Joint kinetics during gait

GRF

highest during initial contact and pre-swing

travels from posterior to anterior and lateral to medial

as the COM moves closer to the groud

the vGRF decreases

center of pressure

• location of where vGRF is applied to the foot

• COP kinematics are used to as measures of balance and stability

how do internal joint moments/torque and external mpments/torque interact

internal moments produced by the muscles counteract the external moments

sagittal plane ankle movements during gait

• plantar flexion after inital contact, DF in stance, PF at toe off

• intital DF moment at intial contact

• PF moment throughout stance with rapid spike just prior to toe off

sagital plane knee joint moments

• small flexion at inital contact, extending during stance, flexion during swing

• extension moments early in stance and late stance

• flexion moment during stance due to vGRF passing anterior to knee

• flexion moment at terminal swing decelerates extending knee

sagital plane hip joint moments

• flexion at intial contact, extending and extemsion during stance, flexion during swing

• large hip extension moment first part of stance

• hip flexion momneet during second part of stance into swing

• extension moment during end of swing to decelerate thigh

frontal knee joint moment

all abduction monemnts, but raises during intial contact, decreases during stance and a bump at swing phase

KAM adduction moment

high KAM is a factor for medial compartment knee OA

frontal plane hip joint moments

• adduction during initial contact and stance and abduction during swing

• hip abduction moment through stance phase (eccentric)

• peaks at more than one time BW during first part of stance

joint angular power

• considers simultaneous joint kinematics and joint moments/torque

• positive and negative

positive power

energy generated

• joint motion direction is same as direction of internal joint moment

• associated with concentric muscle activation

negative power

energy absorbed

• joint motion direction is opposite direction of internal joint moment

• associated with eccentric muscle activation

sagittal plane ankle joint power

positive, energy generation in pre-swing

sagittal plane knee joint power

negative power, energy absorption in initial contact, pre-swing, and swing

sagittal plane hip joint power

• positive power, energy generation, during stance

• negative power, energy absorption, during terminal stance

frontal plane hip joint power

• negative power, energy absorption, initial contact

• positive power, energy generation, terminal stance

mechanical work

force x displacement

gait involves

the seemless transiotnon of energy absorption and generation

kinematic energy saving strategies during walking

• adding horizontal plane pelvic rotation

  • make limb longer w/o raising COM

• adding sagittal plane ankle rotation

  • get BOS w/o lowering COM

• adding stance phase knee flexion

  • prevents COM moving too much

• adding frontal plane pelvic rotation

  • control how low COM goes