If you don't remember the original, it's a simple exercise in which you get on all-fours and lift your opposite arm and leg off the floor -- without allowing your torso or hips to rotate in either direction. The elevated bird dog ups the level of difficulty by having you hold both knees off the floor for the duration of the exercise.
"Lifting your knees off the ground just a couple of inches makes it even more challenging to keep your torso still as you switch arms and legs," says David Jack, director of Teamworks Fitness in Acton, Mass., and creator of the High-Intensity Body-Weight Workout.
That means your entire core -- hips and lower-back muscles, obliques, rectus abdominis (also known as the six-pack muscle) -- is working overtime to keep your spine stable. All of which may look simple, but just try it: This is one hard core exercise. In fact, you may find that simply holding the starting position -- before you raise your arm and leg -- proves to be an adequate challenge.
Watch the video to learn how to do the elevated bird dog with perfect form. Then try performing this movement in a total-body circuit or as part of your core workout. Do 16 reps on each side.
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