A new study has found that being fit in your teens and early twenties can reduce the risk of developing several types of cancer later in life. The study, published in the British Journal of Sports Medicine, analysed data from more than 1 million Swedish men who underwent military conscription between 1968 and 2005.
Fitness and cancer: what is the link?
The researchers measured the cardiorespiratory fitness of the conscripts, which is the ability to perform sustained aerobic exercises such as running, cycling, and swimming. They then followed them for an average of 33 years, until the end of 2019, and recorded any cancer diagnoses and deaths.
They found that higher cardiorespiratory fitness was associated with a lower risk of developing nine types of cancer, including lung, liver, oesophageal, stomach, pancreatic, bowel, kidney, head and neck cancers. The risk reduction ranged from 5% to 42%, depending on the type of cancer.
The researchers adjusted for factors such as age, body mass index, blood pressure, education level, family history of cancer, and alcohol and substance use. They also excluded men who had a history of cancer or cardiovascular disease before conscription.
Fitness and cancer: how does it work?
The exact mechanisms behind the association between fitness and cancer are not fully understood, but there are some possible explanations. One is that exercise has anti-inflammatory effects, which can prevent chronic inflammation that can damage DNA and trigger cancer development.
Another is that exercise can improve metabolism and hormone levels, which can affect cell growth and division. For example, exercise can lower insulin resistance, which can reduce the risk of pancreatic cancer. Exercise can also lower levels of sex hormones such as testosterone and oestrogen, which can influence the risk of prostate and breast cancers.
A third explanation is that exercise can enhance immune system function, which can help fight off infections and eliminate abnormal cells before they become malignant. Exercise can also reduce oxidative stress, which can cause DNA damage and mutations.
Fitness and cancer: what are the implications?
The study is one of the largest and longest to examine the link between fitness and cancer across multiple sites. It adds to the growing evidence that physical activity can have a protective effect against cancer, as well as other chronic diseases such as cardiovascular disease and diabetes.
The study also suggests that fitness earlier in life can have long-term benefits for health later in life. This implies that interventions to improve fitness in youth, such as through school and university programs, could have a significant impact on reducing the burden of cancer in the population.
However, the study has some limitations that need to be considered. First, it only included men, so the results may not apply to women. Second, it only measured fitness at one point in time, so it did not account for changes in fitness over time or other types of physical activity. Third, it did not include other potential confounders such as diet, smoking, or environmental exposures.
Therefore, more research is needed to confirm the findings and to explore the causal relationship between fitness and cancer. In addition, other lifestyle factors such as nutrition, smoking cessation, and sun protection should also be considered for cancer prevention.
Fitness and cancer: what are the recommendations?
The World Health Organization (WHO) recommends that adults aged 18 to 64 should do at least 150 minutes of moderate-intensity aerobic physical activity or 75 minutes of vigorous-intensity aerobic physical activity per week. They should also do muscle-strengthening activities involving major muscle groups on two or more days per week.
For children and adolescents aged 5 to 17 years, WHO recommends at least 60 minutes of moderate-to-vigorous intensity physical activity per day. They should also do activities that strengthen muscle and bone at least three times per week.
Physical activity can be done in various ways, such as walking, cycling, dancing, playing sports, gardening, or taking the stairs instead of the elevator. The key is to find something that you enjoy and that suits your abilities and preferences.
Being physically active can not only lower your risk of cancer but also improve your mood, energy levels, sleep quality, cognitive function, and overall well-being. So why not start today?
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