Exam 1 lecture: gait cycle Flashcards
what is the line of progression?
best fit straight line b/t 2 contacts
what is step, step length?
distance b/t 2 successive imprints (R –> L)
not a full gait cycle
what is stride, stride length?
distance b/t a common spot on both feet
may not be the same from R –> L and L –> R
what is a full gait cycle?
both limbs complete 1 “stride”
what is a stride?
what happens from one imprint to the next on the same limb
not technically a gait cycle; one limb has undergone one full cycle, other is out of phase
how much foot flare is considered acceptable in a normal walking gait?
5˚ - 7˚
what happens to foot flare as cadence (speed) increases?
it decreases
effects of too much toe out
increased stress on lower extremity –> injury
inefficient –> more muscle work, decreased stride length
which is more common: toe in or toe out?
toe out
what are the 2 phases of the gait cycle
swing and stance
in RUNNING, how much of the gait cycle is swing? how much is stance?
60% swing, 40% stance
in WALKING, how much of the gait cycle is swing? how much is stance?
40% swing, 60% stance
what is stance phase?
foot is in contact w/ground; closed kinetic chain
what is swing phase?
foot is not in contact w/ground: open kinetic chain
when the speed of the gait cycle increases, there is an increase in these forces: (6)
compression distraction torsion shear bending inertia
why does compression force increase as speed increases?
increased speed of hitting the ground
how does torsion increase as speed increases?
increased body twisting
how can torsion cause injury?
when torsion increases beyond normal limits, tissue begins to break down –> increased demand on muscles and bones –> failure
what are some problems that can cause increased torsion?
too much foot flare, too much pronation
which force is most damaging?
shear
how can bending help prevent injury?
changes the forces the body has to deal with, takes away initial compression forces as foot hits the ground
how does muscle control help to prevent injury?
muscles interacting w/ground to act as shock absorbers contract more to control increased inertia w/increased velocity; convert energy into managable motions
what increases injury risk?
increased ground reaction forces, increased muscle activity (esp. eccentrically)
what are the 3 divisions of stance phase?
contact/foot strike
midstance
takeoff
t or f: toe off is the same as take off
false. toe off is at the very end of take off.
what is a closed kinetic chain?
distal end of limb is connected to a fixed object (aka the ground)
what is it called when both feet are on the ground in different parts of stance phase?
double support
this only occurs during WALKING
what is it called when both feet are in the air in different parts of swing phase?
float
this only occurs during RUNNING
why is walking less injurious than running?
amount of muscle contraction running takes to control the action
t or f: during contact, the foot lands directly under the center of gravity.
false. the foot lands ahead of the center of gravity.
what are the important functions of contact (phase)?
absorb shock
adapt to ground forces
what is pronation?
medial rotation of the foot
t or f: the foot can be pronating in a supinated position or pronating in a pronated position.
true
what are the 2 important joints of pronation?
subtalar and midtarsal jts.
what is it called when the weight begins to transfer forward on the foot?
heel rocker
what is the calcaneus doing in pronation?
eversion, dorsiflexion relative to talus
t or f: talus dorsiflexes only after pronation has begun.
false. the talus dorsiflexes before pronation of foot occurs., then begins plantar flexion when pronation begins.
how does the foot land when walking at contact?
2˚ supinated
what initiates pronation of the foot?
plantar flexion of the talus
what is the ideal pronation ROM?
6˚ - 10˚
what is the clinical normal pronation ROM?
5˚ - 15˚
what happens to the tibia and femur during contact?
internal rotation
why is it important the the tibia and femur internally rotate?
reduces torque (moves in the same direction as foot; opposite directions would create torsion)
which 2 types of stresses are most deleterious to connective tissue?
shear, torsion
why is torsion so damaging?
wears down collagen fibers quickly
how to calcaneus and talus motion differ?
talus moves w/leg, not at ankle
calcaneus moves w/foot
when is rearfoot strike utilized?
walking, jogging/slow running
when is forefoot strike utilized?
fast running
what muscle eccentrically controls plantar flexion at the ankle joint and pronation of the foot?
tibialis anterior
when does the foot/talus plantar flex during rearfoot strike?
after the heel initially strikes the ground
what large thigh msl does the tibialis anterior assist?
quadriceps
in forefoot strike, when does the foot dorsiflex?
after the metatarsal heads first strike the ground - heel moves toward ground
initial foot strike is pronated or supinated?
