At the close of a commentary in ‘The Blue Cliff Record’, Yuanwu wrote:
Answering the monk who asked, “What is the
meaning of the Patriarch’s coming from the
West?”, Hsiang Lin said, “Sitting for a long time
becomes toilsome.” If you understand this way,
you are “turning to the left, turning to the right,
following up behind.” (1)
I can’t really speak to the exchange between the monk and Hsiang Lin, but I can say that Yuanwu’s description, “turning to the left, turning to the right, following up behind”, has been very helpful to me.
“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 the fascia behind the sacrum and the lower spine.
“Following up behind”—the combination of stretch and resile in the lumbodorsal fascia and pressure from the “fluid ball” of the abdomen allows the vertebrae of the spine to find alignment, and permits the fascia behind the spine to provide support.
1) “The Blue Cliff Record” (koan 117), compiled by Yuanwu Keqin, tr. Cleary & Cleary, Shambala
publications pg 114