Observational studies (an epidemiologic study that does not involve any intervention, experimental or otherwise; a study in which nature is allowed to take its course, with changes in one characteristic being studied in relation to changes in other characteristics) show a direct relationship between physical activity and mortality from coronary heart disease (CHD); these studies show that physical inactivity is an independent risk factor for the development of CHD. Exercise may enhance the beneficial effect of other behavioral interventions.  Data on physical activity and long term survival from CHD are limited.

This information is from the 2001 Hyperlipidemia project. 
 

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.