Work of Gait Flashcards
Smooth progression of gait due to what
concentric and eccentric transferring of power
Joint power
joint motion x joint angular velocity
negative power
eccentric
positive power
concentric
Hip extensors generate power in ____ to ____
in early stance to propel and extend hip
Hip flexors generate power in ____ to _____
in pre and initial swing to advance the limb forward
Knee flexors generate power in ______ to ____
early stance to help extend the hip and propel the body forward
The quads generate power in _____ to _____
stance to re-extend the knee after loading response
The PF generate power in ____ to ____
in terminal stance and preswing to propel the body forward
The hip flexors absorb power through ____ to _____
terminal stance decelerate the extended hip and body’s COM
The quads absorb power in ____ to ____
loading response to control knee flexion
The hamstrings absorb power in ______ to ____
in swing to decelerate the swinging limb
The PF absorb power in ___ to _____
mistance to just prior to end of terminal stance to control the advancement of the tibia over the ankle
What sequence is responsible for COM progression smoothly during gait?
power generation and absorption
Mechanical energy
capacity to performwork
Mechanical work
force x distance through which the force acts
Muscles perform what kind of work to move our bodies
internal work as they shorten and lengthen over a distance
______ is a major determinant in the mechanical cost of walking
mechanical work (force x distance)
When is internal muscle work greatest?
when the COM is moved up and forward. The WAY it is moved up rather than the AMOUNT
Explain the internal pendulum
As we walk the bodies COM repeadedly swings over the stance limb. This happens with no additional energy input because energy cannot be created or destroyed
Potential energy
energy that is stored
kinetic energy
energy the produces work or is released
Once the car goes over the top of the hill what do you have?
both KE and PE
KE and PE are related to what in the body
the distance of the body’s COM from the earth
minimizing mechanical energy expenditure is what?
a dominant characteristic of gait
what contributes to the efficiency of gait?
the muscles ability to absorb and generate energy. Metabolic energy
Mechanical energy (capacity to do work) dictates what?
the metabolic energy you spend and therefore how we move and our efficiency of gait.
Looking at energy expenditure gives us what kind of information on gait performance?
global information: it provides quantifying info on the physiologic penalty due to pathologic gait
Walking speed that minimizes the cost of gait (m/s, mph and m/min)
1.3 m/s
3mph
79.8 m/min
If you walk faster or slower than this you’re increasing the cost of gait
the amount of energy input that is convered into useful work is called what and humans can achieve what?
physiologic efficiency
20%
Energy that is not converted to meaningful mechanical work appears as what?
heat energy
Name the three units of energy we talked about
Cal
kcal
J
Direct calorimetry measures what
physiologic energy expenditure by determining the body’s heat and work production
Impractical
Indirect calorimetry measures the volumes of what two things
O2 consumption and CO2 production
the rate of O2 consumption per kg of body weight is what?
metabolic power
metabolic power determines what?
intensity of sustained exercise
related to the length of time an exercise can be performed
what is O2 consumption rate at rest?
2.8 ml/kb/min
equation for O2 cost
O2 cost = rate of O2 consumption (metabolic power) / walking speed
what two ways can O2 cost be increased by
increased O2 rate consumption
Decreased walking speed with normal O2 rate
What age of people have the “best” efficiency?
adults
ankle fusion and gait efficiency vs. hip and metabolic power/O2 rate
not that different in the ankle. vs hip there is a lot of extra movement and compensation and therefore much higher higher O2 rate of consumption
what jt jusion has the greatest negative impact on the energy expenditure during gait?
Least?
Middle?
hip joint fusion had most impact
Ankle had least
Knee had greater than ankle but less than hip
O2 rate of consumption and prosthetics general idea
the higher the amputation the more O2 rate of consumption
What body system has a large bearing on O2 consumption?
CV system. Physically feet people
What is normal O2 rate of consumption with walking
12
in the study malloy showed us how did limb length afect O2 rate
there was no difference but he said to not take this as a generalization. The point is that both are very different than a normal person.
Experiment data: cane for two months before study period.
How long did it take for can use to decreased energy expenditure in OA patients?
2 months!
It can substantially INCREASE energy expenditure in knee OA patients in the first month of use
LE pathology causing altered ______ ______ can profoundly increase ______ _______
LE pathology causing altered MUSCLE FUNCTION can profoundly increase ENERGY EXPENDITURE
