Movement Science Week 10 - Movement and Task Analysis (Transcripts)

Movement Analysis

• Focuses on observing movement patterns and strategies used to perform a task.
• Observes individuals in their natural movement without initial corrections.
• Utilized in structured, controlled environments for consistent observations.
• Helps generate hypotheses about contributing factors to movement dysfunctions.
• Movement analysis employs a six-stage model by Hamid et al, representing the organization of movement and the environment. Each stage has associated parameters for analysis.
• Motor control factors influencing movement include:
  • Neural factors: structures, pathways, and processes involved in movement control.
  • Musculoskeletal and biomechanical factors: structure and properties of muscles, joints, soft tissues, and physical laws governing movement.
  • Behavioral factors: cognitive, motivational, perceptual, emotional processes, and the success of movement in achieving goals.
• Movement analysis begins with the evaluation of initial conditions, including the environment and starting posture.
• During systematic movement analysis, applying constraints to the environment and initial posture allows for systematic alteration of the environment and observations of changes in movement strategies.
• Movement preparation is a crucial part of motor planning and execution but is not always observable.
• Evaluating an individual's understanding of instructions or task requirements can reflect movement preparation.
• For dynamic tasks, the focus is on observable stages within the movement continuum:
  • Initiation: the start of segment displacement.
  • Execution: the period of actual segment movement.
  • Termination: the moment motion stops.
• Each phase of the movement continuum provides information about movement constructs.
• The final component of the movement continuum is the outcome, which indicates whether the movement goal is achieved.
• The outcome, like initial conditions, is predetermined by instructions and can be systematically altered to increase or decrease task difficulty.
• It is suggested that these six tasks be analyzed:
  • Sitting
  • Sit-to-stand
  • Standing
  • Walking
  • Step up and down
  • Reach, grasp, and manipulate.
• Analyzing movement across these tasks offers insights into a range of task requirements:
• Maintaining positions (sitting or standing)
• Moving within a position (reaching, grasping, manipulating)
• Transitioning between positions (sit-to-stand)
• Moving through the environment (walking, step up and down)
• The core tasks may vary based on the patient or client group and the setting.
• For individuals who are not ambulatory or athletes at a high performance level, the tasks may be limited.
• This framework can serve as a starting point in a wide range of clinical situations, and tasks can be added as needed.
• For all tasks except for sitting and standing, individuals should be instructed to perform the task at least twice.
• If an individual is unable to complete a task as instructed, it's recommended to modify the task or the environmental conditions to promote success.
• Simplifying tasks allows the PT to observe movement in individuals who are unable to perform the task otherwise.
• At least one task regression is recommended for those who have difficulty performing a task.
• Examples of task regressions include:
  • Increasing the base of support
  • Modifying task speed (slower or faster)
• Examples of environmental regressions include:
  • Altering the surface type or height.
  • Providing cues, physical assistance, or external support.
  • Modifying environmental inputs.
• The choice of assistance or cueing depends on the individual's physical and cognitive abilities.
• It's suggested to provide assistance in the following order:
  • Verbal cue
  • Tactile cue
  • Physical assistance
• PTs must judge the safety of both the individual and themselves when deciding whether to attempt tasks without assistance or cueing.
• If a task is not challenging enough for an individual, it's recommended to introduce a task progression.
• Task progressions are variations designed to increase complexity and challenge.
• Adding complexity can help the PT better understand the capacity of the movement system.
• Examples of task progressions include:
  • Narrowing the base of support.
  • Changing the task speed.
  • Adding internal perturbations (head turns).
  • Adding dual tasks.
• Examples of environmental progressions include:
  • Altering surface height or type.
  • Modifying environmental inputs (adding motion to the environment, adding external perturbations).
• At least one task progression is recommended to introduce a challenge when no difficulty is encountered during a task performance.
• The movement continuum framework by Hedman et al provides the foundation for task analysis.
  • Initial conditions define the state of the individual system and the environmental conditions.
  • Environmental conditions are predetermined for the first task performance but can be systematically varied in subsequent repetitions by using progressions or regressions.
• The framework progresses from initial conditions, encompassing:
  • Initial conditions: environment and starting posture
  • Preparation: (not always observable)
  • Assessment of an individual's understanding of instructions and task requirements.
  • Movement Patterns and Strategies: during task performance.
  • Movement Continuum: (for dynamic tasks)
    • Initiation: the moment segments start moving.
    • Execution: the period of actual segment movement.
    • Termination: the moment motion stops.
  • Outcome: Whether the task is successfully accomplished, and the performance reflected through observable movement constructs.
• If the desired outcome is achieved, the task can be repeated, potentially with a progression.
• If the outcome is not achieved, a regression might be implemented.
• The next slide presents a description and instructions for specific tasks.

