Physical Activity and Cancer

Physical Activity and Cancer

A case for exercising after your diagnosis

by Reid Hayward, PhD

When exercise was first suggested as an intervention for cancer survivors, many people, including some in the medical community, thought it wasn’t a viable option. “How can you ask someone with debilitating fatigue and severe treatment-related toxicities to exercise?” they would say. Many oncologists and other healthcare professionals believed not only that cancer survivors undergoing treatment shouldn’t exercise but also that the survivors themselves wouldn’t exercise during treatment, or for weeks or months after.

We now know this is not the case. Many research studies have demonstrated that exercise alleviates toxicities of the cardiovascular, pulmonary, muscular, nervous, and gastrointestinal systems. Others have shown that exercise reduces the suppression of blood cell production and results in favorable changes in body composition. Additionally, exercise improves functional capacity, reduces fatigue, and enhances overall quality of life.

Cancer survivors who exercise find themselves in a better mood, with more energy, better able to perform activities of daily living, feeling more rested, and better able to think and concentrate. The reasons for many of these improvements center around the fact that the benefits of regular exercise directly counteract the negative side effects of cancer and many of its treatments.

Numerous studies show that physically active cancer survivors have a lower risk of cancer recurrence and improved survival compared with those who are inactive.

Your Heart

Heart damage is a serious complication of treatment for many cancer survivors. Aerobic exercise can provide a powerful boost to cardiovascular fitness. Exercise improves the pumping ability of the heart, increases blood volume, enhances the function of the blood vessels, and increases the number of capillaries. Both aerobic exercise and resistance exercise (or weight lifting) can also increase the amount of muscle in the heart.

Significant improvements in cardiovascular fitness can be observed even in cancer survivors performing moderate intensity exercise. Moreover, a number of studies clearly show that moderate-intensity aerobic training can significantly improve cardiac function, even in survivors diagnosed with heart failure. Additionally, although endurance and resistance training have no significant impact on blood pressure in individuals with normal blood pressure, they can lower blood pressure in those with hypertension.

Your Lungs

Lung damage following cancer treatments is most often the result of lung inflammation or pulmonary fibrosis, but it can also accompany pulmonary edema. Aerobic and resistance exercise both can strengthen the muscles of respiration, or those that help you breathe in and out. This allows them to generate more force to better expand the lungs, which can then bring in more air with each breath. Exercise has also been shown to improve blood flow to the lungs and increase the effectiveness of gas transport throughout the body.

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Your Muscles

Cancer and cancer treatments both have been shown to decrease skeletal muscle mass. This can be the result of direct harm to the muscle or a consequence of cancer-related weight loss. A number of research studies show that low- to moderate-intensity resistance exercise leads to significant gains in lean body mass and muscular strength in cancer survivors. This is extremely beneficial for survivors who are experiencing symptoms of muscle loss, malnutrition, or wasting, as the loss of lean mass is associated with higher mortality rates in cancer survivors.

Heart damage is a serious complication of treatment for many cancer survivors. Aerobic exercise can provide a powerful boost to cardiovascular fitness.

Not only does exercise help you maintain muscle mass, but strengthening weakened muscles through exercise can also help your body use energy more efficiently. Lower-body resistance training has been correlated with an increase in the amount of time cancer survivors can walk before they become fatigued. This is because lower-body resistance training improves lower-body strength and endurance, which in turn has been linked to increases in aerobic capacity. Similarly, resistance training of the upper body can help cancer survivors in completing activities of daily living, such as pushing a lawnmower, picking up a basket of laundry, or putting away groceries.

Additional Benefits

In cancer survivors, exercise training programs have been shown to lessen the severity of peripheral neuropathy, reduce the symptoms of chemo brain, increase the number of oxygen-transporting red blood cells, enhance the function of the immune system, reduce nausea, increase appetite, and help survivors maintain a favorable body mass.

While an individual exercise program may not provide all the benefits mentioned above for every cancer survivor, particularly if they are currently undergoing treatment, exercise can help preserve the function of the heart, lungs, immune system, and skeletal muscles, protecting them from the functional declines that often happen during cancer treatment. Exercise programs can also increase cardiorespiratory fitness in cancer survivors, which is associated with a lower all-cause mortality risk. Moreover, numerous studies show that physically active cancer survivors have a lower risk of cancer recurrence and improved survival compared with those who are inactive.

Exercise training is one of the most underutilized tools to help cancer survivors cope with the negative side effects of cancer and cancer treatments. If you want to see the benefits of exercise for yourself, ask your doctor for a referral to an exercise specialist who has been trained to work with cancer survivors, and start your exercise training today.

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Dr. Reid Hayward is a professor of Exercise Science in the School of Sport and Exercise Science at the University of Northern Colorado, as well as the director of the University of Northern Colorado Cancer Rehabilitation Institute, in Greeley, CO. His research focuses on the effects of exercise on cancer- and treatment-related side effects.

This article was published in Coping® with Cancer magazine, July/August 2016.

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