Most studies investigating the relationship between various types of exercise and brain function are focused on its effect on Alzheimer disease risk, memory loss associated with aging or chronic impact on various cognitive functions. Rarely have investigations been concerned with changes related to an acute bout of exercise on cognitive function.

As we have seen, an endogenous substance that plays a central role in the health of neurons is brain-derived neurotrophic factor (BDNF). Acting via CREB (Cyclic AMP Response Element Binding Protein), BDNF can produce improvements in a finding called long term potentiation (LTP) which is a physiologic correlate of memory. Exercise training in animal studies is associated with elevation of BDNF. BDNF produces enhanced connectivity between nerve cells that improves brain function. Human studies have not examined biochemical compounds involved in acute exercise-induced improvements in cognitive function. A recent human trial investigated the effects of acute exercise on BDNF levels in blood and their relationship with associated cognitive functional improvements.

The exercise protocol involved riding an bicycle in an exercise physiology lab for about 30 minutes. Cognitive testing was done using the Stroop Test. It requires the subject to read 100 words as fast as possible. The words are "RED", "GREEN" or "BLUE". Each word is a different color, either red, green or blue but the color and the word can not be the same such as RED and the color red. Thus the word RED could be printed in green or blue ink, but not red ink. The test requires the subject to say the color of the word, not what the letters spell. Hence the word BLUE, printed in green, would require a response of "green". The greater the number of correct responses, the better the score.

BDNF levels were measured before the cycling and immediately thereafter.  BDNF levels were elevated 13% after the single exercise trial compared to baseline levels. The Stroop Test results also improved significantly after the cycling. This study demonstrates that strenuous physical activity induced a simultaneous increase in blood BDNF concentrations and function on the Stroop Test. It should be mentioned that in animal studies there is a close correlation between brain and blood BDNF changes after exercise implying that the changes of BDNF measured in blood are reflected in the brain..

Since BDNF has also been associated with enhanced learning in animal studies, in conjunction with the current findings cognitive activities following strenuous exercise might be expected to produce similar findings. This suggests possible mechanisms for orchestrating exercise and mentally challenging tasks for improved results.