Body and Breath - Yoga Shop Talk

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Yoga shoptalk, September, 2002

Question: A well-known visiting hatha yoga teacher (who happens to be one of my all-time favorites) was leading a class of teachers-in-training through some subtle points about single leglifts, and she emphasized using the abdominal muscles to help create the lift. But in your section on leglifts in Anatomy of Hatha Yoga (pages 160-169), you emphasize that the hip flexors (the iliacus and psoas muscles) in combination with the quadriceps femoris are the muscles that accomplish leglifts. In addition, you make the point later on in the section on the posterior stretch (especially referring to your comments on the abdominal muscles on pages 347-348) that the abdominal muscles "complete the forward bend without having the slightest effect on hip flexion." So my question is: are not my teacher's comments in conflict with yours?

Answer: Yes first, then no. Your teacher's comments can indeed be questioned on a technical basis because the prime movers for leglifts in general are undeniably the hip flexors, and their synergists for keeping the knee or knees extended are undeniably the quadriceps femoris muscles. And for single leglifts in particular in which one extremity is flat on the floor and the pelvis is naturally stabilized, the abdominal muscles ordinarily remain completely relaxed. And finally, it is also true as you noted on page 347 that for completing a forward bend, the abdominal muscles do not have the slightest effect on hip flexion.

On the other hand (that is, no), your instructor was most likely preparing you for the all-important roles of the abdominal muscles in protecting the lower back and for controlling exhalations during the course of accomplishing double leglifts in a graceful and skillful manner. The rationale? When doing double leglifts, the psoas muscles pull forward strongly on the lumbar region (the lumbar vertebrae being their origin), and unless the abdominal muscles are kept in a strong state of isometric contraction to keep the lower back firmly against the floor, the psoas muscles tend to destabilize the lumbar region as they flex the thighs. So even though the abdominal muscles are technically neither prime movers or even synergists for flexing the thighs, they are extremely important for creating a stable foundation for the exercise.

The role of the abdominal muscles in emphasizing exhalation is also crucial. Leglifts feel the easiest and least threatening when the abdominal muscles are strongly pressing inward at the end of exhalation and are only partially releasing for small inhalations. You will instantly feel a loss of strength if you inhale fully as you lift the legs.

On the other hand, two advanced exercises were presented in which we see the opposite situation. Both the superfish leglift and the slow leglift with a relaxed abdomen (pages 166-168) require that the abdominal muscles remain completely relaxed, thus allowing the psoas muscles to tug strongly on the lumbar region and keep it in a stabilized forward position.

Finally, completing a forward bend using the abdominal muscles (which indeed do not have any effect on hip flexion in this circumstance) is not relevant to leglifts for two reasons. First, the rectus abdominis muscles insert only on the front of the pelvis, and thus can not possibly have any direct effect on the thighs, and second, even if that were not the case, the thighs are already flexed to their maximum as the abdominal muscles pull the torso forward and down.