See it: Walking Like a Cat

In the Tai Chi classics, Wu Yu-Xiang (1812-1880) says: "When changing position, you should move like a cat." That implies that you should step naturally, as a cat would. When stalking a bird or mouse, a cat does not commit any weight to the stepping paw before it is already touching the ground. Committing its weight prematurely would produce a discontinuity in the motion that would alert its prey. Also, a cat would not stiffen its joints while walking. When balance is off, it is almost impossible to step like a cat.

Locking the Knees:   Many players stiffen their knee joints while stepping and literally fall onto the stepping foot. Stepping in this manner is unnatural, breaks the balance and continuity of yin and yang, and increases vulnerability to falling in daily life. Poor balance often results from insuficient leg strength, failure to center the weight distribution on the centers of the feet, and fixating rather than softening the vision. Feeling the center of mass of the body to be directly over the center of the weighted leg is important.

Order of Stepping:   In stepping forward, the lowest point is the heel, whereas in stepping backward the lowest point is the toe. In stepping forward it is natural to contact the ground with the heel first, and in stepping backward, it is natural to contact the ground with the toe first. Note that in stepping forward or backward, it is necessary to sink into the rooted leg to achieve continuity in stepping. One reason that beginners step forward toe-first is that it is hard for them to sink low enough for the heel of the stepping foot to touch first, so they reach with their toes.

Stepping to the Side:   When stepping to the side, neither the toe nor the heel touch first - all the parts of the sole of the foot that normally contact the floor in correct standing alignment should touch at the same time. Such an action involves a hinge-like motion of the thigh joint and requires bending at the ankle to keep the foot from tilting or caving in at the arch.

Why should stepping to the side involve the whole foot touching the ground rather than the inner edge? Whenever the foot is touching the ground - even with no weight on it - the alignment should be optimal for bearing full weight, which might suddenly become necessary. Applying full or even partial weight to the inner edge of the foot could cause a sprain of the ankle.