3.8 Gait

One gait cycle begins and ends with

heel strike of same foot

Stance phase

heel strike to toe off (60%)

Swing phase

toe off to heel strike (40%)

The gait (walking) cycle involves mostly

gravity and momentum (like a pendulum), there is very little muscle exertion

Period of activity for gluteus medius and minimus

first ¾ of support phase

Function of gluteus medius and minimus during gait

keeps opposite side of pelvis from dropping (isometric contraction)

Gait change if gluteus medius or minimus is damaged

Trendelenburg gait

Trendelenburg gait

opposite side of pelvis drops, lateral flexion of trunk towards same side to maintain balance over foot

Period of activity for gluteus maximus

a short period following heel strike

Function of gluteus maximus during gait

keeps trunk from bending forward (due to momentum) following heel strike (isometric contraction)

Gait change if gluteus maximus is damaged

slight backwards lean at heel strike to keep body weight behind hips

Period of activity for vastus lateralis/medialis/intermedius

Function of vastus lateralis/medialis/intermedius during gait

prevents slightly flexed knee from collapsing under body weight (isometric contraction)

Gait change if vastus lateralis/medialis/intermedius is damaged

knee locks, use momentum to swing leg into full extension before putting weight on it, lean forwards to keep body weight in front of knee

Period of activity for hamstrings

end of swing and through heel strike

Function of hamstrings during gait

decelerates the thigh at end of swing phase (eccentric contraction. Keeps trunk from bending forward (due to momentum) following heel strike

Gait changes if hamstrings are damaged

short steps that do not involve large swing phase. Backwards lean at heel strike

Period of activity for iliopsoas and adductors

shortly before to shortly after toe off

Function of iliopsoas and adductors during gait

slows down hip extension at end of support phase (eccentric contraction), starts hip flexion for swing phase (concentric contraction)

Gait change if iliopsoas and adductors were damaged

forward swing includes some abduction because if has to use anterior fibers of gluteus medius/minimus and tensor fasciae latae

Period of activity for rectus femoris

just before toe off

Function during gait for rectus femoris

slows down hip extension at end of support phase (eccentric contraction)

Period of activity for sartorius

at toe off and early swing

Function of sartorius during gait

flexes hip and knee, primarily at fast speeds

Gait change if sartorius is damaged

none

Period of activity for gastrocnemius and soleus

second ½ of support phase

Function of gastrocnemius and soleus during gait

prevents ankle from collapsing into dorsiflexion as body weight passes in front of ankle, gives a little forward push at toe off

Gait change if gastrocnemius and soleus are damaged

short steps to keep body weight back on heels, or walk toed out so that the fibularis longus/brevis can be used instead

Period of activity for the anterior leg muscles

from toe off to just after heel strike

Function of anterior leg muscles during gait

holds toes off ground during swing phase (concentric/isometric contraction), slows forefoot from slapping down after heel strike (eccentric contraction)

Gait change if anterior leg muscles are damaged

high stepping gait with excess flexion at hip and knee during swing phase, foot slap (noticeable sound of forefoot hitting floor)

Period of activity for fibularis longus/brevis

end of support phase, as weight is being moved onto ball of big toe

Function of fibularis longus/brevis during gait

everts to oppose the inverting force applied by the ground to the ball of big toe (isometric contraction)

Gait change if fibularis longus/brevis damaged

none apparent, person will shift weight to the lateral ball of foot instead and use triceps surae to oppose the ground force

Period of activity for quadratus plantae and flexor digitorum brevis

very end of support phase

Function of quadratus plantae and flexor digitorum brevis

stabilizes arches of foot, controls rate of metatarsophalangeal dorsiflexion