Bio-Mechanics

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Bio-Mechanics

• Ryan Mahoney
• USA Track FieldLevel 1 Instructor

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Objectives

• To develop a basic understanding of fundamental
  physics, principles as they apply to the human
  body in athletic performance. (The application of
  Newtons Three Laws of Motion to Track and Field)
• To improve the coaches background in the sport
  science of bio-mechanics
• To improve the line of communication between the
  coaches and the athletes
• To improve the athletes performance

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Definition

• Biomechanics is the study of physics applied to
  human movement.

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Newtons Three Laws of Motion

• Law of Inertia
• Law of Acceleration
• Law of Action/Reaction

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Law of InertiaNewtons 1st Law

• A body will stay in a state of rest or constant
  velocity unless acted upon by an external force
  that changes that state. (i.e. gravity, wind,
  friction with the ground or moving into some
  objects way,)

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Law of AccelerationNewtons 2nd Law

• force applied to a body causes an acceleration of
  that body of a magnitude proportional to the
  force, in the direction of the force, and
  inversely proportional to the bodys mass

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Law of Action/ReactionNewtons 3rd Law

• for each and every action, there is an equal and
  simultaneous reaction

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Concepts Necessary to Understanding Newtons Laws
of Motion

• Kinematics-describe motion
• Linear Motion
• Rotary Motion
• Velocity
• Speed
• Acceleration
• Deceleration
• Kinetics
• Force
• Center of Gravity or Center of Mass
• Inertia
• Impulse

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Linear Motion

• motion along a generally straight line
• such as the path of a long jumper during the
  approach run

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Rotary Motion

• motion which is turning or rotating around an
  axis, such as the the turning of a thrower before
  the throw

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Velocity

• the distance a body travels in a specific
  direction divided by time (Vd/t).

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Speed

• Distance traveled, divided by time.
• 100m / 10 seconds 10m/sec

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Acceleration

• a positive rate of change of velocity (speeding
  up)

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Deceleration

• a negative rate of change of velocity (slowing
  down)

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Force

• Force is a push or a pull
• any physical cause that modifies the motion of a
  body
• putter against the shot
• jumper against the ground

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Center of Gravity (COG)or Center of Mass (COM)

• the point where the bodys mass is considered to
  be concentrated.
• It is not a fixed point in the human body.

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Inertia

• The resistance that an object or body has to
  change its state of movement or position or rest.
• Newtons 1st Law

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Trajectory

• The path of a projectile it can be a parabolic
  curve or it can be an aerodynamic curve

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Parabolic Curve

• the regular flight curve followed by the COG when
  projected in air.
• the curve can not altered by movement in the air.

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Torque

• A turning force. The amount of force applied to
  an object away from its center of gravity results
  in a rotary motion.

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Circular Motion

• Rotation of a body outside the point of rotation.

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Centripetal Force

• center seeking force

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Axis

• straight line about which a body, either animate
  or inanimate, rotates

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Stretch Reflex

• a stronger concentric muscle contraction can be
  obtained when it is directly proceeded by a
  previous eccentric contraction. By braking a
  motion opposite to the intended action, the
  stretched muscle will now contract more
  forcefully.

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5 Bio-motor Elements

• Speed
• Strength
• Coordination
• Flexibility
• Endurance