ABOUT BIOMECHANICS: Biomechanics is the study of the anatomical principles of movement, such as how birds and insects fly; how fish swim; and the most efficient ways a human can move. When we walk, with every step, the foot strikes the ground on the outside edge of the heel, the shinbone twists inward, and the foot rolls inward to bear the weight, absorbing the shock of impact. Then the shinbone twists outward and the foot begins to lift at the heel, providing a springboard for the toes to push the body's weight forward off the ground. The foot then swings forward to repeat the cycle. Running has similar mechanics, but can be seen as a series of alternating hops from left to right leg.
ABOUT FRACTURES: A fractured bone is the same thing as a broken bone. They occur because a bone area is unable to support the energy placed on it. That energy can be acute, as from a car crash or a two-story fall, or chronic and low-energy as from a repetitive activity. The latter is responsible for stress fractures, an overuse injury commonly seen in athletes. The increased demand places on the bone causes it to remodel and become stronger in areas of higher stress, but if the repetitive demands become too great, a stress fracture can result.