Any move that only works one part of your body is, frankly, old school. Out are the single-note exercises, and in are those that engage multiple muscle groups. For anyone with less time on his or her hands (isn’t that everyone?), or those with short exercise-attention spans, this Move of the Week, gives double (or triple) the results.
Sculpt your arms, core, and bum with the Push-Up with Alternating Knee Tap—it’s a mouthful, but with a burn like this, who cares what the name is?
Incorporate this move into your usual strength-training routine, do several sets at high-intensity after a sweaty cardio session, or just simply use it to mix up a boring at-home workout.
What to do: Start in "up" part of push-up, hands directly under shoulders, body straight. Engage core; bend elbows to lower body toward floor. Press back up; bring left knee to outside of left elbow; pause for 2 seconds, then return to starting position. Do another push-up, bring right knee to right elbow, return to start; that's 1 rep. If you need a little modification to make it easier, just bring knees to the floor.
This MOW is basically a combo of traditional push-ups and mountain climbers. Be sure to keep your butt down and back straight when you perform the push-up. And when you come up into a plank formation, think of a slowed-down mountain climber with wider knee crunches for the knee-taps.
Another option is to bring your knee across the chest (i.e. left knee to right side of chest) when you crunch in, so you work your obliques as well.