Sit to Stand Flashcards
What are the 3 phases of STS?
- prep phase
- rising phase
- stability phase
Phasing is identified by _____ and divided equally such that each phase is 1/3 of STS cycle.
velocity of GRF
What happens to COM during prep phase?
moves forward and down
Prep phase, AKA _______, goal?
“flexion momentum phase”
goal: est trunk position
Describe the start and end kinematics of the preparation phase:
start: hip/knee 90, ankle 15
end: hip 110, knee 90, ankle 20*
What are the prime movers of preparation phase?
concentric hip flexors = initiation of movement
eccentric back/hip extensors, eccentric ankle PF, isometric knee flexors/extensors
Rising phase, AKA ______, goal?
“momentum transfer phase”
goal: produce extension force
What happens to COM during rising phase?
rises vertically
Describe the start and end kinematics of the rising phase:
start: hip 110, knee 90, ankle 20*
end: hip 10, knee 5, ankle 5*
What are the prime movers of rising phase?
concentric: hip/knee extensors, ankle PF
eccentric: hip flexors decelerate COM at end of phase
What happens to COM during stabilization phase?
COM moves A/P and M/L to attain balance control
Stabilization continues until theres is less than ____ N fluctuation of the vGRF.
<5 N
marks the end of the stabilization phase
What are the two biomechanical strategies for STS and how are they differentiated?
momentum transfer: horizontal velocity COM > 0.4 m/s
stabilization transfer: horizontal velocity COM < 0.4 m/s
Which biomechanical strategy sacrifices efficiency?
stabilization transfer
more stable
Which biomechanical strategy sacrifices stability?
momentum transfer
more efficient, requires speed and balance
