The television advertisement shows a young woman running hard and sweating profusely, smiling but appearing rejuvenated. You might go out and try this yourself. Rather than feeling great, you may find that you are pooped later that day, and still tired the next day. "Just do it" didn't do it.
Not everyone gets a boost from strenuous exercise. This is especially the case for people with chronic fatigue syndrome (CFS). Instead of positive physical and emotional sensations, any overexertion often makes their symptoms temporarily worse.
Chronic Fatigue Syndrome
Chronic fatigue syndrome is more than a persistent lack of energy. The U.S. Centers for Disease Control and Prevention (CDC) defines CFS as a disorder with at least six months of such intense fatigue that it substantially reduces the person's level of activity. The fatigue must be of new or definite onset and not relieved by rest or getting more sleep. In addition, the person needs to have at least four of the following symptoms associated with the severe fatigue:
- Sore throat
- Tender glands
- Aching or stiff muscles
- Painful joints
- Impaired memory or concentration
- New headaches
- Unrefreshing sleep
- Feeling unwell after exertion, lasting for 24 hours or longer
People can have chronic fatigue as part of another illness or condition, but to meet the criteria for CFS a thorough medical evaluation must be performed to exclude other possibilities.
People with chronic fatigue syndrome usually avoid physical activity because any strenuous exertion can make them feel terrible afterward — usually for 12 to 48 hours later, rather than immediately after exercise. Not only do their muscles feel sore, but they can have flare-ups of tender glands, memory problems, and even fevers. Within weeks, muscle deconditioning begins to occur. Weaker, deconditioned muscles make the effort of any exercise that much harder. This can easily lead to a vicious cycle of inactivity and deconditioning.
Several studies have found that aerobic exercise can improve the function of people with CFS — if it is begun very gradually, and increased very slowly. And there is no evidence that exercise actually makes the disease worse or worsens the prognosis, even when it does cause symptoms.
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The Importance of Perceived Exertion
Although level of fitness can be quite variable with CFS, most patients have poor exercise tolerance when formally tested. Compared to sedentary control subjects, they walk for shorter periods of time on stress tests, have lower maximum heart rates, and have lower aerobic capacities as measured by oxygen consumption. Most important, they usually have a considerably higher level of perceived exertion while exercising at a less demanding intensity than the sedentary subjects.
Perceived exertion is a very real sensation that everyone experiences if you exercise hard enough. Moving beyond this unpleasant sensation is what you need to do to get fit. CFS patients have a low threshold for feeling like they are exercising hard. This is consistent with their lower thresholds for other bodily sensations and is a significant impediment to improving fitness.
The paradox in chronic fatigue is that strenuous exercise often makes symptoms worse, but people with the syndrome must exercise to feel more energetic. It sounds like a classic catch-22, but the paradox can be solved by graded exercise done in multiple short sessions during the day.
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The Exercise Prescription
The exercise prescription needs to be flexible to adjust for each individual's threshold of perceived exertion. The goal is to improve exercise capacity gradually over many weeks to months, making progress in small increments.
A reasonable place to start is 10 minutes of slow walking in the morning, midday and evening. Compared to doing 30 minutes all at once, the shorter sessions are less likely to cause CFS symptoms to flare. For some people, even 10 minutes may sound too strenuous. If that is the case, begin with five minutes at a time.
More important than a set time or pace of walking is to become aware and pay attention to your perceived level of exertion. If this is new for you, start slower and shorter on your walks. Keep that steady for several days. If you feel that it was too easy, increase the time by one or two minutes and again hold steady. Then after several more days you can pick up the pace.
When your exercise effort causes you to breathe harder with a faster pulse, especially if it is a little uncomfortable, you have entered a "somewhat hard" zone. Stay at that level for just another minute, and then slow down until your pulse and breathing are comfortable again. Monitor how you feel while resting until your next scheduled walk. If you are very tired, walk a shorter distance at a slower pace for the next few sessions.
Walking may not be right for you, or perhaps you find it boring. You will get the same benefits from riding a bike or swimming. The exercise should be aerobic; strength training and flexibility exercise are good adjuncts, but they don't improve daily function.
Many people who don't have CFS become very tired after exercising or just don't get the energy boost they expected. The same graded-exercise prescription may be the solution. The most important message is to gradually increase your daily exercise, paying attention to perceived effort, slowing down when you need to, and exercising every day.
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Howard LeWine, M.D., is chief editor of Internet publishing, Harvard Health Publications. He is a clinical instructor of medicine at Harvard Medical School and Brigham and Women's Hospital. Dr. LeWine has been a primary care internist and teacher of internal medicine since 1978.