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 .
Television watching and other sedentary behaviors in relation to risk of obesity and type 2 diabetes mellitus in women.
CONTEXT Current public health campaigns to reduce obesity and type 2 diabetes have largely focused on increasing exercise , but have paid little attention to the reduction of sedentary behaviors . OBJECTIVE To examine the relationship between various sedentary behaviors , especially prolonged television ( TV ) watching , and risk of obesity and type 2 diabetes in women . DESIGN , SETTING , AND PARTICIPANTS Prospect i ve cohort study conducted from 1992 to 1998 among women from 11 states in the Nurses ' Health Study . The obesity analysis included 50 277 women who had a body mass index ( BMI ) of less than 30 and were free from diagnosed cardiovascular disease , diabetes , or cancer and completed questions on physical activity and sedentary behaviors at baseline . The diabetes analysis included 68 497 women who at baseline were free from diagnosed diabetes mellitus , cardiovascular disease , or cancer . MAIN OUTCOME MEASURES Onset of obesity and type 2 diabetes mellitus . RESULTS During 6 years of follow-up , 3757 ( 7.5 % ) of 50 277 women who had a BMI of less than 30 in 1992 became obese ( BMI > or = 30 ) . Overall , we documented 1515 new cases of type 2 diabetes .  Time spent watching TV was positively associated with risk of obesity and type 2 diabetes . In the multivariate analyses adjusting for age , smoking , exercise levels , dietary factors , and other covariates , each 2-h/d increment in TV watching was associated with a 23 % ( 95 % confidence interval [ CI ] , 17%-30 % ) increase in obesity and a 14 % ( 95 % CI , 5%-23 % ) increase in risk of diabetes ; each 2-h/d increment in sitting at work was associated with a 5 % ( 95 % CI , 0%-10 % ) increase in obesity and a 7 % ( 95 % CI , 0%-16 % ) increase in diabetes . In contrast , st and ing or walking around at home ( 2 h/d ) was associated with a 9 % ( 95 % CI , 6%-12 % ) reduction in obesity and a 12 % ( 95 % CI , 7%-16 % ) reduction in diabetes . Each 1 hour per day of brisk walking was associated with a 24 % ( 95 % CI , 19%-29 % ) reduction in obesity and a 34 % ( 95 % CI , 27%-41 % ) reduction in diabetes . We estimated that in our cohort , 30 % ( 95 % CI , 24%-36 % ) of new cases of obesity and 43 % ( 95 % CI , 32%-52 % ) of new cases of diabetes could be prevented by adopting a relatively active lifestyle ( < 10 h/wk of TV watching and > or = 30 min/d of brisk walking ) . CONCLUSIONS Independent of exercise levels , sedentary behaviors , especially TV watching , were associated with significantly elevated risk of obesity and type 2 diabetes , whereas even light to moderate activity was associated with substantially lower risk . This study emphasizes the importance of reducing prolonged TV watching and other sedentary behaviors for preventing obesity and diabetes
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 .