INTRODUCTION TO BIOMECHANICS

What is Biomechanics?

The study of how the physical laws of mechanics and physics apply to the “Human Body”

Why?Improve performanceInjury prevention and rehabilitationDesign and development of more

efficient movements

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

Types of Forces

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

Force without Motion

Isometric force Isometric contraction Muscle length does not shorten

Eg: pushing against a wall, gripping a cricket bat

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

Sub-maximal Force

Force needs to be at an optimal level for successful performance

Sometimes we want less than maximum forceEg: tennis drop shot, chip in golf,

basketball lay-up

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

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

Sequential Force Summation

http://www.youtube.com/watch?v=yCyv-Kk5-Mc

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

Sequential Force Summation

Force Summation- Golf

-Read Handout

Velocity

The speed of an object.

Velocity= Distance/Time

Directly related to the “Summation of Forces”.

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)

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.

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 energy—which is proportional to the head's mass times its velocity squared—that will be transferred from the head to the ball. This energy transfer results directly in a faster ball (acceleration) speed off the golf tee.

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?