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?