Exercise Boosts The Brain: What Changes After 12 Weeks of Training

A 12-week exercise program didn't directly increase levels of a substance linked to brain health at rest, but it did cause the body to produce more of it during exercise. This increase was linked to improvements in the efficiency of brain areas responsible for attention and mental control.

In recent years, science has shown that regular physical exercise is not only good for the body but also for the brain. Even so, many of the mechanisms behind this effect are still being investigated.

One of the main focuses of researchers is understanding how exercise influences substances in the body that help brain cells grow, connect, and function better. This study sought to clarify how these changes occur in sedentary people and how they can impact mental performance and brain activity.

This study investigated how regular physical exercise can improve brain function, especially in sedentary people. The researchers were interested in better understanding a substance produced by the body called brain-derived neurotrophic factor, which helps neurons grow, communicate, and adapt.

Although it is already known that exercise increases this substance, it is not yet entirely clear how this translates into real improvements in mental performance.

To explore this question, scientists recruited sedentary adults and divided them into two groups. One group participated in a 12-week cycling exercise program, while the other group did not undergo any intervention. Before and after this period, all participants underwent physical and cognitive assessments, allowing for a comparison of changes over time.

One of the main measurements was physical fitness, assessed through a test that measures the body's ability to use oxygen during intense exercise. This test is important because it indicates the person's overall level of physical fitness. In addition, researchers collected blood samples to measure levels of this substance related to brain growth and health, both before and after physical exertion.

Another important aspect of the study was the analysis of brain activity. For this, a technique was used that indirectly measures blood flow in the brain, indicating which areas are most active during specific tasks. Participants performed mental exercises involving attention, impulse control, and memory, while this brain activity was monitored.

The results showed something interesting: after 12 weeks, the levels of this substance in the blood were no longer high at rest. However, when participants exercised, the increase in this substance was much greater than before training. In other words, the body began to respond more efficiently to physical exertion.

Furthermore, participants who experienced greater increases in this substance also showed changes in the activity of brain regions responsible for planning, decision-making, and behavioral control. These changes indicate that the brain was functioning more efficiently during tasks requiring attention and mental control, although this was not observed in memory tasks.

Overall, the study suggests that improving physical fitness not only benefits the body but also makes the brain more responsive to exercise. This may mean that, over time, physically active people develop a greater capacity to strengthen and adapt their brain connections, contributing to better mental and cognitive health.

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BDNF relates to prefrontal cortex activity in the context of physical exercise Flaminia Ronca, Cian Xu, Ellen Kong, Dennis Chan, Antonia Hamilton, Giampietro Schiavo, Ilias Tachtsidis, Paola Pinti, Benjamin Tari, Tom Gurney, and Paul W. Burgess. 

Brain Research. Volume 1881, 15 June 2026, 150253

DOI:10.1016/j.brainres.2026.150253

Abstract:

Exercise has been shown to support brain health, cognitive function, and increase levels of brain-derived neurotrophic factor (BDNF). While BDNF is known to support the central nervous system through improved brain metabolism, vasculature, neurotransmission and synaptic plasticity, the association between exercise-induced changes in BDNF concentrations and exercise-related cognitive improvements is still unclear. This study investigated the relationship between exercise-induced changes in plasma BDNF (pBDNF) and serum BDNF (sBDNF), and haemodynamic indicators of prefrontal cortex function in sedentary adults. Participants (n = 23, female = 7) were randomized into intervention (12-week cycling programme) and control groups (no intervention). Participants completed V̇O2max tests to assess changes in fitness. pBDNF and sBDNF were measured pre- and post-V̇O2max testing, and a battery of executive function and memory tasks were also conducted, alongside functional near-infrared spectroscopy (fNIRS) to assess haemodynamic changes in the prefrontal cortex activity. Changes were assessed using the correlation-based signal improvement (CBSI) method. Results indicated that participants in the exercise intervention group did not show increased levels of resting-state s/pBDNF levels at the end of the intervention; however, they did exhibit a significant exercise-induced increase in sBDNF at week 12. This increase was correlated with changes in V̇O2max. Higher pBDNF levels and exercise-induced sBDNF were associated with a decrease in CBSI values in the frontopolar, dorsolateral and orbitofrontal prefrontal cortex during attention and inhibition tasks, but not during the memory task. These results suggest that increasing physical fitness can enhance BDNF transcription in response to acute bouts of exercise. This might, in turn, play a part in the modulation of neural function during executive tasks after acute exercise.