Muscle Activation and Movement Patterns
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Questions and Answers

What characterizes phasic muscle activation?

  • Long duration with gradual change
  • Short bursts of activity (correct)
  • Consistent activation over time
  • Steady contraction regardless of movement
  • What is a basic feature of the triphasic EMG pattern observed in movements?

  • Slow and consistent activation
  • Symmetrical amplitude and timing
  • Bell-shaped velocity profile (correct)
  • Continuous muscle engagement
  • Which factors influence the symmetry of movement according to the AG/ANT relationship?

  • Timing and contraction type
  • Timing and amplitude of activation (correct)
  • Environmental factors and muscle size
  • Velocity and muscle fatigue
  • What effect does an increase in AG activation have on maximum velocity?

    <p>Increases maximum velocity</p> Signup and view all the answers

    How have muscles evolved to adapt to the demands of multi-joint movements?

    <p>By developing more phasic activation patterns</p> Signup and view all the answers

    Which statement best describes tonic muscle activation?

    <p>Composed of relatively long, slow changes</p> Signup and view all the answers

    What effect does delaying antagonist (ANT) activation have on acceleration?

    <p>Lengthens the duration of acceleration</p> Signup and view all the answers

    What is the main reason for movements exhibiting a bell-shaped pattern?

    <p>To regulate speed and power output effectively</p> Signup and view all the answers

    What does the term 'symmetry of movement' refer to?

    <p>Consistent timing and amplitude in muscle activation</p> Signup and view all the answers

    How does the central nervous system (CNS) produce symmetry during movement?

    <p>By balancing antagonist and agonist velocities</p> Signup and view all the answers

    What is the first phase in the triphasic pattern for simple arm movements?

    <p>AG1 (initiation)</p> Signup and view all the answers

    The phase-plane paradigm was used to manipulate which aspect of arm movements?

    <p>Temporal structure</p> Signup and view all the answers

    What does the AG2 phase primarily control in the triphasic pattern?

    <p>Oscillations and damping</p> Signup and view all the answers

    Which characteristic had a very tight relationship when studied in the two subjects during the phase-plane experiment?

    <p>Peak velocity</p> Signup and view all the answers

    In the study, what was the second phase of the triphasic pattern referred to as?

    <p>ANT1</p> Signup and view all the answers

    What does 'SR' stand for in the context of the phase-plane experiment?

    <p>Stretch Reflex</p> Signup and view all the answers

    Which of the following was NOT explicitly mentioned as a measured characteristic in the study?

    <p>Control phase duration</p> Signup and view all the answers

    What relationship was primarily examined among the distribution of the three characteristics?

    <p>Correlation strength</p> Signup and view all the answers

    Which term refers to the phase responsible for controlling oscillations in the triphasic pattern?

    <p>AG2</p> Signup and view all the answers

    What experimental manipulation technique was employed to study simple arm movements?

    <p>Phase-plane paradigm</p> Signup and view all the answers

    Study Notes

    Muscle Activation

    • There are two types of muscle activation: tonic and phasic
    • Tonic activation is characterized by a long duration and a slow rate of change
    • Phasic activation is characterized by short bursts of activity

    Phasic Activation - Triphasic Pattern

    • The text uses the example of wrist flexion and extension to illustrate phasic muscle activation
    • The triphasic pattern involves three phases of muscle activation: agonist (AG), antagonist (ANT), and agonist (AG)
    • The timing and amplitude of the AG and ANT activity influence the symmetry of movement
    • Increased AG activation and earlier ANT onset result in shorter acceleration
    • Decreased AG activation and delayed ANT onset result in longer acceleration

    Cooke and Brown 1990a - Symmetry of Movement

    • Cooke and Brown (1990) suggested that simple arm movements follow a bell-shaped pattern
    • The triphasic pattern of AG1, ANT1, and AG2 is consistent with this bell-shaped pattern
    • AG1 initiates the movement, ANT1 acts as a brake and controls movement, and AG2 provides stretch-reflex damping
    • The researchers manipulated different simple reaction time (SR) movements in a phase-plane paradigm

    Cooke and Brown 1990a - Results

    • The phase-plane paradigm demonstrated a tight relationship between the peak velocity, amplitude, and duration of movements
    • The relationship is so strong that the distribution of these three characteristics is nearly identical across subjects
    • The research suggests that the CNS controls the symmetry of movement through the triphasic pattern

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    Related Documents

    MEDI258 Week 7 PDF

    Description

    Explore the concepts of tonic and phasic muscle activation, focusing on the triphasic pattern of muscle activation in movements like wrist flexion and extension. Understand how the agonist and antagonist activities shape the symmetry of motion and the implications of the bell-shaped pattern in muscle function.

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