Article Launched: 07/17/2006 01:00:00 AM MDT
Too fatigued to do anything? Then do something
Studies of nurses, VA patients link exercise, stamina
By Jack Cox, Denver Post Staff Writer
As anyone who has experienced the fabled "runner's high" will tell you, exercise can leave you feeling energized even as it tires you out.
But what about a lack of exercise? Can it make you feel tired even though you're expending hardly any energy?
Sports psychologist Patrick J. O'Connor of the University of Georgia has examined this question with an eye toward motivating sedentary people to become more active.
All the evidence from at least a dozen large studies over the past 20 years, O'Connor says, indicates that "physically active people report less feelings of fatigue."
Perhaps the most compelling findings, he suggests, come from an ongoing study that has followed the health of some 56,000 U.S. nurses since 1976. It shows that those with the lowest level of physical activity report having the highest level of fatigue.
But are they inactive because they are fatigued, or fatigued because they are inactive?
O'Connor, a fellow of the American College of Sports Medicine, says this question might be answered experimentally in either of two ways: By asking active people to stop exercising, or by asking inactive people to start.
As it happens, two recent studies have done just that.
One study, published earlier this year in the journal Psychosomatic Medicine, involved 40 men and women in their 20s and 30s who exercised regularly for at least 30 minutes a day three times a week. Half of the subjects were directed to stop exercising for two weeks, while the other half were allowed to continue as normal.
The lead researcher, Ali A. Berlin of the Uniformed Services University of the Health Sciences in Bethesda, Md., reported that among those deprived of exercise, "fatigue and somatic depressive symptoms emerged after one week," and their moods became increasingly negative as their fitness levels declined into the second week.
"These findings may explain mood changes in response to short-term exercise withdrawal such as injuries and recovery from medical procedures that do not require full bed rest," Berlin noted.
The other study, published in the Journal of the American Medical Association in March 2003, involved some 1,100 veterans diagnosed with Gulf War syndrome. They were randomly assigned to groups given only the usual care, or the usual care in combination with exercise and/or cognitive behavioral therapy.
The researchers, most based at VA hospitals around the country, reported that neither exercise nor cognitive behavioral therapy did much to relieve the subjects' pain, but "exercise alone or in combination with CBT significantly improved fatigue, distress, cognitive symptoms and mental health functioning."
It could be, O'Connor says, that the improvements seen in the veterans were the result of changes in some other behavioral or biological variable, such as sleep, medication or group interaction - or were affected by the so-called "placebo effect," which prompts test subjects to give responses they believe researchers are looking for.
Tim Puetz, one of O'Connor's doctoral students, recently designed a study to control for such variables, with 36 people assigned to do cycling exercises for 20 minutes three times a week for six weeks. The result: Even such low-intensity exercise reduced their feelings of fatigue.
Still, no cause-effect relationship has yet been proved. "We'd really like to say that exercise is beneficial for your mental health," says O'Connor, "but demonstrating that conclusively in a scientific way is tough."
Staff writer Jack Cox can be reached at 303-820-1785 or firstname.lastname@example.org.