Transcript Seven Principles of Biomechanics

PRINCIPLES OF
BIOMECHANICS
BUILDING BLOCKS OF
EXERCISE
SEVEN PRINCIPLES
Grouped into four(4) categories
Category 1 = Stability
 Category 2 = Maximum Effort
 Category 3 = Linear Motion
 Category 4 = Angular Motion

* Pages 231 – 234 in textbook
Stability - Principle #1
“Proper stability &
balance are
essential to efficient
movement.”
See notes on
stability from earlier
in unit.
Max Effort - Principle #2
“Production of maximum force requires
the use of all possible joint movements
that contribute to the task’s objective.”
With more joints coming into play, the
more muscles there will be to contract –
leading to greater force being exerted.
Principle #2…
Example: Throwing a ball
Use as many body joints as possible
Max Effort - Principle #3
“Production of maximum velocity
requires the use of joints/muscles in
order – from largest to smallest.”
Principle #3…
Example: Use legs
to shoot in
basketball
Bend from legs to
generate more force
Linear Motion –
Principle #4
“The greater the applied impulse or
force, the greater the increase in
velocity.”
The harder you hit an object, the farther
it will travel.
Principle #4…
Principle of Impulse – crouch before you take
off to jump.
Reverse Impulse – absorbing forces when
catching an object or landing after a jump. ( in
order to lessen the load on joints and disperse
the large forces at work)
Linear Motion –
Principle #5
“Movement usually occurs in the
direction opposite that of the applied
force.”
Examples: Resistance of water in
swimming, pushing off floor before
jumping, etc.
Related to Newton’s 3rd Law (Reaction)
Angular Motion Principle #6
“Angular motion is produced by the
application of a force acting at some
distance from an axis.”
Angular motion
Principle #6…
Angular velocity
increases closer the
object is to the axis
of rotation.
Examples: figure
skating spinning,
diver spinning,
throwing a curve
ball.
Angular Motion Principle #7
“Angular momentum is constant when
an athlete or object is free in the air (or
airborne).”
Applying Principles
Case 1
You are coaching a peewee football
team and you notice that one of your
50kg linemen is getting knocked down
very easily and often. As a result, your
9-year old all-star quarterback has
suffered his 5th concussion and is forced
to eat all of his meals through a straw.
Case 1
Principle #1 – Work on stability of
linemen.
Principle #3 – Large to small muscles
when pushing off opponent.
Principle #4 – Hit opponent harder to
protect quarterback.
Anything else?
Applying Principles
Case 2
When Silken Lauman was a young
rower she pulled the oars with her arms
and then pushed with her legs, causing
her boat to not travel as fast as she
would like. Somehow she became one
of the best rowers in the world.
Case 2
Principle #3 – Largest to smallest
muscles. Generate force from legs and
then arms.
Principle #5 – Resistance of oars in
water…more efficient strokes.
Anything else?
Applying Principles
Case 3
Ben Johnson could run the 100m in 10
seconds. After pumping his body full of
steroids, he cut his time to a world
record time of 9.79 seconds in 1988.
Case 3
Principle #4 – Greater applied force,
greater the reaction. Push off ground
harder with steroids.
Principle #5 – Movement occurs in
opposite direction of applied force.
Push off starting blocks harder with
steroids.
Anything else?