By: Jacqueline Drouin and Lucinda Pfalzer, Ph.D.

Introduction

Exercise is now being recognized as an important component of the fight against cancer. There is evidence that exercise can be of benefit in three ways to manage cancer and its symptoms. First, epidemiological evidence indicates that exercise, combined with healthy lifestyle practices, appears to prevent certain types of cancers. The cancers that are reported to occur less frequently in active people are cancers of the colon, breast, prostate, and possibly the lung, digestive system, thyroid, bladder and the hematopoietic system (Lichtenstein, et al. 2000; Sternfeld, et al., 1992; Frisch, et al., 1985). Second, aerobic exercise has been shown to provide benefits specifically to people undergoing treatment for cancer. These benefits include improved physical function and relief from fatigue, nausea, and depression (Pinto & Maruyama, 1999). Third, exercise enables people who survive cancer with a means to recover their physical functions and return to a healthy and active lifestyle (Augustine & Gerber, 2000, Friendenreich & Courneya, 1996).

Despite evidence that supports exercise as a means to manage cancer and its symptoms, people with cancer are routinely told to rest and limit their physical activity (Ream & Richardson, 1999). However, rest and diminished physical activity lead to further declines in function that worsen the symptoms of cancer, such as fatigue, nausea and depression (Ream & Richardson, 1999, Dimeo, et al., 1998, Segar, et al., 1998, MacVicar, et al., 1989, Winningham, et al., 1986). This worsening of symptoms leads to chronic disabilities that continue to plague cancer survivors in the recovery and remission phases of their disease. Chronic disabilities that continually affect cancer survivors include limited physical function, chronic fatigue, and depression (Dimeo, et al., 1998, Segar, et al., 1998).

The following discussion on cancer and exercise will present three topic areas. The first topic area will include an overview of cancer epidemiology and pathology, cancer causes, and methods of cancer diagnosis. The second topic area will present a review of the literature on experimental studies related to exercise and cancer. The final portion of this paper will describe guidelines for the development of safe and effective exercise protocols for people undergoing treatment for cancer, recovering from cancer, in remission from cancer, or living with cancer.

Cancer Epidemiology

Cancer is second only to heart disease as the leading cause of death in the United States. One-half of all men and one-third of all women will develop cancer at some time in their lives. Although prostate cancer is the most common form of cancer in males, and breast cancer is the most common form in females, lung cancer causes the highest mortality rates for either gender (American Cancer Society, 2007). African-Americans have lower survival rates for most cancers compared with other groups of people. This may be due to a variety of factors, including limited access to health care, little or no medical insurance, lack of a primary health care provider, homelessness, poverty, lack of knowledge on early diagnosis and treatment, and greater exposure to carcinogens (McCance & Roberts, 1998).

The five-year survival rate from all cancers is currently estimated at 58% (American Cancer Society, 2000). Generally, if there is no detectable recurrence of cancer for five years following the initial diagnosis, a person is considered to be in remission or cured. However, many people considered cured continue to demonstrate limitations or disabilities from their cancer or its treatment. These disabilities include movement dysfunctions, limited physical activity levels, chronic fatigue, and depression. These limitations and disabilities can be improved through rehabilitation and physical training (Gerber & Augustine, 2000, Pinto & Maruyama, 1999, Dimeo, et al., 1998, Segar, et al., 1998, Dimeo, et al., 1997, Friendenreich & Courneya, 1996).

Cancer is primarily caused by environmental factors and lifestyle practices (Lichtenstein, et al., 2000). This phenomenon was originally observed when people from countries with low cancer rates migrated to countries with high cancer rates. As migrating people began to adopt the customs of their new land and to be exposed to new environmental conditions, they would subsequently begin to develop cancers at a rate and type similar to that of their new country or geographical area. This increase in cancer rates was seen in the increases in breast and colon cancer rates in people from Japan who moved first to Hawaii and then to California (McCance & Roberts, 1998, Fraumeni, 1982). Colon cancer and breast cancer are relatively rare in Japan, but as the Japanese became gradually more westernized in their customs and environmental conditions, their cancer rates became similar to those in the United States. Increases in the incidence rates for colon cancer following migration appear to take two or three decades, while increases in breast cancer rates require more than one generation (Fraumeni, 1982).

Variations can also be seen in cancer rates in different geographical locations within the same country. Mapping of mortality rates for different types of cancers within the United States has shown that certain cancers occur more frequently in particular geographical regions and that this phenomenon appears to be related to environmental exposures (Atlas of Cancer Mortality in the United States, United States Department of Health and Human Services, 2000). Examples of geographically influenced cancers include the high rates of colon cancer in the northeast quadrant of the United States compared with the rest of the country, and the higher rates of ovarian cancer in the northern states compared to the southern states.

Upward trends in some cancers over time may reflect changes that have occurred in lifestyles, medical practices, and environmental factors. Smoking is a lifestyle change that dramatically reflects the upward trend seen in lung cancer rates during the last 50 years (Zeegers, et al., 1989). Changes in medical practices that reflect upward trends in cancer rates include the use of menopausal estrogens and increases seen in endometrial, ovarian, and breast cancers, as well as the use of head and neck X-rays during childhood that are reflected in increases in thyroid cancers (McCance & Roberts, 1998, Fraumeni, 1982). Environmental factors that appear to increase cancer rates include radon gas exposures, industrial emissions such as arsenic or benzene, and ultraviolet exposures from thinning ozone layers (McCance & Roberts, 1998; Fraumeni, 1982).

Compared with environmental and lifestyle factors, genetic influences contribute only a small percentage to cancer rates (Lichtenstein, et al., 2000). Inherited cancers tend to occur earlier in life and typically cause multiple growths in the same organ (Fraumeni, 1982). Although some cancers appear to follow racial and ethnic lines, it is difficult to separate genetic influences from environmental and lifestyle factors as the cause of a cancer. Examples of cancers that appear to follow racial and ethnic lines include nasopharyngeal cancers in the Chinese, gallbladder cancer in American Indians and some Hispanic groups, and skin cancers in ethnic groups that lack protective skin pigmentation (McCance & Roberts, 1998, Fraumeni, 1982).

Some families are prone to developing certain types of cancers, but the incidence of family-related cancers is very low. For example, familial breast cancer accounts for only 5% of all breast cancers (McCance & Roberts, 1998). Other types of familial cancers include prostate, stomach, lung, and colon cancer. Even though these cancers tend to occur more often in certain families, not every individual from a “susceptible family” will develop these cancers. Researchers believe that the risk for developing cancer is more related to an individual’s environment and lifestyle than to familial tendencies (Chlebowski, 2000, McCance & Roberts, 1998). A recent study by Lichtenstein and colleagues (2000) demonstrated this phenomenon. These researchers found that an individual’s environment and lifestyle played a greater role in determining whether a person would develop cancer than their familial risk. These investigators examined cancer rates among 44,788 sets of twins. They did find an increased number of prostate, colorectal and breast cancer rates among the twins of an affected twin. However, statistical modeling demonstrated that environmental and lifestyle practices had a far greater impact on determining whether the unaffected twin would, in fact, develop these familial cancers. Therefore, even when there is increased family susceptibility for certain cancers, persons can modify their risk for developing cancer by changing their environment or lifestyle practices.

