Posture & Postural Stability

Posture: alignment/position of the body and its parts

Posture can be Static or Dynamic

MISSED NOTES UP TO SLIDE 35

Measuring Static balance

  • we measure postural sway as the change in center of pressure (CoP)

    • CoP continually moves around CoM to maintain BoS

Factors of Balance

  • vestibular (spatial awareness, rotation, linear movement)

  • sight

  • proprioception (touch)

    • at older and younger ages we rely more on visual than proprioception

      • proprioception makes an inverted U, visual makes a U

Limits of Stability (measure of dynamic balance)

  • LoS = maximum voluntary distance an individual can shift in a direction without losing balance, changing BoS, or taking a step

Perturbation

  • An external force is applied that moves a person’s CoM from their BoS

Ankle Strategy

  • used when perturbation is slow or small and surface is stable

Hip Strategy

  • used when perturbation is fast or large amplitude

  • surface is unstable or shorter than feet

  • head moves out of phase w/ hips

Stepping Strategy

  • used when perturbation is large or too fast

  • other strategies have failed

  • used to stop a fall