Cancer And Exercise: What Does The Science Show?

Excerpted from
Cancer Fitness; Exercise Programs for Cancer Patients and Survivors
By Anna L. Schwartz, FNP, Ph.D., FAAN,

There are many challenging side effects of cancer, but the most common and perhaps most frustrating is fatigue. Everyone has felt fatigue or tiredness during their lives, but the fatigue of cancer and its treatment is different. It is an overwhelming, all-consuming feeling that is not relieved with rest, and fatigue "attacks," sudden periods of utter exhaustion, come on unpredictably, making normal life activities an extreme challenge. Common sense tells us that resting more will make us feel better, but with cancer, rest often is not restorative. Although we may feel too tired to move, activity is key to avoiding the debilitating effects of inactivity, such as muscle atrophy (shrinking), reduced heart and lung function, and decreased endurance and strength to carry out usual activities. This chapter describes the physical and emotional effects of exercise on patients who are receiving cancer treatment.

Cancer Exercise Is Safe

The science of exercise for cancer patients and survivors has evolved rapidly in the last decade. The first study of cancer patients and exercise was conducted in 1986, and it demonstrated that high-intensity aerobic exercise was safe for patients when they were receiving chemotherapy. These early researchers broke some of the barriers and fears that physicians and people in general had about cancer patients exercising during chemotherapy. Since that time, studies have repeatedly demonstrated that exercise is safe, well tolerated, and beneficial during chemotherapy, radiation therapy, immunotherapy, and bone marrow transplant. By building on decades of well-tested research studies in cardiac rehabilitation, the science of cancer and exercise research has progressed quickly, even though exercise prescriptions for cancer patients differ from recommendations for patients with heart disease.

Fatigue

Fatigue is the number one side effect of cancer and its treatment. It is the most pervasive and disruptive side effect of cancer treatment and affects nearly 100 percent of patients. Researchers have observed that fatigue has a profoundly negative effect on quality of life. Although we don't know what causes fatigue, it is clear that exercise reduces fatigue. Research has shown that aerobic exercise during chemotherapy, immunotherapy, radiation therapy, and bone marrow transplant has a positive effect on reducing fatigue. In patients with metastatic disease, exercise has the same effect-it reduces fatigue.

The exciting news is that moderate exercise of short duration (as little as 10 minutes), performed at least every other day, is sufficient to reduce fatigue. For patients who are too tired, weak, or debilitated to exercise for a continuous amount of time, I have found that dividing exercise into short sessions of as little as 2 minutes is just as effective in reducing fatigue as struggling to complete one sustained period of exercise.

Figure 1 shows the differences in fatigue levels between patients with different types of cancer receiving chemotherapy who were assigned at random to exercise or to usual care activities. Moderate-intensity aerobic exercise has an immediate effect on reducing fatigue. Figure 2 shows the differences in fatigue levels between women with breast cancer who did and did not exercise while receiving radiation therapy for breast cancer. Although the fatigue level of the patients who exercised did not decline until the middle of treatment, by the end of radiation therapy the exercise patients had significantly less fatigue. I suspect that the delay before fatigue declines is because the exercise program in this study was of low intensity. Exercise is like a medication: the patients on the low-intensity exercise program may not have reached the therapeutic dose of exercise to reduce fatigue until the middle of radiation therapy.

When we ask patients what their worst (or highest) level of fatigue is, those patients who exercise regularly report lower levels of fatigue, day after day, week after week. Patients who exercise also report lower levels of daily average fatigue, the fatigue that affects our ability to complete everyday activities. Those patients who exercise also tell us that the most important time to exercise is when they feel their worst. This counterintuitive information is hard to explain to someone who is too tired to move, work, or do other things that they value, but I have seen patients over and over go home and start to do basic exercises and return to see me a few weeks later, feeling not only a lot less fatigue but also a whole lot better about life.

Rest - The Big Myth

At the time of cancer diagnosis, most patients are not advised to start an exercise program. The usual dictum, given by well-meaning health care providers and friends, is to "rest" and "take care of yourself." For most people, this means sleeping more and being as inactive as possible to protect the body that yesterday may have felt quite well but today has deceived them. Research is showing us not only the benefits of exercise but also the deleterious effects of rest. The need to become inactive and rest is a myth!

Patients who earnestly follow the rest myth quickly-become weak and debilitated. How much you are physically able to do varies by type of cancer treatment, but on average, patients who are inactive lose 5 percent of their functional ability during 7 weeks of radiation therapy, 16 percent during the first 9 weeks of chemotherapy, and 19 percent during high-dose chemotherapy for bone marrow transplant, usually in a 3- to 4-week time period. In my research, I have seen some patients lose as much as 35 percent of their physical ability. What this means is that as your physical ability decreases, simple activities such as walking up the stairs, grocery shopping, or walking to the car become more challenging and you feel tired more easily. Declines in physical ability have negative effects on emotional and social function and cause other serious physical problems, such as muscle wasting, bone loss, and declines in heart and lung function.

Being fit may not seem to be of great importance when you are confronted with the challenge of cancer and its treatment, but being physically fit is crucial to living a full life during and following treatment. Maintaining or increasing your physical fitness during cancer treatment can improve your quality of life, reduce the number and intensity of your side effects, and help in your overall recovery. Patients who are stronger are able to do more activities without getting so tired. If you become weak and debilitated during your treatment, it becomes much harder to continue with usual activities, such as dressing yourself, going to work or school, and socializing with family and friends.

Science is showing us that exercise has other positive physical benefits, too. Exercise is not a panacea for all the side effects you may experience, but it is a powerful intervention you can use to improve your physical and emotional health.

Luke was a 77-year-old man with recurrent lymphoma. When he was initially treated for his lymphoma, two years earlier, he received chemotherapy and radiation therapy and dutifully rested as the doctor told him to. Luke told me, "I rested so much I barely had the strength to get out of bed. I felt like a really old man as I tried to shuffle from place to place. I had to sit down every few feet to catch my breath and gather my energy. It took me over a year to get most of my strength back." Facing more therapy for his recurrent disease, Luke wanted to try a different approach. He enrolled in one of the exercise programs and learned the essential balance of rest and exercise. After Luke completed treatment he said, "In the darkness of cancer, I was amazed to be invited into an exercise program. I didn't have the terrible fatigue and weakness that I experienced during the first treatments. Actually, I was able to continue doing most of my activities like going to church, visiting with my family and playing poker with my old buddies. Exercise provided a ray of hope."