Just two weeks from tomorrow, thousands of people from around the world will take to the streets of Honolulu to participate in one of the world's largest marathons. For these runners and walkers, the wear and tear of the 26.2-mile course is worth the feeling of accomplishment when they enter Kapiolani Park and cross the finish line.

To prepare for this feat, runners have been training for months. Today or tomorrow should mark their last major workout. Although they may not want to believe it, it is now too late to build up more endurance or speed. In fact, it is now time to start the somewhat counterintuitive process of tapering for the event.

Tapering properly is every bit as important as the months of hard training. Cutting back on training duration and intensity is essential to allow time for the body to recover and repair from the rigors of training and be ready for the marathon effort.

In addition to muscles, the immune system needs to recover during this period. Heavy training is known to lower an athlete's resistance to upper respiratory tract viral infections that cause colds and flu.

  Question: Does running the marathon increase the risk of catching a cold?

Answer: Yes. Studies show that resistance is especially low after a major effort like a marathon. Runners are at increased risk of infection with a cold or flu virus for about two weeks following the marathon.

Q: What precautions can a runner take to reduce the risk of getting sick after the marathon?

A: Probably the best protection comes from taking it easy and avoiding contact with anyone who may be contagious. Frequent hand-washing and avoiding touching the nose, eyes and mouth are also reasonable protective measures to take.

Many types of dietary supplements have been studied and generally found to be ineffective for reducing infections. Most likely, overall good health is the best defense.

Q: What dietary factors could help the immune system?

A: Many nutrient deficiencies have the potential to cause impaired immune function. The immune system requires adequate protein. Although carbo-loading is important right before the marathon, runners may benefit from maintaining an adequate intake of high-protein foods as well.

Iron deficiency, with or without anemia, is known to impair the immune system and distance runners have greater iron needs than sedentary people. If iron stores are getting too low, a doctor can tell by running a blood test for serum ferritin.

Overall, keeping a wide variety of all types of wholesome foods in the diet may be the best defense.