Saving young hearts
Looking for early interventions to restore
cardiac health in overweight kids
It’s no secret that the United States is in the
midst of a childhood obesity epidemic. The numbers behind the
sound-bytes are staggering; according to the 1999–2002 National
Health and Nutrition Examination Survey, 16 percent of American
children ages six to 19 are overweight—triple the proportion of
1980. Add to that the additional 15 percent of American kids who
are at risk for becoming overweight, and one-third of our
children face a dismal medical future due to obesity-related
illnesses.
While the terms “overweight” and “at-risk for
overweight” might seem less grave than “obese,” make no mistake,
the less pointed language, used to help children avoid the
stigma attached to obesity, carries the same definitions and
health risks—including formerly adult-only diseases like
hypertension, elevated cholesterol, Type 2 diabetes, heart
disease, and stroke—as they do for adults.
Perhaps what’s most startling about the
incidence of childhood obesity is its momentum. After holding
steady at five to seven percent from the 1960s through the late
1980s, the current numbers represent a 45-percent increase in
overweight children from just a decade ago.
While a solution to halt the childhood
overweight epidemic remains elusive,
Donald Dengel of
the College of Education and Human Development studies
cardiovascular health in overweight children—looking for
promising early interventions that might give America’s more
than nine million overweight kids a healthy future.
 What the research shows
Dengel, associate professor of kinesiology and
co-director of the General Clinic Research Center’s Body
Composition Human Performance Laboratory, focuses much of his
research on studying the endothelium—or lining of the blood
vessel—looking for signs of dysfunction that are the precursors
of cardiovascular disease, and working on ways to improve the
endothelia of overweight children.
Dengel’s recent research followed a group of
overweight children with known endothelial dysfunction as they
participated in four-times-weekly exercise sessions on a
stationary bike. Their peers in the control group did not change
their exercise habits. The findings at the end of the eight-week
study revealed some eye-opening results, both in the exercise
and control groups.
After just eight weeks, the exercise group
demonstrated dramatic systemic improvement in vascular health,
with endothelial functions returning to normal. This is not the
case in adults, who can improve endothelial function with
exercise, but not totally reverse the damage. In addition, the
kids improved their physical fitness and increased their HDL
cholesterol (the good cholesterol).
Perhaps surprisingly, the study participants who
exercised didn’t lose weight nor reduce their body fat, but from
a vascular health standpoint, Dengel says weight loss appears to
be less important than exercise. “This study shows that if we
get kids to exercise early enough—regardless of being
overweight—they can have a chance at a healthy future.”
An unexpected thing happened in the control
group that shed further light on the acceleration of overweight
among kids. During the eight weeks, the non-exercising control
group’s endothelial dysfunction worsened, fitness decreased, and
they gained weight—each an average of 1.8 pounds of body
weight—on track for an annual weight gain of at least 10 pounds.
Researchers determined that the unstructured nature of
summer—when the research took place—led to unrestricted access
to food and less activity than during the school year.
What others say about this research
Alan Sinaiko, a pediatric nephrologist at
the University of Minnesota, says Dengel’s work explores an area
of research not being adequately addressed in children. “It is
clear that childhood obesity is associated with the usual risk
factors, such as hypertension and elevated lipids, yet we know
far less about the association of these factors with the heart
and blood vessels,” Sinaiko says. “Dengel’s work to identify
these abnormalities in children can provide information needed
to better understand the disease and to develop strategies to
prevent [disease] development in a generation of adults.”
“We know that the cardiovascular disease process
begins in childhood and that it is accelerated in the presence
of obesity,” says Aaron Kelly, senior research scientist
at the St. Paul Heart Clinic and assistant professor of
pediatrics. “It is imperative that we understand the mechanisms
of the disease process as it occurs in youngsters so that we can
target appropriate interventions early in life, and Dengel’s
research is shedding light on many of these important issues.”
Why this research matters
Children are ill-equipped to deal with complex
medical problems and interventions because, after all, they are
kids. Dengel’s exercise study identifies a simple,
non-pharmacological intervention that truly improves heart
health in young individuals.
Dengel hopes his research can lead to societal
changes to promote health among all children, starting with
improvements in the nutritional value of school lunches, and
increased P.E. and recess time. While there is no mystery that
exercise is good for kids, P.E. and recess have been reduced to
a bare minimum, taking away the only source of physical activity
for many kids.
“If we think about schools as just a place where
intellectual learning happens, we will continue to add to the
problem of childhood overweight and obesity,” explains Dengel.
“If we are going be a society with a strong future, we have to
be concerned about academic, social, and physical health. We
need to treat the whole child, not just the academic aspect.”
Dengel thinks the economic impact of obesity
will bring changes. Currently, according to the Department of
Health and Human Services, obesity, poor nutrition, and physical
inactivity result in total health-related costs of $117 billion
annually. “Using current projections, when today’s kids reach
age 44, approximately 87-90 percent will be overweight,” says
Dengel. “Will that cause a drain on the healthcare system? Quite
simply, caring for this generation will ruin our economy.”
For more information:
Donald Dengel, 612-626-9701,
denge001@umn.edu
January 2006
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