Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Stand in a doorway, feet shoulder-width apart. Raise arms to the sides, elbows bent 90 degrees ('goalpost'). Forearms against the door frame, elbows below shoulder height. Step one foot forward through the doorway, back straight, core engaged. Gently lean forward, feeling a chest and shoulder stretch. Hold for 15-30 seconds, breathe deeply. Return to start, repeat on the other side.
Relax shoulders, avoid shrugging. Keep elbows below shoulder height. Engage core for neutral spine. Avoid excessive forward lean. Breathe deeply.
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