In his book “An Introduction to Zen Training”, Rinzai Zen teacher Omori Sogen described the role of strength in the lower abdomen in the practice of seated meditation:
In the Yagyu-ryu (a school of swordsmanship), there is a secret teaching called “Seikosui”. Yagyu Toshinaga, a master of the Yagyu-ryu, taught that it was especially important to concentrate vital energy and power in the front of the body around the navel and at the back of the body in the koshi (pelvic) area when taking a stance. In other words, he means to fill the whole body with spiritual energy. In his “Nikon no Shimei” (“Mission of Japan”), Hida Haramitsu writes:
“The strength of the hara alone is insufficient, the strength of the koshi alone is not sufficient, either. We should balance the power of the hara and the koshi and maintain equilibrium of the seated body by bringing the center of the body’s weight in line with the center of the triangular base of the seated body.”
… It may be the least trouble to say as a general precaution that strength should be allowed to come to fullness naturally as one becomes proficient in sitting. We should sit so that our energy increases of itself and brims over instead of putting physical pressure on the lower abdomen by force. (1)
I do believe Omori is right, that there is a strength that can come to fullness naturally in sitting (even if I can’t say that I’ve attained much of it). I believe that balanced strength in sitting develops through activity that is generated involuntarily by the stretch of paired ligaments on opposite sides of the body.
I have tried to pursue the observations of Moshe Feldenkrais:
…good upright posture is that from which a minimum muscular effort will move the body with equal ease in any desired direction. This means that in the upright position there must be no muscular effort deriving from voluntary control, regardless of whether this effort is known and deliberate or concealed from the consciousness by habit. (2)
Feldenkrais described what he felt was the proper way to get up out of a chair:
…When the center of gravity has really moved forward over the feet a reflex movement will originate in the old nervous system and straighten the legs; this automatic movement will not be felt as an effort at all. (3)
Feldenkrais pointed to a reflex movement in rising from a chair. Haramitsu pointed to a reflex activity in sitting, a reflex activity that is brought about as “the center of the body’s weight” comes “in line with the center of the triangular base of the seated body”. Apparently, given the particular placement of weight Hiramatsu described, reciprocal activity can be expected between the hara and the koshi, activity that can be balanced through the maintenance of equalibrium.
I’ve written about how reflex activity effected by the weight of the body returns from the legs to the lower torso, in my essay “Turning to the Left, Turning to the Right, Following Up Behind”:
“Turning to the left, turning to the right”—stretch in the ilio-tibial bands sets off reciprocal innervation of the left and right sartorious muscles, and consequently reciprocal activity in the tensor and gluteous muscles. The result is a subtle “turning to the left, turning to the right” in an upright posture, and a stretch in both the ligaments that connect the abdominals to the rectus and in the ligaments that connect the gluteous muscles to the fascia behind the sacrum and the lower spine.
“Following up behind”—the combination of pressure from the “fluid ball” of the abdomen and stretch and resile in the fascia behind the sacrum and lower spine allows the vertebrae of the spine to find alignment, and permits the fascia behind the spine to provide support. (4)
My interpretation of “following up behind” is based on a study of the mechanics of the lower spine made by Gracovetsky, Farfan and Lamay (5). The authors speculated that in lifting weight, the abdominal muscles work against the extensors to align the vertebrae of the lower spine. They demonstrated through mathematical models that given an appropriate alignment of the spine, displacement of the lumbodorsal fascial sheet from its normal position by even a small fraction of an inch can provide critical support to the structure of the spine. Whether that displacement was to the rear, effected by hydraulic pressure created by the abdominals, or forward, as a consequence of action of the sacrospinalis muscles, the models were not sufficient to determine. The authors noted, however, that displacement to the rear by pressure created by the abdominals would at least in part explain the heightened activity of the abdominals in weight-lifting.
