby depends on the interaction between the individual and its properties, the task demands and the environmental constraints. Applications of neuromechanics include ameliorating human health problems by exploring how processes such as e.g. development, ageing, loss of sensory information or neurological pathologies affect the movement outcome. One of the most important movements in daily life is gait. During the life span, both developmental processes, such as growth and neuro-maturation, as well as ageing affect the gait pattern. The general consensus is that a lot of adaptations in gait, both in children and elderly, are related to balance control. Characterizing balance during locomotion is recently a hot topic. A range of different measures to quantify stability during locomotion are developed but the validity and reliability of each of these measures is not yet fully understood. The goal is to investigate different parameters for assessing gait stability in children, adults and elderly thereby describing changes in dynamic balance control across the entire lifespan. From the neuromechanical concept it is evident that sensory information is essential in goal directed movement and loss of sensory information might have tremendous effects on the control of locomotion. Knowledge on the processes of development and ageing on balance, together with the results from explorative research regarding good collective output variables describing stability during locomotion, will be transferred to research performed in patients with uni- or bilateral vestibular deficits (both children and adults). Good parameters should be able to detect balance deficits or deterioration of balance and provide insights into possible compensation strategies. Furthermore, therapeutic interventions such as balance training programs can be developed and evaluated based on this knowledge. Also typical problems in neurological populations, such as muscle weakness and problems with selective muscle control, give rise to a deteriorating gait that in its most progressive form is described as a crouch gait. In cerebral palsy a large body of knowledge and expertise has been built over the years on how to treat these gait problems and improve the patient's mobility. The possibilities of knowledge transfer from the treatment of CP patients to other neurological populations with gait deficits, e.g. children with Dravet syndrome, needs to be further explored.

Researcher(s)

• Promoter: Hallemans Ann
• Fellow: Hallemans Ann

Research team(s)

• Movement Antwerp (MOVANT)

Project website

Project type(s)

• Research Project

Abstract

This project represents a research agreement between the UA and on the onther hand IWT. UA provides IWT research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Hallemans Ann

Research team(s)

• Movement Antwerp (MOVANT)

Project type(s)

• Research Project

Abstract

During this project, motor training will be combined with non-invasive brain stimulation in stroke patients. By means of a double-blind, sham-controlled study the effect of additional static balance training which makes use of visual feedback in combination with transcranial Direct Current Stimulation on postural control in stroke patients is examined. This project will contribute to the implementation of a new treatment modality in clinical practice.

Researcher(s)

• Promoter: Van de Heyning Paul
• Co-principal investigator: Hallemans Ann
• Co-principal investigator: Vereeck Luc

Research team(s)

• Translational Neurosciences (TNW)

Project type(s)

• Research Project

Abstract

Not all children learn to crawl on hands and knees. Some of them show other patterns of locomotion, like bottom shuffling, creeping or rolling. It is assumed that these children show a weaker coordination between legs and arms and shoulder- and pelvisgirdle. The aim of this study is (1) examine whether there is a correlation between developmental factors and different crawling patterns and (2) to develop a method to measure the crawling coordination in an objective way.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Hallemans Ann

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

In human, goal directed locomotion is largely dependent on vision. In case of conflicting sensory information, the visual feedback wil dominate the outcome of movement (Desphande & Patla, 2006). Vision is also predominant in maintaining balance (Juodzbaliene et al., 2006). The visually disabled form a population in which visual feedback information is absent for a long period of time. This allows to investigate the effect of visual deprivation on motor control. The goal of this study is to investigate the efficiency of gait in the visually disabled in order to gain more insight into the control of locomotion. Attention is paid to gait for several reasons. First, humans are unique in showing bipedal gait as their habitual way of locomotion. Effecient locomotion is essentiel for survival. Also in our modern society locomotor problems hinder activities of daily life. Secondly, the normal gait pattern is already well characterised, both in adults and in children. This study considers three different populations: congenitally blind adults, congenitally blind children between 3 and 10 years old and children between 3 and 10 showing a severe visual impairment. In all groups, postural control and gait will be characterized.

Researcher(s)

• Promoter: Hallemans Ann

Research team(s)

• Functional Morphology

Project website

Project type(s)

• Research Project

Abstract

In a situation of dynamic equilibrium (e.g. gait) afferent information is essential for a smooth and efficient movement. Research has repeatedly shown that visual information plays an important role in static balance control, but on the importance of vision in dynamical situations little information is available. The goal of this study is to characterize the interaction between visual information and dynamic postural control by describing step-time parameters and muscle activation patterns during walking.

