Your worn shoe soles reveal whether your feet roll excessively from side to side as you walk.

What you'll need

• A pair of your well-worn shoes or sneakers arranged so that they are sole-side-up and side by side, with the arches facing each other.
• ruler
• protractor
• marker that will write on against the shoe sole.

To do and notice

Draw a line lengthwise down the middle of each sole. Place the protractor so that its center is at the approximate center of the shoe's heel. Measure twelve degrees of arc along the curved back of the heel starting from the center line and moving away from the arch side of the shoe. Mark the edge of the heel at twelve degrees.

Starting with either shoe, note where the heel has broken down. Ideally, the heel should be worn away equally on either side of a line from the heel's center to the twelve-degree mark.

Now check the ball of the foot. In a "normal" foot, an area across the ball and evenly spaced with regard to the midline has scuffed away.

Finally, examine the tip of the shoe. An ideal gait causes maximum wear along a line running under the first and second toes.

What's going on?

If your shoe's sole is worn more toward the arched side than the ideal, your foot may roll toward the arch too much, or overpronate. This common problem may cause muscle pain in the lower foreleg ­­ known as shin splints-­ and a weaker push-off from your toes.