An analysis of 9 prospective studies involving in excess of 750,000 individuals reveals that recommended leisure-time physical activity amounts are associated with a reduced risk for 7 types of cancers, with a number of cancer types having a ‘dose/response’ relationship.
Although it’s now commonly known that physical activity is linked to a lower risk of a number of cancers, the details of the association has been less clear and also if the recommended physical activity amounts are linked to reduced risk. The updated activity guidelines now suggest that individuals should be aiming for 2.5 – 5 hours a week of moderate intensity physical activity or 1.25 – 2.5 hours a week of vigorous physical activity. Moderate-intensity physical activities are the type that get an individual moving fast or strenuously enough to burn off 3 – 6 times as much energy a minute as sitting quietly (3 – 6 METs). Vigorous-intensity physical activities burn in excess of 6 METs.
Researchers pooled data from 9 studies for the current analysis, with participants self reporting leisure-time physical activity and cancer incidence following after study commencement. The relationship between physical activity and the incidence of 15 kinds of cancer were looked at.
It was discovered that engaging in the recommended activity amounts (7.5 to 15 MET hours a week) was linked to a statistically significant reduced risk of 7 of the 15 types of cancer researched, and the reduction increased the more MET hours there were. Physical activity was linked to reduced colon cancer risk in men (8% for 7.5 MET hours a week or 14% for 15 MET hours a week), a reduction in endometrial cancer (10%-18%), female breast cancer (6%-10%), myeloma (14%-19%), kidney cancer (11%-17%), liver cancer (18%-27%), and non-Hodgkin lymphoma (11%-18% in women). There was a linear shaped dose response for 50% of the associations and nonlinear dose response for the others.
The research had some limitations: Despite having 750,000 participants, patient numbers were limited for some cancers; individuals were primarily white; there was a limited amount of studies with comprehensive physical activity measures; and the authors depended on physical activity that was self-reported.