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 stroke incidence: the Harvard Alumni Health Study.
BACKGROUND AND PURPOSE Physiologically , it appears plausible for physical activity to decrease stroke risk ; however , epidemiological studies have produced mixed findings . Furthermore , few studies have examined specific kinds and intensities of activities . The purpose of this study was to examine the association between physical activity , including its various components ( walking , climbing stairs , participation in sports and recreational activities ) , and stroke risk . METHODS This was a prospect i ve cohort study of 11 130 Harvard University alumni ( mean age , 58 years ) without cardiovascular disease and cancer at baseline . Men reported their walking , stair climbing , and participation in sports or recreation on baseline question naires in 1977 . Stroke occurrence was assessed with another question naire in 1988 . Death certificates were obtained for decedents through 1990 to determine strokes not previously reported ( total strokes=378 ) . We used Cox proportional hazards regression to estimate the relative risks and 95 % CIs for stroke occurrence associated with physical activity . RESULTS After adjustment for age , smoking , alcohol intake , and early parental death , the relative risks of stroke associated with < 1000 , 1000 to 1999 , 2000 to 2999 , 3000 to 3999 , and > /=4000 kcal/wk of energy expenditure at baseline were 1.00 ( referent ) , 0.76 ( 95 % CI , 0.59 to 0.98 ) , 0.54 ( 0.38 to 0 . 76 ) , 0.78 ( 0.53 to 1.15 ) , and 0.82 ( 0.58 to 1.14 ) , respectively ; P=0 . 05 for linear trend . Walking > /=20 km/wk was associated with significantly lower risk , independent of other physical activity components . Climbing stairs and activities of at least moderate intensity ( > /=4.5 METs , or multiples of resting metabolic rate ) each showed U-shaped relations to stroke risk , with the risk being significantly lower at the nadir of the curve . Light intensity activities ( < 4.5 METs ) , however , were unrelated to stroke risk . CONCLUSIONS Physical activity is associated with decreased stroke risk in men . A decreased risk was observed at energy expenditures of 1000 to 1999 kcal/wk , with further risk decrement seen at 2000 to 2999 kcal/wk but not beyond . Confirmation of the U-shaped relation observed in these data requires similar observations in other population
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 .