Gait
12
Dr. Mushtaq Alazazi
Definitions
• Locomotion = the act of moving from one
place to the other
• Gait = the manner of walking
Definitions
• Walking = a smooth, highly coordinated,
rhythmical, undulating, reciprocal
movement by which the body moves step
by step in the required direction at the
necessary speed
Gait
• = a form of bipedal locomotion
• The result of a series of rhythmic
alternating movement of the legs (arms,
and trunk) which creates forward
movement of the body
Prerequisites of gait
• Maintenance of the position of the head,
arms, and trunk against gravity
(head, trunk, and arms constitute about 75% of the
total body weight)
• Maintenance of upright posture and balance
• Control of foot movement for safe ground
clearance and gentle heel contact
Gait
• Controlled by the central nervous system
(postural reflex activity)
• Major afferent stimuli is provided by:
¾Tactile impulses from the sole of the foot
¾Proprioceptive impulses (from the lower
limb, trunk, and neck)
Essentials for normal gait
1. The body can stand upright and bear the
weight evenly on both lower limbs
2. The body can alternately maintain weight on
one limb while bringing the other limb forward
Essentials for normal gait
3. The movements necessary for walking
are present and coordinated
(such as movement of trunk and arms)
Gait cycle
• Includes the activities that occur from the
point of initial contact of one lower
extremity to the point at which the same
extremity contacts the ground again
• From heel contact of one foot to the
next heel contact of the same foot
Phases of gait cycle
Stance phase Swing phase
Phases of gait
• In normal walking: approximately 50-60
steps are taken per minute
• The stance phase constitutes 60% of the
gait cycle
• The swing phase constitutes 40% of the
gait cycle
Stance phase
Heel strike Mid-stance Push-off
Stance phase
• Begins at the instance that one extremity
contacts the ground (heel strike) and
continues as long as some portion of the
foot is in contact with the ground
• Ends when the reference foot lifts off the
ground (toe off)
Stance phase
• The “weight bearing” phase
• Provides the stability of the gait
• Necessary for accurate swing phase to
take place
Stance phase
1. Heel strike:
• Position of “double support”: the heel of
the leading stance foot and the toes of the
other foot both on the ground
Stance phase
1. Heel strike:
On the leading stance limb:
¾the hip is flexed (approximately 30-35o)
¾the knee is extended
¾the foot at right angle to the leg
¾the heel in contact with the floor
Stance phase
2. Mid-stance
• Foot flat on the floor
• A stable position
Stance phase
2. Mid-stance
• The body is carried forward over the
stance limb with the hip extending and the
foot gradually placed on the floor
• The knee is in slight knee flexion
Stance phase
3. Push-off
• The heel is raised as the body moves
forward over the stance limb
• The end of the stance phase and
beginning of swing phase
Stance phase
3. Push-off
• The hip is in hyperextension, internal rotation,
and adduction
• The knee is extended
Swing phase
• Begins as soon as the big toe of one limb
leaves the ground (after toe off), and
finishes just prior to heel strike or contact
of the same limb
• The “non-weight bearing” phase
Swing phase
Acceleration Mid-swing Deceleration
Swing phase
1. Acceleration (initial swing):
• Begins once the toe of the swing limb
leaves the ground until the point at which
the swing limb is directly under the body or
at maximum knee flexion
Swing phase
1. Acceleration (initial swing):
• Forward momentum is provided by the
ground reaction to the push-off action
(when the heel is off the ground but the
toes are in strong contact with the ground)
Swing phase
1. Acceleration (initial swing):
• The hip is in flexion and external rotation
• Flexion of the knee is necessary for the
swinging limb to clear the ground as it
moves forward
Swing phase
2. Mid-swing (swing through):
• Begins from maximum knee flexion (when
the swing limb is under the body) until the
swing limb passes the stance limb and the
tibia becomes in a vertical position
Swing phase
3. Deceleration (terminal swing):
• From the point at which the tibia is in a
vertical position to the point just prior to
initial contact
• The momentum slows down as the limb
moves into the stance phase again
Swing phase
3. Deceleration (terminal swing):
• The knee is extending in preparation for
heel strike
• The hip becomes more flexed
Swing phase
3. Deceleration (terminal swing):
• The foot in neutral position
• As the heel touches the ground, the foot
moves into plantar flexion (by the
controlling action of the dorsiflexors)
Muscle activity in walking
• As a principle to identify the acting
muscles and type of muscular
