The benefits of regular exercise are well know, however the list of benefits continues to grow and it’s effect on different areas of health continues to expand all the time. A recent paper published in the Medicine and Science in Sports and Exercise journal showed that a mere 5 hours of moderate intensity exercise a week could reduce the risk of developing some cancers. The authors estimated that in the US a staggering 46, 000 cancer cases annually could be potentially avoided as inactivity is a risk factor in the development of some cancers. So how does exercise reduce your risk of developing cancer? Read on to find out!
Before we answer that question, let’s briefly explore the types of cancer that researchers have indicated can be affected by exercise and inactivity. So far it is known that physical inactivity is a significant risk factor in the development of bowel cancer, breast and endometrial cancers. It is also a contributor to the development of another 10+ types of cancer including liver, kidney, stomach and lung cancer. There are potentially other types of cancer that are influenced by activity levels, however further research is needed to confirm this.
One of the benefits of regular exercise is the effect it has on hormones. It regulates hormones such as insulin-like growth factor and estrogen, both of which have been associated with the progression and development of breast and colon cancer. In addition, it helps to regulate the level of insulin in the bloodstream which has also been shown to be linked to cancer development by helping to mobilise the fuel needed for cancer cells to reproduce. Exercise also has a positive impact on body fat levels, as adipose tissues have been shown to produce and secreet estrogen.
Exercise also has positive effects on our digestion. It reduces the time it takes for food to travel through the digestive tract which serves to limit any exposure to possible cancer causing substances. Aerobic exercise in particular has been shown to increase the diversity of healthy bacteria in the gut. This has a number of implications including the improvement of immune system function.
Inflammation is part of our normal defence system, however chronic low grade inflammation has been shown to be a factor that contributes to the development of many chronic diseases including cancer. Studies have shown that higher measures of pro-inflammatory chemical in the body are observed in situations where cancel cells process and develop. Regular exercise of a moderate intensity has been shown to have a beneficial effect on inflammation through the release of anti-inflammatory chemicals.
Moderate levels of physical activity have also been linked to improvements in immune system function. Exercise produces an increase in the number and activity of some important immune cells including the lymphocytes and natural killer cells. Regular exercise can also improve the body’s antioxidant capacity which helps in the elimination of reactive oxygen species. Oxidative stress from highly reactive species has an important role in the progression of different types of cancer and hence preventing and reducing oxidative stress is an important consideration.