Sagittal Plane Hip/Pelvis

initial contact: ROM

-hip 30º flexion
-thigh: 20º flexion
-pelvis: 10º anterior tilt (neutral)

initial contact: torque demand

external flexion torque
-GRF anterior

initial contact: muscle activity

all hip extensors eccentric
- but cannot really comment bc IC is one point in time

initial contact: functional significance

-limb positioning for step length
-limb stabilization

loading response: end ROM

hip remains in 30º flexion
-thigh in 20º flexion

loading response: torque demand

external flexion torque
-GRF anterior to joint

loading response: muscle activity

isometric hip extensors

loading response: functional significance

-hip stability
-maintain trunk position

midstance: end ROM

extending to 10º of flexion
-thigh at 0º

midstance: torque demand

external extension torque by end of midstance
-GRF moves posterior to hip

midstance: muscle activity

-extensor activity diminishes
-resistance from anterior capsule
-NOT hip flexors

midstance: functional significance

-hip stability maintained through passive forces
-forward progression of head, arms, and trunk (passenger unit)

terminal stance: end ROM

hip extending to 10º extension
-thigh 20º extension

terminal stance: torque demand

external extension torque
-GRF posterior to hip

terminal stance: muscle activity

-anterior fibers of tensor fascia lata to restrain hip extension
-anterior capsule resistance

terminal stance: functional significance

-hip stability
-forward progression (trailing limb posture)
-contralateral step length

preswing: end ROM

hip flexing to 0º
-thigh 10º extension

preswing: torque demand

decreasing external extension torque
-GRF shifts to other foot

preswing: muscle activity

elastic recoil of plantar flexors leading to hip flexion
-adductor longus assisting in frontal plane
-rectus femoris in some people

preswing: functional significance

limb advancement due to hip and knee flexion

initial swing: end ROM

hip flexing to 25º flexion
-thigh to 15º flexion

initial swing: torque demand

negligible external torque

initial swing: muscle activity

hip flexors concentrically
-iliacus
-sartorius
-gracilis
-adductor longus

initial swing: functional significance

limb advancement

mid swing: end ROM

hip flexing to 35º flexion
-thigh to 25º

mid swing: torque demand

external FLEXION due to tibial advancement (interaction torque)

mid swing: muscle activity

hamstrings to control hip flexion and knee extension

mid swing: functional significance

-forward progression via swing limb momentum
-foot clearance

terminal swing: end ROM

hip extending to 30º flexion

terminal swing: torque demand

external flexion decreases to 0

terminal swing: muscle activity

-hamstrings eccentrically to decelerate limb
-hip extensors and hip abductors to prepare for initial contact

terminal swing: functional significance

limb positioned for initial contact