Sitting Task

• Description: Individuals sit unsupported on a firm surface, at approximately the height of the fibular head, with a self-selected base of support and hands resting on their lap.
• Instructions: Sit upright with feet on the floor for 30 seconds.

Sit-to-Stand Task

• Description: Individuals stand from a level, firm surface at the height of the fibular head with a self-selected base of support.
• Instructions: Stand up without using your hands.

Standing Task

• Description: Individuals stand on a level, firm surface with a self-selected base of support.
• Instructions: Stand comfortably for 30 seconds.

Walking Task

• Description: Individuals walk at least 20 meters with a 180-degree turn.
• Instructions: Walk at a comfortable speed for 10 meters away, turn around, and come back.

Step Up and Down Task

• Description: Individuals stand facing a 7-inch step. They step up onto the step and then down backward with the same leg. Repeating with the other leg.
• Instructions: Step onto the step with both feet loading with the right leg, avoiding using the hands. Step back down, backwards, leading with the right leg. Repeat the task with the left leg.

Reach, Grasp, and Manipulate Task

• Description: Individuals start by sitting in a chair with back support. They reach with one arm for a cup of plastic foam pieces located about 6 inches beyond their arm length. They grasp the cup, lift it from the table, and pour its contents into a receptacle next to the cup. Then they return the cup to the table without dropping it and repeat with the other arm.
• Instructions: Perform these specific tasks.

Stair-Walking

• Objective: Stair-walking is a common activity with a significant contribution to falls in public places, particularly going down stairs.
• Essential characteristics:
  • Progression: Generation of concentric forces to propel the body upwards or eccentric forces to control the body's descent downwards.
  • Stability: Controlling the center of mass within a consistently changing base of support.
  • Adaptation: Adjusting progression and stability strategies to accommodate changes in the stair environment (height, width, presence/absence of handrails)

Stair-Walking Stance Phases

• Going Upstairs:
  • Weight Acceptance: Initiated with the middle to front part of the foot, absorbing energy through eccentric contraction of ankle and knee muscles.
  • Pull-Up: Knee and ankle extension, primarily via concentric contractions of the vastus lateralis and soleus.
  • Forward Continuance: Ankle generates forward and lifting forces.

Stair-Walking Swing Phases

• Going Upstairs:
  • Foot Clearance: Achieved through tibialis anterior activation (dorsiflexing the foot) and hamstring activation (flexing the knee).
  • Foot Placement: Controlled by hip extensors and ankle dorsiflexors.

Stair-Walking Stance Phases

• Going Downstairs:
  • Weight Acceptance: Energy absorption at the ankle and knee through eccentric contraction of gastrocnemius, rectus femoris, and vastus lateralis.
  • Forward Continuance: Forward motion of the body.
  • Controlled Lowering: Lowering the body through eccentric contraction of the quadriceps and soleus.

Stair-Walking Swing Phases

• Going Downstairs:
  • Leg Pull-Through: Hip flexor activation.
  • Preparation for Foot Placement: Mid-swing hip and knee flexion reversed, all three joints extend in preparation for foot placement.

Stair-Walking Adaptations

• Sensory cues during stair-walking can lead to changes in movement strategies.
• Stair-climbing patterns differ from level walking:
  • Lower cadence
  • Smaller stance phase duration and time
  • Longer cycle duration
  • Lower forward speed
  • Shorter stride length
  • More lower limb flexion at the beginning of the stair-climbing cycle
  • Less hip extension at toe-off.
  • These differences reflect adaptations to the staircase environment.
• Mild restrictions in knee flexion can reduce stair-climbing performance.
• Individuals with limited knee flexion may need to step one at a time, placing both feet on each step for successful stair ascent.
• Stair-climbing requires a larger magnitude of dorsiflexion. Individuals with foot drop or restricted ankle dorsiflexion may need to compensate with more hip and knee flexion to clear steps during the swing phase.
• Stair-walking involves large moments and powers produced in the sagittal plane to support and propel the body against gravity, driving forward movement.

