Lecture 9 Locomotion and Mobility

Question 1

Motor control examines what in gait?

Answer 1

adaptation of gait pattern based on neural, enviorment or task tequirments (activities and perticipation domain)

Question 2

Neuromuscular Requirements for Gait and Mobility

Answer 2

• Generate basic patterns for movement Progression
• Postural Control for orientation and stability​
• Adaptation of movement patterns

Question 3

Key components of gait. Invariant features

Answer 3

1. alternating pattern
2. swing and stance phase
3. double support phase
4. cadence and step length regulation
5. reciprocal arm swing

Question 4

Locomotion Progression

Answer 4

• Rhythmic patterns of muscle activation in legs, trunk, and arms that move body in desired direction
• Ability to initiate and terminate locomotion

Question 5

Locomotion: postural control

Answer 5

• Organization of multiple systems in body to achieve orientation and stability​
• Orientation: aligning body segments to one another and environment to achieve locomotion ​
• Stability: controlling COM to moving base of support​
• Energy efficiency of gait is improved by sagittal plane dynamics

Question 6

What plane of motion is inherentely most stable?

Answer 6

Saggital
Because a small perturbation in the sagittal plane automatically gets dispated out with a change in step length, but frontal plane requires active muscel contractions.

Question 7

Postural contributions to gait

Answer 7

• Organization of multiple systems in body to achieve orientation and stability​
• Steady-state control: constant velocity conditions​
• Anticipatory control: anticipate changes needed for walking over obstacles, changing speed or direction, walking on different terrains​
• Reactive control: recover stability following unexpected perturbation to COM while walking

Question 8

Dual Task and Steady State

Answer 8

• Performance of complex cognitive tasks creates threat for injury during walking​
• Deterioration in gait performance in dual-task context: reduced gait speed, weaving, noticing fewer objects in environment

Increasing risk for injury

Question 9

Dual task and obstacle crossing

Answer 9

• Obstacle contact increases with divided attention
• Naturally direct more attention to gait during precrossing than during crossing
• Postural/locomotor tasks require attention

Question 10

Postural Contributions to Gait

Answer 10

Regulatory Features
* surfaces
* Obstacles
* Open enviorment

Non-regulatory features
* noise
* lighting
* cognitive tasks

Question 11

Control mechanisma for gait

Answer 11

Initating gait
* weight shift (APA) onto stance limb
* relaxation of specific postural muscles, gastrocnemius, and soleus to get DF to advance the limb.

Pattern generatorys for gait
* neural networks control basic rhythmic movements underlying locomotion
* Central pattern generators (CPG) organization.
* Spinal cord and Brain stem locomotor center

Desencing influences
* important in control of locomotor adaptations

Question 12

Descending Influences:

Answer 12

Basal Ganglia - brainstem - spinal cord
* Contribute to automatic control of movements such as locomotion and postural tone

Cerebellum
* Role in modulation of step cycle (refinign)

Cortex
* Important in skills such as walking over uneven terrain (need important for changing skills)

Question 13

Adaptation of Gait: Reacitve Control

Answer 13

• Compensatory automatic postural adjustments integrated into step cycle during recovery from unexpected perturbation to gait​
• Consider passive and active joint moments produced during balance recovery and response patterns of involved muscles

Question 14

Adaptation of gait: Proactive Strategies

Answer 14

Prediction
* Used to minimize destabilizing forces arising from our own movements
* Result of experience​

Visually activated strategies
* Response to potential threats to stability in environment​
* Can be successfully carried out within a step cycle (except when changing directions)

Examples:
* Obstacle crossing​
* Adapting to surface conditions​
* Adapting to inclines​
* Turning strategies

Question 15

Impaired Mobility Function

Answer 15

• One of the earliest and most characteristic symptoms of a wide variety of neurologic disorders
• A critical determinant of independence

Question 16

Weakness/ Paresis

Answer 16

Primary neuromuscular impairment affecting the number, type, and discharge frequency of motor neurons essential for force production during gait

Affects both neural and non-neural components of force production​
* Insufficient supraspinal recruitment of motor neurons (primary impairment)​
* Secondary changes in muscle fibers themselves alter ability to generate tension

Can result in both:​
* Inability to generate force (concentric) ​
* Ability to control movement (eccentric)