Blog by: Yasmin Aboelzahab, Amelia Di Meo and Stephanie Jeanneret Manning
What is the link between cancer and physical activity?
When the journey of a cancer patient begins, all the available interventions that reduce risks and improve survival are considered crucial in this challenging journey. One of these means that has recently received greater attention from researchers is physical activity. Physical activity not only improves the mental health of cancer patients, but there is compelling evidence regarding the relationship between higher physical activity levels and reduced risks of several cancer types. Currently, there are indications that a higher level of physical activity lowers the risks of different types of cancer such as bladder cancer, breast cancer, colon cancer, endometrial cancer, esophageal cancer, kidney cancer, and stomach cancer.
The mechanisms by which physical activity reduces the risk of cancer include several physiological effects such as:
- Reducing the level of sex hormones: Exercise is associated with 25% reduction in risk for breast cancer as circulating sex hormones such as estrogen have been associated with the development and progression of cancer.
- Improving metabolic processes: Exercise helps manage weight by increasing total energy expenditure (the burning of calories). This reduces one’s risk for obesity which is one of the main risk factors for several types of cancers.
- Decreasing inflammation: Prolonged inflammation, which is caused by a surge of molecules called cytokines, can lead to the sustained growth of cancer cells and/or formed tumors (e.g., inflammation of the liver and pancreas has been largely linked to liver and pancreatic cancer, respectively). Exercise, through its complex mechanisms, can reduce inflammation and therefore reduce the risk of cancer.
- Preventing elevated insulin blood level: High insulin levels cause cell growth stimulation which is associated with greater risks for development and progression of different types of cancer such as colon cancer.
- Improving the immune system: Physical activity can alter the metabolism of the cytotoxic cells (a type of immune cell that kills pathogens and/or pathogen-carrying cells), thereby enhancing their ability to attack cancer cells.
What do the Guidelines Say About Preventing Cancer?
So, what is the recommended amount of exercise that will reap some of these benefits? According to the Canadian Physical Activity Guidelines, adults aged 18-64 should exercise for 150 minutes of moderate – to – vigorous physical activity, particularly in aerobics every week. Examples of moderately intense exercises include brisk walking and bike riding, whereas jogging and cross-country skiing, are examples of vigorous physical activity. Ideally, this exercise should be completed in periods of at least ten minutes such as “High Intensive Interval Training (HIIT)”.
The Guidelines also recommend adding muscle and bone strengthening exercises twice a week, which usually includes the use of added weights. This is especially important for older adults as weight-bearing exercises can help with improving balance, ultimately preventing falls. On the other hand, youth under the age of 18 are encouraged to participate in moderate-to-vigorous exercise for 60 minutes daily, with three days a week specifically devoted to vigorous exercise and activities that strengthen muscle and bone. Consequently, this will could lower the risk for chronic disease such as cancer. Exercise is also particularly important for cancer survivors, who should participate in aerobic and resistance exercise for half an hour three times a week, according to recent guidelines published by researchers from the University of British Columbia.
When and How Do I Start?
Today! Starting to become more active can easily be incorporated into your daily routine. You can bike or walk to work every day, rake the lawn and offer to do the same for a neighbour, or try a new sport with your family on the weekends. For children, stopping by the playground after school is an option whereas for older adults, joining a community walking club or dance class are also great options, especially for enhancing mood. No matter what activity you choose, start moving, and have fun!
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Ennour-Idrissi, K., Maunsell, E., & Diorio, C. (2015). Effect of physical activity on sex hormones in women: a systematic review and meta-analysis of randomized controlled trials. Breast cancer research : BCR, 17(1), 139. https://doi.org/10.1186/s13058-015-0647-3
National Cancer Institute. (n.d.). Physical activity and cancer. https://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/physical-activity-fact-sheet