Bio-Mechanics

Ryan MahoneyUSA Track & FieldLevel 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 InertiaNewton’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 AccelerationNewton’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

TrajectoryThe 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