DPT 512: Biomechanics of Gait Introduction

DPT 512: Biomechanics/Kinesiology II - Gait - Introduction

• The course is DPT 512: Biomechanics/Kinesiology II, focusing on gait introduction.
• Learning objectives include differentiating walking and gait, describing observational gait analysis (OGA) context, outlining biomechanical gait analysis categories, understanding how gait speed is affected by acceleration/deceleration phases, describing gait speed components and adjustments (like aging), identifying gait spatio-temporal variables, and describing gait phases using Rancho Los Amigos terminology.

Walking vs. Running

• Walking involves alternating use of legs for support and propulsion, always with at least one foot in contact with the ground.
• Running includes a 'flight phase' where both feet are momentarily off the ground.

Walking - Context Matters

• External factors affecting walking include shoes (e.g., high heels, special shoes), ambient lighting, and crowded areas.
• Internal factors affecting walking are age, gender, habits (e.g., ballet training), and specific conditions like neurological or orthopedic diagnoses.
• Intentions, like texting or holding an object, also influence walking.

Gait

• Gait is a pattern of posture and movement during walking, characteristic for each individual.
• Gait recognition systems (e.g., Watrix) use biometrics for analyses, like forensic gait analysis.
• Gait measurements often utilize CCTV surveillance for recording.

OGA (Observational Gait Analysis)

• OGA is a clinical method, limiting observation to human eye capabilities.
• Four categories of biomechanical gait analysis (Kinematics, Kinetics, Muscle Activity, Energy Consumption) are not all observable by the human eye.
• Standardised instruments are needed for precise gait measurement and analysis.

Standard Context for OGA

• Gait speed tests should be performed at different speeds (e.g., self-selected fast, slow).
• Controlling external environmental factors are crucial.
• Clear instructions for tasks (e.g., walking straight) are important.
• Standardised protocols (e.g., using Timed Up and Go test as a standard) can be helpful and comparing results between different clinics.
• Testing protocols should include excluding dual tasks (e.g., talking) during testing.
• Specific measurements of the distance should be noted.

Gait Speed

• Gait speed (velocity) is a key variable in OGA that holds significant functional meaning and is used to start the analysis.
• It is sensitive to mobility declines and is an indicator of overall health and function risks (e.g., likelihood of falls), and useful in predicting healthcare costs.

Gait Speed Interpretation

• Age and gender-specific standards are used for gait speed analysis.
• Population-specific factors (e.g., Parkinson's disease) affect these standards.
• Challenges exist in interpreting and evaluating the data for some individuals.

Gait Speed Measurement

• Gait speed is calculated by dividing the distance covered by the time taken to cover that distance.
• Common unit in measurements is meters/second (m/sec).
• Example calculation provided using a 9 meters' walk in 12 sec
• Factors influencing measured gait speed should be considered.

Two Components of Gait Velocity

• Gait velocity is impacted by both step length and cadence (steps per minute).
• Example calculations provided for gait speed using these 2 components using an 80 cm/step average and a 140 steps/minute cadence.

Basic Spatial Gait Variables

• Spatial gait variability is determined by foot placement during walking.
• Normal spatial metrics include step width (typical range: 8–10 cm horizontally) and toe-out angle (typical range: 8–10 degrees).
• Step length can be asymmetrical and in some cases negative (i.e., step backward)
• Step width can be negative (cross-over step)

Basic Temporal Gait Variables

• Gait time is measured by successively tracing the same event on the same limb (i.e., right heel strike to right heel strike).
• Stance phase measures the time during which a leg is in contact with the ground; while swing phase refers to the time during which the leg moves forward and is not in contact with the ground.
• Single stance refers to when only one foot is in contact with the ground; while double stance refers to the time when both feet are in contact with the ground.
• Temporal characteristics of gait are commonly expressed in percentages of the complete gait cycle.

Gait Phase Relationship

• The phases of gait for both legs are linked in a cyclical pattern and are commonly expressed using percentages.
• The gait of an opposite leg is impacted by the phase of the active leg.
• Double support phase duration consists of two distinct parts in its total time (L't IC to R't IC)

Gait Phases- Terminology

• Clinical terms and Rancho Los Amigos classifications, comparing clinical terminology (heel strike, initial contact etc) with the Rancho Los amigos system (initiating loading etc) were discussed to help in understanding how gait occurs.
• Right leg is used as the reference point for the remaining slides. Specific phases of gait stages are detailed in some slides.