Research topics

Research is performed in humans, from children to elderly, in physiological, pathological and specific conditions. Topics  of interest are:

Balance and Postural Control

All motor skills require an ultimate integration of postural control and movement coordination. Sensory information is essential to adequately respond in order to prevent damage to the musculoskeletal system or loss of balance. Individuals who experience a loss of sensory information (eg by visual or hearing disabilities) face a major limitation that can largely affect motor performance. It is assumed that balance problems lie at the basis of poor motor performance in these populations.
 

The ability of postural control is evaluated based on clinical tests of balance and postural sway measurements. In the literature, however, weak relationships were found between static balance measurements and performance during e.g. locomotion. From a clinical perspective, the question arises whether it is not relevant to quantify postural control in a dynamic situation, such as during locomotion.
 

A variety of different measurements characterizing balance or postural control during a dynamic task such as walking can be found. The validity and reliability of these balance measurements is currently uncertain. Before one of these measurements can be routinely used to evaluate postural control in patients with sensory deficits, it is important to determine the validity and reliability in a population with no neurological or musculoskeletal disorders.
 

Development of gait and locomotion

Our different research projects aim at understanding how a mature gait pattern takes shape.

In children with normal development independent walking is achieved between the ages of twelve to fourteen months. At this time a toddler is confronted with a constantly growing and changing neuro-musculo-skeletal system. On top of that he has no previous experiences of walking to rely on. Naturally he will not be as skilled as adults in combining the double task of generating propulsion and maintaining balance. Therefore the toddler’s gait pattern will be quite different from mature gait that is observed in adults. Childhood is a period of growth and development during which immature gait will gradually evolve towards a mature and stable pattern.

We aim to answer research questions such as:

  • What are the biomechanical determinants of the normal development of bipedal gait in humans?
  • How can variation in a child's body build explain the variation we observe in gait patterns between children?
  • How do locomotor strategies occuring prior to the development of walking affect the quality of the gait pattern?

Neuromechanics

In 2007 Nishikawa and collaborators put forward the neuromechanical concept of movement control. This concepts refers to the interaction between the neural and mechanical control of movement. Neural control refers to the processes in higher brain centers, descending neural pathways, and central pattern generators (CPG) located in the spinal cord. This cascade is responsible for the production of tuned muscle actions generating movement. The movement outcome is dependent on the interaction between the voluntary generated muscle forces and all other external and internal forces such as gravity, inertia, friction, tension, etc. This equilibrium between external and internal forces is the mechanical control of movement. The resulting movement is shaped by the properties of the task, the environment and the anatomical and neurophysiological properties of the individual. Coordinated movement patterns can only emerge if the generated muscle actions are an adequate response to the task required given the environmental and individual constraints ( Nishikawa et al., 2007 ).
 

Sensori-motor Control of Voluntary Movements

Cervical sensorimotor control (cSMC) is the system providing functional stability of the cervical spine. This system comprises the afferent information from the cervical structures, visual and vestibular system, together with the efferent information from the central nervous system and the central integration and processing.

CSMC can be measured using several parameters. The position sense is the best known parameter, but as sensorimotor control also includes the feedback and feed forward mechanisms during the entire movement trajectory, the content validity of this test can be questioned. To quantify altered sensorimotor functions during movements, several kinematic parameters are used. In relation to cervical spine disorders, reduced range of motion (ROM), altered activation patterns of cervical muscles, reduced maximal velocity and movement smoothness are registered during cervical voluntary movements.

Several types of 3D measuring devices can be used to capture kinematic parameters during movement. In M²OCEAN, a passive optical motion capture system, VICON®, is used. This system is immune to interference from equipment or metal objects and the free line of sight needed, is guaranteed, because 8 cameras are used.