Exercise during breast cancer treatment, regardless of whether the treatment is chemotherapy, radiation therapy or adjuvant therapy, reduces fatigue and bone loss. Continuing to exercise after you’ve completed your therapy helps prevent breast cancer reoccurrence and reduces your risk of death from breast cancer.
Breast cancer reoccurrence
An extensive review of the epidemiologic literature on the effect of physical activity on breast cancer recurrence and mortality was conducted using PubMed up to 2010.
Findings: Of the six studies that examined the influence of physical activity on breast cancer mortality, four (67%) reported a protective effect (i.e., inverse association), two examined the influence of physical activity on breast cancer recurrence and reported a non-significant risk reduction.
To test the effects of aerobic and resistance exercise on changes in bone mineral density (BMD) in women newly diagnosed with stage I-III breast cancer receiving chemotherapy a randomized clinical trial was conducted with 66 women randomized to aerobic or resistance exercise and usual care. At the beginning of chemotherapy and at six months, patients completed exercise testing and bone mineral density (BMD) assessment of the lumbar spine by dual energy x-ray absorptiometry.
Findings: The average decline in BMD over the study period was -6.23% for usual care, -4.92% for resistance exercise, and -0.76% for aerobic exercise. Participants in the usual care group showed a 10% decline in aerobic capacity. Aerobic exercise preserved BMD significantly better compared to usual care. Premenopausal women demonstrated significantly greater declines in BMD than postmenopausal women. Aerobic capacity increased by almost 25% for women in the aerobic exercise group and 4% for resistance exercise.
Death from breast cancer
Physical activity after breast cancer diagnosis has been strongly linked to improved quality of life. There is reason to believe that physical activity might extend survival in women with breast cancer. Using data collected in the Nurses’ Health Study(NHS) cohort of 121,700 female registered nurses from across the United States, aged 30 to 55 years a study of assessed leisure-time physical activity in MET-hours per week beginning in 1986. Women were asked: “During the past year, what was your average time per week spent at each of the following activities?”
Findings: Compared with women who engaged in less than 3 MET-hours per week of physical activity, the adjusted relative risk (RR) of death from breast cancer was 0.80 (95% confidence interval [CI], 0.60-1.06) for 3 to 8.9 MET-hours per week; 0.50 (95% CI, 0.31-0.82) for 9 to 14.9 MET-hours per week; 0.56 (95% CI, 0.38-0.84) for 15 to 23.9 MET-hours per week; and 0.60 (95% CI, 0.40-0.89) for 24 or more MET-hours per week (P for trend = .004). Three MET-hours is equivalent to walking at average pace of 2 to 2.9 mph for 1 hour. The benefit of physical activity was particularly apparent among women with hormone-responsive tumours. The RR of breast cancer death for women with hormone-responsive tumours who engaged in 9 or more MET-hours per week of activity compared with women with hormone-responsive tumours who engaged in less than 9 MET-hours per week was 0.50 (95% CI, 0.34-0.74). Compared with women who engaged in less than 3 MET-hours per week of activity, the absolute unadjusted mortality risk reduction was 6% at 10 years for women who engaged in 9 or more MET-hours per week.
When is the best time to start exercising?
You can start exercising any time during or after treatment for breast cancer. In general, the earlier you start the better; however, it is never too late to start. It’s important to start exercising slowly, and gradually build up to the recommended level of exercise, rather than exercising too much or too intensely when you first begin. This is important even if you have exercised regularly in the past.
You are never too old to begin exercising. In fact, exercise can help to manage some of the physical changes that many women face as they get older, for example, painful joints. No matter how old you are, or whether you are undergoing treatment or not, it’s important to speak with your doctor or a member of your treatment team about your exercise plans before you start exercising.
Summary of recommendations for women
- Two-and-a-half hours of exercise per week (around 30 minutes each day for five days, or around 50 minutes each day for three days)
- Moderate intensity – increased breathing where you are able to talk but not sing
- Start slowly and gradually build up to the recommended level of exercise over time
How much exercise is enough?
Research suggests that any amount of exercise is better than none, and more exercise is generally better than less. It is recommended that women diagnosed with breast cancer complete the same level of exercise recommended for all Australian adults by the Commonwealth Department of Health and Ageing – at least two-and-a-half hours of moderate intensity exercise per week. You can achieve this by doing 30 minutes of exercise five days of the week.
If you are currently undergoing treatment and are just starting to exercise, or if you have not exercised for a while, it is important to gradually build up to the recommended amount of exercise. To do this, you can break down your 30 minutes of exercise into shorter periods throughout the day, for example, exercise for 15 minutes in the morning and 15 minutes in the afternoon.
How ‘hard’ should you exercise?
‘Moderate intensity exercise’ refers to exercise that makes breathing a bit harder, but does not make you feel completely out of breath. For example, walking briskly where you can talk but not sing. Or walking as if you are late for an appointment. If you are doing moderate intensity strength-based exercises with weights, you should be able to lift the weights at least 8–12 times without needing to take a break.
If you are currently undergoing treatment or you are just starting out, it’s important to start exercising at a lower intensity and progress to a moderate level of intensity over time. If you are very physically fit and have been active for some time, you may choose to exercise at a higher intensity. When exercising at a higher intensity, your breathing is increased so that you can still talk but would be quite breathless doing so.
What types of exercises can you try?
While there are many different types of exercise that you can try, the important thing is to find something that you enjoy because you are more likely to maintain it. You may have to try a few different types of exercise before you find one that you enjoy. You may also choose to alternate the types of exercise you do to keep it interesting. For example, you could consider alternating walking, yoga and swimming on different days.
Some breast cancer treatments can lower your bone density and increase your risk of bone fracture, including the hormone therapies tamoxifen (lowers bone density only in pre-menopausal women) and aromatase inhibitors (Arimidex, Femara and Aromasin). Certain exercises have been shown to be very good at increasing bone density and reducing your risk of fracture, including:
These are exercises where your body has to bear its own weight. In general, you do these exercises while on your feet. Examples include walking, jogging, netball, tennis and dancing. Swimming and cycling are not weight-bearing exercises.
Resistance training exercises
These exercises involve exercising with weights, including free weights or weight machines found in gyms.
Other forms of exercise
- Walking or jogging
- Swimming or water aerobics
- Dancing e.g. salsa, belly dancing or ballroom dancing
- Gym classes such as aerobics or step classes
- Group sport such as netball
- Lifting weights
- Dragon boating
- Aqua aerobic classes
You may be at an increased risk of bone fracture, for example, if you have low bone mineral density, are menopausal or post-menopausal, are an older women, or have bone metastases. If you are at an increased risk of bone fracture, avoid high-impact exercise and exercises where you are at an increased risk of falling. Try lower-impact exercises such as walking, swimming or yoga
You may be at an increased risk of infection, for example, if you are currently undergoing chemotherapy and have a reduced white cell count. If you are at an increased risk of infection, and you would like to swim in a pool, it is a good idea to check this with your medical oncologist first.
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