Case 3 Shopping with kids
Learning goals:
What is the relation between cost of transport and body size? (see figure)
When body size increases, the cost of transport (COT) decreases. This means that for larger
animals, moving costs less energy
For example, running at 9 km/h costs an adult less energy than a toddler.
Cost of transport: The amount of metabolic energy needed to move a body a unit of distance
o Step length
o Cadence
o Step width
o Step variability
The relation between walking and COT is parabola-like, preferred walking speed at the
minimum. This means that walking at a slower or faster speed than preferred walking speed,
will increase energetic cost.
What is Froude’s number and what does it explain?
The Froude number is a dimensionless number for the influence of gravity on the motion of
fluid. It incorporates measures of leg lengths, speed, stride frequency and weight, and is
based on the speed-length ratio. It is used in allometry to study locomotion of terrestrial
animals.
Gravity increases the energy expenditure needed to walk, but also increases the
possibility in walking speeds
Explain the gait cycle and its phases in bipedal and quadrupedal animals.
The gait cycle is a repetitive pattern involving steps and strides
Step is one single step
Stripe is a whole gait cycle
The normal forward step consists of 2 phases
Stance phase: 60%, foot touching the surface, one leg and foot are bearing most or
all of the bodyweight
o Weight acceptance: Stabilize the limb, absorb the shock and preserve
progression of the body
o Single limb support: Progression over foot and weight-bearing stability
Swing phase: 40%,foot not touching the surface and bodyweight is bore by other leg
and foot
o Limb advancement
Double support phase: 25%, both feet are in contact with the floor
Phases of gait cycle
1. Weight acceptance:
a. Initial contact: Heel strikes the ground and initiates rotation, first rocker
motion
b. Loading response: Knee flexes to absorb shock as the foot falls on the
ground, stabilizing
2. Single limb support
a. Midstance: Second rocker motion, forward progression of gait
Learning goals:
What is the relation between cost of transport and body size? (see figure)
When body size increases, the cost of transport (COT) decreases. This means that for larger
animals, moving costs less energy
For example, running at 9 km/h costs an adult less energy than a toddler.
Cost of transport: The amount of metabolic energy needed to move a body a unit of distance
o Step length
o Cadence
o Step width
o Step variability
The relation between walking and COT is parabola-like, preferred walking speed at the
minimum. This means that walking at a slower or faster speed than preferred walking speed,
will increase energetic cost.
What is Froude’s number and what does it explain?
The Froude number is a dimensionless number for the influence of gravity on the motion of
fluid. It incorporates measures of leg lengths, speed, stride frequency and weight, and is
based on the speed-length ratio. It is used in allometry to study locomotion of terrestrial
animals.
Gravity increases the energy expenditure needed to walk, but also increases the
possibility in walking speeds
Explain the gait cycle and its phases in bipedal and quadrupedal animals.
The gait cycle is a repetitive pattern involving steps and strides
Step is one single step
Stripe is a whole gait cycle
The normal forward step consists of 2 phases
Stance phase: 60%, foot touching the surface, one leg and foot are bearing most or
all of the bodyweight
o Weight acceptance: Stabilize the limb, absorb the shock and preserve
progression of the body
o Single limb support: Progression over foot and weight-bearing stability
Swing phase: 40%,foot not touching the surface and bodyweight is bore by other leg
and foot
o Limb advancement
Double support phase: 25%, both feet are in contact with the floor
Phases of gait cycle
1. Weight acceptance:
a. Initial contact: Heel strikes the ground and initiates rotation, first rocker
motion
b. Loading response: Knee flexes to absorb shock as the foot falls on the
ground, stabilizing
2. Single limb support
a. Midstance: Second rocker motion, forward progression of gait