contraction during gait, follow those
steps:
1. If the ground reaction force vector is
anterior to the joint, then the muscles in
the opposite direction are acting to
counterbalance the effect of gravity
Muscle activity in walking
2. Determine the normal joint motion (desired
motion) during each sub-phase of the gait
3. If the joint motion occurs in one direction
(e.g., flexion), and the acting muscles work
in opposite direction (e.g., extension), then
the type of contraction is eccentric
Ground reaction force vector
(GRFV)
• The force that acts on the body as a result of
interaction with the ground
• Equal in magnitude but opposite in direction
to the gravitational force in the erect standing
posture
Ground reaction force vector
(GRFV)
• The GRFV and line of gravity form a common
line in the static erect posture
• But during gait and other dynamic activities,
the line of gravity may not coincide with the
GRFV
Hip joint
• At initial contact (in the stance phase,
heel strike):
¾GRFV passes anterior to the hip joint creating
flexion moment
¾this moment is counterbalanced by the action
of the hip extensors (gluteus maximus and
hamstrings)
¾the desired movement is flexion and the
acting muscles are extensors: so the
contraction is eccentric
Hip joint
• At loading:
¾the contraction changes to be concentric as
the limb moves from flexion to extension
¾the gluteus maximus increases its activity
while the hamstrings reduces its activity
Hip joint
• At mid-stance, terminal stance, and
pre-swing:
– the GRFV passes posterior to the hip joint
creating extension moment
– this extension moment is counterbalanced by
the action of the flexors (iliopsoas, tensor
fascia lata, and rectus femoris)
– the contraction is eccentric at mid-stance and
terminal stance, then it becomes concentric to
initiate the swing phase
Hip joint
• At initial swing:
¾hip flexors (mainly iliopsoas, gracilis,
and sartorius) contract concentrically to
initiate swing
¾the gracilis and sartorius show small
levels of activity at the knee (induce
knee flexion at the same time?)
Hip joint
• At mid-swing:
¾momentum of the flexors effort is the
prime mover
• At terminal swing:
¾the hamstring and gluteus maximus
contract eccentrically to control the
forward progression of the limb
Knee joint
• At initial contact:
¾concentric contraction of quadriceps as
a continuation to their role during
terminal swing
Knee joint
• At loading response (after heel strike):
¾the GRFV passes posterior to the knee
joint creating flexion moment
¾this moment is counterbalanced by the
eccentric action of the quadriceps
¾this action serves as a shock absorber
Knee joint
• At mid-stance and terminal stance:
¾the GRFV passes anterior to the knee
joint, thereby the quadriceps relaxes
Knee joint
• At mid-stance and terminal stance:
• Knee extension stability is provided by 3
mechanisms:
1. swing limb momentum
2. strong plantar flexion provides a stable tibia
over which the femur continues to advance
3. passage of the GRFV anterior to the axis of
the knee joint provides a small passive
extensor force
Knee joint
• At pre-swing:
¾the GRFV passes posterior to the knee
creating flexion moment
¾this moment is counterbalanced by the
eccentric contraction of the quadriceps
(rectus femoris) to prevent excessive
knee flexion
Knee joint
• At initial swing:
¾concentric contraction of knee flexors
(biceps femoris, gracilis, and sartorius)
is necessary to lift the leg and allow for
sufficient foot clearance
Knee joint
• At mid-swing:
¾no muscle action is needed and the limb
advances by the effect of momentum
generated by the continuing hip flexion
Knee joint
• At terminal swing:
¾concentric contraction of quadriceps is
necessary to lift the weight of the tibia
and foot
¾excessive hyperextension is prevented
by the eccentric action of the hamstrings
to control the forward motion of the limb
Ankle joint
• At initial contact:
¾the desired motion is dorsiflexion
produced by the concentric action of the
dorsiflexors
Ankle joint
• At loading response:
¾the GRFV passes posterior to the ankle
creating plantar flexion moment
¾the moment is counterbalanced by the
eccentric action of the dorsiflexors to control
the lowering of the foot to the ground
Ankle joint
• At mid-stance:
¾the GRFV passes anterior to the ankle
creating dorsiflexion moment
¾the moment is counterbalanced by the
eccentric action of the plantarflexors to
restrain the forward movement of the
tibia on the foot
Ankle joint
• At initial swing and mid-swing:
¾the dorsiflexors contract concentrically
for toe clearance and to move the foot
from plantar flexed position at pre-swing
to neutral position in mid-swing
¾the dorsiflexors then act isometrically to
maintain the ankle in neutral position
throughout the swing phase
