Overall , the current literature supports clearly the dose-response relationship between physical activity and the seven chronic conditions identified .
Moreover , higher levels of physical activity reduce the risk for premature all-cause mortality .
The current Canadian guidelines appear to be appropriate to reduce the risk for the seven chronic conditions identified above and all-cause mortality
This systematic review examines critically the scientific basis for Canada 's Physical Activity Guide for Healthy Active Living for adults .
Particular reference is given to the dose-response relationship between physical activity and premature all-cause mortality and seven chronic diseases ( cardiovascular disease , stroke , hypertension , colon cancer , breast cancer , type 2 diabetes ( diabetes mellitus ) and osteoporosis ) .
The strength of the relationship between physical activity and specific health outcomes is evaluated critically .
A prospective study of recreational physical activity and breast cancer risk.
BACKGROUND Increased physical activity has been hypothesized to prevent breast cancer , largely by reducing cumulative lifetime exposure to circulating ovarian hormones . However , epidemiologic findings are inconsistent , and there is no consensus on the best way to quantify physical activity . We thus examined this issue in a large cohort of women , using several different measures of adult physical activity . METHODS We analyzed data from the Nurses ' Health Study , a prospect i ve study of women aged 30 to 55 years in 1976 . In 1980 and on subsequent surveys , women were asked about the average number of hours per week spent in various moderate and vigorous recreational physical activity during the past year . We computed a " baseline-only " ( 1980 ) measure of hours per week of physical activity , as well as a cumulative average measure that used up date d reports on physical activity . During 16 years of follow-up , we identified 3137 cases of invasive breast cancer ( 1036 premenopausal and 2101 postmenopausal women ) . Data were analyzed by use of multivariate pooled logistic regression to produce relative risks of breast cancer , and the associated confidence intervals . RESULTS Women who were more physically active in adulthood had a lower risk of breast cancer than those who were less physically active . Comparing those who reported engaging in moderate or vigorous physical activity for 7 or more hours per week with those who engaged in such physical activity for less than 1 hour per week , the relative risk was 0.82 ( 95 % confidence interval , 0.70 - 0.97 ) , using the cumulative average updating . The dose-response trend was statistically significant ( P = .004 ) . Using the baseline-only measure of physical activity produced slightly weaker relative risks . CONCLUSION These results contribute to the body of evidence suggesting that higher levels of adult physical activity afford modest protection against breast cancer
Overall , the current literature supports clearly the dose-response relationship between physical activity and the seven chronic conditions identified .
Moreover , higher levels of physical activity reduce the risk for premature all-cause mortality .
The current Canadian guidelines appear to be appropriate to reduce the risk for the seven chronic conditions identified above and all-cause mortality
This systematic review examines critically the scientific basis for Canada 's Physical Activity Guide for Healthy Active Living for adults .
Particular reference is given to the dose-response relationship between physical activity and premature all-cause mortality and seven chronic diseases ( cardiovascular disease , stroke , hypertension , colon cancer , breast cancer , type 2 diabetes ( diabetes mellitus ) and osteoporosis ) .
The strength of the relationship between physical activity and specific health outcomes is evaluated critically .