DPT 642: Gait

locomotion

what in which an animal moves about

can include swimming, flying crawling, wheelchair, etc

walking

most common form of locomotion and gait

gait

a particular way of moving on foot

can be running, skipping, marching, etc

walking

symmetrical, alternating movement of the 2 lower limbs

0.5 or 1/2

what is the phase lag for walking?

the other leg is always 50% behind the other one

explain the 0.5 phase lag?

ambulation

to walk/move about from place to place. this term is specific to PT and may include wheeling/driving oneself in a wheelchair

progression

movement in the desired direction (usually forward)

stability

not falling down

adaptation

accomodating or avoid obstacles. involves going around or over things, changing speed, etc.

sensory and motor functions

gait involves a complex interaction between these 2 functions, along with coordinated muscle & joint interactions

coordination, balace, kinesthesia, proprioception, joint integrity and muscle forces

what are some things required for gait, which allows body way to be transferred from one leg to another?

falling

gait is a series of what?

sagittal

during gait, each step catches the body from falling. which plane does this occur in?

frontal

during gait, the center of mass constantly shifts from leg, to midline, and then to the other leg. which plane does this occur in?

leaning foward

how is gait initiated?

stride

initial contact of 1 foot to initial contact of the same foot

step

completion of a right OR left step (heel toe, heel toe)

2

1 stride = ___ steps

stride length

distance between successive heel contact of same foot- distance of 1 stride

step length

distance between successive heel contact of the opposite foot- heel contact of 1 foor to heel contact of the next foot

step width

lateral distance between feet- measured M/L between 2 centers

foot angle

toe-out... angle between long axis of foot & line of forward progression of the body

cadence

# of steps per minute... AKA step rate

stride time

time for a full gait cycle.

initial contact of 1 foot to the initial contact of the same foot

step time

time for the completion of a right or left step

1/step time

what is the formula for step rate?

speed

distance/time

most spatial temporal, kinetic & kinematic variables depend on this, therefore will usually change as this increases or decreases

1.37 m/s or 3 mph

normal gait speed

velocity

change in position. consists of magnitude and direction- rarely constant (displacement/time)

step length x cadence

gait speed = ?

longer stride/step and faster cadence

what are 2 ways you can increase gait speed?

gait cycle

begins with heel contact of 1 limb & ends with heel contact of the same limb

stance phase

period of time when foot is touching the ground

60%

stance phance accounts for how much of the gait cycle?

swing phase

period of time when the foot is swinging forward and not touching the ground

40%

swing phance accounts for how much of the gait cycle?

gait analysis

consider from the point of view of 1 LE at a time. Then, consider it from the POV of the other LE

it involves a brief period of flight

how is running different from walking?

single limb support

time when only 1 foot is in contact with the ground

double limb support

Time when both feet are in contact with the ground simultaneously

80%

single limb support makes up ____% of the cycle

20%

double limb support makes up ____% of the cycle

heel strike or initial contact

instant that the heel comes in contact with the ground

double limb support

heel strike/initial contact marks the beginning of what?

foot flat

instant the entire plantar surface of foot comes in contact with the ground

The period of weight acceptance by the lower extremity.

What is the loading response?

Body mass is transferred from one limb to the other, back of foot begins to rise from the ground

What happens during the loading response?

contralateral toe off

instant of opposite toe off. begins single limb supprot phase

What occurs during mid-stance in relation to the center of mass (COM)?

The instant COM passes directly in line with the supporting limb.

Where is the greater trochanter positioned during mid-stance?

The greater trochanter is vertically above the midpoint of the supporting foot in the sagittal plane.

What happens to the opposite lower extremity during mid-stance?

The opposite lower extremity is in the swing phase and passes the leg in mid-stance.

What is the foot position during mid-stance?

The feet are side by side.

What does mid-stance refer to in terms of time duration?

It can also refer to a longer period of time around the mid-stance event.

early or initial swing

immediately after toe-off to mid-swing

mid-swing

midstance ecent of opposite LE; foot of the swing leg passes next to the foot of the stance leg

late or terminal swing

from midswing to just prior to initial contact with the ground

HAT functions

involves postural stability. alignment determines what muscle actions occur throughout the system

head, arms and trunk

lower limb and pelvic functions

provides propulsive force, maintains upright stability, and acts as shock absorbers and energy conservers

anterior to S2

center of mass is located where?

5cm

what is the average vertical discplacement of COM during gait?

single limb support, mid-stance & swing

COM is highest during when?

double limb support

COM is lowest during when?

4cm

what is the average medial-lateral discplacement of COM during gait?

acceleration

change in velocity over time

heel strike to mid-stance

deceleration occurs from ____ to _____

mid-stance to contralateral heel strike

acceleration occurs from ____ to ____

acceleration

are we more unstable during deceleration or acceleration?

This positioning causes the body to "slow down" or decelerate.

What happens when the supporting limb is ahead of the body's center of mass, or when the center of mass is behind the support limb?

This causes the body to "speed up" or accelerate, providing forward momentum.

What happens when the supporting limb is behind the body's center of mass, or when the center of mass is ahead of the support limb?

25-30° of hip flexion

What is the hip range of motion (ROM) at initial contact during gait?

Nearly neutral tilt with ipsilateral anterior rotation.

What is the position of the pelvis at initial contact?

GRF is anterior, creating a flexion torque.

Where is the ground reaction force (GRF) located relative to the hip at initial contact, and what external torque does this create?

Gluteus maximus and hamstrings decelerate the forward limb to prepare for loading. Adductor magnus co-contracts with extensors and abductors to stabilize the hip and assist with hip extension.

Which muscles are active at the hip during initial contact and what are their functions?

They control the lowering of the pelvis on the swing limb side.

What role do the contralateral gluteus medius and minimus play during this phase?

Right erector spinae turn on to control forward angular trunk momentum.

What spinal muscles activate slightly before heel contact, and why?

Approximately 5° of knee flexion.

What is the knee joint ROM at initial contact?

GRF is posterior, producing a flexor torque.

Where is the GRF relative to the knee at initial contact, and what external torque does it create?

Quadriceps concentrically contract to extend knee.

Hamstrings co-activation stabilizes the knee

Which muscles are active at the knee during initial contact and what are their roles?

Neutral or slight plantarflexion/dorsiflexion, between 0-5°

What is the ankle joint ROM at initial contact?