rzen
7c241ec44c
render.py --export bundles the 25 new motion rigs and info pages; figure-fixtures.json regenerated for all 47 (the Swift solver reproduces every new motion, including negative-y pins and the new prop uses). The fixture count assertion moves to 47, and the no-bundled-motion test now uses Treadmill - a permanent COVERAGE.md exclusion - since Bench Press exists. 48 tests green; watch target builds. Coverage handoff complete - TODO-coverage.md retired. Claude-Session: https://claude.ai/code/session_01HJDQQDA9QdP8zByg43H5v3
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1.1 KiB
Back Extension
The roman-chair hinge — hips anchored on the pad, fold forward, then raise the trunk back in line with the legs.
- Category: Main circuit
- Type: Machine-based back extension (hip hinge)
- Targets: Spinal erectors, glutes, hamstrings
- Prescription: 3 × 10–15
Setup
Set the pad so its top edge sits at the crease of your hips — you must be able to fold freely over it. Hook your heels under the ankle rollers, cross your arms over your chest.
Execution
- Fold forward over the pad with a controlled, mostly-flat back.
- Lower until the hamstrings stop you, without going slack.
- Squeeze glutes and back to raise the trunk until it lines up with the legs — no higher.
Cues
- Movement comes from the hips with the back held long.
- Rise to a straight body line, not into an arch.
- Slow down; momentum does nothing here.
Common Mistakes
- Pad set too high, blocking the hinge.
- Hyperextending past the body line at the top.
- Swinging up with momentum.
Progression
Slow the lowering phase, add a pause at the top, then hold a plate to the chest for load.