Runners with high arches are at increased risk for suffering stress fractures, small cracks in the bones of their feet and lower legs; and those with low arches are at increased risk for knee cap pain.
When you run at six miles per hour, your foot hits the ground with a force greater than three times body weight. The faster you run, the harder your heel strikes the ground. This force can break bones, damage joints and tear muscles. The human body is designed so you never land flatfooted when you run. You land on the outside bottom of your heal and roll inward toward the big toe. This helps to distribute the force of your foot strike throughout your foot and leg and protect you from injury. The further you roll inward, the greater the protection against this force. However, when you roll in too much, your lower leg twists inward excessively, causing your kneecap to rub against the long femur bone behind it and cause pain. This is called Runner’s Knee.
If you have pain behind the knee cap during running or walking, ask your podiatrist to look at your feet. If your arches appear to be flat, you usually will have a normal arch, but you roll inward so far that your arch touches the ground. Your treatment is to place special inserts, called orthotics, in your running shoes and to do special exercise that strengthen your vastus medialis muscle that pulls your knee cap inward.
If you develop pain in the medial side of your lower leg or your feet, your podiatrist will probably order a bone scan to check for stress fractures, small cracks in the bones of your feet. If you have stress fractures and high arched feet, you will need specially padded running shoes and have to learn to try to hit the ground with less force when you run.