Bio-Mechanics Ryan Mahoney USA Track & Field Level 1 Instructor

Objectives  To develop a basic understanding of fundamental physics, principles as they apply to the human body in athletic performance. (The application of Newton’s 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 athlete’s performance

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

Newton’s Three Laws of Motion  Law of Inertia  Law of Acceleration  Law of Action/Reaction

Law of Inertia Newton’s 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,)

Law of Acceleration Newton’s 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 body’s mass

Law of Action/Reaction Newton’s 3rd Law for each and every action, there is an equal and simultaneous reaction

Concepts Necessary to Understanding Newton’s 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

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

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

Velocity  the distance a body travels in a specific direction divided by time (V=d/t).

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

Acceleration  a positive rate of change of velocity (speeding up)

Deceleration  a negative rate of change of velocity (slowing down)

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

Center of Gravity (COG) or Center of Mass (COM)  the point where the body’s mass is considered to be concentrated.  It is not a fixed point in the human body.

Inertia The resistance that an object or body has to change its state of movement or position or rest. Newton’s 1st Law

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

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

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

Circular Motion Rotation of a body outside the point of rotation.

Centripetal Force  center seeking force

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

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.

5 Bio-motor Elements Speed Strength Coordination Flexibility Endurance