Cancer Pathophysiology

Cancer describes a group of more than 150 disease processes characterized by uncontrolled growth and spread of cells. Cancer is not a singular, specific disease but a group of variable tissue responses that result in uncontrolled cell growth (McCance & Roberts, 1998; Fraumeni, 1982). Healthy tissues are composed of cells. Healthy cells have a specific size, structure, function and growth rate that best serves the needs of the tissues they compose. Cancer cells differ from normal cells in size, structure, function, and growth rate. These malignant cells lack the normal controls of growth seen in healthy cells, and grow uncontrollably. This uncontrolled growth allows the cancer cells to invade adjacent structures and then destroy surrounding tissues and organs. Malignant cells may also metastasize to other areas of the body through the cardiovascular or lymphatic systems. This uncontrolled growth and spread of cancer cells can eventually interfere with one or more of a person’s vital organs or functions and possibly lead to death. The primary sites of cancer metastasis are the bone, the lymph nodes, the liver, the lungs, and the brain (McCance & Roberts, 1998).

Malignant cells also lose their ability to differentiate or change like normal healthy cells. This inability to differentiate prevents cancer cells from performing the functions required by the tissues and results in a variety of other tissue changes in the body such as pain, cachexia, lowered immunity, anemia, leukopenia, and thrombocytopenia. Some of these changes, such as pain, can be benign but others denote a malignant or premalignant state. Benign neoplasms or tumor cells are made up of the same cell type as the original parent cell, but have abnormal growth rates. Benign cells do not metastasize or invade surrounding tissue. Benign cells can, however, pose a significant problem in the body when they grow too large and compress vital organs or organ systems. The following will describe both malignant and benign tissue changes that occur in the body from abnormal growth and differentiation (McCance & Roberts, 1998).

Dysplasia is a general category that indicates a disorganization of cells. In Dysplasia, a cell varies from its normal parent cell in size, shape, or organization. Dysplasia is often the result of chronic irritation such as the changes seen in cervical tissues from long-standing irritation of the cervix. Metaplasia is the first level of dysplasia (early dysplasia). Metaplasia is a reversible, benign, but abnormal change seen when a cell changes from one type to another. The most common type of metaplasia is in the epithelium of the respiratory tract where columnar epithelial cells change into squamous epithelial cells. Although metaplasia usually gives rise to an orderly arrangement of cells, it may sometimes produce disordered cell patterns. Disorderly cell patterns result in cells of the wrong size, shape or orientation lining up together and may result in inappropriate or faulty tissue behaviors (McCance & Roberts, 1998). Anaplasia is the loss of cellular differentiation. Anaplasia is the most advanced form of metaplasia and is a defining characteristic of malignant cells.

Hyperplasia refers to an increase in the number of cells in a tissue or in a part of a tissue. Hyperplasia, which results in increased tissue size or mass, can be a normal consequence of certain physiologic alterations or it can be a sign of malignancy. Examples of normal hyperplasia are seen in the tissue increases that occur during wound healing, callus formation following a bone fracture, or breast mass increases during pregnancy. An abnormal hyperplasia response is seen in “Neoplastic Hyperplasia,” in which there is an increase in cell mass due to tumor formation (McCance & Roberts, 1998). There are also considerable differences in the growth rates of malignant tumors. Some tumors are very slow-growing, even in a malignant state, and are therefore removed easily. Other tumors may grow slowly at first and then undergo change and continue to grow at a rapid pace. Others tumor types may grow very rapidly throughout their entire existence. Factors that affect tumor growth and development include the status of an individual’s immune system, the rate the tumor cells are growing, the number of tumor cells actively spreading, and the rate that the normal tissues are being destroyed by the tumor. Several factors affect normal immune function, including stress, malnutrition, advancing age, and chronic diseases. Cancer itself appears to suppress the immune system both early and late in the disease process (McCance & Roberts, 1998).

As described above, uncontrolled cell growth is a characteristic of cancer. Cellular growth rates are regulated by proteins produced by the genetic material in cells. Genetic material can be altered or mutated by environmental factors, errors in genetic replication or repair processes, or by tumor viruses. Altered or mutated genes are called oncogenes, and it is these oncogenes that allow uncontrolled growth in cells (McCance & Roberts, 1998).

Causes of Cancer

Understanding what causes cancer is a complex process. Cancer has been linked to many factors, such as environmental exposures, lifestyle practices, medical interventions, genetic traits, viruses, familial susceptibility, and aging. Cancer is most probably the result of interactions between repeated carcinogenic exposures and an individual’s susceptibility status (Fraumeni, 1982).

In 1941, Rous and Kidd described a possible mechanism for the development of cancer called the Initiation-Promotion-Progression Theory. This theory describes cancer development in terms of requiring multiple steps or events. In this theory, a single exposure, event, or trait would not be sufficient for the development of cancer. The first component of this theory is the Initiation Stage. The initiation stage of carcinogenesis occurs when DNA is damaged or altered. This alteration may occur through exposure to a carcinogen, or errors in DNA replication and repair. Examples of initiators include environmental hazards, such as ionizing and non-ionizing radiation, and biological factors, such as hormones and viruses. The damaged or initiated cell will not necessarily become cancerous unless it is subsequently exposed to one or more promoting agents during the Promotion Stage. Promoting agents cause the altered cells to grow, proliferate, and develop into tumors. Promoters include environmental pollutants, drugs, and hormones. Interestingly, even the biological changes of the promoters are reversible through lifestyle factors that include diet, hormones, and a healthy immune system (McCance & Roberts, 1998). The remainder of this section will discuss the primary risk factors that appear to be involved in the initiation or promotion of various cancers.

Environmental exposures and lifestyle practices have been determined to be the major risk factors in the development of cancer (Lichtenstein, et al., 2000, Chlebowski, 2000, McCance & Roberts, 1998, Fraumeni, 1982). The major lifestyle factors that contribute to cancer include smoking, alcohol, diet, medical practices, and ultraviolet exposures. As smoking is a major risk factor for both heart disease and cancer, tobacco exposure is the single largest preventable cause of early death (American Cancer Society, 2000, ACSM, 1998, McCance & Roberts, 1998, Sternfeld, 1992). More than 30% of all cancer deaths are directly related to smoking (American Cancer Society, 2000). Although smoking is most commonly associated with lung cancer, it also causes a three-fold increase in urinary tract cancers and is an established cause in cancers of the bladder, pancreas, larynx, mouth, and esophagus (Zeegers, et al., 2000 Marcus, et al., 2000, McCance & Roberts, 1998).

Alcohol consumption has been linked to increased rates of cancer in the upper respiratory tract, digestive tract, breast, colorectum, and liver (Corrao, et al, 1999). The mechanisms for increased rates of breast cancer from alcohol consumption are unclear but may be related to impairments in the immune function or the inability of the liver to clear the body of carcinogens, or from decreases in cell membrane permeability in the breast (Rohan & McMichael, 1988). For colorectal cancers, alcohol consumption has been shown to increase rectal cell proliferation or growth in the rat. This increase in the proliferation of rectal cells from alcohol exposure may be the mechanism involved in the promotion of colorectal cancers. Alcohol combined with tobacco usage has also been shown to contribute to increased rates of cancer in the mouth, pharynx, larynx, esophagus, and liver (McCance & Roberts, 1998, Fraumeni, 1982).

