Weighted Crunch - Phase 2 - Day 5 - Strength. The purpose of getting strong abs, apart from building them, is that they are crucial for compound movements/exercises, such as the squat & the overhead press, for example. Place a 10kg plate on the chest, using the same form as the plain crunch. Keep the movement strict & controlled at all times. Aim for 15 reps, increasing the amount of weight used each week. Nick Jones - World Bodybuilding Champion & Zoran Lekic - Bodybuilder.