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49 Cards in this Set

  • Front
  • Back
End effector
Sits a tthe end of chain and accomplishes task. It controls what is essential to completing the task.

In reaching, hand is EE.
In kicking soccer ball, toe is EE.
In standing balance, COM is EE.
Effector Systems
All the joints and muscles that help the end effector accomplish the task.

In reaching, the UE is ES.
In kicking a soccer ball, LE is ES.
In standing balance, the entire body is the ES.
Special Purpose device
Device that performs the task

Ex. We are a "tooth brusher" when we are brushing our teeth before bed.
Affordances for action
Possibilites for action serviced by the objects in the enviornment.

Ex. chair = sit on ability
floor = stand on ability

In Parkour and Stomp, the individuals see possibilties we don't see
Nagi Model
a) pathophysiology: cellular level
Ex. ACL tear, spina bifida, Parkinson's, stroke

b) Impairment: organ level
Ex. Contracture, ROM, cardiac output, muscle weakness, poor timing, pain

c) functional limitation: whole body
Ex. walking, climbing, running, reaching, grasping

d) disability: society
Ex. ADL, psychosocial, catching a bus, job
ICF model
a) Health condition: pathophysiology

b) Body functions and structures: impairment

c) Activity: functional limitations

d) Participation: disability

As well as: environmental factors, personal factors
Constraints/Dynamics Model
Control and coordination are properties of a dynamical system that is constructed in the context of 3 types of constraints
Dynamical System
System that moves according to an underlying set of forces
4 Problems
1) DOF freedom problem
2) Movement Form Selection problem
3) Contexted Condition Variability problem
4) Infinite Regress problem
DOF problem
Each joint has an independent DOF. How do they work together to produce an overall movement pattern?
Movement form selection problem
How will I get from here to there? What type of movement pattern should I select? Why are some locomotion forms/patterns kept or preferred but not others?
Context Conditioned Varability Problem
Once you picked a movement for, how do you deal with the fact that the patterns of muscle EMG activity used to produce that form will never be exactly the same?
3 Sources of CCV
CCV: Anatomical
Activation of a particular muscle will result in different torques (and therefore motions) of the limb.
Depends on the the relationship between the muscle's line of pull and joint's rotational axis

Ex. Postural effect, Muscle identity effect
Postural effect
The same muscle will have a different action.
Line of pull and moment arm change above and below the rotational axis.

Ex. Pec Major can do adduction when the limb is near the side and does abduction when the limb is out to the side.
Muscle Identity effect
Different muscles can perform the same action

Ex. adduction: Deltoid (slow) and Lats (fast)

Which one to select?
CCV: Mechanical
Activation of a particular muscle will result in different motions of the limb depending on:
other forces acting on the limb
initial mechanical state of the limb (i.e initial velocity of limb)

Ex. concentric, eccentric, isometric

Also, mass x acceleration = force (sum of forces acting on the limb)
CCV: Physiological
The amount of muscle activation is determined by the sum of all influence (excitatory and inhibitory) on the motoneuronal pool.
Infinite Regress problem
Who/what is responsible for creating coordinated movement patterns?
Homonuculus (executive controller)? But who controls the executive controller...etc...etc.
Self organization
Control of regular movement pattern is distributed through the system

Behaviors emerge from constraits without strict top down executive control. That is, with min reliance on executive intervention.
Coordinated structures
Ensembles of muscles and joints that are recruited temporarily in a function specific manner to perform a given task in a manner consisten with the current set of organismic and enviornmental constraints.

Turn body parts into special purpose devices.
Hierachial Theory
"Top Down"
Higher centers inhibit and control lower level "primitive" center.
Neurocentric Theories
Neural processes account for everything. Movement patterns that are observed or ones that aren't observed (disappear/vanish).