2˚ - 4˚supinated
t or f: pronation occurs much faster during forefoot strike than rearfoot strike
true.
what muscles control dorsiflexion?
gastroc-soleus
what muscles control pronation?
tibialis anterior and posterior
during midstance, where is the center of gravity?
directly over the stance limb
what position is the foot in during midstance?
pronated
t or f: the foot is pronating during midstance
false. the foot is pronated, but pronation should be done by the time midstance begins
what is the foot doing (i.e. what motion)?
supinating (a shift back toward neutral)
when does most pronation occur?
contact
how long does midstance last?
from foot flat to heel lift when walking
what is the ankle rocker?
center of gravity/leg continues to move forward w/foot planted on the ground –> ankle undergoes rocking motion
what are the leg and thigh doing during midstance? why?
externally rotating to reduce torque
when should heel lift occur?
after the swing limb passes the stance limb;
when walking: heel lift same time as heel strike of opposite limb.
why might the heel lift early?
tight stance limb gastrocsoleus/achilles tendon
where is the center of gravity during take off?
anterior to stance foot
what muscles lift the heel?
gastrocsoleus
what does the calcaneus do during take off?
inverts to complete rearfoot supination
what muscle inverts the calcaneus?
tibialis posterior
when is the foot the most rigid?
during supination - at take off (except toes)
why are the toes not rigid during take off?
to prevent injury
what allows the foot to roll onto the ball of the foot?
passive toe extension
what happens to the plantar fascia when toes extend? why?
plantar fascia tenses to help maintain arch
hallux is particularly important for this
what is the metatarsal break?
oblique angle of metatarsal heads
what is toe off?
the very end of take off
t or f: supination occurs at end of take off.
false. slight pronation occurs at end of take off
why does the foot pronate at the end of take off?
to increase load bearing on 1st & 2nd metatarsals - 4th and 5th are too weak to handle weight of take off
which ray is most important to forefoot control just before take off?
1st ray
what muscles are important to 1st ray stabilization & control of pronation just before toe off? (5)
peroneus longus flexor hallucis longus flexor hallucis brevis adductor hallucis abductor hallucis
what happens to the tibia and femur during take off?
externally rotate
what happens if there is too much pronation late in take off?
late pronation –> foot tries to medially rotate, leg and body try to laterally rotate –> torsion –> stress fractures of tibia, pelvis, femur, etc., stress on jts, may affect spine
t or f: all flat feet over pronate
false.
what does peroneus longus do during take off?
lifts cuboid and lateral foot
depresses & plantar flexes 1st ray
maintains contact b/t ground and 1st metatarsal head
what gives peroneus longus the most leverage? (pronated vs. supinated foot)
supinated foot
what is a possible cause of posterior shin splints?
excessive pronation at end of stance phase –> inhibited peroneus longus –> tibialis ant. & post. fatigue
what are the 3 divisions of swing phase?
initial swing
midswing
terminal swing
what division of swing phase is most prominent in walking?
midswing
what division(s) of swing phase is accentuated in running?
initial and terminal swing
what does the tibia do during initial swing?
internally rotates
what does the hip do during initial swing?
extends and externally rotates
what muscles eccentrically decelerate @ the hip and knee?
hip flexors
t or f: there is more initial swing in walking than there is in running.
false. initial swing is drastically increased during running.
what is the problem with over-striding?
more stretch on hip flexors –> more potential for strain injuries
when in initial swing, what is the opposite limb doing when running vs. when walking?
running: terminal swing
walking: end of foot strike
what is the bowling ball effect?
momentum pulls body forward when leg swings forward
hip flexors very important for this
when does midswing start?
when leg starts swinging forward
at the end of midswing, what muscles eccentrically slow the forward swinging limb at the hip and knee?
gluteals and hamstrings
what position is the foot in during midswing?
neutral/slightly dorsiflexed (prevent foot drag)
does the hip internally or externally rotate during midswing?
internally rotate
when does terminal swing begin?
when foot begins moving backward (toward ground to begin heel strike)
what muscles are responsible for terminal swing?
hip extensors and knee flexors
t or f: foot flare and amt of rearfoot inversion at next foot strike is determined during swing phase
true.
when are hamstrings at greatest tension?
terminal swing
what factors can increase risk of hamstring injury?
decreased flexibility and strength of hamstrings
t or f: foot rotates in same direction as leg and thigh
true. this is to reduce torsion on ankle jts.
what could change the direction of rotation in the foot?
over pronation
