Planking is hands down one of the best ways to put your core to the test. Unfortunately, planking can also quickly become one of the most boring ways to put your core to the test.With a series of quick tweaks, though, you can transform the humble plank into a whole array of new muscular challenges to finally build those six-pack abs you've been after.Men's Fitness' Mike Simone demonstrates the 12 plank variations you should be working into your routine immediately.1. Standard plankAlso known as "pushup position."[RELATED1]2. Elbow plankLike a standard plank, except supported on your forearms.3. One-arm plankPuts your torso off-balance, forcing your core to work harder.4. One-leg plankA great way to reveal strength imbalances across your core and challenge your glutes.5. Side plankChallenges not only your abs but also your obliques and your shoulders.[RELATED2]6. Side plank with pull-throughTaxing for total-body strength and balance, especially in your shoulders.7. Shoulder tap plankAdds an upper-body workout to the standard plank. (Focus on keeping your body still—don't rock back and forth.)8. Body saw plankTargets shoulders and back, along with core, glutes, hamstrings, and calves. Also an excellent way to practice the planche plank.9. Reach under plankHelps improve flexibility in the hips, and stability in the core and upper body.[RELATED3]10. Star plankAn ultra-tough variation on the standard plank. See how long you can hold it, and how far out you can span your arms and legs.11. Walk out plankHits the abs like a roll-out while testing your hip flexibility. Try not to bend your back too far forward.12. Planche plankA slightly less difficult variation on the planche, a classic gymnastics move and test of isometric total-body strength. Excellent for testing shoulder mobility and upper-body strength.[RELATED4]