Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Lie on your back, knees bent, feet flat, fingertips lightly behind your ears (not laced behind your head). Press lower back into the mat, elbows out. Crunch and rotate towards one knee, exhaling as you curl your upper back and twist your torso. Drive your shoulder toward the opposite knee, keeping your lower back pressed against the mat. Hold briefly at the peak contraction, feeling oblique engagement. Slowly lower back to the starting position over 2 seconds, maintaining core engagement. Alternate sides; one rep per side. Breathe out during the crunch, in on the return. Beginners: 3 sets of 10 reps per side.
Focus on rotating your ribcage, not your elbow. Keep finger pressure light to avoid neck strain; if needed, regress to regular crunches. Only the rotating-side shoulder blade needs to lift off the mat. Control the lowering phase – take 2 seconds to lower each rep for maximum muscle activation.
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