TI 2 - Exam 1

Discrete Tasks

Have a recognizable beginning and end, such as kicking a ball or moving from sitting to standing or lying down

Continuous Tasks

The end point of the task is not an inherent characteristic of the task but is decided arbitrarily by the performer, such as walking or running

Closed Tasks

Are performed in a relatively fixed or predictable environments

Open Tasks

Require performers to adapt movement strategies to a constantly changing and often unpredictable environment, such as tennis or soccer

Stability Tasks

Are performed with a nonmoving base of support, like sitting or standing

Mobility tasks

Require moving the base of support, such as walking or running

Manipulation Tasks

Involve movement of the upper extremities

Non-Manipulation Tasks

Do not involve movement of the upper extremities

Degrees of Freedom

Body as a mechanical system with many degrees of freedom. Systems theory stresses the importance of the whole body as a mechanical system with many degrees of freedom. Coordination of movement is the process of mastering the redundant degrees of freedom of the moving organism

Synergies

Synergies proposed as a solution to the degrees of freedom problem; concept of synergies modified to reflect the flexible, adaptive nature of synergies rather than fixed stereotypical patterns of activity

Self-organization

Principles of self-organization found in nature are applied to motor control. The degrees of freedom problem is solved through self-organization. Organization emerges from the interaction of elements and does not require central commands

Nonlinear behavior

Self-organizing systems often have nonlinear properties. A nonlinear behavior is one that transforms into a new configuration when a single parameter of that behavior is gradually altered and reached a critical value (e.g., walk, trot, and gallop emerging from a change in velocity)

Variability

Systems theory believes that variability in movement is not due to error, rather a necessary condition for optimal function. The concept of attractor wells is used to characterize the variability and flexibility of a movement pattern. The deeper the well, the less variable and flexible the movement. A shallow well suggests an unstable pattern. There is a significant increase in variability of a movement just prior to a change to a new movement pattern (a shift to a new attractor well). For example, walking patterns become more variable just prior to a shift from walk to trot.

Regulatory factors

Directly shape movement; the demand of the task (force necessary to move object a distance, weight of object, size of target); Further divided into Predictable (weight of object, size of object) and Unpredictable (Football pass distance, position of defenders)

Non-Regulatory factors

May influence, but do not directly impact, movement. Examples include crowd noise, the quality of a court/arena

Reflex Theory

Reflexes were building blocks of complex behavior; Includes a receptor, conductor, and effector. Limited in that it doesn’t explain voluntary or novel movements, how a single stimulus results in various responses (tripping), or fast movements. Clinical implications - predictable response to reflex testing (or presence/absence of controlling reflexes), and can use reflexes to aid movement when motor control is impaired

Hierarchical Theory

Top-down organizational control; each higher level exerts control over levels below it; Strict vertical hierarchy with higher brain levels influencing lower levels within CNS.
Limitations: Can’t explain the dominance of reflex behavior in certain situations in typical adults
Clinical Implications: Can explain disordered motor control in patients with neurologic disorders

Neuromaturational Theory of Motor Development

Definition: Hierarchical and reflex-hierarchical control depend upon development of higher brain centers
- Attributes normal motor development to increasing corticalization of the CNS
- Assumes CNS maturation is the primary agent for change in development
- Assumes hierarchical control

Motor Program Theories

• Abstract representation used to create a class of movements with certain invariant features (order of events, relative timing of events, relative force with which events are executed)
  Specifies how a movement will be performed (duration, muscles involved, overall force)
  Explains ability to generate different movements with the same motor program and the ability to produce novel movements by specifying new parameters

Motor Programming Theories - Limitations and Clinical Implications

Limitations: Minimizes importance of sensory input, cannot be the only determinant of action, does not consider both MSK and environmental demands in achieving motor control
Clinical Implications: Clinicians can move beyond reflexes to explain disordered motor control, retraining movement should involve functional tasks not just reeducation of muscles in isolation

Systems Theory

Coordination of movement is the process of mastering the redundant degrees of freedom of the moving organism

Principle of abundance

Synergies not used by the nervous system to eliminate redundant degrees of freedom, but to ensure flexible and stable performance of motor tasks

Dynamic Systems Theory vs. Systems Theory

Used interchangeably, though Dynamic Systems Theory is an extension of Systems Theory

Dynamic: Broader view of controlling degrees of freedom (principle of self-organization, nonlinear system, and variability)

Dynamic Systems Theory - Limitations and Clinical Implications

Limitations: minimizes importance of the nervous system, does not place much focus on the interaction of the person with the environment

Clinical Implications: Stresses understanding of the body as a mechanical system, Movement emerges from interaction of elements; consider interactions in task practice, Retraining movement in patients with neural impairment should include error, Variability is essential for movement

Ecological Theory

Motor control evolved to help animals cope with their enviornments

Actions require perceptual information that is specific to a desired goal - directs action performed in a specific environment

Ecological Theory - Limitations and Clinical Implications

Limitations: Minimizes the importance of the nervous system, environment/organism interface is key driver of movement

Clinical Implications: Individuals should actively explore environment, multiple ways to accomplish a task, adaptability of tasks are important