Muscular System: Types of Muscle, Contraction, and Movement

    OCR
    GCSE

    Candidates must demonstrate detailed knowledge of the structural and functional characteristics of cardiac, smooth, and skeletal muscle tissues, with specific emphasis on skeletal muscle mechanics during physical activity. Responses should articulate the sliding filament theory to explain contraction and categorize muscle fibre types (Type I, IIa, IIx) according to their physiological properties and suitability for specific sporting intensities. Furthermore, analysis must cover antagonistic muscle pairs and the mechanics of isotonic (concentric/eccentric) and isometric contractions in the context of movement efficiency.

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    Objectives
    4
    Exam Tips
    4
    Pitfalls
    3
    Key Terms
    5
    Mark Points

    What You Need to Demonstrate

    Key skills and knowledge for this topic

    • Identify specific muscle types: voluntary (skeletal), involuntary (smooth), and cardiac, linking them to their function.
    • Analyse movement using the antagonistic pair model: explicitly naming the agonist (prime mover), antagonist, and fixator for a given action.
    • Differentiate between isotonic concentric (shortening under tension) and isotonic eccentric (lengthening under tension) contractions.
    • Apply mechanical principles to specific sporting examples, such as identifying the eccentric contraction of the quadriceps during the downward phase of a squat.
    • Credit responses that correctly identify the fixator muscle stabilizing the origin to allow efficient movement.

    Example Examiner Feedback

    Real feedback patterns examiners use when marking

    • "You have identified the agonist correctly. To access higher marks, specify the type of contraction (concentric or eccentric) occurring in this phase."
    • "Your definition of an antagonistic pair is accurate. Now apply this to the specific sporting example provided, naming the fixator."
    • "Avoid saying the muscle 'relaxes' during the downward phase; analyse how it lengthens under tension (eccentric) to control the movement."
    • "Ensure you distinguish clearly between the muscle classification (e.g., voluntary) and the muscle role (e.g., agonist)."

    Marking Points

    Key points examiners look for in your answers

    • Identify specific muscle types: voluntary (skeletal), involuntary (smooth), and cardiac, linking them to their function.
    • Analyse movement using the antagonistic pair model: explicitly naming the agonist (prime mover), antagonist, and fixator for a given action.
    • Differentiate between isotonic concentric (shortening under tension) and isotonic eccentric (lengthening under tension) contractions.
    • Apply mechanical principles to specific sporting examples, such as identifying the eccentric contraction of the quadriceps during the downward phase of a squat.
    • Credit responses that correctly identify the fixator muscle stabilizing the origin to allow efficient movement.

    Examiner Tips

    Expert advice for maximising your marks

    • 💡When analysing the 'downward phase' of a movement (e.g., squat, press-up), the agonist is usually the same muscle as the upward phase, but acting eccentrically.
    • 💡Always state the specific type of isotonic contraction (concentric or eccentric); 'isotonic' alone is often insufficient for higher tariff marks.
    • 💡Use the 'Joint-Action-Muscle-Type' structure for movement analysis questions to ensure all AO2/AO3 criteria are met.
    • 💡Memorize the specific location of major muscle groups to avoid labeling errors on anatomical diagrams.

    Common Mistakes

    Pitfalls to avoid in your exam answers

    • Confusing 'eccentric contraction' with 'relaxation'; failing to recognize that muscles lengthen under tension to control gravity.
    • Omitting the role of the 'fixator' when describing antagonistic muscle action in complex movements.
    • Identifying the wrong muscle as the agonist during the downward/recovery phase of a movement (e.g., stating the triceps are the agonist in the downward phase of a bicep curl).
    • Vague terminology: using 'tensing' instead of 'contracting' or 'working'.

    Key Terminology

    Essential terms to know

    Physiological classification of muscle fibres (Type I, IIa, IIx)
    Mechanics of antagonistic muscle action and reciprocal inhibition
    Types of contraction: Isotonic (concentric/eccentric) and Isometric

    Likely Command Words

    How questions on this topic are typically asked

    Identify
    Describe
    Explain
    Analyse
    Justify

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