Understanding Gait Cycle Phases

• Gait defines the manner or style of walking.
• Gait cycle signifies the time from when the heel of one foot touches the ground to when it touches the ground again.
• The gait cycle is divided into the stance phase (60%) and the swing phase (40%).
• Traditional gait terminology names phases by events and critical actions, such as heel strike, foot flat, heel off, and toe off.
• Rancho Los Amigos (RLA) terminology names gait phases with functional tasks like initial contact, loading response, and terminal stance.

Stance Phase Subdivisions

• Initial contact accounts for 0-2% of the gait cycle, with the contralateral limb in end terminal stance.
• Loading response makes up 2-10% of the cycle and the opposite limb is in pre-swing.
• Midstance is 10-30% of the cycle; the contralateral limb is in mid-swing.
• Terminal stance covers 30-50%, the opposite limb in terminal swing.
• Pre-swing is 50-60%, with the contralateral limb in initial contact and loading response.

Swing Phase Subdivisions

• Initial swing represents 60-73% of the gait cycle, with the contralateral limb in early midstance.
• Mid swing corresponds to 73-87%, while the contralateral limb is in late midstance.
• Terminal swing occurs during 87-100% of the gait cycle and the opposite limb is in terminal stance.
• In normal walking, one gait cycle lasts 1 second and covers a length of 1.4 meters.
• Double limb support is the time when both feet are in stance, contacting the ground.
• Total double support comprises 20% of the gait cycle, with 10% at the beginning and 10% at the end of the stance phase.
• Single limb support periods encompass the middle 40% of the stance phase plus the swing phase.
• Double support duration varies inversely with walking speed.

Functional Tasks of Gait

• Initial contact is when the foot first touches the ground, typically with the heel.
• Loading response is when the foot lowers to the ground until the entire plantar surface is in contact.
• Mid stance is when the body's center of mass (COM) moves directly over the foot, with the head, arms and trunk (HAT) aligned over the single limb.
• Terminal stance is when the heel lifts off the floor and the limb advances over the forefoot.
• Pre-swing is when the toes leave the ground.
• The foot is no longer in contact with the floor during initial swing, and also lifts and flexes from the knee to shorten the limb.
• In mid-swing, the limb is anterior to the HAT, and the tibia is perpendicular to the floor.
• During terminal swing, the leg prepares to make initial contact with the ground and also occurs in terminal swing.

Joint Range of Motion

• At initial contact (0-2% of gait cycle), the ankle is at 0°, the knee is at 3-5° flexion, and the hip is at 25-30° flexion.
• During loading response (2-10%), the ankle is at 15° plantar flexion, the knee flexes up to 15°, and the hip remains at 25-30° flexion.
• Midstance (10-30%) involves the body's COM moving directly over the foot, the ankle goes from 15° plantar flexion to 15° dorsiflexion, the knee is at 5° flexion, and the hip reaches full extension.
• Terminal Stance (30-50%) involves the heel lifting off the floor, the ankle going to 15° dorsiflexion 20° plantar flexion, the knee moving into full extension, and the hip reaching 10° extension.
• The toes leave the ground during pre-swing (50-60%).
• In initial swing (60-73%), the ankle moves to neutral dorsiflexion, the knee flexes 40° -60°, and the hip extends to 25°-30° flexion.
• The ankle remains neutral and the knee at 60° flexion during mid-swing (73-87%).
• In terminal swing (87-100%), the ankle remains neutral, the knee extends to full, and the hip remains flexed 25°-30°.

Gait Kinematics

• Gait kinematics focuses movements without considering internal/external forces but includes positions, velocities, and accelerations of body segments.
• Temporal and spatial gait variables include stride length, step length, step width, and angle of foot progression.
• Temporal variables include stance time, single limb support time, double limb, support time, swing time, stride time, step time, cadence, and velocity.
• Step length measures feet contact with the opposite foot.
• Stride length measures sequential feet contacts.
• Step width measures horizontal distance between the feet.
• Angle of progression is measured from heel to toe.
• Stance time indicates stance time for one extremity.
• Single support time indicates that only one time is on the surface.
• Double support time indicates both feet being on the ground.
• Step duration indicates one step taken.
• Cadence measures the number of steps per time unit.
• Typical cadence for adults
  • Men: 110 steps per minute.
  • Women: 116 steps per min.
• Shorter step length increases cadence.
• Increasing cadence decreases double support time.
• Walking becomes running at 180 steps per minute.
• Velocity measures the rate of linear motion.
• Measured across a set distance.

Gait Kinetics

• Gait kinetics involves forces that affect movement, including ground reaction force, forces on joints/muscles, moments/torque, mechanical power, and energy patterns.
• Ground reaction force (GRF) is equal and opposite to the forces applied by the foot during stance phase.
• GRFs are expressed using vertical, anteroposterior, and mediolateral axes.
• If the force components combine into two or three planes, then the vector sum is known as ground reaction force vector (GRFV).
• The center of pressure (CoP) is the point where all floor-foot act, which indicates pathology when altered path.
• Pelvic stability is important in the gait cycle.
  • Pelvis remains level in the sagittal plane.
  • Rotation increases with speed.

Muscle Activation

• Muscle activation in gait is complex and depends on speed.
• Requirements for normal gait may depend on tight plantar fascia.
• A tight plantar fascia shortens elevates the medial longitudinal arch.
• Windlass mechanism and supination create stable foot.
• Loss of windlass results in limp or fatigue.
• Windlass test involves moving towards the toes.
• Initial contact to midstance results in arch lowering.
• Medial longitudinal arch lowering, and relaxation prepares the foot for uneven ground.
• Uneven ground involves pronation.

Energy Expenditure

• Energy expenditure in gait measures body functions such as:
  • Oxygen uptake.
  • Consumption.
• Analyzed through different metabolic calculations.
• Gait analysis involves gait qualities that are:
  • Qualitative.
  • Quantitative.

Observational Gait Analysis

• A limp may be caused by different dysfunctions.
• Gait abnormality can result in:
  • Limited ROM.
  • Pain.
  • Muscular imbalance related to posture during gait.
  • Sensory loss or incoordination.

Explore the phases of the gait cycle, including stance and swing. Learn traditional and Rancho Los Amigos terminology. Understand the subdivisions of each phase and the percentage of the gait cycle they represent.