BUFFALO, N.Y. -- A simple morning walk to school could reduce
stress reactivity in children during the school day, curbing
increases in heart rate and blood pressure that can lead to
cardiovascular disease later in life, according to a new University
at Buffalo study.
UB researchers report in the August 2010 issue of Medicine &
Science in Sports & Exercise that children who took a simulated
walk to school later experienced smaller elevations in systolic
blood pressure, heart rate and perceived stress while taking a
short exam than children who had gotten a simulated ride to
Cardiovascular reactivity -- including changes in heart rate and
blood pressure due to stress -- is associated with the beginnings
of cardiovascular disease in children, and atherosclerosis -- the
dangerous build-up of cholesterol, calcium, fat and other
substances in artery walls -- in adults.
"The cardiovascular disease process begins in childhood, so if
we can find some way of stopping or slowing that process, that
would provide an important health benefit," says James Roemmich, UB
associate professor of pediatrics and exercise and nutrition
science and senior investigator on the study, which he completed
with graduate students Maya Lambiase and Heather Barry. "We know
that physical activity has a protective effect on the development
of cardiovascular disease, and one way it may be doing so is by
reducing stress reactivity."
Roemmich says because it's not known how long the protective
effect of a bout of exercise lasts, parents and educators should
promote active play time throughout the day.
"If it only lasts a couple of hours, then it would be most
beneficial if a child walked or biked to school, then had recess
during school, as well as a break at lunch, so they had
opportunities for physical activity throughout the day," Roemmich
says. "This would put them in a constantly protective state against
stressors that they're incurring during the school day, whether
that be taking an exam, trying to fit in with peers or speaking in
front of classmates."
Roemmich says his study is the first to show that
moderate-intensity exercise can reduce children's cardiovascular
reactivity during later, stressful activities. The research builds
on his earlier work, which demonstrated that higher-intensity
interval exercise could afford similar protection in children.
In the more recent investigation, Roemmich and his team examined
a group of 20 boys and 20 girls, all Caucasian and ages 10-14. All
visited the Behavioral Medicine Research Laboratory in the morning.
To simulate a ride to school, half sat in a comfortable chair and
watched a 10-minute slide show of images of a suburban
neighborhood, ending with an image of a suburban school. The other
half performed a one-mile walk on a treadmill at a self-selected
pace, wearing a book bag containing 10 percent of their body
weight. As they walked, the images of the suburban neighborhood
were projected onto a screen.
Following a 20-minute rest period after completing the passive
and active commutes, all children took a Stroop test, which asks
subjects to correctly identify the color of color names printed in
the wrong color (the word "green" printed in blue ink, for
instance). On average, during this activity, heart rate increased
by about three beats per minute in children who walked, compared
with about 11 beats per minute in children who "rode" to school.
Similarly, the rise in systolic blood pressure was more than three
times higher, and the change in perceived stress about twice as
high, for the passive commuters.
"The perception of a stressor as a threat is the beginning of
the stress reactivity process, so if you can dampen that initial
perception, then you reduce the magnitude of the fight-or-flight
response," Roemmich says. "This results in lower heart rate and
blood pressure responses to the stressor. Exercise helped dampen
even the initial response."
The University at Buffalo is a premier research-intensive
public university, a flagship institution in the State University
of New York system and its largest and most comprehensive campus.
UB's more than 28,000 students pursue their academic interests
through more than 300 undergraduate, graduate and professional
degree programs. Founded in 1846, the University at Buffalo is a
member of the Association of American Universities.