Gait Flashcards
What are kinetics?
- Forces that cause motion
- Analysis of forces and moments acting on a joint
- Statics (body in equilibrium)
- Dynamics (accelerating or decelerating)
What are kinematics?
- Description of movements
- Defines the range of motion and describes the motion of joint in three dimensions (or planes)
What are the forces during locomotion?
- Ground reaction force (GRF)
- Muscle forces
- Joint contract forces (or other reaction forces)
Ground reaction force can alter under what conditions?
- Speed
- Incline
- Lameness
The cycle of limb movements in locomotion can be described as what?
1) Stance = when the foot is on the ground
2) Swing = when the foot is off the ground
What happens to the limb in the stance phase?
- Experiences high GRF
- Muscles need to withstand and counteract - GRF at joints (stabilise joints, preventing flexion or hyperextension)
- Muscles also need to provide propulsion
What happens to the limb while in swing phase?
- No GRF acting
- Muscles need to move limb
- Clear the foot off the ground
- Protract the limb
- Prepare limb for stance phase
Name the modes of locomotion
1) Terrestrial
2) Swimming (most efficient)
3) Jumping
4) Flying
5) Climbing
Name different movement patterns - gaits
- Walking
- Running
- Trotting
- Hopping
- Galloping
You can define gaits based on what?
1) Footfall patterns
2) Biomechanical principals
3) Pendular vs spring
4) Duty factor
Describe the process of walking
- 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)
Describe trotting and running
- 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)
Describe canter and gallop
- 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
How do animals select their gait? (speed)
- Increase speed by stride frequency or stride length
- Mammals tend to increase stride frequency first
- Then shift to gaits that increase stride length
Animal gait selection (stability)
- Difficult terrain might favour static stability
- Energy efficiency
