| abstract |
Introduction: Numerous benefits of physical activity relating to cardiovascular health, sleep and
mood have been largely examined in the current scientific literature. However, a lesser
understood relationship is that of physical activity and brain health. Brain health has typically
been described as cognitive performance, but it can also be elaborated and include brain structure
and brain function. Various brain structures have been shown to increase or decrease in size as a
result of physical activity, as well as activity in those areas has been shown to either increase or
decrease. Research regarding the impact of physical activity on brain structure and brain function
is already largely understood, however, the resulting changes in cognition have yet to be
explored extensively, specifically in adolescents.
Methods: PubMed, PsychINFO, and ERIC were used for the literature search. Search terms
relating to "physical activity", "cognition", and "adolescent" were used in each database. The
inclusion criteria as for which studies were reviewed included if it used an RCT study design, it
included adolescents between the ages of 12 and 18, the population didn't have preexisting
health conditions, and it examined the effects of various manipulations (frequency, intensity,
duration, time of day, and time of cognitive testing) of physical activity on cognitive functions.
Results: A total of 13 RCT studies were reviewed. When looking at how the duration of physical
activity affected cognition, it was shown that short durations were effective at improving
attention, concentration, and inhibitory control, while memory didn't improve for either short or
long durations. Single bouts of exercise were more effective at improving attention and
inhibitory control, compared to increased frequencies of activity. No clear conclusions were
drawn from looking at the intensity of physical activity because different studies defined
moderate- and high-intensity differently, limiting the ability to directly compare results. For
participants that were tested immediately after engaging in physical activity, attention,
concentration, and inhibitory control were improved immediately. However, memory didn't
begin to show improvements until up to 48 hours after activity. And finally, one study looking at
physical activity in the morning showed improvements in attention and concentration, but not
memory. Studies that looked at physical activity in the middle of the day showed improvements
in inhibitory control and executive function.
Discussion: When considering the mechanisms by which cognition improved as a result of
physical activity, CBF and BDNF are two possibilities. CBF may be responsible for the
immediate, short-lived improvements in attention and inhibitory control because it is delivering
additional glucose and oxygen to the brain which aids in functioning. However, longer term
effects relating to memory didn't improve immediately most likely because the brain needs to
undergo structural changes, which would require greater expression of BDNF overtime. When
considering why increased frequencies didn't improve cognitive functions as effectively as single
bouts, the idea of energy depletion in which the body begins to utilize oxygen and glucose
elsewhere in the body, is considered.
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