WALKING

Description • Alternating action of the 2 lower extremities• Translatory motion of the body brought about

by rotary motion of some of its parts • 2 parts:

swing support

Description • Kinematics are often described in terms of

strides and steps one strides = one full lower extremity cycle

• Strides : from heel strike to the next heel strike of the same leg

• Stride length: distance covered in one stride• Step: from heel strike of one leg to heel strike of

opposite leg

Description• Chief sources of motion in the swing phase are

gravity and momentum, ballistic movement• Sources of motion for support phase are:

1st half: momentum of forward moving trunk 2nd half: contraction of extensor muscles of

supporting leg

Action of Upper Extremities in Walking• Arm tends to swing in opposition to the legs• This reflex action is usually without obvious

muscular action and serve to balance rotation of the pelvis

• Max flexion of shoulder and elbow occur at heel strike of opposite foot

• Max extension of shoulder and elbow occur at heel strike of same foot

Anatomical Principles1. Alignment

Reduces friction and decreases the likelihood of strain and injury

Stability of weight bearing limb and balance of trunk over this limb are factors in smoothness of gait

2. Unnecessary lateral movement decrease gait economy Excessive trunk rotation with excessive arm motion Pelvis may drop on one side without support Pelvic rotation should be just enough to enable the

leg to move straight forward

Anatomical Principles3. Normal flexibility of the joints reduces resistance

Tendons of 2 joints muscles of lower extremity contribute to economy of muscular action in walking

4. Properly functioning reflexes contribute to a well coordinated, efficient gait Injury, diseases or substances abuse can interfere

with the walking reflexes

Mechanical Principles• Inertia of the body must overcome with every step• Brief restraining action of the forward limb serve

as a brake on the momentum of the trunk in order to not move the center of gravity beyond the base support

• Translatory movement is achieve by alternating the lower extremity rotary movement between the foot (support phase) and hip (swing phase)

Mechanical Principles• Vertical component of ground reaction force

serves to counteract the pull of gravity horizontal component serves to:

Check forward motion heel stroke Produce forward motion during toe off

• Speed is increased by increasing stride length and rate

• Speed is directly related to magnitude of force and direction of application

Mechanical Principles• Efficiency of locomotion partially depend on

friction and ground reaction force• Most efficient gait is one that is timed to

permit pendular motion of the lower extremities

• Alternating loss and recovery of balance