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Donald Dengel
Kinesiology
A child receives an ultrasound
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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, contact Donald Dengel at 612-626-9701 or
denge001@umn.edu.
Reprinted with permission from ResearchWorks,
an online publication of the College of Education and Human Development.
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