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Questions and Answers
What angle decrease occurs in the foot angle/angle of progression as walking speed increases?
What angle decrease occurs in the foot angle/angle of progression as walking speed increases?
What is the average gait cadence for adults measured in steps per minute?
What is the average gait cadence for adults measured in steps per minute?
Which muscle activates to stabilize the body during initial contact while walking?
Which muscle activates to stabilize the body during initial contact while walking?
During what phase does the knee exhibit 60 degrees of flexion?
During what phase does the knee exhibit 60 degrees of flexion?
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What is the primary function of stabilizer muscles during the gait cycle?
What is the primary function of stabilizer muscles during the gait cycle?
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What is the required average gait speed for safety purposes in meters per minute?
What is the required average gait speed for safety purposes in meters per minute?
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What is primarily involved in achieving postural control during locomotion?
What is primarily involved in achieving postural control during locomotion?
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Which phase of the gait cycle directly involves generating forces against gravity?
Which phase of the gait cycle directly involves generating forces against gravity?
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What is the term for the pattern of movement in the limbs during normal bipedal gait?
What is the term for the pattern of movement in the limbs during normal bipedal gait?
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What aspect of locomotion is primarily covered by the term 'adaptation'?
What aspect of locomotion is primarily covered by the term 'adaptation'?
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Which functional task is associated with the reactive balance aspect of gait?
Which functional task is associated with the reactive balance aspect of gait?
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During which phase of gait does the body move forward while maintaining contact with the ground?
During which phase of gait does the body move forward while maintaining contact with the ground?
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What primarily characterizes the 'swing phase' of a gait cycle?
What primarily characterizes the 'swing phase' of a gait cycle?
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What is a common task during daily walking that affects gait mechanics?
What is a common task during daily walking that affects gait mechanics?
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Which of the following best describes 'progression' in locomotion?
Which of the following best describes 'progression' in locomotion?
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What percentage of the gait cycle does the stance phase encompass?
What percentage of the gait cycle does the stance phase encompass?
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Which subphase occurs between 60-73% of the gait cycle?
Which subphase occurs between 60-73% of the gait cycle?
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When does double-limb support typically occur during the gait cycle?
When does double-limb support typically occur during the gait cycle?
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Which phase begins when the heel of the stance limb leaves the ground?
Which phase begins when the heel of the stance limb leaves the ground?
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Which term describes the weight transfer occurring during the loading response phase?
Which term describes the weight transfer occurring during the loading response phase?
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What happens to double-limb support as walking speed increases?
What happens to double-limb support as walking speed increases?
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Which of the following gait phases is associated with body weight acceptance?
Which of the following gait phases is associated with body weight acceptance?
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During which swing phase does the swing leg directly align beneath the body?
During which swing phase does the swing leg directly align beneath the body?
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What is the average stride length for an individual during walking?
What is the average stride length for an individual during walking?
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What term describes the phase where only the metatarsals of the stance limb are in contact with the ground?
What term describes the phase where only the metatarsals of the stance limb are in contact with the ground?
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Study Notes
Essential Requirements of Locomotion
- Locomotion requires progression, postural control, and adaptation
- Progression refers to the rhythmic patterns of muscle activation in the legs, trunk, and arms that move the body in the desired direction.
- Postural control involves aligning the body segments in relation to each other and the environment to achieve the requirements of locomotion.
- Stability involves controlling the center of mass relative to the base of support.
- Steady-state balance control maintains orientation and stability while walking at a constant velocity.
- Reactive balance recovers stability after an unexpected perturbation.
- Anticipatory balance activates muscles to counteract potentially destabilizing internal and external forces during the gait cycle.
- Adaptation is the ability to change gait in response to environmental demands.
What is Gait
- Gait is the manner of walking.
- Normal locomotion is bipedal gait in which limbs move in a symmetrical alternating motion.
- A gait cycle (or stride) is a sequence of events that take place between 2 successive initial contacts (or heel strikes) of the same foot.
Phases of Gait
- Stance Phase is when the foot is in contact with the ground. It involves generating forces to move the body forward and support the body weight.
- Swing Phase is when the foot is not in contact with the ground. It involves advancing the swing leg to reposition it for the next stance phase.
- Double-Limb Support occurs when both feet are simultaneously in contact with the ground.
- Single-Limb Support occurs when only one foot is in contact with the ground.
Gait Terminology and Phases
- Initial Contact: The foot first comes in contact with the ground.
- Loading Response: Body weight is transferred to the stance foot.
- Midstance: The body weight is fully over the stance limb.
- Terminal Stance: The heel of the stance foot leaves the ground.