The study presupposed a flattening of the lumbar curve, like that of a person bent over to lift weight from the floor, but acknowledged that the control of the ligament system afforded by activity between the abdominals and extensors could not be directly accounted for in the models. My assumption is that a bent-knee posture like the lotus together with a “tuck” in the tailbone and sacrum can engage the mechanism of ligamentous support the authors
described, through alignment of the vertebrae of the spine.
The activity of the extensor muscles behind the sacrum might also bear on the displacement of fascia. Dr. H. F. Farfan wrote:
There is another peculiarity of the erector muscles of the spine. Below the level of the fifth lumbar vertebra, the muscle contracts in a compartment enclosed by bone anteriorly, laterally, and medially. Posteriorly, the compartment is closed by the lumbodorsal fascia. When contracted, the diameter of the muscle mass tends to increase. This change in shape of the muscle may exert a wedging effect between the sacrum and the lumbodorsal fascia, thereby increasing the tension in the fascia. This may be one of the few instances where a muscle can exert force by pushing. (6)
Farfan doesn’t address whether or not the “wedging effect” between the sacrum and the lumbodorsal fascia might contribute to the displacement of the lumbodorsal fascia behind the lower spine, nor does he discuss how the rotation of the tailbone and sacrum might affect the location of the tension produced by the “wedging effect” of the extensor muscles.
Omori Sogen gave specific advice about strength in the lower abdomen:
… we should put strength in the area above the coccyx (tailbone). This does not mean that we should strain ourselves and put excessive strength in the lower abdomen. It means we should expand the area ranging from the coccyx to the area right behind the naval in such a way as to push out the lower abdomen, while at the same time contracting the muscles of the anus. (1)
Omori is careful not to advise pushing out the abdomen and contracting the muscles of the anus directly, but instead advises to “expand the area ranging from the coccyx to the area right behind the navel” in such a way that the abdomen is pushed out and the muscles of the anus are contracted (I’m confident this is what he’s advising, although the punctuation might say otherwise).
I believe the same effect can be realized by relaxing into the stretch of ligaments between the sacrum and the pelvis. In addition to the ilio-sacral ligaments that hold the sacrum to the wings of the pelvis, there are the sacrospinus ligaments from the sacrum to the sitbones and the sacrotuberous ligaments from the sacrum to the pelvic tuberosities (where the hamstrings attach). I believe stretch in the sacrospinus and sacrotuberous ligaments
in particular is responsible for activity in the pelvic muscles that can “tuck” the tailbone and sacrum (and perhaps contract “the muscles of the anus”).
The rotation of the tailbone and sacrum adds vertical stretch to the lumbodorsal fascia behind the sacrum, and lowers the contact point between the mass of the extensors and the lumbodorsal fascial sheet. The lowered press of the mass of the extensors, together with stretch at the attachments of the abdominals and at the attachments of the gluteous muscles, can generate activity that produces pressure in the lower abdomen and stretch on the lumbodorsal fascia in support of the spine.
Activity of the transverse abdominal muscles related to the alignment of vertebrae particularly comes forward for me at such a time, activity that correlates the placement of the jaw, the arms, and the legs with the alignment of the spine.
If my sitting is geared toward the cessation of voluntary or habitual activity in the inhalation or exhalation of breath, then action of one kind or another, even “bringing the center of the body’s weight in line with the center of the triangular base of the seated body”, must eventually be abandoned. As near as I can tell, what remains is one-pointedness of mind, centrifugal and centripetal force at the location of mind, and the action of inhalation or exhalation.
☞ PDF, A Natural Mindfulness
2) “Awareness Through Movement”, Moshe Feldenkrais, pg 76
3) Ibid, pg 78
4) “Turning to the Left, Turning to the Right, Following Up Behind”, from “A Natural Mindfulness”
5) Gracovetsky, S., Farfan HF, Lamay C, 1997. A mathematical model of the lumbar spine using an
optimal system to control muscles and ligaments. Orthopedic Clinics of North America 8: 135-153
6) “Mechanical Disorders of the Low Back”, H. F. Farfan, pg 183