Dietary practices and obesity have been linked to certain types of cancer. High consumption of dietary fat is being examined as a contributing factor to endometrial, breast, prostate, ovarian, and rectal cancers (McCance & Roberts, 1998). Not all of the mechanisms for these associations are clear. High consumption of dietary fat may increase bile acids and cholesterol metabolites that may increase carcinogens in the body that are associated with colorectal cancers. Diets low in fiber have also been linked to increased rates of colon cancer. Food additives and food preparation are also suspect as cancer-causing agents. Nitrates, salts, and saccharin have been investigated as possible carcinogenic substances. Saccharin has not been shown to increase cancer risk in humans; however, this is not the case for nitrates and salts. Nitrates and salts that are used to preserve foods appear to increase rates of glandular stomach cancers. There are high rates of stomach cancers in countries where large quantities of salted fish or similarly preserved foods are consumed (McCance & Roberts, 1998). Methods of food preparation may also increase cancer rates. Excessively smoked or broiled fish or meat, or repeatedly reused fats for frying foods release Benzo(a)pyrene and other polycyclic hydrocarbons that may potentially cause cancer (McCance & Roberts, 1998). Dietary guidelines associated with lowering the risk of cancer include increasing the use of fiber, fruit, and vegetables in the diet, limiting alcohol consumption, and limiting foods that contain preservatives, or foods that are grilled or blackened (American Cancer Society, 2000).

Obesity caused by a sedentary lifestyle and/or a high consumption of dietary fat appears to contribute to an increased risk for cancers of the breast, the ovaries, and the endometrium in females (National Heart, Lung, and Blood Institute, 2000, Wu, et al., 1999). Obese females have higher numbers of fat cells, and fat cells produce estrogen. Since higher levels of estrogen have been associated with higher levels of endometrial, ovarian, and breast cancers, it has been suggested that higher levels of estrogen from increased numbers of fat cells in obese females may increase their cancer risk (McTiernan, 2000).

Medical practices and drugs have also been linked to increases in cancer rates. Androgen -anabolic steroids used to promote athletic performance and prevent muscle wasting cause cancers in the liver, prostate, and breast (Conway, et al., 2000; Fraumeni, 1982). Estrogen replacement medications and steroid contraceptives may contribute to increased risk for developing cancers of the endometrium, vagina, ovaries, and breast (Coughlin, et al., 2000; Koukoulis, 2000; McCance & Roberts, 1998). Immunosuppressants, such as those used in transplant procedures, are linked to lymphomas, skin cancer, and soft tissue sarcomas. Interestingly, some chemotherapeutic drugs used to treat cancer, such as alkylating agents, are linked to cancers of the bladder and to leukemia (McCance & Roberts, 1998). In situations where long-term prognosis is a factor, the benefits must be weighed against the risks when choosing to use these drugs.

Environmental factors that may increase cancer rates include air and ground pollution, occupational hazards, ultraviolet radiation, and radon gas. Air and ground pollution caused by industrial emissions and insecticides are associated with a variety of cancers (Ojajarvi, et al., 2000, McCance & Roberts, 1998, Fraumeni, 1982). Arsenic from pesticide applications, and from mining and smelting, contaminates groundwater and causes lung, skin, and liver cancers (Ojajarvi, et al., 2000). Industrial glues and varnish, as well as benzene byproducts from the petroleum industry, may contribute to increases in leukemia (McCance & Roberts, 1998; Fraumeni, 1982). Asbestos, mustard gas, heavy metals, aromatic hydrocarbons, and halogenated organic compounds from water chlorination are associated with increases in lung, bladder, liver, and pancreatic cancers (Ojajarvi, et al., 2000; McCance & Roberts, 1998). Radon gas trapped in houses contributes to an estimated 10% of lung and larynx cancers (Lubin et al., 1997; Tirmarche, 1997). Increases in ultraviolet exposures from tanning lamps and from diminished ozone levels contributes to increases in skin cancers and melanomas (Swerdlow, et al., 1998). Highway maintenance workers and roofers exposed to bitumen fumes and coal tar fumes from asphalt are at increased risk for cancers of the lung, stomach, and skin, as well as leukemia (Partanen & Boffetta, 1994).

Although environmental factors are the major cause of cancer, age is the single best predictor of the risk of developing cancer (American Cancer Society, 2000). Rates for the development of cancer begin to increase at 40 years of age and then increase rapidly at 50 years of age (American Cancer Society, 2000; Pfalzer, 1994; Pfalzer, 1992). The increasing risk for developing cancer with aging may be related to the increased likelihood of cumulative effects from environmental exposures, the potential for long latency periods, and increased opportunities for multi-stage processes to occur with aging (McCance & Roberts, 1998; Fraumeni, 1982).

Genetic or inherited cancers and familial susceptibility contribute to only a small percentage of cancers (McCance & Roberts, 1998; Fraumeni, 1998). A primary cause of cancer is damage to a specific gene. If the damaged gene is part of the genetic line, then the cancer can be inherited by succeeding generations. However, if the damaged gene is a somatic or general body cell, as most cancers appear to be, then the cancer will not be passed to future generations. The genetic or inherited cancers can be passed along through autosomal dominant, autosomal recessive, and X-linked transmission. Examples of inherited cancers include familial breast cancer, familial polyposis of the colon, adenomas of the colon, retinoblastomas (a childhood cancer of the eye), Wilms tumor (a childhood cancer of the kidney), and neurofibromatosis (McCance & Roberts, 1998).

The mechanisms involved in familial susceptibility for cancer are less well understood than those for inherited or genetic cancers. Cancers that tend to run in families include breast, colorectal, and prostate cancers. The impact of the environment in determining whether an individual with a familial susceptibility for cancer will actually develop cancer is not fully understood at this time. Most researchers believe that lifestyle and environmental factors markedly influence whether a person with a familial susceptibility for cancer will develop cancer (Lichtenstein, et al., 2000; McCance & Roberts, 1998; Fraumeni, 1982). Therefore, even when there is increased familial susceptibility for certain cancers, a person can modify his or her risk for developing cancer by changing environment or lifestyle practices.

Cancer also can be caused by a virus. Oncogenic viruses infect normal cells and cause alterations in the cell’s genetic material. These genetic alterations can cause specific types of malignant and benign cancers in susceptible individuals by allowing uncontrolled growth in cells. Oncogenic viruses can affect DNA or RNA. Oncogenic viruses that affect DNA can cause cancers in the cervix, liver, anogenital area, mouth, larynx, nasal and paranasal tissues, and conjunctival tissues (McCance & Roberts, 1998). Oncogenic viruses that affect the RNA can cause Human T-cell leukemia. Interestingly, infection by an oncogenetic virus does not necessarily lead to the development of cancer. In some industrial regions, the Epstein-Barr virus, which causes Burkitt lymphoma, nasopharyngeal cancer, and B-cell lymphoma, has an infection rate of up to 90% of the young adult population; however, low numbers of infected individuals in these areas develop cancer (McCance & Roberts, 1998).

Cancer Diagnosis

Cancer diagnosis can be simple or complex depending on the type, location, and the extent of the disease. Early detection offers the best opportunity for recovery. Early detection requires knowledge of an individual’s risk factors for developing cancer, regular cancer screening, and attention to subtle symptoms that might signal cancer. Risk factors for cancer include environmental exposures, lifestyle practices, occupational hazards, and a family history of cancer. Some of the early symptoms of cancer are fatigue, weakness, weight loss, depression, headache, pain, changes in bowel habits, and a persistent cough or hoarseness (American Cancer Society, 2000). Timely screenings, such as breast self-examinations, mammography, prostate screenings, chest X-rays, and colonoscopy, have markedly improved early detection and survival rates from cancer. Physicians may also use evidence from laboratory tests, X-rays, CT scans, ultrasound examinations, bone scans, liver and spleen scans, and biopsy analysis to confirm a diagnosis of cancer.

