Current evidence convincingly indicates that physical activity reduces the risk of colon and breast cancer. Physical activity may also reduce risk of prostate cancer. Scientists are also evaluating potential relationships between physical activity and other cancers.
The consistent findings for colon and breast cancer have led researchers to recommend that individuals increase physical activity to reduce the risk of cancer. However, it is not yet possible to provide a specific activity prescription for the population.
To better understand the relationship between physical activity and cancer and to make specific activity prescriptions, it is necessary to be able to accurately assess levels and types of activity. This poses a challenge because existing assessment methods are crude and imprecise. In particular, better methods are needed to:
- assess physical activity from transportation, occupation, and household tasks in addition to that from recreation;
- assess physical activity over longer time periods, including across the lifetime;
- assess more completely the frequency, duration, and intensity of physical activity;
- improve the validity and reliability of physical activity assessment instruments; and
- incorporate cognitive aspects into the design of assessment instruments.