Building Your ‘Girdle of Strength’

plankNearly 100 years ago, Joseph Pilates talked about developing a “girdle of strength.” Another Pilates term for these core body muscles is “powerhouse.” They are the physical center of the body, crucial to virtually every movement we make.

Joseph Pilates called the physical fitness system he developed “contrology.” His goal was to build stability, flexibility, strength, endurance and control through exercises involving the muscles of the abdomen, lower back and hips–the body’s powerhouse or core.

Today, more than 11 million Americans practice Pilates as an exercise form. But even if you have never taken a Pilates class, you have undoubtedly heard plenty from trainers and others around the gym about the importance of building and maintaining a strong core.

These core muscles include not just the external abdominals that we ordinarily think of but the inner abdominals and smaller muscles that line the spinal column. Your gluteals and pelvic floor muscles are also important parts of your core.

If you are just beginning to exercise or learn dance, core muscles are crucial to developing good form and posture. If you are already an accomplished athlete, these muscles help protect you from injury, particularly problems of the lower back.

To understand the importance of the body’s core, you need to consider the design of the human body. You have a spinal column that is expected to keep your body upright and bear loads. Yet this spine consists of vertebrae that allow you to be flexible–to turn, bend over, run and dance.

Imagine how you are able to lift and carry a 50-pound suitcase with one hand up a flight of stairs and still keep your body reasonably straight and upright. You need strong muscles on the carry side but also on the other side to keep you from tipping over. The stress goes all the way from the shoulders to the heels and toes. And it requires a well developed core.


Core Stiffness Is Key

According to Stuart McGill, Ph.D., a Canadian professor of spine biomechanics and a noted back pain expert, the key is core stiffness, which is crucial for both performance and injury prevention.

And that’s why your trainer might advise you to include at least some one-legged, one-armed weight lifting, such as curls or kickbacks, in your routine. As McGill puts it, “stiffness prepares the joint to bear load without buckling.”

THE PLANK: One of the most basic core exercises is the plank. While lying face down on the floor, turn your body into a plank. Lift yourself on your forearms and maintain that position, keeping your body as straight as possible.

Gravity is trying to force you to sag; your core muscles are keeping you stiff and straight. You might start with a 20-second hold, then work yourself up to 30 and 60 seconds.

When the plank becomes relatively easy to perform, try variations. Lift one leg and move it outward and then back. Repeat with the other leg.

Now do the same with each arm. And finally lift your left leg and right arm together.

You get the idea. You are stressing your body with movement and counting on your core muscles to keep you stable.

THE SIDE PLANK is the same but on the side, resting on one forearm.

For the initial level of difficulty make the plank between your forearm and your bended knees. Make it more difficult by placing the outer hand on the hip for greater mass.

Then create the plank from the feet to shoulders and make it more difficult by placing the upper hand on the hip. Finally, lift the upper leg and hold for 20 seconds. You might also try extending the arm at the same time that you are extending the top leg.

The side plank targets many of the smaller muscles that are rarely used plus the obliques. Remember the importance of stiffness. Keep your body straight and perpendicular to the floor; don’t let your hips sag.

 THE BIRD DOG is another variation of the plank. Go to all fours on the floor. Then, like a bird dog, lift one arm and point it forward while lifting and straightening the opposite leg. Hold for 10 seconds and do 8 to 10 repetitions for each side.

You can increase the challenge by drawing squares in the air with both the arm and the leg.

PUSHUPS, YES; SITUPS, NO. Traditional pushups are clearly good for building core strength as long as you use proper form. And you can make the pushup harder by elevating either your legs or your hands on a barbell or bench.

Situps and crunches, on the other hand, traditionally recommended for strengthening abdominals are really not so helpful and may even have a detrimental effect. If you have no abdominal fat whatsoever (how many of us don’t?), doing several hundred crunches a day might give you the semblance of “six-pack abs.”

Yet you will rarely have an occasion to use your abdominals in that way during daily life. The muscles in the core body are more important as stabilizers than as flexors. Doing repeated crunches, moreover, involves repeated bending of the spine that, according to Dr. McGill,“is a potent injury mechanism.” Do enough situps or crunches to get six pack abs, and you will likely end up with one or more herniated discs.

Doing crunches on a gym ball may be just as unsafe, Dr. McGill says, because these too are likely to stress the discs. It’s much better to rest your forearms on the gym ball and form a plank with your body–an exercise he calls “Stir the Pot.”

Move your forearms in a circular fashion, keeping your abdominal muscles braced and your gluteals tight. Control your core so that it moves as little as possible.  

It’s not easy; as with all core exercises, the goal should be to challenge yourself as much as possible.

With a strong core that provides stability and stiffness, you can run faster, lift better, dance with greater fluidity. And, even more important, you will be protecting your back and the rest of your body from injury.



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“The benefits of Pilates,” Balanced Body.

Matthew Ibraham, “The best core strengthening exercises to a healthier spine,” The PTDC.

Rael Isacowitz and Karen Clippinger, “Core stability plays key role in body alignment,” Human Kinetics, Excerpt from Pilates Anatomy.

Mayo Clinic Staff, “Fitness,”, August 1, 2016.

Stuart McGill, Ph.D., “Core training: evidence translating to better performance and injury prevention,” Strength and Conditioning Journal, June, 2010.

Stuart McGill, “Why everyone needs Core Training.”

“7 Pilates core moves,” Daily Burn, March, 2015; updated August, 2016.

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 “What’s the link between Pilates and core stability?”, last updated December 3, 2015.