Staging and Classification

After a diagnosis of cancer is made, anatomic staging is performed to describe the rate of growth and the extent of the disease. The practice of dividing cancer cases into groups according to stages arose from the fact that survival rates were higher for cases where the disease was localized than when the disease had spread beyond the organ or site of origin. Staging helps to establish treatment options, predict life expectancy, and determine the prognosis for a complete recovery. Factors noted in staging include:

• Location and size of the primary site of the tumor
• Extent of lymph node involvement
• Presence or absence of metastasis
• Type of tumor and the tumor-host relationship

Tumors are classified according to the American Joint Committee on Cancer using the TNM Clinical Classification System. In this system, T stands for tumor, N stands for node, and M stands for metastasis. This system is based on criteria for classification by specific anatomic sites. Staging of cancer is determined and noted as Stages 0 to IV. This system is used to describe the extent of the disease, for example, 0 indicates undetectable, and I, II, III, and IV indicate a progressive increase in the size or the extent of the disease. A code letter or number that represents a particular designation or description follows each letter in the TNM classification system. The TNM Clinical Classification System is represented as follows:

Tumor (T) codes:

• TX: Cannot be assessed
• T0: No evidence of a primary tumor
• Tis: Carcinoma in situ
• T1, T2, T3, and T4: Increasing size, local extent, or both, of primary tumor

Regional lymph node (N) codes:

• NX: Cannot be assessed
• N0: No metastasis
• N1, N2, and N3: Increasing involvement of regional lymph nodes

The spread of cancer cells from the primary site, or site of origin, is called metastasis. Cancer cells can spread throughout the body through the bloodstream, the lymphatic system, or through local invasion and infiltration into surrounding tissues.

Metastasis (M) codes:

• MX: Cannot be assessed
• M0: No distant metastasis
• M1: Distant metastasis

Combining the TNM Clinical Classification codes leads to the actual tissue staging. The following are the stages of cancer:

Stage	Code	Description
Stage 0	Tis	Cancer in situ (encapsulated)
Stage I	T2, N0, M0	Cancer is limited to original site or organ
Stage II	T2, N1, M0	Cancer has spread to surrounding tissue in same anatomic region
Stage III	T3, N2, M0	High probability of metastatic disease
Stage IV	T4, N3, M1	Metastatic spread to other anatomic regions

Seven Warning Signs of Cancer

• Change in bowel or bladder habits
• A sore that does not heal
• Unusual bleeding or discharge
• Thickening or lump in the breast or elsewhere
• Indigestion or difficulty swallowing
• Obvious change in a wart or mole
• A nagging cough or hoarseness

Aerobic Exercise Training Effects on Cancer

Endurance training from aerobic exercise is an important component in the management of symptoms associated with cancer and its treatment and in the rehabilitation of people following treatment for cancer (Gerber & Augustine, 2000; Pinto &Maruyama, 1999; Friendenreich & Courneya, 1996). Research has linked aerobic exercise training with several specific benefits for people with cancer. These benefits include diminished signs and symptoms of distress and improved physical function. Improvements experienced by people with cancer from aerobic exercise training include reductions in fatigue, nausea, anxiety, and depression and improvements in self-esteem, physical activity, and weight control (Pinto & Maruyama, 1999; Friendenreich & Courneya, 1996; Dimeo, et al., 1997; Dimeo, et al., 1998; Dimeo, et al., 1999; Segar, et al., 1998; Pfalzer, 1989; Pfalzer, 1988; Mock, et al., 1997; Winningham, et al., 1989; Winningham & MacVicar, 1988; MacVicar, et al. 1989).

Although traditional recommendations for people with cancer include rest and reduction in physical activity, limiting activity appears to contribute to a deterioration of function and a worsening of signs and symptoms related to cancer and its treatments (Ream & Richardson, 1999; Dimeo, et al., 1998). Interestingly, moderate-intensity aerobic exercise training has been shown to benefit people with cancer through the various stages of treatment, recovery, remission, and palliative care (Dimeo, et al., 1999; Dimeo et al., 1997; Dimeo, et al., 1997; Segar et al., 1998; Mock, et al., 1997; Sayre and Marcoux, 1992; Pfalzer, 1989; Pfalzer, 1988; Winningham, et al., 1989; Winningham and MacVicar, 1988; Winningham, et al., 1988).

Historical Perspective

The impetus for using aerobic exercise during treatment and recovery from cancer came from the exercise physiology literature on the hazards of immobility (Saltin, 1968). The decrements that result from bed rest and diminished physical activity include reductions in musculoskeletal performance, cardiovascular efficiency, pulmonary function, neuromuscular function, and psychological well-being.

Reductions in activity cause muscle atrophy, changes in muscle properties, and reductions in bone density. Muscle atrophy and reduced bone density lead to diminished musculoskeletal strength and performance, and contribute to an increased risk for bone fractures and musculoskeletal injuries (American College of Sports Medicine (ACSM), 1998). Musculoskeletal atrophy and changes in muscle properties contribute to declines in cardiovascular efficiency. Declines in cardiac efficiency are reflected in increases in heart rates and blood pressures at rest and with submaximal exercise. Reductions in cardiovascular efficiency combined with elevations in cholesterol levels and decreases in HDL levels from inactivity contribute to an increased cardiovascular risk profile (ACSM, 2000). Declines in pulmonary function that result from inactivity may include a blunting of the ventilatory response, diminished airflow and respiratory muscle function, and impairments in gas exchange from ventilation/perfusion mismatches, shunting, and declines in diffusion that predispose people to respiratory diseases such as pneumonia (ACSM, 1998).

Recent reviews of the literature support aerobic exercise training as positively influencing psychological well-being in both healthy subjects and people with cancer (Pinto & Maruyama, 1999; Petruzello & colleagues, 1991). Aerobic exercise training may influence psychological well-being through psychological and physiological factors. The psychological factors that result from aerobic exercise training and may positively influence psychological well-being include distraction from the stressful condition, enhanced self-esteem, improved self-efficacy from mastery of a task, improved physical independence, and the development of a social support group. The physiological factors that result from aerobic exercise training that may influence psychological well-being include reductions in heart rate and blood pressure in response to stress, increased opioid activity, reductions in stress hormones, such as catecholamines and corticosteroids, and alterations in brain monoamines related to depression and anxiety, such as serotonin (Petruzello, et al., 1991).

In addition to the above benefits attributed to aerobic exercise training, there is evidence in the literature that supports moderate-intensity aerobic exercise training as a means to improve immune function and decrease oxidative damage (Nieman & Pedersen, 1999; Powers, et al., 1999). Nieman and Pedersen (1999) reviewed the literature on exercise and immune function and concluded that people who performed moderate-intensity aerobic exercise most days of the week had markedly fewer sick days as compared to sedentary individuals. There is also evidence that people who participate regularly in moderate levels of aerobic exercise training develop enhancements in their anti-oxidant defense mechanisms that may lead to reductions in oxidative damage (Powers, et al., 1999). Since cancer and cancer treatments cause immunosuppression and oxidative damage, aerobic exercise may be investigated as a method to assist in managing these conditions.

