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 .
Physical Activity and Colon Cancer Risk among Women in the California Teachers Study
Background : Existing data suggest that physical activity reduces colon cancer risk , but the association is not consistently observed in women . One potential explanation for this inconsistency is that hormone therapy , which is associated with lower colon cancer risk , acts as a modifier of the physical activity/colon cancer relationship . Methods : Participants in the California Teachers Study ( N = 120,147 ) , a prospect i ve cohort of female teachers and administrators residing in California , ages 22 to 84 years at baseline and with no prior history of colon cancer were eligible for study . Between 1996 and 2002 , 395 patients were diagnosed with invasive colon cancer . The relative risks ( RR ) associated with lifetime ( high school through age 54 years or current age ) and recent ( past 3 years ) strenuous and moderate recreational physical activity were estimated using Cox proportional hazards regression models . Results : Combined lifetime moderate and strenuous recreational physical activity was only modestly associated with colon cancer risk in the cohort [ ≥4 versus ≤0.5 h/wk/y : RR , 0.75 ; 95 % confidence interval , 0.57 - 1.00 ; Ptrend = 0.23 ] . Lifetime physical activity reduced colon cancer risk among postmenopausal women who had never taken hormone therapy ( ≥4 versus ≤0.5 h/wk/y : RR , 0.51 ; 95 % confidence interval , 0.31 - 0.85 ; Ptrend = 0.02 ) . Postmenopausal women with histories of hormone therapy use had lower colon cancer risk , but their risk was not associated with physical activity . The likelihood ratio test for interaction between hormone use and lifetime moderate plus strenuous physical activity was of borderline statistical significance ( P = 0.05 ) . We observed no effect modification by age , body mass index , smoking status , menopausal status , or folate intake . Conclusions : Lifetime recreational physical activity may protect against colon cancer among postmenopausal women who have never used hormone therapy . Among hormone therapy users , who have lower risk of colon cancer , recreational physical activity does not seem to provide any additional benefit . With declining rates of hormone therapy use , physical activity offers one possible means for reducing women 's colon cancer risk . ( Cancer Epidemiol Biomarkers Prev 2007;16(3):517–25
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 .