Joint types and the articulating bones, the movement patterns and planes and axes of movement, the agonist, antagonist, fixator and synergist roles, and the types of muscle contraction at the shoulder, elbow, hip, knee and ankle.

What this dot point is asking

AQA wants you to analyse movement at the shoulder, elbow, hip, knee and ankle: name the joint type and articulating bones, the movement produced, the plane and axis it occurs in, the agonist and antagonist (and the fixator and synergist), and the type of contraction taking place.

Joints, movements and muscle roles

The major joints are mostly synovial joints, which share common features that AQA expects you to name: a joint capsule, a synovial membrane secreting synovial fluid (lubrication and nutrients), articular (hyaline) cartilage covering the bone ends to reduce friction, ligaments joining bone to bone for stability, and tendons joining muscle to bone. The shoulder and hip are ball and socket joints (allowing flexion, extension, abduction, adduction, rotation and circumduction); the elbow, knee and ankle are hinge joints (allowing flexion and extension, with dorsiflexion and plantar flexion at the ankle).

To analyse any sporting action, AQA wants a fixed sequence: name the joint type and the articulating bones (for example, the elbow joins the humerus, radius and ulna), state the movement produced (flexion, extension, abduction, adduction, rotation, dorsiflexion or plantar flexion), give the plane and axis, name the agonist and antagonist, and identify the type of contraction. Working through this checklist guarantees the marks in a movement-analysis question.

Muscles work in antagonistic pairs, for example the biceps brachii (agonist) and triceps brachii (antagonist) at the elbow, and the quadriceps and hamstrings at the knee. The roles swap depending on the movement: in elbow flexion the biceps is the agonist and the triceps the antagonist, but in elbow extension (such as the upward phase of a press-up) the triceps becomes the agonist and the biceps the antagonist. This is why you must always identify the agonist by the movement being produced, not by the muscle's usual name.

Types of muscle contraction

Planes and axes of movement

Movements occur in three planes, each paired with an axis running through the body at right angles to it.

• Sagittal plane, transverse axis: flexion and extension, such as a forward somersault or a biceps curl.
• Frontal plane, sagittal axis: abduction and adduction, such as a star jump or a cartwheel.
• Transverse plane, longitudinal axis: rotation, such as a full twist in trampolining or a discus turn.

For example, a squat at the knee occurs in the sagittal plane about the transverse axis: on the way down the quadriceps contract eccentrically, and on the way up they contract concentrically.