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29 Cards in this Set
- Front
- Back
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PEC
Parrallel elastic component |
Provided by muscle membranes
Supplies resistance when musle passivley stretched |
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SEC
Series elastic component |
Tendons transfer musle force to bone
acts as a spring storing elastic energy when a musle is stretched |
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CC
Contractile component |
muscle property allowing muscle tension development
actin/myosin |
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What is the Stretch Shorten Cycle?
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eccentric to concentric contracion
uses stretch reflex |
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What is a Stretch Reflex
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muscle stretched, sends signal to CNS, impulse then sends message back to muscle to contract, injury prevention mechanism
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Benefit of Stretch Shorten Cycle?
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isometric period inbetween
allows more time for cross bridges to be formed, therefore more force I=FxT |
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Verticle Jump
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*uses Stretch shorten cycle
*SEC - elastic recoil effect of stretched muscle increase muscle force *forcesummation *countermovement, arms |
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What is a scaler?
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quantities posessing magnitude but no direction eg. speed, mass, volume
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What is a vector?
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quantities possessing both magnitude and a direction eg. velocity, acceleration
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Things affecting trajectory of a projectile...
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angle of release, speed of release and height of release.
gravity, air resistance |
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what determines time in the air?
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vertical velocity and gravity
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horizontal displacement =
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horizontal velocity x time in air
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Walking GRF
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2 active peaks (muscular activation) keller et al (1996) no impact peak generally seen
Long contact time |
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Running GRF
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impact peak occurs rapidly and is very sharp
small contact time similar impulse/force to walking but happens over much shorter time period |
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Force characteristics determining outcome of force
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Magnitude, direction, and point of application of force upon body
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Newtons 1st Law - Linear
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a body will remain at rest or at constant velocity unless acted on by an external force
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Newtons 1st Law - Angular
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a rotating body will maintain constant rotational motion unless acted on by external torque
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Newtons 2nd Law - Linear
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Force applied toa body causes acceleration proportional to magnitude of force, direction of force, and bodys mass. F=ma
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Newtons 2nd Law - Angular
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a net torque produces angular acceleration of a body that is proportional to the magnitude of the torque , same direction, and proportional to bodys moment of inertia
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Newtons 3rd Law - Linear
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for every action there is an equal and opposite reaction
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Newtons 3rd Law - Angular
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for every torque exerted by one body on another there is an equal and opposite torque extered by the second body on the first
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Principles of stability
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Lower COG
Broader BOS line of gravity above center of BOS greater mass = greater force nedded horizontally place COG at edge of BOS or oncoming force |
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1st class lever
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F A R
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2nd class lever
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A R F
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3rd class lever
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A F R
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1st class lever +ve & -ve
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force must be applied over a long distance in order to make the load move a small amount
closer to fulcrum more force need be applied |
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2nd class lever +ve & -ve
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load moves in same direction as applied
put load closer to fulcum to use less force |
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3rd class lever +ve & -ve
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requires large force to move
increased speed distance and range of Motion |
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Free body diagrams
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show magnitude and direction of all forces upon an object at or in a given situation
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