Force Summation & Balance and Stability

When the body is in BALANCE during a sporting movement, is it in a static (still) position or dynamic (in the middle of moving)

• Static

• Dynamic

A body is in balance and stability when:

• Centre of gravity is low

• Line of gravity falls within base of support

• Centre of gravity is over the base of support

• All of centre of gravity, line of gravity and base of support are in one line vertically

Are these people most likely to be stable, unstable, balanced or unbalanced?

• Stable

• Unstable

• Balanced

• Unbalanced

What are the three key factors in force summation?

• Using sum of the forces of all body parts

• Using larger and smaller muscles in the right order

• Utilising larger and smaller muscles with the right timing in the movement

• Adding together all the forces a movement makes by measuring their power output

When we did the medicine ball throw, why did throw 1 with legs out, sitting on our gluteus maximus produce the shortest throw?

• No use of quadriceps, hamstrings and gastrocnemius

• No use of the abdominal muscles and latissimus dorsi

• Limited range of motion and use of pectorals, biceps, triceps

• No use of gluteus maximus, rectus abdominus

What are the three factors in stability and balance? (use all lower case letters, spell correctly!)

Why is stability and balance so important in sumo wrestling?

• Because you are simultaneously trying to execute a skill (pushing) while your opponent tries to push you out of stability

• Because the wrestlers are big and can easily knock you out of the ring with their low centre of gravity

• Because the wrestlers are big, have a naturally high centre of gravity so need to adjust by having a wider base of support and lower centre of gravity

When a human stands in the anatomical position, where does centre of gravity naturally end up?

• Belly button

• Groin

• Chest

• Between knees

Is this crazy man likely to be stable, unstable, balanced or unbalanced? Why?

• Stable, because he is in the middle of a dynamic movement and his LoG is over his BoS

• Unstable, because he is in the middle of a dynamic movement and his LoG is very unlikely to be over his BoS

• Balanced, because he is in a static movement and his LoG is likely to be over his BoS

• Unbalanced, because he is in a static movement and his LoG is very unlikely to be over his BoS

Why do we place our arms out for counterbalance when we are crossing a narrow beam/rope/platform?

• The larger leg muscles are unable to be used so we use the arms for leverage to bring our line of gravity back inside base of support

• To make our body area wider so the base of support is wider and line of gravity falls within it

• To make our body area wider so centre of gravity naturally becomes lower and the body is more stable

• To utilise force summation to use larger muscles to bring us back into balance