running and injury – GRF
- high GRF over short period of time
- vertical ~ 250% of body weight
- AP 40-50% of BW
- ML 10-15% of BW
incidence up to 79%
1 cause of injury in running
history of previous injury
also sleep, nutrition, new runners, lack of rest
running alone does not deliver suffiecient doses of deliverate practice to elicit
sub-cortical changes to movement patterns
volume doesn’t matter as much as skill
running alone does not deliver suffiecient doses of deliverate practice to elicit
sub-cortical changes to movement patterns
volume doesn’t matter as much as skill
task related determinants of running
- shock absorption
- adequate pelvic/trunk alignment and stability
- adequate limb alignment and stability
- adequate foot alignment and stability
running stride cycle - phases
- stance phase variable
- stance phase also down as speed increases
kinematics
where is the joint, angles
kinetics
what forces on the body, what is the torque
big toe kinematics
- first MTP extension important in propulsion
- highest right at TSt/toe off (30 degrees)
kinetics - vertical forces
- impact peak: can be changed, immediate compression, care more about slope and speed (1.5x BW)
- active peak: in middle of loading, due to GRF, cannot change (2.5x BW)
kinetics - AP forces
- braking pulse: posterior directed force as foot hits ground, increases the farther foot is ahead - want shorter stride
- propulsive force: swing phase
kinetics - ML forces
- most variable due to where foot is compared to COM (abd vs add)
joint torque and power - absorption and generation
- energy absoprtion - eccentric
- energy generation - concentric
path of center of pressure in foot
- lateral landing
- medial push-off
- no matter what foot strike
what can you see in side view running gait analysis
- foot strike pattern: foot inclination at loading response
- tibia angle at loading response
- knee flexion during stance
- hip extension during late stance
- trunk lean
- overstride
- vertical displacement
hip flexion in swing?
foot strike
side view
- forefoot
- midfoot
- rear foot
- shoe runners: 75-80% rearfoot strikers, 1% forefoot
- barefoot runners: 59% forefoot, 20% rearfoot
why do we care about foot strike
- can change impact peak
- but this might also be due to shoes/terrain
changing foot strike patterns
- one technique vs another does not change force or pressure but may change joint impact or demand if not their normal
foot inclination angle
- rearfoot strike = higher foot inclincation angle
tibia angle
- extended, vertical, or flexed
knee flexion during stance
- need 20 degrees on impact > extend > 40-45 degrees in stance (less with FFS)
- increases absorption, decreases joint compression
- post-op patients have less flexion
hip extension late stance
- can be impacted due to joint ROM, flexibility, lumbar extension, movement coordiantion
trunk lean
- at mid stance
- angle of trunk and tibia should be close or same
- not just leaning through waist but from ankle
tibia and trunk angle
- more upright trunk - higher patellofemoral joint stress
- more forward lean trunk - less patellofemoral joint stress with 8-10 degree lean
