There are three things to remember when giving your abdominals a workout: protect your neck and lower back; work all three sets of abs for symmetry; and, work slowly to get noticeable results.
Many ab exercises put unnecessary strain on the lower back. In every ab exercise, engage the muscles by contracting towards the spine. In a traditional crunch, the temptation is to pull on the neck and use momentum to lift the chest rather than use the lower belly muscles. Flatten the chest and lift from the core abdominal muscles. You will feel your core working.
Most people focus on the “six pack” muscles of the middle of the midsection of rectus abdominals. It is important to equally develop all three major ab muscle groups to not create an imbalance. Only developing the six pack group can create a posture that slouches forward. Work on crunches, but also side to side actions and curl ups to develop all the abs equally.
Fast movements in ab exercises do not work effectively to shape the muscles. Rushing through sit ups, for example, uses the hip flexor muscles and not the abs. If you rush through the exercises, the work is no longer muscle dependent and you will not get the desired muscle development or visible shaping. Doing three sets of ten repetitions slowly is better than doing thirty reps quickly.
Michael Kasprenski, Wellness Coach, Steel Fitness