GAIT Cycle

Stride length

How far the same foot moves in each stride

• Right foot to right foot

• Left foot to left foot

Step length

Distance from point of initial contact on one foot to the point of initial contact of the other foot

• So from one heel to the next

Step width 

Distance between centre of one foot’s heel and the centre of the other foot’s heel

Cadence

 The number of steps per minute

• Strides per minute OR steps per minute 

Walking speed equation

= stride length divided by stride time

Parallax error

Apparent displacement of an object due to a change in the observer’s point of view - dependent on distance and angle from field view  

What is the first prerequisite of gait

Stability in stance

What is the second prerequisite of gait

Sufficient foot clearance in swing

What is the third prerequisite of gait

Appropriate swing phase prepositioning of foot

What is the fourth prerequisite of gait

Adequate step length

What is the fifth prerequisite of gait

Energy conservation 

What % of gait cycle does stance phase make up

60%

What % of gait cycle does swing phase make up

40%

Stance phase: Heel strike

Initial contact of heel on ground

Stance phase: Loading response

Foot flattens (shock absorption), weight transfers to this limb

Stance phase: Mid stance

Body weight completely transferred to supporting limb, single leg support

Stance phase: Terminal stance

As other foot hits ground heel of foot comes off ground

Stance phase: Pre Swing

Toes push off and weight transfers to other foot

Swing phase: Initial Swing

Toe off, foot lifts off floor and hip flexes to propel leg forward

Swing phase: Mid Swing

Leg swings beneath body allowing for foot clearance on the ground

Swing phase: Terminal Swing

Leg decelerates, tibia becomes vertical, prepare for initial contact with ground again

What phase of gait do ankle rockers occur?

ONLY in stance not in swing

1st ankle rocker

Heel strikes onto ground

• Controlled eccentrically by tibialis anterior

• Tibia at 90 degrees to ankle (neutral not dorsiflexed)

What gait cycle phase does ankle rocker 1 occur?

In the initial contact phase (to loading phase)

2nd ankle rocker

Tibia moves from reclined to inclined position

• Controlled mainly by soleus + gastrocnemius

What gait cycle phase does ankle rocker 2 occur?

In mid stance

3rd ankle rocker

Heel lifts off

• Controlled by concentric calf (mainly gastrocnemius)

What gait cycle phase does ankle rocker 3 occur?

In terminal stance (to pre swing push off)