Results from the Tower of London Task showed that an
acute bout of exercise did not significantly influence perfor-
mance on this task. This finding was somewhat surprising
given past evidence that planning tasks are sensitive to the
effects of a single session of exercise performed by college-
aged students17 and by physically active older women.30
Again, identifying a reason for the lack of an effect in this
study is challenging. It is possible that the difference is due to
the differences in the age of the participants and this expla-
nation is supported by meta-analytic evidence that effects from
acute exercise are negligible for elementary-aged children, but
are significant and positive for young adults and older adults.14
However, given that the examination of moderators within a
meta-analysis is inherently confounded by other variables (see
Etnier et al.18 for an explanation) and the aforementioned
evidence supporting benefits of acute exercise for cognitive
performance by children,18,19 this explanation seems unlikely.
Another possible explanation might be related to the intensity
of the exercise. Co´rdova et al.30 demonstrated that significant
benefits to performance on the Tower of Hanoi (which is
similar to the Tower of London and also assesses planning)
were only evident when older women exercised at w79% of
age-predicted HRmax (90% of anaerobic threshold) and were
not evident at lower or higher intensities of exercise. This is a
higher intensity of exercise than was used in this study and
hence might explain the different results. However, this
explanation falls flat when one considers that the exercise
intensity in the Chang et al. study17 was very similar to that
used in this study. A possible explanation for differences be-
tween the Chang et al. study17 and this study could relate again
to the difference in design. Chang et al.17 tested participants
pre- and post-treatment and so the disparate findings may
again suggest that exercise effects on executive function tasks
differ depending upon the presence of within-day learning
effects. Of course, we are merely speculating as to potential
reasons for our different results and future research will be
needed to ascertain the veracity of these explanations.
Results from the TMT indicated that performance (total
time) on TMT A was faster than TMT B regardless of exercise
or ADHD diagnosis. This difference in performance was ex-
pected because TMT A is a measure of cognitive processing
speed while TMT B is a measure of set shifting. Compared to
simple processing speed, set shifting requires a greater amount
of cognitive capacity, which may be reflected in the time to
complete the task. However, the lack of an effect of exercise
was unexpected given that the TMT is a frontally dependent
task that was expected to benefit from an acute bout of exer-
cise and given past studies supporting beneficial effects.30
Again, the failure to observe benefits in this study may have
been due to the intensity of the exercise. Co´rdova et al.30 only
reported benefits for TMT B and only during the 90% of
aerobic threshold condition (w79% age-predicted HRmax) and
this is a substantially higher exercise intensity than was used
in this study