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1 Start each set tight and engaged
When you train your abs you must ensure there is tension on your entire core before starting a set. Doing so will recruit more muscle fibres into action, and the greater number of fibres you fatigue during a workout, the better your size and strength gains. Fully contract your abs at the top of moves like crunches or hanging leg raises, and lower slowly and under complete control. For static holds such as the plank, focus on keeping your core braced for the entire duration of the move.