1. Principles of Motion and STability
Chapter 3

2. Sir Isaac Newton’s 3 Laws of Motion
Movement Principles can be applied to a variety of movements to improve performance
Sir Isaac Newton’s 3 Laws of Motion
(inertia) An object at rest stays at rest, and an object in motion stays in motion unless acted upon by another force
The amt. of acceleration an object has when you apply a force to it is proportional to the amount of force applied and inversely proportional to its MASS,
For every action there is an equal and opposite reaction. e.g. pushing off floor during walking – push down and back, you go forward and up
Infants push more down than back and move slower as a result.

3. Movement principles Rotational force to linear force
The objects linear velocity= rotational velocity and radius of rotation (thus a longer arm = greater force production)
Shorter limb length = less resistance to motion
Thus to produce a quick throw you need a compact motion
To produce the greatest force you need a long motion.
(e.g. javelin vs baseball)
Ice skater
Batter compact swing to start, full extension on contact

4. Kinetic Chain – involvement of various muscles and body parts in a timed sequence to maximize force production. e.g. – throwing, batting, tennis serve, etc.
Force Absorption – the impact of a force is affected by the time over which the impact occurs and the area that the impact effects.
Knees bending decreases impact of jump
Knees straight increase impact of jump
“Giving” with ball
“Giving” with collision
---Stability= resistance to movement (large heavy box)
--Balance= the ability to maintain equilibrium (equal distribution of wt.) around the Center of Gravity (CG)
--Larger the base of support(BOS)=greater balance and stability
--Balance = CG being over the base of support
--The lower the CG is to the BOS, the more stable one is.

5. In Locomotor Skills
--You sacrifice stability in order to move
--Alternating losing and gaining balance
from one foot to the other
--CG is pushed out over the BOS, and then the
individual quickly moves his other leg forward
to regain balance (dynamic balance).

6. Website Document (Movement Principles)
Using Principles to Detect and Correct Errors
Complete and full observance of the movement (technology)
Analyze each phase and its key elements
Break it down into parts (kinetic chain)
Use movement principles to analyze the movement
Can you improve stability?
Kinetic chain sequence?
Release Point?
Correct errors through isolation and repetition