732 Running

double float

when neither foot is in contact with the ground

when does double float occur in the running cycle

40-50% and 90-100% both in swing phase

foot strike

initial contact with the ground that can be on rearfoot, midfoot, and forefoot

as speed increases, what happens to foot strike

transitions to a forefoot strike

running stance phase

40% or less

running swing phase

60% but could vary depending on how much time spent in stance phase

weight acceptance or absorption

occurs between initial contact and foot flat

stance limb must accept and absorb weight of body

propulsion

the muscles of the lower extremity during heel off and toe off generate mechanical energy to propel the body forward

in early swing

the knee reaches maximal formation. this shortens the limb decreasing the moment of inertia, making it easier to move the limb forward

in late swing

the limb prepares for the next foot strike

as running speed increases

• stride length increases

• stride time decreases

• step width decreases

foot angle with running

between 4-9°

in regard to joint kinematics- as speed increases

joint range of motion increases

hip flexion ROM needed for running

65°

hip extension ROM needed for running

20°

knee flexion ROM needed for running

130°

knee extension ROM needed for running

25° (flexion)

ankle dorsiflexion ROM needed for running

10-25°

ankle plantarflexion ROM needed for running

30°

pelvis in the sagittal plane during running

in a position of anterior tilt (total motion ~5°)

hip in the sagittal plane during running

peak hip flexion occurs around mid swing

hip extension occurs in prep for next stance phase

knee in the sagittal plane during running

flexes during both stance and swing

does not reach full extension

peak knee flexion (100-120°) occurs during swing

what is the benefit of increasing knee flexion during swing while running

bring’s the limb center of gravity closer to the trunk reducing moment of inertia making it easier to move

ankle in the sagittal plane during running

initial contact with rearfoot strike occurs at 10° of dorsiflexion

ankle dorsiflexes through midstance

in terminal stance, rapid plantarflexion to propel forward

during swing ankle slowly dorsiflexes

pelvis and hip in the frontal plane during running

swing side of the pelvis is lower than the stance side

hip adduction during stance

hip abduction during swing

knee in the frontal plane during running

minimal movement

subtalar joint in the frontal plane during running

3° of inversion at initial contact

ranges from 5inversion-10°eversion

joint everts (pronates) through initial stance and then inverts (supinates) in terminal stance

pelvis in the transverse plane during running

during stance there is external rotation (CW)

during swing, there is internal rotation (CCW)

ASIS anterior to stance limb at initial contact

hip in the transverse plane during running

10° of motion of internal and external rotation across the gait cycle

arm swing during running

as one leg swings (hip flexion) the ipsilateral arm swings backward (shoulder extension)

arm swing and momentum

arm swing offsets the angular momentum generated by the lower extremity and helps us remain facing forward

elbows during running

typically held around 90° of flexion

center of mass and running

COM is lower because we stay in a more flexed position

muscle activity in stance phase

muscles are more likely to be eccentrically working during absorption and concentrically working during propulsion

muscle activity in terminal swing

knee flexors eccentrically contract to control knee extension

vertical ground reaction forces relative to body weight

impact peak- 2x body weight

active peak-2.2x body weight

vertical ground reaction forces occurring while running

will increase with increasing speed

maximum GRF occurs during heel off and toe off

anterior-posterior GRF

posterior directed force- braking impulse

anterior directed force- propulsive impulse

rearfoot strike

initial contact on the posterior 1/3 of foot

midfoot strike

initial contact with the mid portion of the foot

forefoot strike

initial contact with the ball of the foot