Stability, balance and levers

• Stability and balance is important as it enables us to maximise the amount of force we can generate.
• Stability is the ability to resist disruptions to equilibrium
• Balance is the ability to control equilibrium.
• Balance is how well you can maintain your COG within your base of support when only gravity is acting on you, whereas stability is your ability to resist against other external forces acting on you.
• The base of support is the area bound by the outside edges of the body parts in contact with the ground. For an object to become off balance the centre of gravity must move outside the base of support.

  
• Centre of gravity is the average location of all the weight of an object. Often around the belly button for a human.

  
• The line of gravity is an imaginary line which passes through the centre of gravity and continues down into the ground (in the direction of gravity).

  
• All levers have 3 parts – Axis, Resistance, Force
• In our bodies, the bones act as levers, the joints are the axis and the muscles are the force. The resistance can come from body weight or an external object.

  
• 1st class lever- axis is in the middle (F-A-R). Can multiply/amplify both force or speed.

  E.g. See Saw, Body – Neck – up & down movement

  
• 2nd class lever- RESISTANCE is in the middle (A-R-F). Multiples force only.

  Eg. Wheelbarrow, Body – Calf Raise