DPT 642: Gait Cycle & Clinical Implications

Locomotion

way in which an animal moves about, e.g., swimming, flying, crawling, or climbing, among others.

Gait

a particular way or manner of moving on foot: can take many forms such as running, skipping, or marching, but the most commonly employed is walking.

Walking

characterized by symmetrical, alternating movement of the two lower limbs with a phase lag of 0.5.

Ambulation

To walk from place to place; move about. Specific to PT - also includes wheeling/driving oneself by wheelchair.

Progression

movement in the desired direction.

Stability

not falling down.

Adaptation

accommodating or avoiding obstacles.

Normal gait

the result of highly efficient motor control responses, programmed at the spinal cord level.

Gait efficiency

depends on the amount of available joint mobility & muscle activity that is selective in timing & intensity.

Stride

initial contact of 1 foot to initial contact of same foot.

Step

completion of a right or left step (e.g., heel strike R to heel strike L).

Stride length

distance (AP) b/w successive heel contacts of same foot. avg = 144 cm (4.5').

Step length

distance (AP) b/w successive heel contacts of the opposite feet; avg= 72 cm (28"); Normal range: 70-80 cm.

Step width

lateral distance b/w feet, measured (ML) b/w two heel centers; avg = 8-10 cm.

Foot angle

Angle b/w long axis of foot (heel center to 2nd MT) & line of forward progression of body. Avg = 5°-7°.

Cadence

# of steps per minute. Normal range: 1.87 steps/sec; 110 steps/min.

Stride time

time (s) for a full gait cycle: from initial contact of 1 foot to initial contact of same foot. Usually takes slightly > 1 sec.

Step time

time (s) for the completion of a right or left step (e.g., heel strike R to heel strike L).

Speed

distance/time (in m/s). Most spatial, temporal, kinetic & kinematic variables depend on speed.

Normal gait speed

1.37 m/s (3 mph). Reported as the best functional measure of one's ability to walk.

Velocity

change in position (displacement)/time (in m/s). Has magnitude & direction.

Gait Speed

step length * cadence

Gait Cycle

Begins with heel contact of 1 limb (0% of cycle) & ends with next heel contact of that same limb (100%).

Stance Phase

Period of time when foot is touching the ground (60% of gait cycle).

Swing Phase

Period of time when foot is swinging forward and not touching the ground (40% of gait cycle).

Single-limb Support

Time when only 1 foot is in contact with the ground: 80% of cycle.

Double-limb Support

Time when both feet are in contact with the ground simultaneously (20% of cycle).

Heel-strike (Initial Contact)

Instant heel comes in contact with ground; begins period of double limb support. (0%)

Foot Flat (FF)

Instant entire plantar surface of foot comes in contact with ground. (8%)

Loading Response

Period of weight acceptance by LE, initiating contact with ground. Body mass transferred from 1 limb to other. (0 - 10%)

Contralateral Toe Off

At 10% - instant of opposite toe off; begins single limb support phase.

Mid-stance (MS)

Instant COM passes directly in line with supporting limb - GT is vertically above midpoint of supporting foot in sagittal plane.

Heel-off (HO)

Instant heel comes off ground. (40%)

Terminal Stance

Period - begins when heel rises, ends at contra-lateral HC. (40 - 50%)

Pre-swing

Period from foot contact of contralateral limb to toe-off of ipsilateral foot; corresponds to 2nd double limb support. (50-60%)

Toe-off (TO)

Instant toes come off the ground. (60%)

Early or Initial Swing

Immediately after toe-off to mid-swing. (60%-75%)

Mid-swing

Midstance event of opposite LE; foot of the swing leg passes next to the foot of the stance leg. (75%-85%).

Late or Terminal Swing

From mid-swing to just prior to initial contact with the ground. (85%-100%)

HAT

(head, arms, trunk)

HAT Functions

1. postural stability 2. HAT alignment determines what muscle actions occur throughout the system.

Lower Limb & Pelvic Functions

1. provides propulsive force

Lower Limb & Pelvic Functions

Provides propulsive force, maintains upright stability, shock absorption, and energy conservation.

Center of Mass (COM)

Is approximately anterior to S2 vertebrae.

Vertical Displacement of COM

Is approximately 5 cm during gait.

Medial-Lateral Displacement

Is approximately 4 cm, with the foot placed slightly lateral to COM to control side-to-side movement.