Sit-To-Stand Task

• Objective: Task analysis requires an understanding of the essential characteristics of the task, the sensory motor strategies normally employed, and adaptations needed when environmental conditions change.
• Essential Characteristics
  • Progression: Generating sufficient joint torque for rising.
  • Stability: Ensuring stability as the center of mass transfers from the base of support of the chair to the base of support defined solely by the feet.
  • Adaptation: Modifying movement strategies to accommodate environmental constraints (chair height, armrests, chair surface).

Sit-to-Stand Task Phases

• Phase 1: Flexion Momentum Phase

  • Initiation: Movement starts.
  • Termination: Just before the buttocks are lifted from the chair seat.
  • Muscle Activity: Erector spinae contract eccentrically to control trunk movement.

• Phase 2: Buttocks Lift-Off Phase

  • Initiation: Buttocks are lifted, and maximal ankle dorsiflexion is achieved.
  • Muscle Activity: Co-activation of hip and knee extensors.

• Phase 3: Extension Phase

  • Initiation: Just after maximum dorsiflexion.
  • Termination: When hip extension ceases.
  • Muscle Activity: Hip and knee extension.

• Phase 4: Stabilization Phase

  • Initiation: After hip extension is reached.
  • Termination: When all motion associated with stabilization is complete.

Sit-to-Stand Task Key Insights:

• Phase 1: Weight Shift Flexion Momentum Stage

  • Forward momentum of the upper body generated through trunk flexion.
  • The center of mass moves forward but remains within the base of support (chair seat and feet).

• Phase 2: Buttocks Lift-Off

  • Momentum transfers from the upper body to the total body, allowing lift-off.
  • Critical transition phase involving horizontal and vertical motions.
  • The center of mass moves from the base of support of the chair to that of the feet.
  • The body is inherently unstable.

• Phase 3: Lift-Off or Extension Phase

  • Extension at the hips and knees.
  • The goal is vertical movement of the body.
  • Less stability compared to Phase 2 because the center of mass is within the base of support (feet).

• Phase 4: Stabilization Phase

  • The body stabilizes in the vertical position.

• The described sequence is called the momentum transfer strategy for sit-to-stand.

• This strategy involves:

  • Adequate strength and coordination to generate upper body movement.
  • Eccentric contraction of trunk and hip muscles to apply braking forces to slow horizontal center of mass trajectory.
  • Concentric contraction of hip and knee muscles to generate vertical forces that lift the body.

• The momentum transfer strategy necessitates a trade-off between stability and force.

  • Momentum transfer between upper and total body reduces lower body force requirements.
  • However, the body is in a less stable equilibrium during the transition phase where momentum is transferred.

Joint Motion and Muscle Activity in Sit-to-Stand

• Hip, knee, and ankle joint excursions are comparable in standing up and sitting down, but different approaches to reaching the edge of a chair are possible.
• In preparation for rising, individuals might move their hips forward by walking them forward in the chair or pushing back against the chair back.
• Walking hips forward involves shifting body weight from side to side and rotating the pelvis forward until the hips are at the edge of the seat.

Sit-to-Stand Movement

• The sit-to-stand task requires force generation in various lower extremity muscles
• The tibialis anterior muscle helps in foot placement and stabilization
• Hip and knee extensors are activated when thighs lift off the seat
• Aging impacts muscle performance, requiring adaptive strategies for sit-to-stand
• Returning to a seated position involves eccentric muscle activity in the lower extremities

Sit-to-Stand Strategies

• Flexing the trunk brings the center of mass within the base of support
• The "zero momentum" strategy involves lifting off the chair with minimal momentum
• Using armrests assists with stability and force generation, reducing lower extremity muscle effort
• Lowering the seat height increases the demand for sit-to-stand
• Research suggests 120% of lower leg length as the minimum chair height for successful rising
• Using armrests can reduce the moments at the knee and hip

