There are
three main phases of each step. The first phase of the step is called
heel-strike. Then as you put more weight on you foot you enter the
mid-stance phase of the step. Finally you push off with your toes in the
phase toe-off.
As the foot
goes thru the three phases of gait it goes thru two main motions, pronation
and supination.
The easiest
way to visualize supination and pronation is to pretend you hand is a foot
and turn the palm to the floor. The palm of the hand represents the bottom
of your foot. As you turn your hand so that the palm is facing up you are
supinating your hand. As you turn the palm back to face the floor you are
pronating your hand.
Pronation
is the flattening out of the arch. Pronation
is also referred to as rolling
in of the arch. Probation turns the bottom of the foot toward the outside.
The opposite motion is called supination. Supination results of the foot
turning in puts the weight on the outside of the foot.
As the foot
pronates the bones of the foot unlock. When the bones unlock they allow the
foot to change shape and adapt to changes in the ground (ie uphill downhill,
rocky or smooth). Supination locks the bones and allows the foot to become
rigid again. Supination gets the foot ready to push-off with the toe and
propel the body forward.
Biomechanical dysfunctions of the foot can be described in terms such as
over-pronation, and delayed supination.
