Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Stand facing a box, feet hip-width apart. Shift weight to one leg, slightly bending the knee. Swing arms back, then explosively jump onto the box, swinging arms forward. Land softly, bending your knee to absorb impact. Step down and repeat on the same leg, then switch.
Use a stable box at a comfortable height. Engage your core for balance. Swing arms to generate upward momentum. Start with a lower box height and gradually increase as you get stronger. Land softly by bending your knee.
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