In the human pelvis with weight loading on the sacrum, primary loading is on the posterior inter-osseous ligaments, which suspend the sacrum. A secondary loading takes place on the sacro-tuberous ligaments in the opposite direction, which is equal to the primary loading. This is a kinetic loading.

Movement begins when the innominates move from symmetry to asymmetry. The balanced loading creates interactive force couples to facilitate ambulation. The pelvic asymmetry alternates at mid-step when the pelvis is briefly symmetrical with a bio-tensgrity movement.

In the Springy rat, does the pelvis remain symmetrical with springing?