Push-ups are known as a fantastic upper-body strengthener, used to build endurance and power in the chest and shoulders. When done properly, however, the push-up activates the core — including the ab muscles — for stabilization. In fact, push-ups use the same muscles as the plank exercise to keep your body rigid as you press up and down.
Core Work With a Push-Up
Your core muscles are intrinsic to keeping your hips from hiking or sinking each time you perform a push-up. The rectus abdominus, which forms the front sheath of your abs, stabilizes your center, as does the deep core muscle of the transverse abdominis and the obliques at the sides of your waist. The muscles of the lower back also help keep your body parallel to the floor.
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Maximizing Abdominal Recruitment
If you perform push-ups too quickly or fail to move through your full range of motion, you'll cheat your abs from working as hard as they could during the move. To perform a push-up with proper form, lower your body until your chest almost touches the floor.
Keep your abs contracted throughout the movement. To do this, tighten your abs the way you might when bracing for a punch. Even if you need to modify and place your knees on the floor to lessen the intensity, you'll still get a great workout if you use proper form.
Once you've mastered the classic push-up, add challenge using a balancing device. Putting your hands or feet on a stability ball as you perform the push-up increases the activation of the core muscles. Lifting one leg or pulling a knee in toward your elbow as you lower down — spiderman-style — recruits your abdominal muscles even more.
Try push-ups with shoulder taps by lowering into a push-up and, upon rising, quickly tapping one shoulder with the opposite hand, then switch hands. This move requires your abs to activate and provide the extra bit of stabilization at the top as you balance on just three points.
A 2014 study published in the "Journal of Sports Science and Medicine" demonstrated that a suspended push-up effectively recruits the abdominals — more so than the standard push-up.
To perform this move, adjust a pully system so that both handles are just a few inches from the floor. Get into a push-up position with your hands in the handles of the suspension cables and proceed as you would with a standard push-up.
Read more: 10 Push-Up Variations for a Stronger Body
Truly Toned Abs
Push-ups do activate your abs, but alone aren't enough to give you a defined middle. Combine them with cardio exercise, to burn calories and help you lose fat, a quality diet and total-body strength training.
You'll build a more toned and muscular body and abdomen by regularly including resistance moves that work your back, arms, legs and hips, in addition to other moves that address your abdominals, such as plank holds, crunches and torso twists.