Health and fitness for life.

Core strength, core stability, lean and mean, lengthened not bulked: these are buzz words now in dance conditioning. What do they mean? How do they apply to you? It's all a matter of getting to know your inner unit.

To begin with, we know that all movement emanates from the torso. We've heard that in beaucoup dance classes, right? Every time we imagine a movement prior to executing it, our brain has already done enormous calculations to stabilize some body areas in order to move others. That's why having a thought rehearsal can be quite effective.

The center of gravity of a dancer's body lies in the bowl of the pelvis, generally accepted to be around the second sacral fused vertebra. You can find it by placing both your hands on your hipbones and sliding your thumbs down floe back of your pelvis, heading toward making a letter V. Think internally--your center's not on your back but actually a couple of inches inside the bowl of your pelvis. This inner unit is "computer central." If you can manage it well, you have better control of your torso, spine, and head, and you're in business.

So what exactly is the inner unit? It's a term used by Canadian researcher Diane Lee, PT, in her informative book The Pelvic Girdle (1999; Churchill Livingstone). She has done groundbreaking work with Scandinavian orthopedic researcher Dr. Andry Vleeming to better understand how the pelvis functions. What she's discovered is that the inner unit has four elements. There's the deep abdominal layer (transversus abdominus); the muscular sling of the pelvic floor at the base of the pelvis; the muscular respiratory diaphragm, which cuts the torso top from bottom; and the small but prolific multifidi postural muscles of the lower back.

So how do you work it? Get familiar with all parts individually, and then integrate them. First acknowledge that breath uses the diaphragm. In Pilates, we say to think of the breath coming from the expansion of the sides and the back of the ribs. Dancers need the stability of the lower back while they're moving. Exercises like those taught in Pilates knit the ribs to the pelvis in front, and then percussively use the breath, inhaling through tire nose and out through the mouth, to train the diaphragm to work like a piston inside the muscular cylinder of the torso.

To activate the deep abdominals, lie on your back with your legs bent and your feet on the floor. Keep a neutral back, with a small lower back curve; do not tuck or overarch your back. Then imagine making a big smile across your hipbones. This image usually activates a co-contraction through the small muscles of the lower back and the abdominals. To feel this more strongly, roll onto your side and balance there. Break at the hips like a puppet and then alternate bending and straightening both legs. Then find your pelvic floor muscles. They form a diagonal shape at the bottom of the torso, and can be divided into the front triangle and the back triangle. Try the above exercises again, using this next layer of imagery.

Gently pull up on the front triangle by trying to stop an imaginary flow of urine, and find the back triangle by gently pulling up on the muscles that stop you from breaking wind. Be sure not to grip your buttock muscles.

Before and after class or rehearsal, and whenever you exercise on your own, get in touch with your "computer central" as part of your initial warmup. I'd go so far as to recommend doing these exercises at least once a day.

Suzanne Martin is principal physical therapist for Smuin Ballet. She also has her own practice in physical therapy and Pilates.