Planks are great abs because they work the back and shoulders creating better posture and alignment which tones the abs faster. They also burn more calories and more body fat which is necessary for creating lean abs. The two plank versions below look similar but they aren't the first targets the upper abs, hips, glutes, upper back and shoulders while the second one targets the low abs, shoulders, chest, low back, and quads.

Exercise
Belly Blaster 1. Start in a plank position with your elbows and forearms on the ground, your body parallel to the floor and up on your toes. 2. Make sure your belly button is drawn in toward your spine and raise your hips up into the air and hold for a 1 second count. 3. Return to the starting and repeat for the prescribed number of repetitions. Trainer's comments:	Sets Reps Weight/ Resistance Tempo Time
Plank Knee-ins 1. Start by getting on your hands and knees in a push-up position. 2. Keeping your abs tight and your trunk parallel bring one knee in towards your chest. 3. Return the foot back to the starting position and repeat with the other leg. Trainer's comments:	Sets Reps Weight/ Resistance Tempo Time