Effects of Worksite Wellness Interventions on Vascular Function, Insulin Sensitivity and High-Density Lipoprotein in Overweight or Obese Women

Employees in developed societies are becoming increasingly sedentary at work and at home due
to technological advances. Physical inactivity coupled with excess intake of calorie-rich
foods are responsible for the epidemic of obesity. In population cohorts, physical inactivity
and obesity increase the risk of cardiovascular disease and death. Because of the impact on
productivity and health care costs, many businesses and other organizations have initiated
"wellness" programs, often with facilities at the work site to encourage exercise. Although
these programs have often resulted in improved fitness for participants, weight loss has been
more difficult to achieve. In this regard, in our initial study of NIH employees
participating in NHLBI's Keep the Beat program--two-thirds of whom were overweight or
obese--we found improved exercise fitness after 3 months of participation, with exercise
averaging 20 minutes each work day, but no significant weight loss. Associated with greater
fitness in our participants was improvement in endothelial function, an important biomarker
of cardiovascular risk. Because level of fitness is a strong predictor of cardiovascular (and
total) mortality in population studies, some investigators and thought leaders have proposed
that it is acceptable to be "fat and fit." We found in our study, however, that exercise
alone has little effect on insulin sensitivity and other biomarkers of risk, including
C-reactive protein, which could limit further improvement in endothelial function and even
greater risk reduction. We propose to test in this protocol whether weight loss through
supervised nutritional counseling and daily exercise at worksite facilities confers health
benefits beyond those achieved with improved fitness alone, such as improvement in
endothelial function, arterial compliance, insulin sensitivity, markers of inflammation in
blood and high-density lipoprotein (HDL) structure and function. Because obesity in a
sedentary workforce environment is especially prevalent among women, with additional
contribution of menopause to obesity, our study will be restricted to overweight and obese
women to allow appropriate analysis in a cohort of manageable size for our testing resources.
The primary endpoint will be differential improvement in endothelial function, as determined
by brachial artery reactivity to shear stress, from baseline to 6 months in participants
randomized to exercise coupled with weight-loss intervention versus subjects randomized to
exercise alone. Secondary analyses will include comparisons of adiposity, arterial stiffness,
insulin sensitivity, HDL subparticles and function, and markers of inflammation and
adipokines in blood, with exploratory analyses of minorities and age/hormonal interactions.
Demonstration of improved vascular function and other biomarkers of cardiovascular risk with
improved fitness combined with weight loss may serve as an incentive for greater
participation in organization-initiated wellness programs with emphasis both on exercise and
on personalized nutritional counseling....