I'm sure by now you've heard just how great planks are for flattening your belly, not to mention toning your entire body. The reason they work well: Holding a plank requires the transverse abdominis muscle (the deepest layer of abs) to rapidly fire. Plus, the pose engages other areas, like your arms, shoulders, back and legs. But when your body gets used to an exercise, it's important to switch it up. Here, new spins that will challenge you even more. Now plank on!
Come into a traditional plank, keeping everything stable in the upper body and core (imagine holding a cup of water on your back). Kick your left heel twice toward your butt, then kick your right heel twice toward your butt. Continue alternating for 10 reps on each side.
3 of 6alex-beauchesne
Bird Dog Plank
Hold plank, then lift and stretch your right arm forward and your left leg back and up. Hold for 1 second, then switch sides. Continue alternating arms and legs for 10 reps on each side.
4 of 6bird-dog-plank
Start in plank, then lower your left forearm to the mat; come back up to plank. Then drop your right forearm to the mat and come back up. Continue alternating for 10 reps on each side.
From plank, lower knees at the same time until they touch the mat, then lift them back up while keeping rest of body still. Repeat 15 to 20 times.
6 of 6alex-beauchesne
While in plank, move your hands close together and your legs out into a wide V. Then step your feet together and move your hands open wide. Continue alternating hands and feet in and out for 10 reps of each.