Researcher(s)

• Promoter: Hallemans Ann

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Afferent information is crucial in the control of voluntary movements. This information comes from the visual, vestibular and somatosensory systems. Visual information is crucial for maintaining balance in a static situation. However, during the execution of a movement, a situation of dynamic equilibrium needs to be maintained. It is logical to assume that vision also is important in these situations. Furthermore, vision may also play a role in the coordination of movements. This research project studies the effects of visual deprivation on the control and development of walking using biomechanical gait analysis.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Hallemans Ann

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Within a few months, infants adopt the co-ordination required for a stable habitual walk. Two ways of analysis are open to study this development. In the phenomenological approach (dynamical systems approach), the complex system is reduced to a few variables considered to be the collective result of the dynamical behaviour of all of the systems components. Analysis of variance of the cyclic behaviour of these variables offers insight in the developmental processes (Thelen & Smith, 1994; Clark, 1997). In case of the mechanistic approach, insight is gained in the causes underlying the cyclic behaviour through detailled analysis of the structure and biomechanics of the locomotor 'de nieuwe loper', we verwachten eerder een aantal algemene trends te kunnen system. vaststellen. The phenomenological and mechanistic approaches are to be considered as highly complementary in understanding the fenomenon of motor development. Most of the longitudinal studies investigating the early development of independent walking, preferably used the phenomenological approach, hereby not taking into account a few exceptions (Sutherland et al.,1980; Grimshaw et al.,1998). Our project tends to gain insight in the biomechanical causes underlying the observerd changes in children learning to walk. As mentioned in literature, independent walking requires the combination of balance and the generation of a propulsive movement. We tend to investigate how this challenge is realised by the morphology of a toddler, wich differs from the adult morphology, by means of detailed 3D- kinematical analysis, together with measurement of the 3D-ground reaction forces, the pressure distribution pattern under the feet (registrated with high spatial and temporal resolution) and perhaps electromyographical registration. Attention is paid to the dynamics of the the center of mass and the body segments. Kinetics and energetics will teach us how much energy it costs to walk. Joint-moment are used to calculate wich joints produce energy and where the energy disappears. We will also study the forces and pressures under the feet and the pathway of the center of pressure. In combination with the ground reaction forces, this information allows us to determine the stability in the joints. Attention must also be paid to the occasional trials when the child fails to stay upright. Wich parameter differs and make the infant lose his balance? Amongst children the variability in gait patterns is large, therefore it is not our goal to define an average gait pattern of 'the new walker'. Rather we want to determine some general trends in the development of independent walking.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Hallemans Ann

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Within a few months, infants adopt the co-ordination required for a stable habitual walk. Two ways of analysis are open to study this development. In the phenomenological approach (dynamical systems approach), the complex system is reduced to a few variables considered to be the collective result of the dynamical behaviour of all of the systems components. Analysis of variance of the cyclic behaviour of these variables offers insight in the developmental processes (Thelen & Smith, 1994; Clark, 1997). In case of the mechanistic approach, insight is gained in the causes underlying the cyclic behaviour through detailled analysis of the structure and biomechanics of the locomotor system. The phenomenological and mechanistic approaches are to be considered as highly complementary in understanding the fenomenon of motor development. Most of the longitudinal studies investigating the early development of independent walking, preferably used the phenomenological approach, hereby not taking into account a few exceptions (Sutherland et al.,1980; Grimshaw et al.,1998). Our project tends to gain insight in the biomechanical causes underlying the observerd changes in children learning to walk. As mentioned in literature, independent walking requires the combination of balance and the generation of a propulsive movement. We tend to investigate how this challenge is realised by the morphology of a toddler, wich differs from the adult morphology, by means of detailed 3D- kinematical analysis, together with measurement of the 3D-ground reaction forces, the pressure distribution pattern under the feet (registrated with high spatial and temporal resolution) and perhaps electromyographical registration. Attention is paid to the dynamics of the the center of mass and the body segments. Kinetics and energetics will teach us how much energy it costs to walk. Joint-moment are used to calculate wich joints produce energy and where the energy disappears. We will also study the forces and pressures under the feet and the pathway of the center of pressure. In combination with the ground reaction forces, this information allows us to determine the stability in the joints. Attention must also be paid to the occasional trials when the child fails to stay upright. Wich parameter differs and make the infant lose his balance? Amongst children the variability in gait patterns is large, therefore it is not our goal to define an average gait pattern of 'the new walker'. Rather we want to determine some general trends in the development of independent walking.

Researcher(s)

• Promoter: Aerts Peter
• Fellow: Hallemans Ann

Research team(s)

Project type(s)

• Research Project