You should be doing anti-core training. The muscles of your core are meant to resist movement, not create it. Your core is the link between the upper and lower body, transferring power from the hips (mobile) to the shoulders (mobile) through a stable spine. Therefore, it should be trained that way.
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Eliminate the sit ups, crunches, russian twists, hanging leg raises, and pikes (where the core is the main mover). Instead, opt for exercises like front planks, side planks, anti-rotation presses, wheel rollouts, stability ball circles and suitcase carries (where the core is the main stabilizer and the hips and shoulders are the main movers).