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Force absorption in plié

This is an excerpt from Dance Imagery for Technique and Performance 3rd Edition by Eric Franklin.

One of the key skills to acquire in plié is verticality, the ability to descend and ascend though the flexion and extension of your lower limbs in the most efficient and effortlessly expressive manner. Visualizing your center of gravity (COG) traveling up and down an imaginary plumb line promotes verticality and provides maximum force for jumping, balance, and centered pirouettes.

Increasingly, dancers are instructed to allow for the natural pelvic movements during plié. This adjustment in cueing is a welcome and healthy development, in contrast to former demands to grip the gluteus and abdominal muscles to hold the pelvis in an abnormally tucked position. Tucking, or actively rotating the pelvis posteriorly, causes a flexion of the spine and a tightening of the pelvic floor muscles that disturbs the alignment of your legs and feet. When the pelvis is “tucked,” the heads of your femur bones push against the front of the hip socket, reducing the amount of contact between the socket and the head of the femur. This predisposes the dancer to injuries such as anterior labral tears, iliopsoas tendonitis, or bursitis. In this chapter, you’ll learn how a healthy supportive pelvis is designed to function.

In classical and modern dance, the basic plié exercise is executed on both legs to allow for concentration on the essentials—alignment (vertical motion in space); flexibility in the hip, knee, and ankle joints; rhythm; and flow of movement through the muscles and joints. Throughout your healthy plié you will sense your weight as equally balanced on both legs, keeping it level and steady as you descend and return to upright. The shape and interaction of your bones in your spine and joints as well as the design of your leg, foot, and pelvic muscles function to facilitate this horizontality, increase the ease and fluidity of movement, and reduce pressures. By allowing the pelvis to absorb force naturally, its safe and full coordination ensures it remains horizontal.

If you have been tucking your pelvis and flattening the belly or pulling in the buttocks to make them seemingly vanish, you may not feel comfortable at first eliminating these tucking-oriented actions. You might worry that your pelvis is dropping forward too much, that you are letting go of control of the movement, or that you don’t have any strength or tone in your abdominals.

During the relearning time, a dancer needs a clear mental image to help them master the new movement. The following section creates the basis of understanding a plié based on sound biomechanics. Executing a healthy and technically strong plié will lead to a dynamically aligned pelvis with muscles that feel toned and balanced—and it starts with knowing and experiencing the many bones at play! During your well-aligned plié, several bones are moving together to allow for healthy function. It is not a question of how to hold your one-piece pelvis into place, but rather of how to allow for the natural harmony of its many moving parts. In other words, you will be creating dynamic alignment in movement.

The human pelvis can be defined as a ring with variable stiffness; it can be more elastic or more rigid depending on the immediate demands placed upon it. If you are doing a high leg extension, the pelvis will have to be somewhat elastic to accommodate the leg, or the pelvis could literally break. If you are partnering someone, the pelvis has to be strong enough to sustain the additional weight. The pelvis also has some flexibility because it is designed to allow for human birth. Since the human birth canal is a tight fit, the pelvic bones can subtly adjust to widen the path, especially for the baby’s head. The three joints that allow for the elasticity of the pelvis are the sacroiliac joints at the back of the pelvis and the pubic symphysis at the front.

While the shoulder joint is the most mobile joint in the body, the sacroiliac joint is quite the opposite—it is designed to transfer large loads and absorb force. This makes the pelvis the body’s primary shock absorber. Healthy force absorption occurs when an impact is absorbed over a certain amount of time rather than abruptly. Just as the arrangement of shocks in a car helps dampen the irregularities of the road and provide a more comfortable ride, the force absorption of your pelvis protects your knees and back. Landing on a hard floor hurts your body, because the surface has no give, and the momentum of your body is halted rapidly. It’s a good thing that your pelvis has built-in force absorption available through functional movement among its parts.

Through a slight downward and rotary movement of the sacrum called nutation, or flexion, force is distributed to the many ligaments and muscles of the pelvis such as the strong sacroiliac ligaments and the pelvic floor (figure 8.1a). As the top of the sacrum (the base) moves forward and down, the bottom of the sacrum (the apex) moves back and up in a cantilever-like motion. The opposite of this movement is called counternutation (figure 8.1b). In this case, the top of the sacrum moves up and back and the bottom moves forward and down. The sacroiliac articulations are not like normal joints with a large range of movement; therefore, it is important that they be balanced on the left and right.

These movements load the muscles and ligaments, which break the movement of the sacrum and absorb the force so that it cannot do any damage (figure 8.2). It’s as if you allow your weight to be supported by the pelvic floor and these ligaments. Because ligaments in general can resist stretch more efficiently than bone can resist compression, loading the muscles and ligaments is a wise choice of human design. Nutation of the sacrum is key to experiencing the legs, pelvic halves, spine, and sacrum meeting each other in an elastic manner.

Holding your pelvis rigid during a plié blocks force absorption, because it reduces the distance over which force is absorbed. The force cannot properly move to the ligamentous and muscular system. This rigidity leads to hip, knee, and lower-back pain and overuse injuries. Sacral nutation causes the sit bones to move laterally (figure 8.3), allowing the muscles of the pelvic floor to contract eccentrically (lengthening contraction) during a plié, which builds a lot of strength. Dancers may think of this as letting go, but in reality muscles can produce more strength when they are lengthening as opposed to shortening. Also, a lengthening muscle can very well help with stability. The idea that you have to shorten muscles (Pull in abs!) to stabilize is a popular but scientifically incorrect notion.

More Excerpts From Dance Imagery for Technique and Performance 3rd Edition

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