- Pre Swing: Only the metatarsals of the stance foot are in contact with the ground.
- Initial Swing: The foot lifts and the knee flexes.
- Mid Swing: The swing leg is directly beneath the body.
- Terminal Swing: The swing limb begins to extend to prepare for initial contact.
Functional Tasks of Gait
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Stance phase tasks:
- Weight acceptance
- Single limb support
- Limb advancement
-
Swing phase tasks:
- Limb advancement
Gait Spatial and Temporal Characteristics
- Spatial characteristics are variables easily visualized by looking at the feet’s walking pattern on the ground.
- Temporal characteristics are variables that have to do with time.
- Spatial characteristics*
- Stride length: The distance between 2 successive events of the same foot.
- Step length: The distance between 2 successive events of opposite feet.
- Step width: The distance between the midpoints of the heels of each foot.
- Foot angle (angle of progression): The angle formed by the foot’s line of progression and a line that intersects the heel and the space between the 2nd and 3rd toes.
- Temporal characteristics*
- Gait speed: The average horizontal speed of the body measured over one or more strides.
- Gait cadence (step rate or step frequency): The number of steps taken per unit of time.
- Stride time: Time it takes to complete one stride.
- Step time (duration): Time it takes to complete one step.
Gait Kinematics
-
Sagittal Plane:
- Pelvis: Anterior and posterior pelvic tilt of about 3 degrees.
- Hip: Flexion of 25-30 degrees at initial contact; extension of 10 degrees prior to pre swing.
- Knee: Flexion of 60 degrees at mid swing; full extension at terminal stance.
- Ankle: Dorsiflexion of 10 degrees before terminal stance; plantarflexion of 20 degrees after pre swing.
-
Frontal plane:
- Pelvis: Lateral pelvic tilt of about 5-8 degrees on each side.
- Hip: Adduction of 10-15 degrees at loading response; abduction of 5 degrees at initial swing.
- Knee: Abduction of 3 degrees during loading response; abduction of 8 degrees during swing phase.
- Ankle: Eversion of 5 degrees after loading response; inversion of 8 degrees at pre swing.
-
Transverse plane:
- Pelvis: Rotation of 4 degrees in each direction.
- Hip: Internal rotation at the end of loading response; external rotation at the end of the pre swing.
- Knee: Internal rotation as the limb accepts weight; external rotation in pre swing and initial swing.
Gait Kinetics
- Kinetics involves the internal and external forces impacting gait.
- Internal forces: muscle forces and passive tension from connective tissue.
- External forces: inertia, gravity, and friction.
- Ground Reaction Force: The force exerted by the ground in response to the forces a body exerts on it.
- Center of Pressure: The point where the resultant ground reaction force acts on the foot.
Gait Muscle Activation
- Stabilizers: Muscles work isometrically to position one joint or segment while another joint or segment moves.
- Accelerators: Muscles contract concentrically to move a segment forward.
- Decelerators: Muscles eccentrically contract to slow a movement or absorb energy.
Overall ROM needed for gait
- Hip: 30 degrees of flexion, 10 degrees of extension.
- Knee: 60 degrees of flexion, full extension.
- Ankle: 20 degrees of plantarflexion, 10 degrees of dorsiflexion.
Muscle Activation in Steady-State Gait
-
Trunk muscles:
- Transversospinal, erector spinae, and quadratus lumborum: Active during initial contact.
- Internal and external obliques: Continuous, low activity at terminal swing.
-
Upper extremity muscles:
- Reciprocal motion of the arms helps to stabilize the body and reduce lateral motion of the Center of Mass (COM).
- Posterior and middle deltoid: Active before the arm starts backward swing and continues through backward swing.
- No activity of the shoulder flexors.
Adaptation of Gait, Balance, and Sensory Systems
- Reactive balance control: Automatic postural adjustments integrated into the step cycle.
- Proactive strategies: Used to modify and adapt gait by predicting potential destabilizing forces and adapting to obstacles, surface conditions, inclines, turns, and initiating gait.
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Sensory systems: Provide feedback and feedforward modulation of gait.
- Somatosensory system: Sensory information from limbs contributes to stepping frequency, the onset of swing phase, and interlimb coordination.
- Vision system: Helps determine the speed of locomotion and influences body alignment in relation to gravity and the environment.
- Vestibular sensory system: Stabilizes the head and contributes to gaze stabilization during head movement.
Cognitive Systems
- Dual-task performance during steady-state gait: Reaction times are slowed for standing and walking tasks, causing a decrease in gait speed and an increased risk of injury.
- Dual-task performance during obstacle crossing: Obstacle contact increases when attention is divided. Obstacle crossing requires attentional resources.
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