Although it is interesting to consider why benefits of acute
exercise were not observed for all of the executive function
tasks administered in this study, it is impossible to identify an
incontrovertible reason for this a posteriori. Rather, we hope
that the demonstration that effects may differ as a function of
the particular type of executive function being assessed willencourage further research. This is consistent with Etnier and
Chang’s31 plea for researchers to acknowledge that all exec-
utive function tasks may not respond in the same way to ex-
ercise. The finding that the effects of exercise on cognitive
performance were not moderated by ADHD status is an
important finding. This is consistent with findings reported by
Pontifex et al.23 indicating that the beneficial effects of acute
exercise for response accuracy during a Flankers Test are
equivalent for children with and without ADHD. This is an
intriguing finding because it suggests that children with
ADHD can benefit from a single session of exercise just as
much as children without ADHD. It is of further import
because of the fact that the children in this study were
instructed to take their prescribed medications for ADHD and
all (except 4) were taking stimulant medications.c Hence, the
benefits of exercise upon cognitive performance were
observed above and beyond any benefits achieved through
pharmacological intervention. Although our small number of
unmedicated children did not allow us to statistically test the
effects of this variable in this study, it is interesting to
contemplate whether or not the benefits of acute exercise
might be greater for participants who are not medicated. To
our knowledge, this has only been examined in one study24
previous to this study and the results indicated that the ef-
fects of exercise (which in that study were detrimental) were
not influenced by whether or not the children with ADHD
were medicated or not medicated. Further study focused on
examining whether or not medication use moderates the in-
fluence of exercise on cognitive performance by children with
ADHD is an important direction as benefits of exercise as an
adjuvant behavioral therapy have been demonstrated,16,21,23
but it is also possible that exercise may be able to provide
benefits in the absence of medications.
It is important to point out some of the limitations of this
study. First, and as previously mentioned, it might have been
beneficial to have asked participants to perform the cognitive
tasks prior to the treatment condition in addition to performing
them after the treatment condition. This is not really a limi-
tation per se, but it is a design consideration that would have
helped to control for any day-to-day variability in cognitive
task performance. However, the design that was used is very
similar to that used by Pontifex et al.23 and, similarly, benefits
were observed on an executive function task measuring inhi-
bition. A second consideration is that participants were
instructed to take their medications as they normally would
which resulted in variety in the medications being taken by the
participants in this study. Four children were not taking
medications at all and others differed with regards to the
medication type, the dose, or the dosing regimen. Clearly, this
limits our ability to understand the extent to which exercise
benefits children on various medications and the extent to
which it benefits children with ADHD on- and off-medication.
It has been said that “Few studies will answer all of the
questions surrounding a topic, and most good studies will raise
new ones .”.32 This statement aptly describes the findings of
this study. Although we anticipated that exercise would benefit
performance across a variety of executive function tasks, we
found that exercise only benefited performance on speed of
processing and inhibitory control as measured by the Stroop
Task and did not benefit performance on planning, set shifting,
or speed of processing as measured by TMT. Given that pre-
vious studies have not compared the effects of acute exercise
across a variety of executive function tasks for children, this is
clearly an important direction for future research. Addition-
ally, future research could be designed to see if a more intense
exercise session would result in more comprehensive benefits
on measures of executive function, or on cognitive perfor-
mance more broadly, or if there is a way to design the exercise
intervention to achieve a larger cognitive benefit. Finally, we
anticipated that exercise might benefit cognitive performance
by the children with ADHD more so than it benefited the
children without ADHD. This was based on the expectation
that since ADHD is characterized by frontal lobe dysfunction,
exercise would have the opportunity to result in a bigger
cognitive benefit for these individuals. However, we found that
where exercise did have benefits, the benefits were equal be-
tween the two groups and this is consistent with past
research.23 However, we recognize that our findings are
limited by the inclusion of children with ADHD who were off-
medication and by the wide variety of medication regimens
used by our sample. Hence, future research would benefit from
testing the effects of acute exercise in children with ADHD
on-medication and off-medication and in cases where the
medication regimen is similar. Mahon et al.24 did pursue this
question in their research, but their exercise protocol was not
one that would have been expected to result in significant
benefits given meta-analytic evidence14 that high intensity
exercise and exercise shorter than 10 min in duration has
negligible effects on cognitive performance performed
immediately after the exercise session. Hence, this is clearly a
direction for research that could be dramatically expanded
upon