Physical activity and cancer

  • Health
  • Sunday, 19 Oct 2008

All forms of physical activity protects against cancer.

CANCERS are among the most important causes of death in this country. In many of its forms, cancer is a disease that can cause great suffering and claims many lives.

However, cancer is not an inevitable consequence of ageing, and people’s susceptibility to it varies. There is now general consensus shared by scientists, health professionals, and policy-makers on the relationships between food, nutrition, physical activity, body composition, and the risk of cancer.

I will continue to highlight from the World Cancer Research Fund (WCRF) expert report on Food, Nutrition, Physical Activity and the Prevention of Cancer, released in November 2007 to emphasise the importance of the prevention of cancers.

I had previously discussed the first recommendation of the WCRF recommendation, i.e. the importance of overweight and obesity in cancer. I had emphasised that you can reduce your risk of cancer by maintaining a healthy body weight.

The second WCRF recommendation is closely linked to this and calls on everyone to be physically active as part of everyday life.

Physical activity and cancer prevention

Physical activity is any form of movement using muscles. Until the middle of the 20th century most people had fairly active lifestyles. People were necessarily engaged in regular, moderate and at least occasional vigorous, physical activity. Our working life required a lot of physical activity, as did housework.

In the second half of the 20th century, this began to change. With urbanisation and industrialisation, general levels of physical activity have declined.

Machines now do most of the work previously done by hand; driving and using public transport have largely replaced walking and cycling.

While people in higher income countries and in urban settings in most countries may engage in some active forms of recreation, they remain largely inactive, and many spend much time in sedentary recreation, such as watching television and using home computers. In general, lifestyles have become too sedentary.

The WCRF expert panel reviewed available evidence and concluded that:

·Since the early 1990s, the evidence that physical activity can protect against cancer and obesity has continued to grow.

·The expert report found convincing evidence that physical activity protects against bowel/colon cancer. It probably also protects against breast cancer (in postmenopausal women) and endometrial (womb) cancer.

·Studies show that regular activity can help to keep our hormone levels healthy, which is important as having high levels of some hormones can increase our cancer risk.

·Studies show that regular activity can help to keep our hormone levels healthy, which is important as having high levels of some hormones can increase our cancer risk.

·Physical activity may also strengthen our immune system, help keep our digestive system healthy and allow us to consume more food €“ and more cancer-protective nutrients €“ without gaining weight.

The expert panel is impressed by the overall consistency of the evidence that suggests or shows that regular, sustained physical activity protects against cancers of some sites.

To prevent these cancers, the overall evidence supports the message that all types and degrees of physical activity are or may be protective, excluding extreme levels of activity.

It also means that the more physically active people are, the better. It should be noted however that there is limited evidence for any specific type or degree of physical activity.

The expert panel further agrees that the evidence can equally be interpreted as showing that sedentary ways of life increase or may increase the risk of these cancers.

WCRF recommendations

The recommendation of WCRF is therefore to be physically active as part of everyday life.

The public health goals, which are for populations and are therefore principally for health professionals are:

·The proportion of the population that is sedentary to be halved every 10 years.

·Average physical activity levels (PALs) to be above 1.6. PAL is a way of representing the average intensity of daily physical activity.

The personal recommendations, meant for people, as communities, families, and individuals are:

·Be moderately physically active €“ equivalent to brisk walking for at least 30 minutes every day.

·As fitness improves, aim for 60 minutes or more of moderate, or for 30 minutes or more of vigorous, physical activity every day.

·Limit sedentary habits such as watching television.

What is moderate activity?

Moderate activity is anything that gets your heart beating a bit faster and makes you breathe more deeply. You need not set aside specific amounts of time to do these activities because shorter bouts of activity are just as beneficial. It’s the total time that’s important.

There is a wide range of these activities that you can do, some of which you can build into your daily activities, such as walking briskly, swimming, dancing, walking up the stairs instead of taking the elevator and doing housework briskly.

What is vigorous activity?

Vigorous activity means raising our heart rates so that we warm-up, start to sweat and feel out of breath.

If you want to make vigorous activity a regular part of your life, it’s important to find something that is fun and accessible. Good examples include jogging, hill walking, fast cycling, aerobics classes, working out at the gym, for example running on the treadmill, and team games like football.

Malaysians are largely sedentary

The physical activity levels of Malaysians have been declining and will continue to decline if we do not make conscious efforts to arrest this trend.

The nationwide Second National Health and Morbidity Survey (NHMS II) carried out in 1996 in the country reported that the prevalence of “ever exercise” was 30.9% and those with “adequate exercise” was 11.6%.

Ten years later, the Third National Health and Morbidity Survey (NHMS III) conducted in 2006 showed that the overall prevalence of physical inactivity was 43.7%, of which 35.3% were males and 50.5% were females.

In other words, almost half of the Malaysian adult population is physically inactive.

The findings also showed that physical inactivity was higher in women, older age persons, urban people and certain groups of occupations (the highest being among unemployed and housewives).

We are a sedentary lot. That is clear. We cannot continue to ignore the fact that a sedentary lifestyle is unhealthy. That is clear. Increased physical activity can reduce the risk of cancer and many other chronic diseases. That is abundantly clear.

The full WCRF report can be obtained from the World Cancer Research Fund International website:

n NutriScene is a fortnightly column by Dr Tee E Siong, who pens his thoughts as a nutritionist with over 30 years of experience in the research and public health arena. For further information, e-mail The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.

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