Chapter 3 Flashcards
Movements of inexperienced movers:
- inefficient
- jerky
- separate, discrete movements instead of whole movements
- optimize one aspect of the movement (eg. balance) at the expense of another (eg. speed) to increase likelihood of success
Principles of _____ and _____ act on all movements and movers.
- motion
- stability
As movers become more proficient at skills, they use principles….
to their advantage
Certain physical laws of motion _____ your movements. Give an example.
- limit
- gravity
How do individual constraints/characteristics of the performer influence the movement patter?
- muscles have particular shapes and sizes
- nervous system coordinates muscle contractions
To develop skills, children and adults must learn to use ______ _____ to optimize performance.
movement patterns
How does growth complicate using movement patterns?
alters proportions
Movement pattern can change if any one of the _____ change.
constraints
Changing bodies =
- changing individual constraints
- individuals must recalibrate the interactions between individual and environmental constraints
As kids grow, more _____ _____ become possible.
movement patterns
_____ or _____ can change individual constraints for either short or long periods.
- injury
- disability
When injury or disability occurs, we need to relearn how to use ______ of ______ given their unique body _____ and _____.
- mechanics of movement
- structure
- function
With _____ and ____ (maybe ______), new movement patterns may emerge that provide for better performance.
- time
- experience
- technology
Newton’s first law of motion
- To move either yourself or objects, you must produce force
- Will not move until force is applied
- An object at rest stays at rest
- An object in motion stays in motion until acted on by a force
Newton’s second law of motion:
- F=ma
- Acceleration of a person or object is proportional to the force applied to it
- Acceleration is inversely proportional to its mass
We can use Newton’s laws to understand how to …
maximize performance
There is a relationship between _____ applied and the _____ over which you apply it.
- force
- distance
We can improve performance by applying _____ over a greater _____.
- force
- distance
Give an example of force distance relationship.
- can throw farther by moving legs
- doing this can reduce compromises to balance (child)
How can we maximize performance with rotary/angular distance?
increasing body ROM = increased rotary distance over force applied = maximized performance
In most laws, there is a ______ level for each factor. Exceeding these can lead to….
- optimum
- decrease in performance
Newton’s third law of motion:
- For every action there’s a equal and opposite reaction
- Every force you exert on an object, the object exerts an equal force back on you in the opposite direction
Example of Newton’s third law of motion:
- walking
- pushing down on the floor and the floor pushes back
When walking, adults tend to push _____ to propel them ___ and _____. Toddlers often push _____ instead of _____. Why?
- backwards
- up and forward
- downwards
- backwards
- keeps their balance, forward progression is slow
For full force exertion, we want to exert force in ____ ____.
1 direction/plane
____ _____ of limb = max force
full extension
Newton’s third law: When the upper body twists one way, the lower body…
twists the other way
Newton’s third law: arm and leg movement:
- oppositional
- 1 leg swings forward, opposite arm swings backward
Rotational movement:
- Limbs rotate around one or several joints
- Limb traces part of a circle when projecting an object (throwing, kicking, hitting)
Relationship between velocity of rotating arm and velocity of projected object:
- velocity of the ball as it leaves the player’s hand is dependent on how fast the player’s arm moves
- also depends on length of arm and release point
Object linear velocity is the product of…
its rotational velocity and its radius of rotation
As children grow, their limb length increases =
increased projectile velocity (and distance)
How to optimize rotational velocity and limb length:
extend limb at point of release (increase radius of rotation)
Why not extend limbs all the time?
- law of inertia
- as limb length increases for a given mass, so does resistance to motion = amount of energy required
- bending limb decreases the energy required to move the object
Inertia:
- object’s resistance to motion
- related to mass
Sprinter optimizing rotational velocity and limb length:
- fully extend legs before contact with ground = maximize projected velocity
- bend limbs as they recover and swing forward = energy/effort conservation
Batter (baseball) optimizing rotational velocity and limb length:
- Conserve effort at the beginning by keeping elbows bent
- Just before point of contact, they extend their arms as fully as possible
Maximal effort must involve _______ movement of body parts.
sequential
Sequential movement says movement must be timed right so the ____ of each succeeding movement occurs just after the previous environment.
force
Sequential movement of throwing:
- step forward
- rotate pelvis
- rotate upper trunk as the throwing arm comes forward
- extend arm
- rotate inward
Open kinetic chain:
correctly timed sequence of movements an individual uses to successfully perform a skill
2 elements of sequential movement:
- optimal sequence of movement
- timing of events
In the skill development of children, there is a transition from using ____ action to executing skills in a patter of _____, _____ _____ sequential movements.
- single
- efficient
- properly timed
How do we absorb force when bending knees to land?
increases the time and distance of the landing
To decrease the impact of a reaction force, you must either:
- increase the time that impact occurs
- increase the area over which the impact occurs
Force absorption is important for:
injury prevention when attempting a max performance
People have difficulty optimizing performance from an _____ position.
unstable
Sports that require max stability:
- powerlifting
- golf
Sports that requires maintaining stability while disturbing other’s stability:
- judo
- wrestling
Sports where athletes need to maintain balance in relatively unstable positions:
- gymnastics
- ice skating
____ and _____ are not the same thing.
- stability
- balance
Stable =
resist movement
Balance =
ability to maintain equilibrium
Standing on one foot while closing eyes means you have…
- good balance
- bad stability
In most cases increasing stability ______ balance.
ensures
Maintaining ______ does not guarantee ______.
- balance
- stability
Stability can restrict _____.
mobility
Stable = increased _____ of _____.
base of support
Stability = keeping _____ of _____ low and…
- centre of gravity
- inside their base of support
Centre of gravity:
concentration point of the earth’s gravitational pull on an individual
Maximum _____ might be needed first to increase mobility.
stability
In locomotor skills, the person momentarily sacrifices ____ in order to move by _____ and ____ _____.
- stability
- losing and gaining balance
Young children, people with certain disabilities older adults, people learning new skills often try to improve balance by…
- improving stability
- ex. young kids duck footing
5 steps in using principles of motion and stability to detect and correct errors:
- observe the complete skill
- analyze each phase and its key elements
- use your knowledge of mechanics in your analysis
- select errors to be corrected
- decide on appropriate methods for the correction of errors
