Study of runners aids couch potatoes.

• Position: Exercise and oxidative stress - Brief Article - Statistical Data Included

A study from the Linus Pauling Institute, Oregon State University, Corvallis, suggests that intense exercise can increase oxidative stress in humans, as the body struggles to detoxify free radicals while muscles use oxygen at 100 to 200 times their normal rate. The findings could be of value not only to athletes, but to people suffering from degenerative diseases that increase oxidative stress and those who are obese, smoke, or are just couch potatoes in lousy shape.

"Everyone knows that there are many health benefits of exercise, but fewer people understand that it can also cause some metabolic damage," explains Maret Traber, associate professor of nutrition and food management. "When running or doing other intense exercise, there's a 10- to 20-fold increase in whole body oxygen consumption. This can produce reactive oxygen species, which can be harmful, at rates that exceed the body's natural capacity to detoxify them."

Some theories hold that even the process of muscle strengthening is actually a form of damage control, she points out. By this perspective, cells and weak muscle fibers may be damaged and then replaced by stronger ones. After this type of activity, the body is literally in a recovery period.

The researchers studied the effects of exercise on ultramarathon runners--people who have competed in races of 50 kilometers on a route in McDonald Forest near Corvallis that includes a total elevation gain and loss of 12,000 feet. "In our last study of runners who competed in this ultramarathon, we found that this type of intense exercise did increase...