Everyone knows that exercise is great for kids’ physical health, but the evidence is building to show that exercise can also be great for their minds.

By Candace Hill CrossFit OldTown

July 10, 2010

In my role as a site coordinator for one of the 10 sites involved in the NICHD Study of Early Child Care and Youth
Development (SECCYD), I had the opportunity to be a part of a study researching the development of American children
across the country. It was an exciting experience to track the same group of children, over 1,000 kids, from their birth
in 1991 through high school. A few of the many areas of interest for the SECCYD investigators were children’s health
outcomes and their cognitive and achievement outcomes. Data on the participants’ amount and type of physical
activity were collected and linked to their health outcomes or body mass indices (BMI), but to date they have not been
linked to their cognitive and achievement outcomes.

The priority of the SECCYD analyses was to find out how
kids were faring with the obesity epidemic and the limited
opportunities available for physical activity during the school
day, not to discover how to improve their thinking skills.
Having tracked the physical assessments of the children
at my site, I can attest that the BMI of many children did
increase over the years to unhealthy levels. The study’s data
also showed that physical activity decreases significantly for
boys and girls in the U.S. between the ages of nine and 15
years (Nader, et.al, 2008). This information supports the notion
that children are potentially at risk for negative outcomes that
result from inactivity.

Getting back to those other outcome measures, cognitive
and achievement, the SECCYD did not look for links, but
other research studies have, and they have shown that it’s not
physical health alone that suffers from inactivity. In fact, there
are many cognitive and achievement benefits to exercise.
Vigorous physical activity for school-age children has been
associated with better grades (e.g., Coe, et. al, 2006) and
higher academic achievement (e.g., Chomintz, et. al, 2009;
Castelli, Hillman, Buck, & Erwin, 2007). Somewhat surprisingly,
these positive outcomes resulted even if children’s increase
in physical activity at school led to a decrease in their time
devoted to academic learning in the classroom (e.g., Sallis
et al., 1999). In turn, inactive children may be at a disadvantage.
In a study of overweight children eight to 16 years
in age, increased body weight was independently associated
with decreased visuospatial organization (the ability to see
and analyze objects in relation to their surroundings) and a
decrease in general mental ability (Li, Y., et. al, 2008).

Most recently, research has focused on whether or not
physical activity can have a direct effect on brain activity and
children’s cognitive development (Etnier, Nowell, Landers,
& Sibley, 2006). In the past, physical activity has been
described as affecting blood flow, which in turn stimulates
the brain. The newer studies have incorporated technology,
including the electroencephalogram (EEG) test (Hillman,
2008) and functional magnetic resonance imaging (fMRI)
(Colcombe, 2004; Davis, et. al, 2007; in press) to measure
if a direct impact is possible. Specifically, the EEG test
and fMRI have been used to document the effects
of exercise on activity in the prefrontal cortex (PFC).

Figure 1 (see pdf)provides a picture of the PFC located in the
frontal lobes of your brain. Researchers have focused on this
area in children, as it’s predominantly responsible for much of
their cognitive processing, or executive functions (EF).

Why is EF important? EF encompasses cognitive processes
responsible for goal-directed behavior (e.g., Olson & Luciana,
2008). In other words, EF allows for planning and carrying
out actions that often require attention and memory,
decision-making, goal setting, inhibition and self-control,
self-monitoring, and the use of strategies for problem solving
(Davis, et. al, in press; Eslinger, 1996). Cyndi Rodi wrote a great
CrossFit Kids article in January 2009 (Issue #38) in which she
defined EF and described how motor-skill development is
tied to EF development in children. The bottom line, EF is
used in virtually every learning experience that occurs in a
child’s classroom and requires one of the longest periods for
full development, beginning at birth and continuing through
childhood into adulthood.

A brief review of the literature indicates many researchers
support the notion that vigorous physical activity does
have direct effects on the brain and the development of
EF in particular. Hillman and colleagues (2008) found that
“fit” kids’ brains showed more activity in the PFC than those
kids classified as “unfit.” Researchers have even tested if the
benefits exist for those kids starting out an exercise program
as sedentary and overweight. In the randomized control trial
study conducted by Davis and her colleagues (2007; in press),
participants were placed into three groups:

1. The control group, or those remaining sedentary.

2. The group that was given 20 minutes of vigorous physical
activity a day.

3. A third group participating in 40 minutes of exercise a day.

Vigorous physical activity was measured by heart rate and
consisted of running exercises during this time. As a CrossFit Kids
coach, it would be interesting to do the same study doing a WOD
and measuring intensity or work capacity, but I’m sure that is a
future study CrossFitters will conduct someday.

In the meantime, findings of the current study showed a
significant improvement in EF and cognitive and achievement
outcomes for the active children only (groups 2 and 3).
Specifically, children saw an increase in math scores. This research
corroborates earlier studies completed with older adults, in
which physical activity improved cognition (Hillman, et.al, 2009)
and memory (Erickson, et. al, 2009). The benefits of exercise can
stop, however, once exercise is discontinued, which supports the
importance of permanently incorporating fitness into our lives.

Discovering this direct link is a big deal in the world of research
and can only bode well for those out there participating, or
thinking of participating, in vigorous physical activity; i.e., CrossFit.
With the evidence that vigorous exercise can stimulate a child’s
brain in areas that are responsible for cognitive development, it
can also provide the groundwork for a child to have the potential
for great success in school.

There’s good news for adults too. New research shows that
vigorous physical activity can also increase the size of the
hippocampus and improve spatial memory. That’s important,
too, as it’s the type of memory adults need in order to maintain
independence through the Golden Years (Erickson, et. al, 2009).

As these findings are relatively new, future research should focus
on the impact to the brain by the various forms of exercise—
strength training vs. running, for example. Think of how great it
would be to track our CrossFit Kids’ EF development alongside
their WOD times.

On a final note, these research findings have policy implications
as well. Most physical education curriculum in schools provide
less than the amount of physical activity necessary to achieve the
positive results discussed in this article. Getting enough physical
activity for healthy brain and cognitive (EF) development requires
supplementing your child’s PE classes with extracurricular, after-
school programs and activities to keep your child moving and
building brain power every day.

References

Best, J. R., Miller, P. H., & Jones, L. L. (2009). Executive function
after age 5: Changes and correlates. Developmental Review, 29(3),
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Castelli, D. M., Hillman, C. H., Buck, S. M., & Erwin, H. E. (2007).
Physical fitness and academic achievement in third- and fifth-
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Chomitz, V.R., Slining, M. M., McGowan, R. T., Mitchell, S. E., Dawson,
G. F., & Hacker, K. A. (2009). Is there a relationship between physical
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Coe, D. P., Pivarnik, J. M., Womack, C. J., Reeves, M. J., & Malina,
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