Lecture Week 7
Balance and Stability, Core
Stability, COG
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EDU4SBM Sports Biomechanics
Balance and Stability
“How balanced are you?”
Skilled athletes are able to employ certain tactics to increase their stability under
oncoming forces, practically bracing themselves to be immovable.
Chris Judd and Jimmy Bartel
Young athletes learning a skill:
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EDU4SBM Sports Biomechanics
Some sports depend almost exclusively on
As soon as the athlete loses balance, he or she loses the contest. The following
sports fall into that category:
Cycling
Speed skating
Judo
Figure skating
Diving
Weightlifting
Skiing
Gymnastics
EDU4SBM Sports Biomechanics
Fencing
Wrestling
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Other sports require athletes to
These sports have similar movement patterns and include the following:
Baseball and softball
Ice hockey
Football
Tennis
Basketball
Field hockey
Soccer
Volleyball
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EDU4SBM Sports Biomechanics
Types of stability
1. Linear Stability
is the resistance of an athlete or object
against being moved in a certain direction
Sport dependent
Football
Baseball Catcher
2. Rotary Stability
is the resistance of an athlete or object against
being tilted, tipped over, up ended or spun
around in a circle.
EDU4SBM Sports Biomechanics
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Centre of Gravity
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EDU4SBM Sports Biomechanics
Factors which affect balance and stability
 The size of the base of support
 The position of the line of the COG relative to the base of
support
 The height of the COG
 The mass of the body
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EDU4SBM Sports Biomechanics
The Size of the Base of support
A person is more stable when standing on two feet than does a person
standing on one
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EDU4SBM Sports Biomechanics
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EDU4SBM Sports Biomechanics
The position of the line of the COG relative to the base of support
The closer the line of the COG is to being
directly over the base of support ->
The closer the line of the COG is to being at the
edge of the base of support ->
This is required by many sports: ie: diving, sprint
start
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EDU4SBM Sports Biomechanics
The position of the line of the COG relative to the base of support
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EDU4SBM Sports Biomechanics
The height of the COG
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EDU4SBM Sports Biomechanics
The mass of the body
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EDU4SBM Sports Biomechanics
Centre of Gravity, Stability & Balance
Stability and balance will be easier if:
• The mass is large
• The base is large
• The centre of gravity is low
• The centre of gravity is located over the base
Headstand
Handstand
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EDU4SBM Sports Biomechanics
The nature of the crouch position reflects three important principles of stability:
1) A broader base of support increases stability. (A catcher’s stance places feet more
than hip-width apart.)
2) Centralizing the line of gravity inside the support base increases stability. (A straight
back and head held upright centralize the line of gravity.)
3) A lower center of gravity increases stability. (Crouching’s deep knee bend lowers
the center of gravity.)
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EDU4SBM Sports Biomechanics
Many times, stability depends on an athlete’s ability to put the line of gravity towards
an oncoming force.
The movement temporarily unbalances the athlete, but then the impact of the force rebalances him or her.
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EDU4SBM Sports Biomechanics
CORE STABILITY
http://www.brianmac.co.uk/corestab.htm
Most throwing and striking sports require an efficient transfer of force from the
ground up to achieve maximum acceleration of the upper limb or implement.
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This transfer of force is often a function of how well the upper body and lower
body are connected.
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By strengthening the trunk, the athlete creates a solid unit capable of developing
and transferring forces from the legs through the trunk to the arms and possibly the
implement.
•
The sum of these integrated forces results in optimal acceleration of the ball or
implement. Major sports in which this transfer of forces is critical for good
performance include the following:
•
Baseball, Softball, Discus, Shot Put, Football, Tennis, Golf, Basketball, Javelin
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EDU4SBM Sports Biomechanics