What Muscles Do Planks Strengthen?

Modifying the plank for increased difficulty is easy.
i Motoyuki Kobayashi/Photodisc/Getty Images

The next time you catch yourself listening in on what the really fit gal next to you on the treadmill says she does for a taut, strong midsection, chances are you'll hear the word "plank." Although it's primarily known as an abdominal exercise, the plank is so much more than just abs. This no-equipment-required move not only tightens your belly, it strengthens your chest, arms, back, glutes and legs, too.

How the Front Plank Works

    The front plank builds strength in these areas with body weight rather than equipment, making it a great, no-excuses-tolerated exercise. Lie on your stomach and put your elbows underneath your shoulders. Place your palms face down in front of you and rise up, so you support yourself using only your forearms and your toes. As you gain strength in your abs, back, shoulders, chest, quads, glutes and calves, you'll be able to hold the pose for a minute or longer. Don't worry if you can't do it right away -- like all worthwhile exercises, it takes practice.

The Technical Stuff

    Specifically, supporting yourself with only your forearms and toes forces the rectus and transversus abdominis of the abs, the erector spinae, trapezius and rhomboids of the back, the rotator cuff and deltoids of the shoulders, the pectorals and serratus anterior of the chest, the quadriceps and gastrocnemius of the legs and, finally, the gluteus maximus to contract and exert force. And, like all strength moves, the more you perform the plank, the stronger these muscles will become -- enabling you to hold the pose for even longer periods of time.

The Side Plank

    You may be thinking, big deal! What about my obliques? Fear not, because you work those waist-slenderizing side muscles with the -- you guessed it -- side plank. During the side plank, you support your body's weight with only one forearm and the side of one foot while you lift your hip in the air. It works the transverse abs, the obliques and the muscles of the butt and hips, the abductors and adductors. It also works the gluteus maximus and the bottom leg's quadriceps and hamstrings. Unlike the front plank, it doesn't work the back or chest muscles. And don't forget to switch sides.

Modifying the Plank for Difficulty

    If you are just beginning a plank workout and you find the move too difficult to hold for more than a second or two, put your knee or knees on the ground. As you gain strength, holding the pose for longer periods of time should become much easier. Are you a hotshot? Then try holding one arm and one leg in the air as you hold the pose. This forces your muscles to work even harder, building greater strength. Soon it will be you on the treadmill, bragging about your rock-hard abs.

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