Gait Kinetics

Question 1

Force (load)

Answer 1

• push or pull can produce, stop, or modify movement

- F=ma

Question 2

Descriptors of force

Answer 2

1. Magnitude (N)
2. Direction (sense)
3. Point of application
4. Spatial orientation (in this case, the degrees)

Question 3

Examples of external forces acting on the body

Answer 3

• gravity
• external loads
• contact
• friction
• buoyancy
• inertia

Question 4

Internal forces acting on the body

Answer 4

• active: muscle

- passive: intramuscular connective tissue, ligaments, joint capsules

Question 5

Newton’s 3rd law

Answer 5

For every action there is a reaction of equal magnitude, but in opposite direction

Question 6

Joint reaction force

Answer 6

-happens when there is both an internal and an external force

Question 7

Moment (torque)

Answer 7

• force acting a distance from the center of rotation of a segment
• Torque=F x d

Question 8

Moment Arm

Answer 8

The perpendicular distance from the force vector to the center of rotation

Question 9

External forces during walking

Answer 9

• primarily generated by the ground

- consist of vertical, A/P and M/L forces

Question 10

Internal forces during walking

Answer 10

• primarily generated by muscle and other soft tissue such as ligaments, tendons, and joint capsule
• measured by 3D gait analysis combining kinematic and kinetic data
• EMG is also helpful

Question 11

Sagittal Plane Kinetics

Answer 11

External moments: Ankle PF, knee flexion, hip flexion

Internal moments: ankle DF, knee ext, hip ext

Question 12

Frontal plane kinetics during loading phase

Answer 12

• The ground creates an external adduction moment at the hip and knee
• the body must create an internal abductor moment at the hip and knee

Question 13

Moment terminology in research

Answer 13

-be careful to identify whether the moments reports in teh results are internal or external