How do muscles generate movement in IB SEHS terms?

In IB SEHS, muscles generate movement by producing force through contraction and pulling on bones via tendons. The pull creates rotation around a joint, changing the joint angle and creating visible movement. The muscle does not have to shorten to create force, because isometric contractions produce tension without movement. Most movements involve multiple muscles working together rather than one muscle working alone. High-scoring answers mention the joint action, the muscle roles, and the contraction type. Adding neural control (motor units) often separates good answers from great ones.

Why do muscles work in pairs if they create movement?

Muscles work in pairs because they can only pull, not push. If one muscle creates the movement, another muscle must control it, slow it down, or return the limb to the starting position. In IB SEHS, this is described as the agonist--antagonist relationship. The antagonist often provides stability and precision, especially during skilled performance. This is why the antagonist is frequently active even when it looks like it’s “doing nothing.” In exams, explaining control (not just movement) helps you access more marks.

How is this assessed in IB SEHS exam questions?

In IB SEHS, exam questions usually test whether you can explain a movement with correct terminology and a clear chain of cause and effect. You may be asked to identify the agonist and antagonist for a joint action, describe contraction types, or explain how force is regulated. Many questions also reward application: linking the concept to a sport skill such as sprinting, jumping, or throwing. Examiners typically penalise vague statements like “muscles contract to move bones” if you don’t explain roles and control. To train this, RevisionDojo’s Questionbank is ideal because it forces you into exam wording and timing. You can also reinforce definitions quickly with Flashcards and tighten explanations with AI Chat.

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IB SEHS: How Muscles Generate Movement | RevisionDojo

IB SEHS: How Muscles Generate Movement

IB SEHS

RevisionDojo Team

•1/7/2026•6 min read

Movement rarely feels complicated until you try to explain it in an exam.

You take a step, you throw a ball, you hold a plank for 30 seconds longer than you thought you could. It all feels automatic. But in IB SEHS, that “automatic” feeling is exactly what you have to unpack: force, joints, muscle roles, and the nervous system turning intention into motion.

This is your clean, exam-friendly map of how muscles generate movement in IB SEHS.

IB SEHS quick checklist: what to say in an answer

When a question asks how muscles generate movement (especially in B.1), hit these points:

Skeletal muscles attach to bones via tendons and create movement at joints
Muscles pull (they don’t push), so they work in pairs
Force comes from contraction (tension with or without shortening)
Movement is coordinated by motor unit recruitment and neural control
Name roles: agonist, antagonist, plus stabilisers/synergists when relevant

For extra practice in this exact style, use B.1--Generating movement in the body.

Skeletal muscle: the pull that moves the joint

In IB SEHS, the core idea is simple: skeletal muscle creates force, force acts on bone, and bone moves around a joint.

A skeletal muscle is connected to bone by a tendon. When the muscle contracts, it generates tension and pulls the bone. The joint angle changes, and you see movement.