postural control Flashcards
posture
- also called “postural orientation”
- ability to maintain an appropriate relationship between:
1) body segments
2) body & environment
examples of relationship between BODY SEGMENTS (that will determine posture)
- between head and trunk
- between trunk and lower ex.
- between arm and forearm
t/n: their alignment w/ eao will determine posture
examples of relationship between BODY & ENV (that will determine posture)
- sitting on a chair
- lying on bed
t/n: orientation between body segment + body + environment =posture
quadrupedal stance vs bipedal stance
quadrupedal
- BW distributed in UE and LE
- ancient times
- ambulating/exploring env using (ALL 4) bilateral ex.
bipedal
- only 2 LE used
- reduced BOS, increased work at heart, increased stress on vb column & LE
- weight of HAT transmitted down to vb column
reduced BOS challenges
- challenging stability
- make some control to maintain balance
COG
- center of gravity
- vertical projection of COM
- dependent on the body position
- in whatever we do, there is a chance that we are shifting our COG fwd, bwd, sideways, or combo
control mechanism of the body
everytime COG is moved, body must maintain its equilibrium/balance, adjustments are made
postural stability/balance
ability to maintain body in equilibrium
t/n: whether body is at rest or in motion (static posture vs dynamic posture)
True/False:
Postural stability entails muscle contractions.
true
t/n: it is a dynamic process when certain muscles (internal forces) will exert their forces to be able to maintain your position
COM
- center of mass
- COM should be maintained OVER BOS for STABILITY (COM/BOS = stability)
t/n: a point at the center of the total body mass represents the concentration of all the mass of the entire body (weighted average of the COM of each body segment)
BOS
- base of support
- support surface
- area of object that is in contact with support surface
Static vs Dynamic Posture
static
- body and its segments are
1) aligned
2) maintained in certain positions
dynamic
- body and its segments are
1) moving
postural control
- postural adjustments body HAS TO MAINTAIN
- muscle activation patterns and segmental movements (that enable us control the body’s segmental linkages in relation to the BOS)
- allow us to properly execute our functional activities without placing too much stress on certain structures
(2) types of postural control
1) reactive = compensatory
2) proactive = anticipatory
reactive/compensatory postural control
reacts to external force displacing body’s COM/external force came intro contact with your bodu
compensatory postural control by which the force is already displaced the body’s COM
e.g. if we try to push someone; and that push came into contact with body = challenges reactive/compensatory postural control
proactive/anticipatory postural control
responds to internally-generated anticipated destabilizing forces
anticipates arrival of external force/force hasn’t come contact into body yet
internally-generated muscle contractions will happen early prior to destabilizing force effect
e.g. riding a roller coaster/fast vehicle, encountering a curve, body adjusts already (bend sideways)
perturbation
sudden nudges/change in conditions that displaces the body away from equilibrium
(2) types of perturbation
1) sensory perturbation
2) mechanical perturbation
sensory perturbation (w/ examples)
alteration of visual input
e.g. covering someone’s eyes when walking in a dark room > challenges visual > challenges posture > sensory perturbation
mechanical perturbation (w/ examples)
displacements affecting COM & BOS/EXTERNAL forces displacing COM out of BOS
e.g. we nudge someone, push someone, ride a train and it suddenly stops
strategies to sensory perturbation
postural strategy
widening BOS (slouch, extend arms, widen legs apart, bend knees)
(3) strategies to mechanical perturbation
1) ankle strategy (prevent too much dorsiflexion)
2) hip strategy (used in stronger force)
3) change-in-support strategies (stepping/grasping)
change-in-support strategy
there is a change in support = your feet/foot STEPS FORWARD
stepping strategy
pushed > step forward > catch COG within that BOS