Symptoms of a biomechanically weak foot can appear in various places, including in the ankle, leg and knee.

A problem in the foot can cause secondary troubles anywhere from the sacroiliac joint to the forefoot. That's the reason we must have a thorough understanding of the biomechanics of the body from the back all the way down the leg to the foot. You cannot separate one factor from the other. They are interrelated.

All sports present their own types of overuse syndromes. Distance runners' problems include the knee, heel and Achilles tendon. The long distance runner is subjected to shin splints and ankle troubles as well.

Sprinters, who run on the balls of their feet, develop bunions and tight posterior muscles. Basketball players have a high incidence of hammertoes. All athletes are susceptible to recurrent lateral ankle sprains.

The orthopedic approach to the overuse syndrome has been quite successful, esspecially in young athletes with immature bone growth that absorb constant pounding in their respective sport. The orthopedic approach means the establishment of motions and positions will cause maximum function of the foot and the entire skeletal system. There will be a postural and structural balance.

In biomechanical balancing, athletes attempt to cause their feet to function as close to their neutral position as possible. Neutral position duplicates the joint positions assumed by a normal foot while standing and when running.

Many of the problems leading to the Overuse Syndrome can be treated by biomechanical balancing. This is accomplished by using a functional sports orthotic. A functional sports orthotic or a functional orthotic -- used for people on their feet for many hours during the day -- is a device that controls motion and position of the foot and leg during locomotion. It is well tolerated and usually results in improved foot function with athletes and people who walk to prevent injury.

Dr. Robert Weiss lives in Westport and has a sports podiatry practice in Darien. He is a former marathon runner and was a member of the Medical Advisory Committee of the 1984 and 1988 Olympic Trials.