Leg Tension

Stances use either inner, outer tension, or no tension (natural):

• Inner tension occurs when the tension in the legs and feet is directed inward toward the center of balance, as in the cat and sanchin stances.
• Outer tension occurs when the tension in the legs and feet is directed outward away from the center of balance, as in the front and sitting stances. Individual stances may use either inner or outer tension, but not both.
• Some stances have little or no tension, such as in front and back stances. Using unnecessary muscles will hamper speed, power, and balance, and cause unnecessary fatigue and a lack of control.

Some instructors speak of squeezing the feet into the floor while creating leg tension to strengthen the stance. Some claim this acts as a suction cup to make the body more solid on impact so it may resist any attacking force by using friction.

Friction is the interaction between two (or more) surfaces, expressed as a coefficient of friction. It relates only to the type of materials, the smoothness if the surfaces, and their geometry. Since you cannot change the composition of your feet or the floor, or the coefficient of friction, you can only change your geometry by maximizing your foot to floor contact, so do not curl toes, or rise on balls or heels.