Muscle outlines from Body Muscles by Ivan Vulović, Apache 2.0 — regrouped and recoloured for Muscle Train.
Stand behind a line on the ground with your knees bent and shift most of your weight to the balls of your feet. Engage your core, keep your back straight, and (if possible) maintain a forward gaze to hold proper form during this exercise. Start to shift your weight over the line, and flex your calves to jump forward over the line. Land on the balls of your feet on the other side of the line with a slight bend in your knees. Quickly flex your calf to reverse direction, and jump back over the line.
Keep your core tight and stay on the balls of your feet. Use quick, controlled hops. Land softly with knees slightly bent to absorb impact.
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