Forearms, wrists and hands
A palm can turn without the wrist bending. A wrist can bend without the forearm turning.
With the elbow bent and upper arm still, supination turns the palm up and pronation turns it down. Wrist flexion brings the palm toward the forearm; wrist extension brings the back of the hand toward it. The transcript discusses more wrist extension during a forward shift in Plank. The app shows that relationship without teaching a universal safe load or a required depth.
Lock one modeled motion while exploring the other. Compare a free forearm demonstration with the hand-on-mat reference.
This release does not implement this lesson’s full animation. Its behaviour is specified in the PRD and content data. Step controls will accompany every drag interaction.
Which two body parts are moving relative to each other?
Guardrail: The task is observation, not a wrist-loading challenge. Watching is a complete way to participate.
Source: MANUAL p.14 / CLASS 01:09:06-01:14:44
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