Today, the relationship between exercise and improved physical and mental well- being is well established for healthy people as well as people with cancer (Hacker, 2009). However, most research on exercise and cancer has involved patients with breast cancer, possibly because of the high number of breast cancer survivors in the population as compared to other cancers. For example, a large retrospective analysis of multiple studies involving patients and/or survivors of breast cancer (Wanchai, Armer, & Stewart, 2011) demonstrated overwhelmingly that supervised and home-based exercise programs could provide benefits for participants, ranging from improved QOL scores, to enhanced self-esteem, improved mood, greater aerobic fitness, higher level of functioning, and decreased pain and fatigue. Unfortunately, because many early studies were conducted with women with breast cancer only, their generalizability is limited (Visovsky & Dvorak, 2005).
BENEFITS OF EXERCISE ON CANCER PATIENTS (video)
Other studies conducted involved patients of varying types of cancer, but due to the number of variables and differences among then, drawing conclusions from such cohorts is difficult. Two large prospective observational studies suggest, however, that regular exercise following treatment for colon cancer may reduce the risk of recurrence and death. These data are significant in that they suggest that lifestyle factors, not just the molecular aspects of the tumor play a role in treatment outcomes (National Cancer Institute, 2006).
Demonstrating exercise’s physical effect on functional status, weakness, and cancer-related fatigue (CRF) has been primary endpoints in many studies (Hanna, Avila, Meteer, Nicholas, & Kaminsky, 2008). Although few studies have focused solely on CRF, exercise has been demonstrated as successfully reducing CRF in multiple studies, leading some to postulate that exercise currently offers the best nonpharmacologic option for reducing CRF (Hanna et al., 2008). Unfortunately, much is still unknown, including the best timing, duration, or intensity of exercise.
Other studies have measured the effect of exercise on depression, anxiety, and stress. In one study, a significant reduction in anxiety was observed following just one exercise session (Blanchard et al., 2001). Still others have found the aerobic physical exercise during or after cancer treatment resulted in improved QOL, body composition, fatigue, and endurance; additional benefits included decreased pain, diarrhea, nausea, and sleep disturbances, and improved life satisfaction, symptoms of depression, and self-esteem (Visovsky & Dvorak, 2005).
Evidence is strong that exercise in general promotes and enhances health (Fentem, 1994). Additional studies support the concept that exercise may play a protective role in the development of cancer in some populations. Researchers found that strenuous exercise more than five hours per week lowered the risk of invasive breast cancer, particularly of estrogen receptor-negative invasive breast cancer, when compared with less activity. These findings were supported even as other cancer risks were controlled for in the study population (National Cancer Institute, 2007). Multiple observational studies have concluded that the evidence for decreased risk with increased physical activity is convincing for colon and breast cancers, probable for prostate cancers, possible for endometrial and lung cancers, and remains inconclusive for other cancers (Friedenreich & Orenstein, 2002). Although compelling, some of these studies were confounded by incomplete data or uncontrolled variables; therefore, further research remains important. Possible biologic factors which may play a role in prevention include changes in metabolic and endogenous sex hormone levels, growth factors, decreased obesity, and central body adiposity.
The Specific Effects of Aerobic ExerciseStudies of aerobic exercise regimens ranging from supervised treadmill tests to stationary bike programs three times a week for 10–12 weeks showed that participants experienced (Visovsky & Dvorak, 2005)
- Decreased fat mass; increased lean mass
- Less noticeable symptoms
- Less nausea
- Increased maximal oxygen uptake during exertion (VO2 max)
- Increased functional capacity
- Less depression, anxiety, emotional distress
- Less fatigue.
The Specific Effects of Resistance/Strength Training ExerciseResearch in people without cancer demonstrates that strength training (Hacker, 2009)
- Increases muscle mass, strength and endurance
- Improves physical functioning
- Enhances endurance.