December 6 - 7, 2007 Advisory Committee Meeting Minutes
Cardio-Respiratory Health Subcommittee Report
William Kraus, M.D. opened the presentation on
cardio-respiratory health. Dr. Kraus acknowledged the work of fellow
subcommittee members William Haskell, Ph.D. and Judith Regensteiner, Ph.D. and
CDC liaison Janet Fulton. Consultants to the subcommittee included Jason Allen,
focusing on vascular function, Brian Duscha, focusing on peripheral artery
disease, JoAnn Manson, focusing on cardiovascular mortality and George Kelley
who focused on hypertension.
Dr. Kraus indicated while the emphasis of the sub-committee's work is on prevention it is also important to consider the progression of the cardiovascular disease given the significant impact of the disease on the U.S. population. The sub-committee focused it's research on cardiovascular events and mortality, cerebrovascular disease and stroke, peripheral vascular disease, vascular function, atherogenic dyslipidemia and hypertension. Additionally, the following research questions were posed:
What is the relationship between physical activity and, for example, cardiovascular mortality or lipids?
Is there evidence of a dose-response relationship?
What types and amounts of physical activity were used in the studies?
Dr. Kraus next outlined the body of data available to the subcommittee. At the time of the Surgeon General's report 7 studies on physical activity and cardiovascular disease were available. For coronary heart disease, 36 studies were available and 14 for stroke. Subsequently there have been 21 observational studies on physical activity. For coronary heart disease there are now 36 observational studies and 22 for stroke.
Over the last ten years these studies indicate active men and women generally have fewer cardiovascular disease clinical events, including fatal and non-fatal coronary heart disease and stroke. An emphasis has also been placed on leisure time activity. For amount of dose-response some studies report lower cardiovascular disease event rates for moderate intensity activity. For intensity dose-response most studies, but not all, show a lower cardiovascular event rates with both moderate and vigorous intensity leisure time physical activity, while some only show lower cardiovascular disease rates with vigorous intensity activity.
Dr. Kraus continued the presentation focusing on actual specific disease categories including, peripheral vascular disease, vascular function, arterial stiffness and artherogenic dyslipidemia. There is a dose response effect seen for different components of artherogenic dyslipidemia. In general, more volume of physical activity is better fraising HDL cholesterol; however, overall the HDL effect is relatively small at 10%. There are also a few studies on small dense LDL and in general volume also seems to be the primary determiner of dose-response. For triglycerides, there is some evidence that moderate-intensity physical activity is as good as vigorous intensity.
Dr. Kraus introduced George Kelley, M.D., who addressed hypertension in the context of using meta-analyses to come to evidence-based conclusions. Dr. Kelley overviewed his presentation as a look at the effects of exercise on hypertension, specifically the chronic effects of exercise in adults. The approach used in the research was to look at meta-analyses of randomized controlled trials and focusing on two studies dealing with aerobic exercise and progressive resistance training. The rationale for focusing on meta-analyses is that it provides very strong evidence-based data from which to draw general conclusions. Through the research it appears both aerobic and progressive resistance exercise yield important reductions in systolic and diastolic blood pressure in adults; however, the case for aerobic exercise seems more compelling.
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