Force SummationIntroduction to Biomechanics - 2

Lorna McAvoy - AJHS PE Dept

Recap - Balance

STATIC DYNAMIC

Men's Rings

B-Boys

Recap - Principles of Balance

Balance is a desirable attribute in the performance of skills.

A body is most stable when the principles of balance are applied.

1. Anything can be balanced if its centre of gravity is directly over its base of support

2. The wider the base of support the more balanced or stable the object or body is.

3. The lower the centre of gravity the more balanced or stable the object is.

4. As one body part moves another must move to compensate that movement

Maintaining balance and stability during sporting performance has a number of benefits:

It allows a person to put more force into a movement and complete that movement accurately and with control.

Lorna McAvoy - AJHS PE Dept

Balance & Force

Balance & Force – A quick experiment!

Lorna McAvoy - AJHS PE Dept

In pairs, one person acts as the pushing force and the other person acts as the object being pushed. The person acting as the pushing force now attempts to push their partner off balance with the person acting as the object, positioning their body in such a way as to resist being pushed over.

1. Describe the things the person being pushed did to resist being pushed off balance. Explain these in terms of centre of gravity, line of gravity and base of support.

2. Describe in detail the implications of these results when engaged in contact sports such as rugby or judo.

Maximum force is produced when a person is able to use:

• As many body parts as possible.• In the correct sequence (use large muscles first & then

the smallest muscles last but fastest).• With the correct timing.• Through the greatest range of motion.

in order to perform a movement.

Force Summation

This is known as the principle of force summation.

The more body segments involved, the greater the force or speed generated.

The speed of the last body part during the release of an object will determine the velocity of the object as it leaves the hand or foot.

Force Summation

Force Summation in Action:

Force Summation in Action:

McAvoy - Jump Serve

Practical Lab

The Medicine Ball Experiment

Collect an experiment sheet from Miss McAvoy

Summary

Lorna McAvoy - AJHS PE Dept

To gain maximum momentum, the force needs to be generated by:

• Using as many body parts as possible.• In the correct sequence (use large muscles first & then the smallest muscles last but fastest).

• With the correct timing.• Through the greatest range of motion.

Homework Task

Collect a worksheet from Miss McAvoy

Stick this in your book and complete Adductors

Hip Flexors

Quads

Deltoid

Pectoral

Triceps

Quadriceps

Obliques

Abdominal Rectus

Deltoid

Quadriceps

Hamstring

Gastrocnemious

Pectoral

Triceps

Wrist Flexors