INTRODUCTION TO BIOMECHANICS

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INTRODUCTION TO BIOMECHANICS
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What is Biomechanics?

• The study of how the physical laws of mechanics
  and physics apply to the Human Body
• Why?
• Improve performance
• Injury prevention and rehabilitation
• Design and development of more efficient movements

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Force Production

• Force is any push or pull activity that tends to
  alter the state of motion of a body.
• The body could be a human body, ball, discus,
  javelin, racquet, bat, etc
• The force can get the body to
• Move
• Speed it up
• Slow it down
• Stop
• Change direction

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Types of Forces

• Force without motion isometric force
• Force with motion isotonic force
• Sub-maximal force
• Maximal force

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Force without Motion

• Isometric force
• Isometric contraction
• Muscle length does not shorten
• Eg pushing against a wall, gripping a cricket bat

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Force with Motion

• Isotonic force
• Isotonic contraction
• Muscle length shortens
• Changes the state of motion of the object (body)
• Eg shot put, taking a catch in cricket, diving
  into a pool

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Sub-maximal Force

• Force needs to be at an optimal level for
  successful performance
• Sometimes we want less than maximum force
• Eg tennis drop shot, chip in golf, basketball
  lay-up

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Maximal Force

• Some activities require maximal force for a
  higher chance of success.
• This usually happens through combination of a
  number of forces FORCE SUMMATION
• Eg high jump, javelin, throw from the outfield
  in softball, golf drive

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Force Summation

• Combination of forces to produce a maximal force
• 2 types
• Simultaneously explosive action of all body
  parts occurs at the same time
• Eg high jump take-off, vertical jump for rebound
  in basketball
• Sequentially body parts are moved in sequence to
  generate a greatest force
• Eg throwing, striking, kicking

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Sequential Force Summation

• http//www.youtube.com/watch?vyCyv-Kk5-Mc

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Sequential Force Summation

• To sequentially produce maximal force
  effectively, the following principles need to be
  applied
• The summation of force is influenced by the
• number of body parts used in the movement
• order and timing of their involvement
• way in which the body and body parts are
  balanced

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Sequential Force Summation
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Force Summation- Golf

• -Read Handout

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Velocity

• The speed of an object.
• Velocity Distance/Time
• Directly related to the Summation of Forces.

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Momentum

• Momentum Mass x Velocity
• So ten pin bowling ball and a tennis ball are
  traveling at the same speed, which has more
  momentum?
• Momentum can be transferred from one object to
  another (Kinetic Energy)

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Impulse

• Impulse is the time over which a force is applied
  to an object Impulse changes the motion of an
  object.
• Impulse force (F) x time (t)
• Impulse is used by golf players to increase the
  speed and distance the golf ball travels eg
  follow through v stabbing.

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Golf Application

• Since most club heads weigh approximately the
  same, the head's velocity at the impact point is
  an important concept for hitting a golf ball long
  distances. The faster the head is swung, the
  greater the amount of kinetic energywhich is
  proportional to the head's mass times its
  velocity squaredthat will be transferred from
  the head to the ball. This energy transfer
  results directly in a faster ball (acceleration)
  speed off the golf tee.

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Questions

• From you video, describe how your summation of
  force is directly affecting the velocity of
  your club head and momentum transferred to the
  golf ball.
• Also how would a big bend in your front arm
  affect force summation?