gait intro

What are the two primary phases of the gait cycle and their approximate percentage breakdown?

1. Stance Phase (~60% of total cycle)\n2. Swing Phase (~40% of total cycle)

What are the 4 sub-phases of the Stance Phase in order (including percentages)?

1. Initial Contact (IC): 0-2%\n2. Loading Response (LR): 2-10%\n3. Mid-stance (MSt): 10-30%\n4. Terminal Stance (TSt): 30-50%

What are the 4 sub-phases of the Swing Phase in order (including percentages)?

1. Pre-swing (PSw): 50-60%\n2. Initial Swing (ISw): 60-73%\n3. Mid-swing (MSw): 73-87%\n4. Terminal Swing (TSw): 87-100%

Define the Loading Response phase of gait and its main functional goal.

Occurs at ~2-12% of gait cycle. Lead limb accepts body weight. Key functional goals: Shock absorption, stability, and maintaining forward progression.

Define the Mid-stance phase of gait.

Occurs at ~12-31% of gait cycle. Represents the first half of single-limb stance as body weight progresses directly over the stationary foot.

Define the Terminal Stance phase of gait.

Occurs at ~31-50% of gait cycle. Initiated by heel-rise as body weight moves ahead of the forefoot during single-limb support.

Define the Pre-swing phase of gait.

Occurs at ~50-62% of gait cycle. Body weight is transferred from the trailing limb to the lead limb; unweighting enables the limb to prepare for swing.

Define Initial Swing, Mid-swing, and Terminal Swing phases.

• Initial Swing (62-75%): Foot lifts from ground and advances to opposite stance foot.\n- Mid-swing (75-87%): Limb advances until tibia reaches vertical.\n- Terminal Swing (87-100%): Tibia advances past vertical and limb prepares for heel-first initial contact.

What are the 3 functional task requirements of the Weight Acceptance task in gait?

1. Shock absorption\n2. Initial stabilization\n3. Maintenance of forward progression

What are the 3 functional task requirements of Swing Limb Advancement in gait?

1. Foot clearance\n2. Forward progression\n3. Limb preparation for stance

What are common causes of altered joint ROM in gait?

• Structural/congenital joint deformities\n- Joint laxity or instability (e.g., ACL rupture)\n- Contracture or reduced muscle length\n- Pain or osteoarthritis (OA)

Define joint/muscle contracture and state when it commonly occurs.

Structural change in the fibrous connective tissue component of muscles, ligaments, or joint capsules. Commonly occurs following prolonged immobilization, disuse, scarring, or surgery.

How does neurological impairment (e.g., stroke, SCI, TBI) affect muscle function in gait?

Causes central nervous system deficits resulting in muscle weakness (paralysis or paresis), loss of coordination, and spasticity, altering normal gait mechanics (e.g., hemiplegic gait).

How does pain alter normal gait mechanics?

1. Induces protective resting postures, limiting available ROM (e.g., calf tear avoiding dorsiflexion).\n2. Causes muscle inhibition/overactivity, leading to muscle imbalance, disuse atrophy, or compensatory gait deviations.

How do individuals compensate for impaired sensory/proprioceptive function during gait?

They substitute by relying on visual input to monitor limb position, slowing their gait speed, and widening their base of support for balance.

Define spatial vs. temporal variables in gait.

• Spatial variables: Distance measurements (e.g., step length, stride length, step width).\n- Temporal variables: Time measurements (e.g., cadence, stance/swing duration, gait speed).

What are typical normal values for gait speed, cadence, step time, and stride time?

• Gait speed: 1.1 - 1.4 m/s\n- Cadence: ~90 - 120 steps/minute\n- Stride duration: ~1.0 second\n- Step duration: ~0.5 seconds

Define kinematics vs. kinetics in gait analysis.

• Kinematics: "What you see" - spatial/temporal description of motion (angles, displacement, velocity, acceleration).\n- Kinetics: "What causes what you see" - study of forces acting on the body (GRF, joint moments, muscle contractions).

How does Newton's Law of Action-Reaction apply to gait kinetics?

The foot exerts a force against the ground, and the ground generates an equal and opposite Ground Reaction Force (GRF) vector back against the foot, producing external moments across lower limb joints.

What are the main external and internal forces acting during gait?

• External forces: Ground Reaction Force (GRF), gravity, and limb segment inertia.\n- Internal forces: Muscle forces (concentric/eccentric) and passive tissue tension (ligaments, capsule).

How do stance duration, cadence, and step width change in response to balance deficits or fatigue?

• Stance duration: Double-leg support time increases.\n- Cadence: Decreases or becomes irregular.\n- Step width: Widens (to increase base of support) or becomes abnormally narrow (e.g., Parkinsonian gait).

What is the systematic approach for conducting a clinical visual gait analysis?

1. Observe overall global gait (limp, posture, gait speed).\n2. Observe from multiple planes (sagittal, frontal, transverse) and views (front, side, behind).\n3. Analyze joints systematically (ankle, knee, hip, pelvis, trunk, upper limbs) from proximal-to-distal or distal-to-proximal.\n4. Observe both stance and swing phases.

How should a clinician describe a single-joint gait deviation?

1. State the primary deviation and the phase/event affected (e.g., Inadequate dorsiflexion in mid-stance).\n2. State the functional impact on gait (e.g., Disrupts forward tibial advancement).\n3. State secondary compensatory deviations (e.g., Decreased hip extension in late stance).

What tools are used for laboratory objective gait analysis (kinematics vs. kinetics)?

• Kinematics: 3D motion capture systems, electrogoniometers, instrumented walkways (e.g., GAITRite).\n- Kinetics: Force platforms/sensors and Electromyography (EMG).

Match the standardized clinical outcome measures to their target populations/purposes: TUG, HiMAT, and Dynamic Gait Index (DGI).

• Timed Up & Go (TUG): Functional mobility, balance, and gait speed.\n- HiMAT: High-level motor/mobility tasks in adults with traumatic brain injury.\n- Dynamic Gait Index (DGI): Gait stability and dynamic balance in individuals with vestibular dysfunction.