Ex. Disappearing pattern: infant stepping reflex at 6 weeks
Systems Theory / Dynamic Systems Theory
Task, environmental, and organismic constraints

Provides link between local parts and global (function) levels of disablement models
Constraints: Physical and Psychological
Physical Domain: Task + Environment + Organism = Coordinated Movement pattern

<---Task Selection --->

Psychological Domain: Action capabilities (Effectivities)+ Perception (Affordances) + Cognition, Motivation, Personality
Affordances (Perception)
Opportunity for action as perceived in the environment
Action Capabilities (Effectivities)
Things that you can do; Functions you can perform
Cognition, Motivation, Personality
How you feel, what you want to do, decision making
Task Constraints
Goals of actions

Performance depends on:
-Reinforcement source (type of reward associated with performing the task)
-Demands made upon the movement pattern
Reinforcement Source
Type of reward

Extrinsic reward: obtained with reference to externally defined goals (height of pole vault, the time to swim, etc).

Intrinsic reward: obtained with reference to "inner" defined goals-- satisfaction, joy, or feel of moving through the action
Extrinsic rules: relationship between movement pattern and external rules (Ex. swim strokes, gymnastic vaults, etc)

Intrinsic processes: shock absorption, pain reduction, economy of effort
Environmental Constraints
Physical: gravity. barriers, steps, traffic, surfaces

Social: peer groups, cultural normas
What do mimes do?
Create movement patterns that lead an observer to believe in the presence of environmental constraints that are not actually there
Ecological Psychology theory
James Gibson
Mutual fit between organism and environment

Perception-Action Coupling
Nicolai Bernstein's theory
coordination and regulation of movement

mechanical system in a physical environment

Desired movement patterns depends on creating the total amount of force: active forces complement passive forces!!
Ex. passive walking robots
biomechanics and current set of environmental constraints create coordinated pattern
Self-optimizing theory
Satisfying constraints as well as can be done

Integration of everything to perform coordinated movements at a minimal cost to the organism
When constraints go bad...
Constraints due to task/organism/environment conflict. These conflicts may be the underlying cause of injury

Ex. runner with hyperpronated feet
task does not = organism
Organism is the problem

Ex. ballet dancer with normal anatomical constraints
task does not = organism
Task is the problem (extreme demands)
Perception-Action Coupling
Perception (Affordances) and Action (Effectivities) are mutually related to one another

Organism that can walk will want to walk on a surface that affords it

2 types: Action selection or Movement form

Perception for action is body-scaled (from jumping through hole) and energy scaled (riser heigh selected is least costly).
Action selection
Whether a particular action is performed or not depends on the individual's action capabilities (effectivities) as they relate to what the environment offers (affordances).

Choice/decision to jump over, climb over or walk around a barrier depends on barrier height.
If too high, won't do the action
Movement form selection
Normal walk or ducking down or twisting sideways as go through doorway depends on height and width of passageway

Grip type depends on size and/or weight of object
Self Optimization: Gait
Preferred stride frequency during gait:

At a given running speed, there is an optimal stride frequency
Gait Transition and Self Optimization
Horse Study:

What controls transitions between each stride? (self-organized)
Body realizes that the transition will make it easier (in terms of metabolic costs)

impact is getting stronger (lots of energy on joints as get faster in each stage)

when no load, impact force takes less time to increase with speed.
with lots of load, impact force quickly increases with speed.
no matter the load, horse transitions at the same point.

both oxygen and impact force can have an effect on the horse
surface can effect impact force more (ex of situation). both are constraints
Systems/Constrains Theory: 3 Short Comings
1) Does not give tools to under than different level of disablement
2) Does not tell us how to construct coordinative structure that transform local pieces into global function levels (body parts to special purpose devices)
3) Does not tell us how self-organization can occur (as opposed to top-down control by homunculus)
Changes in behavior over time
a regularly interacting or interdependent group of items forming a unified whole
Dynamic System

A system who behavior changes over time

Theory: concerned with the laws or rules that govern the changes in system behavior over time
Dynamics, Self-Organization, Infinite Regress
Self organization underlies the motion patterns of human and non-human biological systems

Ex. Human locomotion (Wagenaar): arms and legs prefer to move in different patterns relative to one another when walking at slow vs. normal speeds

Ex. Taylor Couette Flow
Regular layers-- wavy layers--- turbulence
Gluteus max weakness
Impact at heel strike creates hip flexion torque.
Glut max creates hip extension torque.

If glut max is weak, the torso will be thrown into flexion at heal strike and balance will be lost.
But with compensatory extension posture, the induced flexion moment is reduced and balance is maintained