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GC Initial Double Stance

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aacilla's version from 2017-08-15 04:36

Initial Contact

Question Answer
What percentage of the GC does IC make up?0-2%
What is the Objective of IC?Initiate foot rocker and Impact deceleration
What is phase is the contralateral foot in?End Terminal Stance
What is the healthy ankle position in initial contact?0º -Neutral
What controls the foot positioning in initial contact?Anterior Tibialis (ecc) dorsiflex ankle
What position is the subtalar joint in during initial contact?Neutral
What position is the knee in during initial contact?Neutral to slightly flexed (0-5 degrees)
What are the knee stabilizers during initial contact?Co-contraction of Quads and Hams
What position is the hip in during initial contact?20 degrees of flexion
What is controlling the hip position during initial contact?The hip extensors (glut max and hams) which are isometrically preventing collapse into flexion
What position is the pelvis in during initial contact?5 degrees of forward rotation.
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IC Forces

Question Answer
GRF location at ankleposterior GRF = external PF= internal DF
GRF location at kneeanterior GRF = external KE=internal KF
GRF location at hipanterior GRF=external HF=internal HE
Ankle muscle activityTA (ecc) dorsiflex to position foot for IC
Knee muscle activityco-contraction of hams and quads (ecc)
Hip muscle activitygluteus maximus (ecc), hams, adductor magnus stabilize
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Loading Response

Question Answer
What percentage of the GC does the Loading Response make up2-12%
What are the objectives of Loading ResponseShock absorption, WB activity, forward progression
What phase is the contralateral leg in?Pre-Swing phase
What is the position of the ankle during loading response?5-10 degrees of rapid plantar flexion
What is controlling the position of the ankle in loading response?Eccentric contraction of the anterior tibialis
What do the ankle dorsiflexors do?decelerate foot drop
True or false, the anterior tibialis is initating forward motion of the tibia to flex the knee, in order to plantar flex the ankle in loading responseTrue!
What is the position of the sub talar joint during loading response?calcaneus eversion 5 degrees, mid tarsal is unlocked allowing foot to pronate.
Why is it neccesary for the foot to pronate during loading response?It allows for shock absorption
What muscles are working eccentrically to prevent foot collapse during loading response?The inverters
What other muscle is firing eccentrically to internally rotate the tibia during loading reponse?The posterior tibialis.
What position is the knee in during loading response?Flexion 0-20º
What muscle is controlling knee flexion during loading response, in order to absorb shock and prevent collapse of the knee?The quads are firing eccentrically.
What position is the hip in during loading response?Flexion 20º
What muscles are controlling the hip position during loading reponse, and what is their goal in doing so?Hip extensors (glut max and hams) eccentrically firing to counteract high flexion torque in order to stabilize hip and assist hip into extension.
What is the position of the pelvis during loading response?5 degrees of forward rotation and 5 degrees of pelvic drop
What muscles stabilize pelvic drop in frontal plane?hip abductors
GRF at hipanterior=external HF=internal HE
memorize
GRF at knee: posterior=external KF=internal KE
GRF at ankle: posterior=external PF=internal DF