Movement Strategies For Balance; Ankle Strategy; Appendix D: Balance Overview - biodex BALANCE SYSTEM SD Operation & Service Manual

APPENDIX D
BaLaNCE OVERVIEW
Maintaining postural balance involves complex coordination and integration of multiple sensory,
motor, and biomechanical components as graphically represented below. Balance is a motor skill
most people take for granted. An individual senses body position in relation to gravity and envi-
ronmental surroundings by combining vestibular, visual, and proprioceptive (somatosensory)
inputs (1). Body position and smooth functional movement patterns result from these coordinated
actions along with integration of graded ankle, knee and hip movements along the kinetic chain (2).
A person's ability to maintain Balance becomes compromised when one action does not function
accordingly and or equilibrium becomes altered. A variety of consequences can occur due to
poor balance therefore clinicians need to address each component in order to prevent injury, re-
injury or further trauma. The Biodex BioSway provides valuable objective assessment of neuro-
muscular control and somatosensory input important to balance.
MOVEMENT STRaTEGIES FOR BaLaNCE, SENSORY ORGaNIZaTION, aGE-RELaTED
CHaNGES IN BaLaNCE aND CTSIB TEST RESuLT INTERPRETaTION.
MOVEMENT STRaTEGIES FOR BaLaNCE (Robertson)
According to the Systems Approach to motor control, the nervous system uses preprogrammed
strategies or synergies to simplify movement. The central nervous system (CNS) takes advan-
tage of pathways that link together groups of muscles in a flexible and repeatable sequence. This
linking or packaging of muscle groups allows the brain to respond to an infinite variety of cir-
cumstances by drawing on muscle responses that have been successful in the past. This linking
or packaging of muscles in a repeatable sequence is called a movement strategy.
Utilizing a movement strategy simplifies the way the nervous system accesses a motor reaction
in response to sensory input. Strategies are automatic reactions that have evolved over time, tak-
ing into account biomechanical and environmental constraints. Strategies that are successful for
maintaining balance are stored so that the CNS is not forced to start from scratch each time a
loss of balance occurs. Strategies are automatic reactions, slower than reflexes but much faster
than voluntary movements. Three anterior-posterior movement strategies have been identified:
the ankle, hip and stepping strategies.

ankle Strategy

The nervous system employs the ankle strategy in response to small losses of balance and to
adjust balance in quiet standing. The ankle strategy is also called ankle sway and uses the length
of the foot as a lever to correct for minor losses of balance. In the ankle strategy, activation of the
leg muscles is from the floor up or distal to proximal. A small loss of balance in the forward
direction causes contraction of the gastrocnemius, hamstrings, and lower-back muscles, in that
order, to bring the body back into balance.
— D-1 — APPENDIX D