Unit 1 Study Guidance: Motor Control and the Nature of Movement

Definition and Clinical Application of Motor Control

Motor Control is defined by Shumway & Cook as:

“The ability to regulate or direct the mechanisms essential to movement.”

In clinical practice, motor control refers to the organization and coordination of sensory, motor, and cognitive systems to produce purposeful, goal-directed movement.
It involves planning, executing, and adapting movement through feedforward (anticipatory) and feedback (corrective) control.

Application in Physical Therapy:

Therapists assess how patients regulate movement and adapt to environmental constraints.
Treatment focuses on task-specific, functional movement retraining, emphasizing adaptation, feedback use, and active problem-solving rather than isolated muscle training.

Dynamic Systems Theory of Motor Control (Systems Theory)

The Dynamic Systems Theory (DST) explains that movement emerges from the interaction of multiple systems — neurological, musculoskeletal, and environmental — rather than being commanded by one hierarchical controller.

Key Principles:

Movement is distributed across multiple neural and musculoskeletal subsystems (ascending, descending, and parallel pathways).
Each movement is shaped by the interaction of the individual, the task, and the environment.
The nervous system is flexible and adaptive, allowing movement to reorganize (self-organize) based on changing demands.
Control is nonlinear: small changes in parameters (e.g., velocity) can lead to large transitions (e.g., walking → jogging → running).
Emphasizes functional, task-oriented practice—movement learned in meaningful contexts transfers better to daily life.

Nature of Movement (According to Systems Theory)

Movement arises from the interaction of three components:

1. Individual

The individual contributes three subsystems that determine how movement is produced and controlled:

Subsystem	Description	Examples
Motor/Action Systems	Muscles, joints, and neuromotor control responsible for force production and coordination.	Sit-to-stand, walking, grasping objects
Sensory/Perceptual Systems	Provide feedback about body position and environmental context; integrate sensory info into meaningful perception.	Visual, proprioceptive, vestibular, tactile feedback for balance
Cognitive Systems	Involve attention, motivation, problem-solving, and emotion to plan and direct movement.	Deciding how to approach a movement or reach a goal

Stages of Information Processing

(O’Sullivan Chapter 10, pp. 393–396)

Stage	Description	Example
Stimulus Identification	Recognize and interpret sensory input about the environment and body position.	Seeing a glass of milk on a counter.
Response Selection (Motor Plan)	Choose a movement strategy based on sensory data, prior experience, and goal.	Decide whether to stand on toes or use a stool to reach the glass.
Response Programming (Motor Program)	Translate plan into muscle activation patterns and timing; coordinate synergies.	Activating arm, trunk, and leg muscles to reach.
Response Execution (Movement Output)	Carry out movement; muscles contract in a specific sequence.	Performing the reach and grasp.
Feedforward Control	Anticipatory planning before movement begins.	Predicting how much force is needed to lift the glass.
Feedback Control	Real-time sensory adjustments during movement.	Adjusting hand position as you feel the glass slipping.

2. Task

Tasks define what the individual must do. Each task has specific constraints that influence movement control.

Task Constraints:

Goal of movement
Rules or requirements (speed, precision, posture)
Tools or objects involved

Task Classifications and Examples:

Type	Definition	Example
Discrete Task	Clear beginning and end	Sit-to-stand, reaching for a cup
Multiple Discrete / Serial Task	Series of discrete movements combined	Wheelchair transfer, gymnastics routine
Continuous Task	Repetitive, cyclical with no clear end	Walking, running, swimming
Closed Task	Performed in a stable, predictable environment	Standing at a desk, treadmill walking
Open Task	Performed in a variable, unpredictable environment	Playing soccer, walking in a crowd
Stability Task (Static Postural Control)	Base of support (BOS) remains stationary	Sitting, standing
Dynamic Stability Task (Dynamic Postural Control)	BOS moves while maintaining control	Standing on a BOSU, walking on uneven terrain
Mobility Task	Entire body moves through space	Running, climbing stairs
Manipulation Task	Involves use of upper extremities or fine motor control	Carrying groceries, holding a baby
Non-Manipulation Task	No upper limb movement required	Standing balance, walking with arms still

Clinical Application:

Begin with closed, stable tasks and progress to open, mobile, manipulation tasks.
For example, start with standing balance on a firm surface → progress to walking on uneven terrain while carrying an object.

3. Environment

Environmental factors influence how movement is performed.

Type	Definition	Examples
Regulatory Features	Directly shape the movement—affect kinematics and kinetics.	Stair height, surface type, object size, weight, shape
Non-Regulatory Features	Indirectly influence performance—require cognitive or attentional adjustment.	Noise, lighting, distractions, temperature

Clinical Application:

Modify regulatory features (e.g., surface firmness) to grade task difficulty.
Train in varying non-regulatory conditions to improve real-world adaptability.

Theories of Motor Control

Theory	Description	Limitations / Clinical Perspective
Reflex Theory	Movement controlled by reflex chains; sensory stimulus → motor response.	Cannot explain voluntary or novel movement; too simplistic.
Hierarchical Theory	Top-down control: higher centers (cortex) inhibit and direct lower centers.	Does not account for lower-level reflexes influencing higher centers.
Motor Programming Theory	Movement controlled by central motor programs stored in memory; explains movement without sensory input.	Does not fully account for sensory or environmental influences.
Systems (Dynamic Systems) Theory	Movement emerges from the interaction of multiple systems (individual, task, environment). Distributed, adaptable, self-organizing control.	Most comprehensive; forms foundation of modern task-oriented motor control practice.