Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Start with a hip hinge: feet shoulder-width, push hips back, bend knees slightly, torso 45-60 degrees from vertical, spine neutral. One hand behind your head (elbow out), the other for balance. Exhale, rotate your upper back, driving the head-hand elbow down and under, reaching toward the opposite knee. Hips and lower back remain stable; rotation is from the shoulder blades. Inhale, reverse the movement, driving the elbow up towards the ceiling, following it with your eyes. Fully open your chest. Pause. Repeat slowly (3-4 seconds per direction) for 6-8 reps, then switch sides. Maintain the hip hinge throughout; avoid waist rotation – keep your belt buckle facing the ground. Focus your gaze on your elbow during rotation to engage the entire spine. Don't force range of motion; gradually increase with each rep. Exhale during the closing rotation, inhale during the opening rotation.
Engage your hips by placing a hand on them to maintain stability. Initiate the movement with a neutral spine before rotating. Perform each repetition slowly, taking 6-8 seconds. Hinge your torso forward at least 45 degrees to isolate thoracic rotation.
MuscleTrain is actively being built. If something looks broken, or you have a suggestion, let us know — it really helps shape the app.