Acceleration

Change in velocity/time, measured in m/s².

Deceleration

The reduction of velocity of COM from heel strike to mid stance.

Potential Energy at Mid-Stance

Is highest, while kinetic energy is lowest.

Kinetic Energy during Double Limb Support

Is highest, while potential energy is lowest.

Initial Contact (Heel Strike)

Moment foot strikes the ground.

Hip ROM at Initial Contact

Is 25-30° flexion, maintained from terminal swing.

Pelvic ROM at Initial Contact

Is nearly neutral tilt with ipsilateral anterior rotation.

Ground Reaction Force (GRF) at Initial Contact (Hip)

Is anterior.

Muscle Activity at Initial Contact (Hip)

Glut max and hamstrings decelerate forward limb, preventing 'jackknifing'.

Knee ROM at Initial Contact

Is initially 5° flexion.

GRF at Initial Contact (Knee)

Is posterior.

Muscle Activity at Initial Contact (Knee)

Quads concentrically contract to extend the knee, with hamstrings co-activation for stability.

Ankle ROM at Initial Contact

Is neutral or slight plantarflexion (0°-5°) with slight STJ supination (2°-3° inversion).

GRF at Initial Contact (Ankle)

Is posterior.

Muscle Activity at Initial Contact (Ankle)

Dorsiflexors eccentrically contract to decelerate passive ankle plantarflexion.

Hip ROM at Loading Response

Is 25° flexion, starting to extend and adduct.

Pelvic ROM at Loading Response

Is slight posterior tilt with left pelvis dropping and right pelvis elevating.

GRF at Loading Response (Hip)

Is anterior.

Muscle Activity at Loading Response (Hip)

Glut max and hamstrings eccentrically control flexion torque, then begin to concentrically extend the hip.

Glut medius, minimus, TFL

Eccentrically control pelvic drop on swing side.

Hip ER's

Eccentrically control IR of the lower limb in early stance.

Knee ROM

15°-20° flexion, then begins to extend.

Knee GRF

Posterior.

Knee External torque

Rapid flexion torque caused by body being behind foot.

Knee Muscle activity

Major burst of quadriceps activity eccentrically controls knee flexion in 1st 10% of gait cycle.

Knee Co-contraction

HS co-contract with quads to stabilize the knee.

Ankle ROM

5°-10° of rapid plantarflexion.

Ankle GRF

Posterior.

Ankle External torque

Plantarflexor torque forces the foot to the floor.

Ankle Muscle activity

Dorsiflexors (tib anterior) counteract PF torque.

Tib posterior

Decelerates foot pronation.

Fibularis longus & brevis

Contribute to PF & counteract strong inversion created by tib posterior and deep posterior muscles.

Midstance

Point at which the body passes over the supporting limb.

Hip ROM in Midstance

Hip extends to neutral (0°).

Pelvic ROM in Midstance

Ipsilat pelvis starts to rotate posteriorly, anteriorly tilt, L pelvic drop reaches maximum.

Hip Muscle activity in Midstance

Glut max extends the hip until end of midstance.

Knee ROM in Midstance

Knee continues to extend (0°).

Knee GRF in Midstance

Anterior.

Knee External torque in Midstance

Extensor torque created by muscle activity and forward momentum of the contralateral limb.

Knee Muscle activity in Midstance

Quadriceps contract concentrically to extend the knee and support body weight.

Ankle ROM in Midstance

5° dorsiflexion as body glides over the stable foot.

Ankle GRF in Midstance

Anterior.

Ankle External torque in Midstance

Marked dorsiflexion torque.

Terminal Stance Hip ROM

15°-20° extension.

Terminal Stance Pelvic ROM

5° backward (posterior) rotation and slight anterior tilt.

Terminal Stance Knee ROM

Knee reaches maximal extension (0°).

Terminal Stance Knee GRF

Anterior.

Terminal Stance Ankle ROM

10° dorsiflexion (at max when knee is extended).

Tib anterior & plantarflexors

Supinate (invert) foot; controlled by fibularis longus & brevis.

Fibularis longus

Holds 1st MT rigidly to ground so foot can act as rigid lever.

Tib posterior

Supinates foot.

Intrinsics

Stabilize foot, raise MLA.

EDL & EDH

Co-contract with PF's for stability (PF activity at this time = 70% of MVIC!).

PRE-SWING

Phase known as 'push-off'.