Fatigue is a ubiquitous complaint in clinical practice. It is also remarkably nonspecific. Thus, any major illness, whether infectious or degenerative, may manifest as fatigue. I find it useful to distinguish between weakness and fatigue.
Weakness can occur in the setting of specific musculoskeletal diseases. For example, polymyositis is an inflammatory condition in which the muscle tissue is attacked by the body’s own immune system. Profound weakness may result.
Similarly, patients with thyroid gland dysfunction, electrolyte abnormalities, or inherited muscle diseases may manifest severe weakness, interfering with walking, standing up from a chair or driving. Treatment of such conditions must be tailored to the specific diagnosis. For example, polymyositis typically requires high dose cortisone-type medications in order to cut down on inflammation. Thyroid disease may require either ablation of thyroid tissue, through chemical or surgical means, or supplementation with additional thyroid hormone.
Fatigue, by contrast, tends to be a pervasive sense of weariness that may sap one’s ability to get through a workday or to fulfill social obligations.
Fatigued patients may have normal muscle strength. We can, for example, test the strength of the hands through the use of a specific instrument, called a dynamometer. A fatigued patient may have normal objective hand strength, even in the face of pervasive generalized malaise.
Whenever I am confronted with a case of “chronic fatigue syndrome,” I strive to make a more specific diagnosis. I don’t want to miss a treatable condition. As a rheumatologist, for example, I am aware that about 40 percent of patients with rheumatoid arthritis experience severe fatigue.
Treatment should be geared toward decreasing the underlying inflammatory joint disease, typically through the use of so-called disease-modifying anti-rheumatic drugs.
An article out of the Netherlands by Rongen-van Dartel and co-authors recently appeared in the journal Arthritis Care & Research, confirming an observation that may seem surprising. It turns out that among patients with RA, physical activity decreased fatigue levels in an inverse manner. The greater the exercise and activity level, the less the fatigue.
Among the 167 patients studied, physical activity levels were measured by self-report on a questionnaire and by direct measurement through an ankle-worn device called an “actometer.” A statistically significant difference in fatigue levels between the two groups was noted, with active patients scoring lower on fatigue scores as measured by a standardized questionnaire.
As is the case with many medical studies, the problem with the Dutch RA/fatigue study lies in its interpretation. Although the authors tout this as the first analysis of “physical activity and activity pattern in patients with RA,” they admit that a correlation and causation are different animals. In other words, it may be that sicker patients move about less because they are ill, or it may be that moving around a lot prevents illness. No one really knows for sure. If sick patients move less, then any correlation of exercise with generalized energy level may be spurious, or simply an indirect way of reflecting the underlying disease activity.
Nonetheless, there are reasons to suspect that exercise and activity are beneficial in fighting fatigue. We know, for example, that exercise tends to raise levels of epinephrine, creating a greater tolerance for epinephrine release in response to stress. Pain-killing chemicals called endorphins are released by the brain in response to exercise. General fitness improves with activity, both cardiovascular and musculoskeletal. Sleep disorders improve with a program of regular exercise.
Every patient is different, and consulting with one’s physician is prudent before beginning any new exercise regimen. It may be, however, that the best way to prevent fatigue may not be to take a nap. To the contrary, it might make more sense to take a walk.
Scott T. Anderson, M.D. (email firstname.lastname@example.org), is clinical professor at UC Davis Medical School. This column is informational, and does not constitute medical advice.