A final important change occurred in the guidelines required to achieve health benefits from aerobic exercise training that has had a profound impact on exercise and rehabilitation protocols for people with cancer. Blair and colleagues (1996) and Paffenbarger and colleagues (1991) published studies that supported moderate-intensity levels of aerobic exercise, when performed most days of the week, as sufficient to achieve marked health benefits. The health benefits that could be achieved from regular participation in moderate-intensity aerobic exercise include the following (A Report of the Surgeon General, 1996):

• Reductions in premature death
• Reductions in premature death from heart disease
• Reductions in the development of diabetes
• Reductions in the development of high blood pressure
• Reductions in the development of colon cancer
• Reductions in depression and anxiety Improvements in weight control
• Maintenance of bone, muscle, and joint health
• Improved strength and fall prevention in older adults
• Improved psychological well-being

The original guidelines for aerobic exercise training required people to exercise for 30 to 45 minutes at a high intensity (70% to 90% of their maximal heart rate) in order to achieve these health benefits. The new guidelines support moderate levels of exercise (50% to 70% of the individual’s maximal heart rate), performed most days of the week, as sufficient to promote significant improvements in health. The new guidelines for aerobic exercise training are at a level that is realistic, safe, and achievable for people undergoing treatment for cancer or recovering from cancer. These revised guidelines led the Surgeon General of the United States to develop a new position paper on exercise for the American people (A Report of the Surgeon General, 1996). The recommendations for aerobic exercise training for fitness and for health are provided in the following table.

	Physical Training for Fitness	Physical Activity for Health
Definition	Ability to perform a sport or task10+ METS	Ability to perform daily activities Reduced Health Risk Factors8-10 METS
Exercise Type		Moderate Intensity Training
Exercise Prescription	30 to 45 minutes -of continuous activity, 3 to 5 days per week Training Heart Rate: 70% to 90% of max HR (% Heart Rate Reserve: 60-85)Rate of Perceived Exertion: 14-16	Accumulate 30 minutes of activity most days of the week Training Heart Rate: 50% to 70% of max HR (% Heart Rate Reserve: 40-60) Rate of Perceived Exertion: 11-13

(American College of Sports Medicine, 2000)

Based on the benefits ascribed to apparently healthy subjects as a result of aerobic exercise training, several health care professionals began to examine the possibility that these benefits would aid in the management and rehabilitation of people with cancer.

More recently, the 2008 Physical Activity Guidelines for Americans provides science-based guidance to help individuals with disabilities aged 6 and older improve their health through appropriate physical activity.

A Review of the Literature on Cancer and Exercise

A review of the current literature reveals that there are few randomized, clinically controlled studies on the topic of exercise training in people with cancer (Pinto & Maruyama, 1999; Friendenriech & Courneya, 1996). Only eight randomized, controlled studies were found for this review. Winningham, MacVicar, and colleagues published the earliest studies on aerobic exercise training and cancer. These touchstone studies were performed on subjects with breast cancer who were undergoing chemotherapy during the time of the studies. Aerobic exercise in these studies was performed three times per week for 10 weeks, at 60% to 85% of the individual subject’s maximal heart rate. The first publication from this group examined the effects of aerobic exercise training on nausea (Winningham and MacVicar, 1988). In this study, 42 female subjects were divided into an aerobic exercise-training group, a placebo group, and a control group. Measures of nausea, on the Derogatis Symptom Check List-90-Revised, were significantly lower in the exercise group as compared to either the placebo or the control groups (p < .05). Patients reported that feelings of nausea disappeared following a few minutes of aerobic exercise and that the nausea did not return for the rest of the day. This study supported aerobic exercise training as a method to use to manage nausea in women undergoing chemotherapy treatments for breast cancer.

The second study published by this group investigated the effects of aerobic exercise training on body weight and body composition (MacVicar, Winningham, and Nickel, 1989). Twenty-four female subjects were randomized to an exercise group or a control group. As is common in breast cancer, all the subjects gained weight. The exercise group gained 0.82 kg and the control group gained 1.99 kg. The weight gain for each group was not statistically different. However, skinfold measures at the end of the study revealed a significant difference between the exercise group and the control group (p < .05). The exercise group lost 3.19 mm of subcutaneous fat while the control group gained 9.6 mm. The skinfold measures suggested that there was a marked difference in lean body mass between the exercise and the control group. The exercise group gained 2.04 kg. of lean body mass and the control group lost 1.26 kg of lean body mass (F = 5.26, p = .033). This study supported aerobic exercise training during chemotherapy regimens as a method to maintain muscle tissue and limit fat weight gain in women with breast cancer.

The final study published by these investigators examined the effects of aerobic exercise training on functional capacity (Winningham, MacVicar et al., 1989). Forty-five subjects were randomized to an exercise group, a placebo/flexibility group, or a control group. The exercise group demonstrated significant improvements on VO2max in liters, in workload, and in test duration, compared to the control and the placebo groups (p < .05). The authors concluded that aerobic exercise training would improve the physical functions of women undergoing chemotherapy treatments for breast cancer. It was suggested that these improvements in physical function would enable people with cancer to have more energy and be more independent in self-care and activities of daily living. Enhanced energy might also limit feelings of fatigue from cancer and its treatments. The authors recommended further research to investigate the impact of this phenomenon in cancer patients. However, there were no additional controlled studies on this topic until 1995.

In 1995, Nieman and colleagues examined the effects of eight weeks of exercise on the immune function of females with a previous diagnosis of breast cancer. The people in this study had a previous diagnosis of breast cancer that averaged 3.0 to 1.2 years prior to the start of this study. Subjects were randomly assigned to an exercise or a control group. Six subjects completed the exercise-training regimen, and six subjects served as controls. The exercise group participated in 60 minutes of supervised aerobics and weight training, three times per week for eight weeks at 75% of their maximal heart rate. The results from this study were equivocal. Changes in circulating immune cells and Natural Killer Cell Activity (NKCA) were reported to be non-significant, even though the two parameters used for natural killer cytotoxic activity (NKCA) increased by 11.6% and 42.9% in the exercising group. The authors indicated that the limitations of their study included the small sample size and, possibly, insufficient training time. Additionally, the parametric statistical analysis chosen for this study had insufficient statistical power to detect a significant difference between the exercise and the control group, and the immune parameters did not appear to be similar for the exercise and the control group at the start of the study.

The six remaining studies on exercise and cancer were published between 1997 and 1999. In 1997, Mock and colleagues examined the effects of moderate-intensity aerobic exercise on physical function, fatigue, emotional distress, and sleep disturbances in subjects with breast cancer undergoing radiation therapy. Statistically significant differences (p < .05) were found between pre- and post-test values in the exercise group for fatigue, anxiety, and sleep disturbances, but not for depression. The authors found that moderate, self-paced walking exercise during the weeks of radiation treatment for breast cancer improved adaptive responses as demonstrated by improved physical function and lower reported levels of fatigue, anxiety, and sleep disturbances. The authors concluded that people undergoing radiation treatment for breast cancer would benefit from moderate-intensity aerobic exercise training to manage symptoms related to their treatment.

Segar and colleagues (1998) performed a study on the influence of moderate-intensity aerobic exercise training on psychological well-being in subjects with breast cancer. This study examined the influence of aerobic exercise on self-esteem, depression, and anxiety in 24 breast cancer survivors. Subjects were randomly assigned to an exercise group, an exercise group with behavior modification, and a control group. Self-paced aerobic exercise was performed for 30 to 40 minutes, four days per week for 10 weeks, at 60% of the subjects’ predicted maximal heart rate. The results of this study indicated a significant difference between the two exercise groups and the control group on measures of state and trait anxiety, and depression, but not on self-esteem (p < .05). The authors in this study concluded that self-paced exercise training appears to be safe for subjects undergoing radiation treatment for breast cancer, and that aerobic training will improve symptoms of anxiety and depression in this population.

