Motion Analysis

Question 1

Describe a complete gait cycle

Answer 1

A complete gait cycle begins when one foot strikes the ground and ends when the same foot strikes the ground again

Question 2

What are the two phases in the gait cycle?

Answer 2

Stance phase

Swing phase

Question 3

What is the stance phase of the gait cycle?

Answer 3

• the period of time when the foot is in contact with the ground
• begins with initial contact and ends at toe off

Question 4

What is the swing phase of the gait cycle?

Answer 4

• the period of time when the foot is not in contact with the ground
• occurs from toe off to when the foot is on the ground again

Question 5

Define stride length

Answer 5

1 stride length = the sum of left and right step lengths

Question 6

What is the effect of acceleration on stance width?

Answer 6

The effect of acceleration on stance width is a gradual reduction as the player gets upright and into their stride

Question 7

What are the phases of the stance phase of the gait cycle?

Answer 7

▶️ weight acceptance
--- initial contact
--- loading response
▶️ single limb support
--- mid stance
--- terminal stance
Pre swing

Question 8

What are the phases of the swing phase of the gait cycle?

Answer 8

▶️ limb advancement

• • initial swing
• • mid swing
• • terminal swing

Question 9

Why is the gait cycle normalised at 100%?

Answer 9

So each event can be defined sequentially:

- initial contact = 0% and 100% of the gait cycle

Question 10

At what point of the gait cycle does toe off occur? (In normal non-pathological gait)

Answer 10

At approx 60% of gait cycle

Question 11

How long is the swing phase of the gait cycle?

Answer 11

40%

Question 12

What is the difference between Newtonian mechanics and Lagrangian mechanics?

Answer 12

Newton: considers movement with respect to forces acting on a body

Lagrange: considers movement with respect to kinetic and potential energy of a system of bodies

Question 13

What are the methods of measuring gait?

Answer 13

• Eyeballing someone walking
• Video observation
• Infra-red motion capture
• Video-vector systems

Question 14

What is the gait cycle definition?

Answer 14

Bipedal gait in the human being is the mechanism by which the human body is transported by use of coordinated movements of the major limbs of the lower body

Question 15

What are the advantages of eyeballing method of gait?

Answer 15

Clinically friendly and low cost

Question 16

What are the disadvantages of eyeballing method of gait?

Answer 16

Not very informative

Question 17

What are the advantages of video observation for gait?

Answer 17

• Provides permanent record for subsequent analysis
• Can be used for demonstration to patient and family
• Free frame and slow motion can be used to increase accuracy of analysis

Question 18

What are the advantages of video analysis for analysing gait?

Answer 18

• low cost and readily available
• quick analysis and easy to use
• permanent record which can be digitised and stored
• can be used in the absence of instrumented gait analysis
• can display information such as limb movement, balance, pathological movement which is not readily available in instrumental gait
• quality control measure
• useful for teaching purposes
• some objective measures can be calculated from video

Question 19

What are the two types of motion capture systems?

Answer 19

1. Passive infra-red motion analysis system
   - manufactured by Vicon and Qualsys
2. Active infra-red motion analysis system
   - manufactured by Charnwood dynamics

Question 20

What are the anatomical marker placements?

Answer 20

• calcaneous
• 5th metatarsal
• lateral malleolus
• lateral epicondyle of femur

Question 21

What are the embedded axis for marker placement?

Answer 21

Pelvic segment
Femoral segment
Tibial segment