Trunk Twists (Rotary Torso)
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Seated machine torso rotation (rotary torso) working the obliques and erector spinae; rotates the torso ~40 degrees with hips fixed.
Detail
Trunk twists / rotary-torso work train torso rotation. Torso rotation is produced by the erector spinae and the external and internal obliques; contraction of an external oblique and the opposite internal oblique causes trunk rotation. The torso rotates approximately 40 degrees with the hips in a fixed position (spinal rotation is very limited in the lumbar region). Performed on Cybex/Paramount rotary-torso machines — the source explicitly states free bars are NOT allowed for this movement. The standing torso twist with a barbell is a contraindicated ("X-rated") version.
Key facts
- Works external oblique, internal oblique, and erector spinae (rotation).
- Torso rotation ROM ~40 degrees with fixed hips.
- Machine only — no free bars allowed.
Connections
- External Oblique / Internal Oblique — produce rotation.
- Erector Spinae (Sacrospinalis) — assists in torso rotation.
- The Standing Torso Twist — Contraindicated Stretch — the dangerous standing barbell version.
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Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.