The remaining three studies on exercise training in subjects with cancer were performed at the Freiberg University Medical Center in Germany under the direction of Dr. Fernando Dimeo. All these studies were performed on subjects with various types of cancers who were concurrently undergoing high-dose chemotherapy. The first study published by this group was in 1997. Dimeo and colleagues performed a pilot study that examined the feasibility and effectiveness of aerobic exercise training in 16 patients undergoing high-dose chemotherapy and autologous peripheral stem cell transplantation. 32 subjects diagnosed with solid tumors or non-Hodgkin’s lymphoma were assigned to either an exercise group or a control group. Subjects in the exercise group walked on a treadmill five days per week for six weeks at 85% of their predicted maximal heart rate. Subjects were kept at corresponding lactate concentration levels of 3 (0.5 mmol/L) during exercise. The variables examined in these subjects were physical function, cardiac function, fatigue, and hemoglobin concentrations. Following six weeks of training, hemoglobin concentrations and walking speed values for both groups improved. However, the exercise group’s values were significantly statistically higher than those of the control group (p < .05). The conclusions from this study were that cancer patients recovering from high-dose chemotherapy should not be instructed to rest, but should increase physical activity to reduce their feelings of fatigue and improve their physical function.

The second study published by this group examined the effects of moderate-intensity aerobic exercise training on physical performance and on the number and severity of treatment-related complications (Dimeo, et al. 1997). 80 subjects with solid tumors undergoing high-dose chemotherapy were selected to participate in this study. Subjects were randomly assigned to a training group or a control group. Twenty-eight subjects completed the training and 32 subjects served as controls. All subjects were evaluated one week prior to hospitalization and again at discharge. Aerobic training was performed for 30 consecutive minutes daily on a supine cycle ergometer, at 50% of the subject’s maximal heart rate, for approximately six weeks. At discharge, the exercise group had significantly higher maximal physical performance levels than the control group. The loss of physical performance in the control group was 27% greater than the loss in the exercise group (p < .05).

Treatment-related complications were markedly different for some of the variables between the exercise and the control groups. The duration of neutropenia, the severity of diarrhea, the severity of pain, and the duration of the hospitalization were significantly reduced in the exercise group as compared to the control group (p < .05). The authors concluded that low to moderate levels of aerobic exercise training could be safely performed by people during high-dose chemotherapy treatments to prevent physical performance declines and lessen the severity of some symptoms related to cancer and its treatments.

In the final study published by this group, Dimeo, et al. (1999) evaluated the effects of moderate-intensity aerobic exercise training on fatigue and psychological well-being in 59 subjects undergoing chemotherapy followed by autologous peripheral blood stem cell transplantation. Twenty-seven subjects participated in the exercise group and 32 subjects were in the control group. Subjects trained on a supine bicycle ergometer for 30 minutes daily at 50% of their cardiac reserve during their hospitalization. Psychological distress and fatigue were evaluated before and after the training regimen using the Profile of Mood States Test (POMS) and the Symptom Checklist 90. The results of this study showed that the exercise group had significantly decreased levels of fatigue and physical complaints compared to the control group (p < .01). The training group also had significant improvements in several values related to psychological distress (p < .05). The authors concluded that aerobic training during chemotherapy should be used to reduce fatigue and improve symptoms of psychological distress in subjects undergoing treatment for cancer.

A summary of the literature to date supports moderate levels of aerobic exercise training as an effective method for people with cancer to use in order to manage their disease, its symptoms, and symptoms related to its treatment. Aerobic exercise training has been used safely and effectively for various types of cancer and during different phases of the disease process. Aerobic exercise training can be safely used during chemotherapy and radiation treatments to relieve treatment-related symptoms of fatigue and nausea. Aerobic exercise can be used effectively to promote physical function that may enhance a person’s ability to perform self-care, vocational, and social activities. Aerobic exercise has been found to improve psychological well-being and to relieve depression and anxiety. Aerobic exercise training is an effective rehabilitation method for the recovery of function following cancer treatment and during the remission phase. Aerobic exercise can also be used as a palliative measure to maintain function in the event that a person begins to fail. In light of the existing research support, aerobic exercise training should be an integral component in the lifestyle of people fighting through or recovering from cancer.

Aerobic Exercise Training Guidelines

A successful aerobic training protocol for a person with cancer should include education on aerobic exercise training, an exercise evaluation, and an individualized exercise prescription. Ideally, education, the exercise evaluation, and aerobic exercise training should begin when a person receives a diagnosis of cancer. In the event that a person with a new diagnosis of cancer is already performing aerobic exercise activities, they should be encouraged to continue their exercise regimen. However, these aerobically trained individuals should receive an updated exercise evaluation and exercise prescription, and should be provided with information on precautions and contraindications for exercise during this time.

The exercise evaluation for people with cancer should consist of a medical screening, a physical examination, and an exercise test (ACSM, 2000). Following are guidelines for the components of a medical screening and a physical examination (American College of Sports Medicine, 2000; Canadian Standardized Test Manual, 1995).

Medical Screening

Medical screening should be conducted for all clients with a diagnosis of cancer prior to their participation in an exercise program (ACSM, 2000). A medical screening is composed of the medical history and a medical examination. The medical screening should include:

• The medical diagnosis
• Previous physical examination findings such as abnormal cardiovascular or pulmonary findings, and abnormal blood studies or tests
• A history of symptoms
• Recent hospitalizations, illnesses, or surgeries, or orthopedic problems
• Medications, allergies, or habits such as caffeine, tobacco or alcohol usage, recreational drug usage, and drug interactions
• Exercise history and work history
• Family medical conditions

The physical examination should include the following:

• Body weight or body composition
• Pulse rate and heart rhythm
• Blood pressure
• Heart and lung auscultation
• Palpation of peripheral arteries and inspection of limbs for edema
• Presence of xanthoma or xanthelasma
• Follow up for orthopedic or other medical conditions that would limit exercise
• Neurological function and reflexes

The following table modified from the Canadian Standardized Test Manual (Canadian Society for Exercise Physiology and the Fitness Program, 1995) provides information on absolute and relative contraindications, and special prescriptive conditions for aerobic exercise training:

	Absolute Contraindications	Relative Contraindications	Special Prescriptive Conditions
	No exercise until condition is treated, stable, or past the acute phase.	Exercise ability is based on the individual’s condition. Exercise may be restricted or require medical supervision	Exercise training may require medical monitoring, special limitations, or special exercises.
Cardiovascular	Aortic aneurysm Aortic stenosis (severe) Congestive heart failure Crescendo angina Myocardial infarction (acute) Myocarditis (active or recent Pulmonary or systemic embolism (acute) Thrombophlebitis Ventricular tachycardia or other dangerous dysrhythmias	Aortic stenosis (moderate) Subaortic stenosis (severe) Marked cardiac enlargement Supraventricular dysrhythmias Ventricular ectopic activity Ventricular aneurysm Hypertension (uncontrolled) Hypertrophic cardiomyopathy Compensated congestive heart failure	Aortic or pulmonary stenosis Mild angina * Post acute infarct Cyanotic heart disease Shunts Conduction disturbances Dysrhythmias-controlled Fixed-rate pacemakers Intermittent claudication Hypertension
Infections	Acute infectious diseases	Subacute, chronic, recurrent infectious diseases	Chronic infections HIV
Metabolic		Uncontrolled metabolic disorders (diabetes mellitus, thyrotoxicosis, myxedema)	Renal, hepatic and other metabolic insufficiency
Pregnancy		Complicated pregnancy	Advanced pregnancy

(Modified from the Canadian Standardized Test Manual, Canadian Society for Exercise Physiology and the Fitness Program, 1995.)

