Improving fitness boosts brain-boosting protein release after a single workout

Increasing our level of physical fitness leads to a bigger release of brain-boosting proteins following one session of exercise, a new study led by a UCL researcher has found.

The study, published in Brain Research, took a group of inactive unfit participants through a 12-week training programme of cycling three times per week and made them fitter. Researchers found as their fitness increased, so did the amount of brain-derived neurotrophic factor (BDNF) released following exercise, resulting in improved brain function.

Just 15 minutes of moderate to vigorous aerobic exercise releases BDNF, a brain protein which is known to support the formation of new neurons and new synapses (connections between brain cells), and maintains the health of existing neurons. This is the first study to show that for unfit people, just 12 weeks of consistent training can boost the brain's response to a single 15-minute workout.

The study, led by Dr Flaminia Ronca (UCL Surgery & Interventional Science, and the Institute of Sport, Exercise and Health), involved 30 participants – 23 male and seven female – taking part in the 12-week programme. To assess fitness levels throughout the programme, participants completed VO₂max tests every six weeks, which measures the maximum rate of oxygen your body can consume and use during intense exercise.

BDNF levels were measured pre- and post-VO₂max testing, alongside a series of cognitive and memory tests, while also measuring changes in brain activity in the prefrontal cortex – where executive functions such as decision-making, emotion regulation, attention and impulsivity are controlled.

By the final week of the trial, results showed that baseline levels of BDNF did not change, but participants did show a larger spike of BDNF following intense exercise, compared to how their brains responded to intense exercise before the 12-week programme. This was linked to improvements in VO₂max (aerobic fitness).

Higher overall BDNF levels and stronger exercise-induced increases were also associated with changes in activity across key areas of the prefrontal cortex during attention and inhibition tasks, though not during memory tasks.

Overall, the results showed that increasing physical fitness can enhance the brain's ability to produce BDNF in response to acute bouts of exercise, which can have a strong positive influence on neural activity.

We've known for a while that exercise is good for our brain, but the mechanisms through which this occurs are still being disentangled. The most exciting finding from our study is that if we become fitter, our brains benefit even more from a single session of exercise, and this can change in only six weeks."

Dr, Flaminia Ronca, Lead Author