Physical activity is defined as any movement that uses skeletal muscles and requires more energy than resting. Physical activity can include walking, running, dancing, biking, swimming, performing household chores, exercising, and engaging in sports activities.
A measure called the metabolic equivalent of task, or MET, is used to characterize the intensity of physical activity. One MET is the rate of energy expended by a person sitting at rest. Light-intensity activities expend less than 3 METs, moderate-intensity activities expend 3 to 6 METs, and vigorous activities expend 6 or more METs.
Sedentary behavior is any waking behavior characterized by an energy expenditure of 1.5 or fewer METs while sitting, reclining, or lying down. Examples of sedentary behaviors include most office work, driving a vehicle, and sitting while watching television.
A person can be physically active and yet spend a substantial amount of time being sedentary.
There is strong evidence that higher levels of physical activity are linked to lower risk of several types of cancer.
For several other cancers, there is more limited evidence of an association. These include cancers of the pancreas,liver, and rectum.
Exercise has many biological effects on the body, some of which have been proposed to explain associations with specific cancers. These include:
Relationship between being sedentary and the risk of cancer?
Although there are fewer studies of sedentary behavior and cancer risk than of physical activity and cancer risk, sedentary behavior—sitting, reclining, or lying down for extended periods of time (other than sleeping)—is a risk factor for developing many chronic conditions and premature death. It may also be associated with increased risk for certain cancers.
How much physical activity is recommended?
The U.S. Department of Health and Human Services Physical Activity Guidelines for Americans (2018) recommends that, for substantial health benefits and to reduce the risk of chronic diseases, including cancer, adults engage in
Is physical activity beneficial for cancer survivors?
Yes. A report of the 2018 American College of Sports Medicine International Multidisciplinary Roundtable on Physical Activity and Cancer Prevention and Control concluded that exercise training and testing are generally safe for cancer survivors and that every survivor should maintain some level of physical activity.
In addition, studies have shown a possibility that physical activity may have beneficial effects on survival for patients with breast, colorectal, and prostate cancers.