Balance

• Anticipatory postural control (proactive)


  Pre-tuning sensory and motor systems; based on previous experience and learning; feedforward control
• Reactive postural control


  Responses to unanticipated external perturbation; feedback control
• Sensory inputs that aid in balance


  • Muscle proprioceptors
  • Vestibular receptors
  • Visual input
• Ankle, Hip and Step Strategy

  1. Ankle (1st strategy)

  2. Hip (2nd strategy)

  3. Step (3rd strategy)
• Ankle strategy


  • Maintain balance for small amounts of sway
  • Muscles activated on the side opposite to which COG is shifted or perturbed
  • Distal to proximal activation of muscles
• Hip strategy


  • Larger, faster displacements
  • Muscles activated on the side towards which COG is shifted or perturbed
  • Proximal to distal activation of muscles
• Step strategy


  • During large, gross displacements
  • Limits of stability have been reached or exceeded
  • Last strategy before fall
• As we age, we lose ankle ROM and start using hip strategy more
• Encourage use of stepping strategy to avoid falls
• 1 in 3 over 65 will experience a fall, 1 in 2 over 80 will experience a fall
• Fall prevention is key!
• Balance Assessment Progressions


  • Vision
  • Base of support
  • Internal perturbations
  • Expected external perturbations
  • Unexpected external perturbations
• Balance Testing Sitting Progression


  • Vision: eyes open -> eyes closed
  • Base of support: feet wide -> feet together, arms by side supporting balance -> no arm support
  • Internal perturbations: turns to look over shoulder, raise arm overhead, reaches within BOS -> outside BOS
  • Expected external perturbations: inform patient on direction of push, stand in front and gently push front, backwards, sideways
  • Unexpected external perturbations: do not tell patient direction of push, stand in front and gently push front, backwards, sideways
• Balance Testing Standing Progression


  • Vision: eyes open -> eyes closed
  • Base of support: feet wide -> feet together -> tandem stance -> single leg stance
  • Internal perturbations: turns to look over shoulder, raise arm overhead, reaches within BOS -> outside BOS (reach for shoe)
  • Expected external perturbations: inform patient on direction of push, stand in front and gently push front, backwards, sideways
  • Unexpected external perturbations: do not tell patient direction of push, stand in front and gently push front, backwards, sideways
• Muscle proprioceptors 


  part of the sensory input required for balance. This is also known as somatosensory, and focuses on orientation and movement in space. It is influenced by postural responses (stretch reflex, postural tone, and automatic postural reactions).
• Visual System

  required for balance sensory input. provides cues for righting via sight and guides safe movement and trajectory
• Vestibular System


  Part of the sensory input for balance. Responds to gravity acting on the head and stabilizes gaze during activity (VOR). Allows you to stay upright when visual cues are not available.
• Vestibulo-occular Reflex (VOR)


  allows objects to remain stable in the visual field when the head is moving.