Could Cardio Fight Cancer?
Could Cardio Fight Cancer?
Could cardio be a powerful weapon in the fight against cancer?
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According to the NHS, 1 in 2 of us will develop some form of cancer during our lifetime. In light of such a frightening prediction we clearly need to take every precaution to reduce this risk. This can involve making some simple changes to our lifestyle, such as not smoking, consuming a nutritious diet, maintaining a healthy body weight, and limiting our alcohol intake.
Regular participation in exercise has also long been shown to help protect against cancer, yet the mechanism responsible for this and exactly how much exercise and what intensity is required to optimise this effect, have remained unclear. However, a number of studies published recently answer these questions (1,2) and provide us with clear guidance on the most effective exercise regimes to reduce the risk of cancer.
What is cancer?
Before we look at these studies in some detail, we need to understand a little about cancer. In short, cancer is a condition where cells in a specific part of the body grow and reproduce uncontrollably. These cancerous cells can invade and destroy surrounding healthy tissue.
Sometimes cancer begins in one area of the body before spreading to others. This process is referred to as metastasis. For example, cancer may begin in the bowel but ultimately spread to the bones or brain.
There are more than 200 different types of cancer, with the 4 most common types in the UK being bowel cancer, breast cancer, lung cancer and prostate cancer. There is no one single cause of cancer. Rather, it is believed that it results from the interaction of various factors such as those relating to an individual’s genetics and the environment.
Exercise and cancer: What does the science say?
Health experts have known for a long time that exercise is linked with a lower risk of several cancers, but there has been limited evidence about how much exercise is needed. Mathews and colleagues (1) analysed the results of 9 prospective studies involving the leisure time activities of more than 750,000 adults. The results showed that getting 2.5 – 5 hours of moderate-intensity activity or 1.25 – 2.5 hours of vigorous activity per week significantly lowered the risk for 7 of the 15 types of cancer studied.
These included colon (8%-14% lower risk in men), breast (6%-10% lower risk), endometrial (10%-18% lower risk), kidney (11%-17% lower risk), myeloma (14%-19% lower risk), liver (18%-27% lower risk), and non-Hodgkin lymphoma (11%-18% lower risk in women). The results showed a dose response relationship with increased exercise time associated with an even greater reduction in risk some types of cancer.
Could Cardio Fight Cancer – Intensity is the key
The study by Mathews and colleagues (1) has helped to demonstrate the importance of achieving the right amount, or volume, of exercise to reduce cancer risk. Another important variable of an exercise programme is intensity, or how hard an individual is working. With regard to cardiovascular exercise, this tends to be expressed as a percentage of maximum heart rate or VO2max.
The results of a recent study by Sheinboim et al., (2) showed that people participating in high-intensity aerobic exercise, or ‘cardio’, were 72% less likely to develop metastatic cancer than those who did not exercise. The study analysed data from 3,000 people over a 20-year period. The results showed that while exercise prior to cancer had a modest impact on the incidence of cancer in low metastatic stages, it significantly reduced the likelihood of highly metastatic cancer.
The researchers set out to discover why high intensity exercise can provide such a protective effect against cancer. Using data from both human and animal studies, the team found that exercise induces the metabolic reprogramming of internal organs that increases nutrient demand and protects against metastatic cancer by limiting nutrient availability to the tumour, thereby, generating an exercise-induced metabolic shield.
In short, high intensity exercise causes muscles and organs, such as the lungs, to grow more glucose receptors on their surface. This allowed them to uptake more glucose from the blood, depriving the cancer cells of the fuel they need to spread. While any exercise can be beneficial in reducing the risk of cancer, the scientists suggest maximum benefit is achieved using exercise that employs intensities of at least 80% of maximum heart rate (2).
Could Cardio Fight Cancer? – In conclusion….
For many years we have known that exercise helps to reduce the risk of cancer by, for example, boosting immune function and helping us to maintain healthy levels of bodyfat. Now, for the first time, we have an understanding of how exercise, particularly high intensity exercise, can provide a protective effect against metastatic cancer by depriving tumours of their energy source. The science also tells us the optimal volume and intensity of exercise needed to achieve this protective effect. While it is unlikely that we can totally eradicate the risk of cancer, it is clear that a relatively small investment of our time in exercise can potentially pay big dividends in terms of our health.