Gait

Question 1

what are kinetics?

Answer 1

• forces that cause motion
• analysis of forces and moments acting on a joint
• statics (body in equilibrium)
• dynamics (accelerating or decelerating)

Question 2

What is Kinematics?

Answer 2

• description of movements
• defines the range of motion and describes the motion of joint in three dimensions (or planes)

Question 3

What are the forces during locomotion?

Answer 3

• ground reaction force
• muscle forces
• joint contract forces (or other reaction forces)

Question 4

Ground reaction force can alter under what conditions?

Answer 4

• speed
• incline
• lameness

Question 5

The cycle of limb movements in locomotion can be described as what?

Answer 5

• stance - when the foot is on ground
• swing - when foot is off ground

Question 6

What happens to the limb in the stance phase?

Answer 6

• experiences high GRF
• muscles need to withstand and counteract GRF at joints (stabilise joints, preventing flexion or hyperextension)
• muscles also need to provide propulsion

Question 7

What happens to the limb while in swing phase?

Answer 7

• no GRF acting
• muscles need to move limb
• clear the foot off the ground
• protract the limb
• prepare limb for stance phase

Question 8

Name the modes of locomotion

Answer 8

• terrestrial
• jumping
• flying
• swimming (most efficient)
• climbing

Question 9

Name different movement patterns - gaits

Answer 9

• walking
• running - trotting- hopping
• galloping

Question 10

You can define gaits based on what?

Answer 10

• footfall patterns
• biomechanical principals
• pendular vs spring
• duty factor

Question 11

Describe walking?

Answer 11

• overlapping period of support among limbs
• at low speeds, centre of mass is between supporting limbs
• 3 points of support, static stability
• duty factor >0.5
• modelled as an inverted pendulum (potential and kinetic energy out of phase, energy exchange between forms)

Question 12

Describe trotting and running?

Answer 12

• no overlapping periods between altering phases of limb support
• centre of mass may not be between supporting limbs
• duty factor is less that or equal to 0.5
• modelled as bouncing spring
• potential and kinetic in phase
• instead converted to elastic energy in spring elements of limb (tendon)

Question 13

Describe canter and gallop

Answer 13

• shifts in support phases to allow fore and hind limbs to act in pairs
• allows spinal flexion-extension
• allows rotation of pectoral and pelvic girdle
• increases stride length
• allows quadrupedal mammals to achieve fast speeds

Question 14

How do animals select their gait? (speed)

Answer 14

• increase speed by stride frequency or stride length
• mammals tend to increase stride frequency first
• then shift to gaits that increase stride length

Question 15

Animal gait selection (stability)

Answer 15

• difficult terrain might favour static stability
• energy efficiency

Question 16

Animal gait selection (minimize GRFs)

Answer 16

• reduce impact on tissues
• reduce fatigue (muscle damping)

Question 17

What is lameness?

Answer 17

• Lameness = any deviation from “normal” gait

Question 17

What are the signs of injury or pathology?

Answer 17

• use of a different gait (pacing instead of walking)
• distribution to the usual gait rhythm
• shortened steps or swing phase
• non-weight bearing
• head motions for forelimb lameness
• hip motions for hindlimb lameness