Movement analysis Flashcards
What are the 2 phases of sit to stand?
Pre-extension phase
Extension phase
What is COG and BOS doing in the pre-extension phase of sit to stand?
COG goes from static when sat back on the chair to forwards over the feet in preparation.
Large BOS.
What are the 2 principal movements in the pre-extension phase of sit to stand?
Foot position
Body mass moving forwards
What does the foot position part of the pre-extension phase involve.
The feet coming back around 10 degrees further back than the knees, producing dorsiflexion.
Without this, increased effort and momentum is required for the extension phase.
How does the body mass move forwards in the pre-extension phase?
A. Flexion of hips allowing forward inclination of extended trunk.
B. Feet fixed to stabilise tibia - further DF at ankles to bring knees over feet.
What muscles adjust foot position at the start of pre-extension phase?
Dorsiflexion is produced by the concentric contraction of the tibialis anterior and the hamstrings.
What muscles move the body mass forwards through the feet (B) and hips (A) in the pre-extension phase?
A. Concentric contraction of iliopsoas initiates hip flexion - the movement is continued by the rectus femoris, momentum and the force of gravity
B. Tibialis anterior stabilises foot and contracts concentrically to rotate the tibia forward at the ankle
What occurs in the extension phase of sit to stand?
Vertical movement
Co-ordinated extension of the knees, hips and then finally ankles
How do the muscles work to produce the extension phase of the sit to stand?
→Glut. max + hamstrings extend the hips concentrically
→Quadriceps extend the knee concentrically
→Co - contraction at the ankle = creates stable tibia for knee extensors to operate with a reverse origin insertion.
Horizontal momentum of body mass must be controlled to terminate movement in quiet standing.