An exercise evaluation or test is important for people with cancer. Exercise tests assess the safety of exercise for a person with cancer and enable the design of an individualized exercise prescription. The individualized exercise prescription describes the level of exercise that is safe and effective for the person with cancer. Exercise evaluations for people with cancer are typically submaximal tests. These submaximal exercise evaluations can be simple field tests, clinical tests, or more formal graded exercise tests. (For an excellent review on methods for administering the various submaximal tests, see Noonan & Dean, 2000).

Field tests, which are simple to perform and require only limited equipment or training, provide information on a subject’s fitness category. Typical field tests are the 6- and 12-minute walk tests, the Cooper 1.5-Mile Walk Test, the Rockport Fitness Test, and the 12-minute run test. Clinical exercise tests provide additional information on coordination, balance, and motor planning. Examples of clinical exercise tests include the Timed Up and Go Test, the Modified Shuttle Walk, and the Bag and Carry Test. The formal exercise tests provide good predictive information on a person’s maximal oxygen consumption and level of fitness.

Formal exercise tests appropriate for persons with cancer include the Modified Bruce Treadmill Test, The Astrand-Rhyming Cycle Ergometer Test, and The Single Stage Submaximal Walking Test. Formal exercise evaluations that are combined with electrocardiographic (ECG) analysis are the most valid and reliable measure of fitness, cardiovascular function, and safety for performing aerobic exercise. These formal tests should be used for people with a complex health status, or when there is a need to assess potential risk factors associated with performing exercise. Formal testing with a 12-lead ECG monitoring of cardiac responses is recommended by the ACSM (2000) when people have any of the following:

• Known cardiac, pulmonary, or metabolic disease
• Two or more risk factors for cardiac dysfunction such as elevated cholesterol levels, smoking, hypertension, or diabetes mellitus
• One or more signs or symptoms of cardiac disease such as dizziness, chest pain, or irregular heart rates or rhythms, or shortness of breath
• Chemotherapy medications which are toxic to the heart or lung such as doxorubicin hydrochloride (Adriamycin), or bleomycin sulfate (Blenoxane).
• Radiation treatments that may have caused pulmonary fibrosis, pneumonitis, or pericarditis

Re-evaluations should be performed at a 6- or a 12-week interval, depending on the subject’s progress or frailty. Thereafter, exercise evaluations can be performed on an annual basis to monitor a person’s health and fitness status, as well as provide them with motivation and encouragement to continue their exercise regimen. Exercise testing should also be performed when clients develop new signs or symptoms associated with abnormal responses to exercise, or a decline in function.

The Exercise Prescription

The exercise prescription will provide a person with cancer with guidelines for safe and effective levels of aerobic exercise training. The intensity level for aerobic training will be based on the individual’s exercise test, their present physical status, and the individual’s current phase of treatment or recovery. The following chart describes the three intensities of training for the individual with cancer and the subsequent discussion will describe guidelines for determining the appropriate training intensity.

	High Intensity	Moderate Intensity	Low Intensity
Purpose	Training to promote fitness	Exercise to promote health	Activity to maintain function or prevent deconditioning
Exercise Prescription	30 to 45 minutes3 to 5 days per week Training Heart Rate: 70% to 90% of HR Max(60% to 85% of HRR)RPE 14-16	Accumulate 30 minutes most days per week Training Heart Rate: 50% to 70% of HR Max(40% to 60% of HRR)RPE 11-13	3 to 5 minutes of activity that is well-tolerated Several times per day at or below 50% of HR max gradually increase exercise time and intensity

(Adapted from ACSM’s Guide to Exercise Testing and Prescription, 6th Ed., 2000.)

Not all people with cancer will be able to participate in moderate-intensity aerobic exercise training. People who are confined to bed or who fatigue with mild exertion may not be candidates for moderate-intensity aerobic exercise training but may benefit from low levels of physical activity (Winningham, 1991). These people may require supervision in the early stages of their recovery by a health care professional. These severely compromised individuals may benefit from range of motion exercises and gentle resistive work within their tolerance levels in the early stages of rehabilitation. This low-level physical activity will allow them to gradually build up their tolerance for activity. These people in the early stages of recovery may later progress to short (3- to 5-minute) bouts of walking or bed bicycling several times per day in order to gradually build their endurance and allow them to advance to moderate-intensity levels of aerobic exercise training.

A study by Dimeo and colleagues (1998) demonstrated this concept. In this study, five people with profound weakness following treatment for a variety of cancers began aerobic exercise programs that consisted of treadmill walking. The beginning exercise sessions for these people lasted for only 3 minutes but were performed five times per day. Following six weeks of training, all of the people in this study were able to increase their exercise session durations from 5 minutes to 30 to 35 minutes of uninterrupted walking. Subjects anecdotally reported returning to regular activities such as re-enrolling in school, returning to work, or taking up jogging. Not all individuals with cancer can begin moderate levels of aerobic exercise training, but with proper instruction, and gradual applications of low levels of training, they may progress to higher levels of training and function.

For persons undergoing chemotherapy or radiation treatments, moderate-intensity aerobic exercise training should be performed to maintain endurance, strength, and function. The goal of exercise at this time is to maintain function and prevent the loss of endurance and strength. Cancer treatments exhaust physical and emotional reserves, so the goal of moderate-intensity aerobic exercise training is to maintain these resources. Persons undergoing intensive chemotherapy or radiation may benefit from routine physical therapy, occupational therapy, and ambulation, as well as strength and flexibility exercises. These people are easily fatigued but appear to benefit from moderate-intensity aerobic activities. Moderate-intensity aerobic exercise during this time improves strength and endurance and assists in countering signs and symptoms associated with the cancer and its treatments, such as fatigue and nausea. Moderate-intensity aerobic exercise training may also offer profound psychological benefits for persons in cancer therapy, particularly with regard to depression. It is not known, however, at this time, whether moderate-intensity aerobic exercise training helps individuals withstand the rigors of treatment. Additionally, special modifications in the type of exercise performed may be required if orthopedic limitations, such as range of motion deficits, occur as a result of cancer surgery or cancer treatments.

Persons with generalized weakness and musculoskeletal atrophy should, whenever possible, include strength and cardiovascular training in their rehabilitation programs. Generalized weakness associated with cancer treatments can be more debilitating than the disease itself. Strength training appears to maintain lean body mass that prevents weakness, while aerobic training has been shown to improve endurance, promote physical function, and diminish fatigue (Pfalzer, 1988). People with generalized weakness and musculoskeletal atrophy typically benefit a great deal from exercise training. These subjects typically begin with low-intensity aerobic exercise and then progress to the moderate level within approximately six weeks (Dimeo, et al. 1998).

People recovering from cancer treatments or in remission from cancer have the most to gain from rehabilitation and exercise training. For cancer survivors, the objective of exercise training is to return them to their former level of physical and psychological function. Following appropriate medical screening and exercise evaluation, people in this group can participate in aerobic exercise training not merely to maintain function, but to improve fitness, physical work capacity, and cardiovascular responses to exercise. People in the recovery or remission phase typically begin in the moderate-intensity level of exercise training, but can progress to high levels of training. THINK LANCE ARMSTRONG!

