Arm/Leg Reach Plank
Start in the regular plank position. Raise and fully extend your right arm and left leg, and hold the position for 5 to 10 seconds. Return to the starting position and alternate sides. Continue alternating sides for 1 minute.
Why it works: "As you lift up your opposite leg and arm, this is a great way to improve your balance as you work on building core strength," Geigle says.
More: 30-Day Plank and Push-Up Challenge
Jack Plank
From the regular plank position, keep your body stationary. Jump both legs out, then jump your legs back in. Repeat the jumping jack movement for 30 seconds to 1 minute.
Why it works: "This move continues to work your core, and is also a great way to add in extra leg and glute work to your routine," Geigle says.
Knee-to-Elbow Plank
Start in the regular plank position. While balancing on your right side, take your left knee and bring it up to your left elbow. Move your leg back to the starting position, and repeat the movement on the opposite side. Continue to alternate sides for 30 seconds to 1 minute.
Why it works: "This version of the plank is great for working the side core muscles. As your leg moves from your elbow back into the plank position, you will feel your obliques working," Geigle says.
Side Plank
From the regular plank position, turn to your left and balance on your right side with your left arm and left leg stacked over your body. Hold the position for 30 seconds. Briefly return to the starting position and repeat the movement on the opposite side.
Why it works: "This move hits all components. It works the center of your core and obliques while also building extra balance and arm strength," Geigle says.
More: The Minimum Amount You Can Strength Train and Still See Results
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