Physicians often recommend exercise, but scientific evidence on how it affects fatigue had not previously been quantified, according to researchers at the University of Georgia. They analyzed 70 controlled, randomized trials involving a total of 6,807 volunteers. They found that people taking medications such as a narcolepsy drug had some relief from their fatigue, but that regular exercise was significantly more effective.

Routine physical activity reduced fatigue in nearly every population studied, including healthy people and patients with conditions such as diabetes, heart disease or cancer.

"More than 90 percent of the studies showed the same thing: Sedentary people who completed a regular exercise program reported improved fatigue compared to groups that did not exercise. It's a very consistent effect," Georgia exercise physiology professor Patrick O'Connor stated in a news release.

"A lot of times when people are fatigued the last thing they want to do is exercise. But if you're physically inactive and fatigued, being just a bit more active will help."

The researchers noted that people suffering fatigue may assume that physical activity will reduce their energy, but they pointed out studies showing that exercise raises levels of neurotransmitters that elevate mood and promote energy.

Patients are advised to consult their physician before starting an exercise program.

The study was published in the Psychological Bulletin.

Copyright 2007 iVillage Total Health.