Shorten, lengthen, hold
A muscle can work while shortening, lengthening or holding its length approximately steady.
The manual names concentric, eccentric and isometric contraction. The app adds a clearly labeled explanatory model: elbow flexors raise a light represented load, control its lowering, or hold it. The model specifies the muscle and movement phase. It does not label an entire yoga pose as having one contraction type.
Watch the same elbow-flexor model in each phase. The load stays the same; the direction and muscle behavior change. No real weight or movement is required.
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 muscle is the question about? Is the example moving or holding?
Guardrail: The elbow demonstration is an authored supplement checked against an external anatomy source. A still picture cannot establish all the muscles' contraction behavior.
Source: MANUAL p.15 / EXT-CONTRACTION
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