Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Sit on a stability ball, feet hip-width apart. Roll back until thighs are parallel to the floor and lower back is supported. Hands behind head or crossed over chest. Engage core, pulling navel towards spine. Exhale, lift upper body, curling shoulders towards hips. Pause, contracting abs. Inhale, slowly lower back down. Repeat.
Ensure proper ball inflation for balance. Keep feet firmly planted. Use abdominal muscles to lift, avoiding neck strain. Maintain slow, controlled movements. Avoid excessive back arching. Exhale during crunch, inhale on descent. Increase difficulty by extending arms or holding a weight.
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