Podcast
Questions and Answers
What are the external forces acting on the body during normal gait?
What are the external forces acting on the body during normal gait?
Which force is equal in magnitude and opposite in direction to the force of gravity during walking?
Which force is equal in magnitude and opposite in direction to the force of gravity during walking?
What does the line of gravity (LOG) represent?
What does the line of gravity (LOG) represent?
Which structure primarily creates internal forces during gait?
Which structure primarily creates internal forces during gait?
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From a lateral view, where does the line of gravity (LOG) pass during standing?
From a lateral view, where does the line of gravity (LOG) pass during standing?
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What assists muscles in resisting, transmitting, and absorbing forces during gait?
What assists muscles in resisting, transmitting, and absorbing forces during gait?
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What is the result of the gravitational torque passing anterior to the axis of the ankle joint?
What is the result of the gravitational torque passing anterior to the axis of the ankle joint?
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How is the counterbalancing torque to the gravitational torque mainly created?
How is the counterbalancing torque to the gravitational torque mainly created?
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What are the three forces that compose the Ground Reaction Force Vector (GRFV)?
What are the three forces that compose the Ground Reaction Force Vector (GRFV)?
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In which posture are the GRFV and the Line of Gravity (LOG) aligned along a common action line?
In which posture are the GRFV and the Line of Gravity (LOG) aligned along a common action line?
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Where is the body's center of pressure (COP) located in unilateral stance?
Where is the body's center of pressure (COP) located in unilateral stance?
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What characteristic pattern does the COP produce during gait?
What characteristic pattern does the COP produce during gait?
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Where does the pattern of ground reaction force vector (GRFV) start during the stance phase of gait?
Where does the pattern of ground reaction force vector (GRFV) start during the stance phase of gait?
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What effect does a greater perpendicular distance of the GRFV from a joint's axis have on the moment or torque produced at that joint?
What effect does a greater perpendicular distance of the GRFV from a joint's axis have on the moment or torque produced at that joint?
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When is the GRFV located medially across the ball of the foot at the second and first toes?
When is the GRFV located medially across the ball of the foot at the second and first toes?
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What type of moment is produced around the ankle joint when the GRFV is located anterior to it?
What type of moment is produced around the ankle joint when the GRFV is located anterior to it?
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Where does the GRFV need to be in relation to the hip joint to cause an extension moment?
Where does the GRFV need to be in relation to the hip joint to cause an extension moment?
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At what point in the gait cycle does the GRFV move laterally to the midline?
At what point in the gait cycle does the GRFV move laterally to the midline?
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What muscle group is responsible for eccentric contraction to counterbalance the flexion moment behind the knee during gait?
What muscle group is responsible for eccentric contraction to counterbalance the flexion moment behind the knee during gait?
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During initial swing of the gait, which muscle group exhibits concentric contraction to aid in obtaining toe clearance?
During initial swing of the gait, which muscle group exhibits concentric contraction to aid in obtaining toe clearance?
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At midswing of the gait cycle, how does the limb advance?
At midswing of the gait cycle, how does the limb advance?
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What is the primary muscle action at terminal swing to prevent excessive knee hyperextension?
What is the primary muscle action at terminal swing to prevent excessive knee hyperextension?
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During initial contact in gait, what muscles counterbalance the planar flexion moment created by the GRFV passing posterior to the ankle joint?
During initial contact in gait, what muscles counterbalance the planar flexion moment created by the GRFV passing posterior to the ankle joint?
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What is the main function of the pretibial muscles during the swing phase of gait?
What is the main function of the pretibial muscles during the swing phase of gait?
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What type of torque is generated at loading response in gait that moves the foot toward the floor?
What type of torque is generated at loading response in gait that moves the foot toward the floor?
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Why do the adductor muscles, mainly adductor magnus, show increased activity at initial contact in gait?
Why do the adductor muscles, mainly adductor magnus, show increased activity at initial contact in gait?
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What is the role of tibialis anterior at terminal swing in gait?
What is the role of tibialis anterior at terminal swing in gait?
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During which gait phase do the gastrosoleus muscles reduce their intensity of action?
During which gait phase do the gastrosoleus muscles reduce their intensity of action?
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What is the purpose of soleus and gastrocnemius eccentric contraction during gait?
What is the purpose of soleus and gastrocnemius eccentric contraction during gait?
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Why does there need to be an opposite moment balanced at the hip joint during gait?
Why does there need to be an opposite moment balanced at the hip joint during gait?
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Study Notes
Forces Acting on the Body during Gait
- External forces acting on the body during normal gait include ground reaction force, gravity, and muscle forces.
- The force equal in magnitude and opposite in direction to the force of gravity during walking is the ground reaction force.
Line of Gravity and Internal Forces
- The line of gravity (LOG) represents the vertical direction of gravity's force on the body.
- The primary structure creating internal forces during gait is the muscles.
- From a lateral view, the line of gravity (LOG) passes anterior to the ankle joint during standing.
Muscle Function and Force Resistance
- Muscles, assisted by tendons and ligaments, resist, transmit, and absorb forces during gait.
- The result of the gravitational torque passing anterior to the axis of the ankle joint is a dorsiflexion moment.
- The counterbalancing torque to the gravitational torque is mainly created by the tibialis anterior muscle.
Ground Reaction Force Vector (GRFV)
- The Ground Reaction Force Vector (GRFV) is composed of three forces: vertical, anterior/posterior, and medial/lateral.
- The GRFV and the Line of Gravity (LOG) are aligned along a common action line in double support posture.
- The body's center of pressure (COP) is located under the heel in unilateral stance.
Gait Cycle and Movement Patterns
- The COP produces a characteristic pattern of lateral to medial movement during gait.
- The pattern of ground reaction force vector (GRFV) starts at the heel during the stance phase of gait.
- A greater perpendicular distance of the GRFV from a joint's axis increases the moment or torque produced at that joint.
Joint Movement and Muscle Action
- When the GRFV is located anterior to the ankle joint, it produces a dorsiflexion moment.
- The GRFV needs to be lateral to the hip joint to cause an extension moment.
- The GRFV moves laterally to the midline at the end of the stance phase.
- The hamstrings muscle group is responsible for eccentric contraction to counterbalance the flexion moment behind the knee during gait.
- The hip flexor muscle group exhibits concentric contraction to aid in obtaining toe clearance during initial swing.
Limb Advancement and Muscle Function
- At midswing, the limb advances through hip flexion and knee extension.
- The primary muscle action at terminal swing is to prevent excessive knee hyperextension.
- During initial contact, the muscles counterbalancing the planar flexion moment created by the GRFV passing posterior to the ankle joint are the gastrocnemius and soleus.
- The main function of the pretibial muscles during the swing phase of gait is to aid in toe clearance.
Muscle Activity and Gait Phase
- The adductor muscles, mainly adductor magnus, show increased activity at initial contact in gait to assist in stabilizing the pelvis.
- The tibialis anterior muscle function at terminal swing is to counterbalance the gravitational torque.
- The gastrosoleus muscles reduce their intensity of action during the swing phase.
- The purpose of soleus and gastrocnemius eccentric contraction during gait is to control the descent of the body's center of mass.
- There needs to be an opposite moment balanced at the hip joint during gait to maintain posture and stability.
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Description
Explore the pathway of Ground Reaction Force Vector (GRFV) during the stance phase of gait with a focus on sagittal plane analysis. Understand how GRFV location relates to lower extremity joints and the moments acting in various parts of the foot.
