Normal and pathological gait

Question 1

Human gait is bipedal, reciprocating, upright and terrestrial. What are the functional requirements of gait?

Answer 1

Shock absorption
Stability
Propulsion
Energy conservation

Question 2

How is shock absorption achieved?

Answer 2

Through controlled “shortening” of the limbs during gait e.g. knee flexion. It is required to prevent damage to the joints

Question 3

What 3 types of stability are considered?

Answer 3

Joint stability - prevent buckling of joints against gravity
Global stability - keep centre of mass within base of support (speed, step length, foot position)
Foot clearance - Prevents stumbling (knee flexion and ankle dorsiflexion)

Question 4

How is gait inherently efficient?

Answer 4

Little muscle force to resist gravity

Efficient exchange between potential and kinetic energy

Question 5

What is the normal toe-clearance in walking?

Answer 5

1.2 +/- 0.4 cm

Question 6

Why is gait measurable?

Answer 6

It is cyclic and repeatable

Question 7

What is the stride length equal to?

Answer 7

Stride length = Right step length + Left step length

Question 8

What is cadence?

Answer 8

The rate at which a person walks in steps per minute

Question 9

How much of the gait cycle is stance phase and how much is swing?

Answer 9

Stance = 60%
Swing = 40%

Question 10

Task phases of the gait cycle?

Answer 10

Weight acceptance
Single support
Limb advancement

Question 11

What is the basic lower body model for clinical gait analysis?

Answer 11

Consists of 3 rigid segments connected by pin joints with 3 degrees of motion
Use markers on segments to calculate angles at joints as they walk
Can analyse in 3 planes of motion

Question 12

For info - look at graphs of motion for each joint

Answer 12

.

Question 13

Phases of the gait cycle?

Answer 13

Initial contact
Loading response
Mid stance
Terminal stance
Pre swing
Initial swing
Mid swing
Terminal swing

Question 14

3 factors of kinetics to consider in the gait cycle?

Answer 14

Forces
Moments
Powers

Question 15

Gait involves body acceleration and therefore relies on an external force (Newton’s 1st law). What external forces acts on the body during gait?

Answer 15

Ground reaction force

Question 16

What is the vertical force of gait?

Answer 16

It refers to the vertical acceleration of the centre of mass during gait.

There are also Ant-Post forces and Med-Lat forces

Question 17

Moment refers to the turning effect about a point. What is its equation?

Answer 17

M = F.d

Question 18

Moments are balanced by muscles. Why do muscle tend to have to apply a greater force than the applied external force?

Answer 18

Because the moment arms of muscles tend to be small as they are close to the centre of rotation of the joint

Question 19

Equation for power?

Answer 19

P = Moment x angular velocity

Generation of power when moment arm and angular velocity are acting in the same direction

Absorption of power when they are acting in opposite directions

Question 20

Concentric vs eccentric muscle contractions?

Answer 20

A concentric contraction causes muscles to shorten, thereby generating force. Eccentric contractions cause muscles to elongate in response to a greater opposing force