Center of Gravity Flashcards
(22 cards)
what does isometric contraction additionally involve?
small burst in concentric to get in position
when would an OT want isometric contraction?
moving in cast after fracture to keep muscles toned
inflammed joints that shouldnt move much (RA pts shouldnt overload)
way to initiate exercise
which contraction is less natural and more damaging?
eccentric
what are factors that determine muscle strength?
number, size, arrangement of fibers
when does a muscle have physiologic advantage to produce tension?
when at its resting length or slightly beyond?
what should be considered when testing muscle strength?
tension relationship for 1 & 2 joint muscles
what is the length-tension relationship?
muscle will be at its strongest at midpoint in its extensibility
within 10% of resting length of the muscle, the tension the muscle exerts is maximum
at lengths above or below this optimum length the tension decreases
What is normal positioning for MMT vs. challenging position?
normal: pt in midrange
challenge: pt in shortened/lengthened
what is center of gravity?
point about which the bodys weight is equally balanced
what are gravities vector qualities?
magnitude: wt. of body part
direction: always vertical
point of application: hypothetical point about which weight is balanced
where is the body’s COG?
S1-S2 where 3 cardinal planes intersect in anatomical positioning
how does COG vary?
vary with body proportions (shape, proportion)
shifts as we move
where is COG in men, women, infants?
men: high (broad shoulders)
women: low (broad hips)
infant: highest (big head)
what are events that change COG?
pregnancy, amputation, cast, stroke
how does COG change as we age?
starts to move forward and backward
what weight shifts affect COG?
one leg standing (smaller BOS)
holding on to something (bigger BOS)
what is static equilibrium?
when COG is distributed slightly but returns to former position
(reach down and come back)
what is unstable equilibrium?
when COG doesnt return but seeks a new position
no strength to reposition and falls
what is neutral COG?
COG displaced but is level
wheelchair
what are the principles of stability?
increase body mass increase size & BOS position COG as low as possible keep COG within BOS increase friction btwn body & curface contact (shoes)
what are the rules of lifting?
keep feet flat (not on toes)
keep legs comfortable distance apart (6 inch)
keep weight close to lifter
keep spine straight
use leg muscles
face direction you want to go (2 avoid twist)
how do you eliminate gravity for hip abductors?
put pt in supine