Sit-to-Stand Factors

• Chair design affects movement requirements, including seat slant and ejector mechanisms
• Increasing the speed of the movement increases flexion at the hip, knee, and ankle
• Feet placement influences movement time, with posterior placement resulting in shorter movement times

Rolling Movement

• Rolling is a fundamental movement for floor mobility and bed mobility
• Rolling from supine to prone is more challenging than prone to supine
• Adult rolling patterns involve trunk rotation and segmental dissociation
• Rolling strategies vary based on individual strength, flexibility, and age
• Common components of rolling include arm, head/trunk, and leg patterns

Supine-to-Stand Movement

• Three common strategies in young adults: symmetrical trunk/symmetrical squat, symmetrical trunk/asymmetrical squat, asymmetrical trunk/half kneeling
• Older adults may use different strategies due to lifestyle factors and physical activity levels
• Strength plays a role in transitioning from asymmetric rotation to symmetric sit-up strategy
• Infants use arm support for supine-to-stand, progressing to independent standing
• Elderly individuals may revert to using arms for support

Rising from Bed

• Strategies include pushing up with arms, flexing the head/trunk, and rolling up to standing
• Another strategy involves pushing off with arms, rolling to the side, and pushing up to standing
• Rising from the bed requires generating momentum and maintaining stability

Running

• Running involves a longer swing phase and a shorter stance phase compared to walking
• The center of mass movement is similar to a bouncy ball, utilizing muscle stiffness for propulsion
• Walking generates forward momentum during stance, while running utilizes arm and leg movement during swing
• Running requires a greater range of motion and eccentric muscle activity
• Running has a distinct double float phase, resulting in more time during swing
• The absorption phase of stance focuses on absorbing impact forces

Running Phases

• Initial swing begins with a double float period and limb acceleration
• Terminal swing features a deceleration phase in preparation for landing
• The propulsion phase focuses on propelling the body forward
• The ankle reaches maximum dorsiflexion just before midstance and plantarflexes during propulsion
• The foot provides a rigid lever for gastrocnemius and soleus muscle function

Running Speed and Kinematics

• Increasing running speed lowers the center of mass, increases stride length, and shortens stance duration
• Speed affects joint range of motion, with higher speed requiring greater movement
• Muscles work eccentrically during initial impact to absorb forces
• Running kinematics can be analyzed in the sagittal plane, focusing on trunk, pelvis, and lower extremity movements
• The hip moves into extension towards the end of terminal swing
• The knee flexes to provide foot clearance during swing and extends during propulsion
• The ankle dorsiflexes during initial contact and plantarflexes during propulsion

Muscle Activity During Running

• Muscle activity in running is greatest during the propulsion phase, which occurs in the last half of stance
• Major differences in muscle activity between running and walking:
  • Onset timing is sooner in running
  • Intensity of activity is greater in running
  • Sprinting has even quicker onset timing and greater muscle activity
• The most important muscle groups producing power for running are:
  • Hip flexors
  • Hip extensors
  • Abductors
  • Knee extensors
  • Gastroc soleus groups

Kinetics and Power in Running

• Running involves forces that cause motion, specifically power
• Key power sources for forward propulsion in running:
  • Hip extensors during late swing and early stance
  • Hip flexors after toe-off
  • Quadriceps, gluteus medius, and plantarflexors throughout stance

Ground Reaction Forces

• Ground reaction forces are equal and opposite to the forces applied to the ground
• Vertical ground reaction force is significantly greater during running than walking due to the body leaving the ground
• Vertical ground reaction forces create a double bump pattern in both running and walking, but with different shapes:
  • Running: Smaller impact force at initial contact (first 20% of stance) followed by a larger and longer impact during the propulsion phase.
  • Walking: A more even distribution of force
• The propulsive phase in running has a greater vertical force than the initial impact force
• Magnitude of impact forces:
  • Walking: 1.3 to 1.5 times body weight
  • Running: 2 to 3 times body weight

This quiz explores the concepts and principles of structured movement analysis within the context of physical therapy. It covers key questions about motor control, task progressions, and the assessment of patient movements. Test your knowledge on essential factors and techniques used in evaluating and facilitating movement.