Work, Energy and Power Flashcards
What is the link between the mechanics and the muscle physiology?
energetics
What are the roles of muscles?
• Only
What is energy?
measure of the state of a body at an instant in time. it represents its ability to do work
What energy is used in biomechanics?
mechanical energy
What is energetics?
concerned with the transformation and exchange of energy
What is work?
measure of energy flow from one body to another over time
occurs when a force acts to cause a movement
for work to be done, movements must occur
How is metabolic energy liberated?
by the oxidation of carbohydrates and fatty acids in the muscle (aerobic respiration)
or by glycolysis (anaerobic respiration)
What does oxygen consumption relate to?
cost of locomotion
ATP- conversion of chemical energy to movement energy
What is resting/ basal metabolic rate?
energy expenditure at rest
What is net cost of locomotion?
energy input required to move the animal by 1m (ignores resting rate and start up cost)
What is the specific cost of locomotion?
the amount of energy input required to move 1kg body mass by 1m
What is total cost locomotion?
the total amount of energy to move 1m
includes resting rate and start up cost/ total cost greater at slower speeds
What is the net cost of transport?
• Metabolic power required for locomotion increases
linearly with speed.
• Exception: horse
• Larger animals use relatively less energy per kg
body mass to travel a given distance compared to
smaller animals
What did Hoyt and Taylor 1981 find?
– Cost increases when speed is extended beyond normal gait range. – Metabolic cost not uniform within and between gaits. – Within each gait, a speed exists where metabolic cost is minimal. – ‘Preferred speed’.
What is positive work?
displacement of the object is in the same direction as the force applied
What is negative work?
displacement of the object and the force applied are in opposite directions
What is external work?
work done on the environment or on an external load
during locomotion it is the work done to move the whole body relative to the environment
What is internal work?
work done within the body
during locomotion it is the work done to move the limbs relative to the body
How do muscles work?
by contracting and pulling on their points of attachment
When does positive muscle work occur?
when the points of attachment move in the direction of muscle force
CONCENTRIC CONTRACTIONS
When does negative muscle work occur?
when the points of the attachment are moving in the opposite direction to the muscle force
ECCENTRIC CONTRACTIONS
What is power?
rate at which you are doing work
measured in watts W
What is kinetic energy?
movement energy
moving object has capacity to do work due to its motion
kinetic energy affected by its mass and velocity
What is potential energy?
Also called Gravita