Following the exercise session, it is important to allow 5 to 10 minutes for the body to “cool down.” The cool-down period allows the heart rate and blood pressure to return to resting levels in a gradual and safe manner. It is important to monitor vital signs during this post-exercise period. People with cancer should be taught to monitor their heart rate, blood pressure, and heart rhythm following exercise. A general guideline is that the cool-down phase has successfully ended when an individual’s heart rate returns to 100 beats per minute or less, heart rate and rhythm are regular, and blood pressure response is normal. Hot showers or heavy meals should also be avoided for several hours following a bout of aerobic exercise.

People undergoing treatment for cancer and survivors of cancer may have disease or treatment-specific obstacles to exercise training. The side effects of anti-cancer therapy are often permanent; amputations cause permanent disability; radiation and chemotherapy can cause permanent scar formation in the joints, the lung, and the heart tissues; and drug-induced cardiomyopathies usually cause a permanent limitation on cardiovascular function. Many cancer survivors can reap rewards from exercise training, because many of the benefits occur in skeletal muscle and in psychological status.

The usual precautions and contraindications for exercise should be followed. The following are the absolute and relative indications for terminating an exercise test or an exercise session as defined by the ACSM (2000).

Indications for the Termination of Testing or Training

Absolute

• A drop in systolic blood pressure (10 mm. Hg. from baseline despite increases in workload, when accompanied by other indications of ischemia)
• Moderate to severe angina
• Increasing nervous system symptoms (i.e. ataxia, dizziness or near syncope) Signs of poor perfusion (cyanosis or pallor)
• Sustained ventricular tachycardia ST segment elevation (1mm.) in leads without diagnostic Q waves (other than V1 or a VR)
• Technical difficulty monitoring the ECG or systolic blood pressure Subject’s desire to stop

Relative

• Drop in diastolic blood pressure (10 mm. Hg.)
• ST or QRS changes such as excessive ST segment depression (less than 2 mm. horizontal or down-sloping ST segment depression) or marked axis shift
• Arrhythmias other than sustained ventricular tachycardia, including multifocal PVC’s, triplets of PVC’s, supraventricular tachycardia, heart block, or brady arrhythmias
• Development of bundle branch block or intraventricular conduction delay that cannot be distinguished from ventricular tachycardia
• Hypertensive response (Systolic > 250 mm. Hg., Diastolic > 115 mm. Hg.)
• Increasing chest pain
• Fatigue, shortness of breath, wheezing, leg cramps or claudication

(ACSM, Guidelines for Exercise Testing and Prescription, 6th Ed., 2000, Chapter 5, p. 104, Box 5-3)

In addition to the above general guidelines, certain precautions and contraindications are specific to cancer patients and should be noted and monitored:

• Monitoring physiologic responses (e.g., vital signs) to exercise is important in the immunosuppressed population. Watch closely for early signs of cardiopulmonary complications of cancer treatments, such as dyspnea, pallor, sweating, and fatigue during exercise. Patients should always monitor their pulse rate, breathing frequency, blood pressure and, when warranted, use pulse oximetry.
• The Rate of Perceived Exertion (RPE) should not exceed 11 to 13 for moderate intensity training or submaximal testing.
• Current guidelines recommend that patients should be advised not to exercise within two hours of chemotherapy or radiation therapy as increases in circulation may increase the effects of the treatments (Gerber, 2000).
• People with cancer are advised to contact their physician if any of the following abnormal responses develop:
  • Fever
  • Extreme or unusual tiredness or unusual muscular weakness
  • Irregular heartbeat, palpitations, or chest pain
  • Leg pain or cramps, unusual joint pain, unusual bruising or nosebleeds
  • Sudden onset of nausea during exercise
  • Rapid weight loss, severe diarrhea or vomiting
  • Disorientation, confusion, dizziness, lightheadedness, blurred vision, or fainting
  • Pallor or gray-colored appearance
  • Night pain, or pain not associated with an injury
• The activity level of someone with anemia also may require adjustments in exercise intensity and duration due to increases in pulse and respiratory rates from hypoxia leading to fatigue with minimal exertion. Interval exercise or bedside exercise programs should be performed during frequent but short sessions throughout the day and may be the only treatment possible in this circumstance.
• It is important to monitor the hematological values in patients receiving these cancer treatments. The PT must review these values before any type of vigorous exercise or activity is initiated.
• The following table is a helpful guideline to indicate when aerobic exercise may need to be re-examined in chemotherapy patients:Normal Values/UnitsNo ExerciseLight ExerciseRegular ExerciseHematocrit
  Females:
  Males:37% to 47%40% to 50%<25%>25%>25%Hemoglobin Females: Males:
  12 to 16 g/dl.14 to 18 g/dl.<8 g/dl.
  8-10 g/dl.>10 g/dl.White Blood Cells
  4,000 to 10,000/mm3<500/mm3>500/mm3>500/mm3Platelets200,000 to 400,000/mm3<5,000/mm35,000 to 10,000/mm310,000/mm3
  (From Sayre & Marcoux, 1992; Pfalzer, 1988; Winningham, 1986)
• Exercise intensity determined by training heart rate may be difficult to use as some people have inappropriate heart rate responses to exercise and large physiologic changes on a day-to-day basis from the disease, the treatments, or changes in medications.
• Exercise intensity can be guided by heart rate response based on VO2 or metabolic equivalent (MET) levels along with monitoring of blood pressure, heart rate and rhythm, and Borg’s rating of perceived exertion scale (RPE) (Pfalzer, 1987).
• Compromised skeletal integrity may prevent weight-bearing activities. Non-weight-bearing aerobic activities, which may be utilized for people with bone and joint disease, include cycling, rowing, and swimming [water activities may not be appropriate for the immunosuppressed, and people with severe muscular weakness may tolerate cycling better than ambulation] (Pfalzer, 1987).
• Energy-conservation techniques and work simplification may be necessary for the person with chronic fatigue and for those whose functional status is declining. Therapeutic exercise can be scheduled during periods when the person has the highest level of energy. Interval exercise may be preferred at first, with work-rest intervals beginning at the person’s level of tolerance. This may include 1 minute of exercise activity followed by 1 minute of rest, then 1 minute of exercise, and so on. As the person’s endurance level increases, the duration of work may be increased while the interval of rest declines.

Summary

Moderate-intensity aerobic exercise training is an important but often overlooked method for promoting health and managing symptoms in people undergoing treatment for or recovering from cancer. Moderate-intensity aerobic exercise training has been successfully used for various types of cancer and during the different phases of cancer. Moderate-intensity aerobic exercise training has been used during chemotherapy and radiation regimens to maintain physical function and relieve symptoms of fatigue, nausea, and depression. Moderate-intensity aerobic exercise training has been used safely and effectively during the recovery and remission phases of cancer to promote strength and endurance to enable people with cancer to return to vocational, social, and recreational activities.

Appropriately paced physical activities can be used for people who have profound weakness and fatigue from cancer to enable them to progress gradually to higher physical functioning. Appropriately paced physical activities can also be used for people with cancer who require palliative treatment to maintain functional capacities in the event that a person begins to fail. Several controlled research investigations have demonstrated that moderate-intensity aerobic exercise training is a safe and effective method for maintaining health and managing symptoms related to cancer and its treatments. It is the responsibility of health care professionals to apply medical screening and exercise evaluations in order to appropriately design exercise prescriptions that are safe and effective for people in the various phases of cancer treatment and recovery. When used appropriately, moderate-intensity aerobic exercise can be an important component in managing symptoms related to cancer and its treatment, in improving the physical function of people with cancer, and in improving the quality of life for people fighting through or recovering from cancer.