You need to add cross body mountain climbers to your ab exercise routine. This exercise will build strength and help tone your "six pack" and obliques. Cross body mountain climbers also work the calves, quadriceps, glutes, back, chest, triceps and shoulders. You will need high levels of core strength to do this exercise the right way for each set.
1. Start by getting in the push up position with your arms fully extended. Keep your hips and torso in a straight line. Don't let your hips sag and don't point your butt in the air during this exercise.
2. Do the exercise by moving your left knee straight up and across your body to the right armpit area (keep your abs braced). Also, don't let your foot touch the ground as you do the movement. Move your left leg back to the starting position and repeat with your right leg. Alternate your leg movements until you have completed all repetitions.
If you are doing the mountain climber exercise then just add on the cross body mountain climber!