Six Minutes of Intense Exercise Boosts Crucial Molecule in Brain

The specialized protein in question is called brain-derived neurotrophic factor (BDNF), and it promotes both the growth and survival of neuron cells in the brain, as well as facilitating the development of new links and signaling pathways, the Journal of Physiology reported.

"BDNF has shown great promise in animal models, but pharmaceutical interventions have thus far failed to safely harness the protective power of BDNF in humans," says environmental physiologist Travis Gibbons, from the University of Otago in New Zealand.

"We saw the need to explore non-pharmacological approaches that can preserve the brain's capacity which humans can use to naturally increase BDNF to help with healthy aging."

In this study, 12 physically active volunteers (aged 18 to 56 years) were put through three tests to see which was best at generating BDNF in the brain: 20 hours of fasting, 90 minutes of cycling, or 6 minutes of vigorous cycling.

The brief and intensive burst of cycling saw the best results in terms of BDNF production. In fact, it boosted BDNF levels in the blood by four or five times, compared with a slight increase after light exercise, and no change with fasting.

The next question is why this is happening – and that's something for a subsequent study. Ultimately, high-intensity exercise could be used as a convenient, inexpensive way of keeping the brain healthy and protecting against the development of disease.

It's possible that the increase in blood platelets that naturally occurs with exercise could explain these findings. Platelets store a large amount of BDNF, which might account for the spike that coincides with intense cycling.

Alternatively, the increase might be caused by the brain switching between fuel sources following intense exercise, the researchers say, forcing the body to draw on lactate rather than glucose reserves.

"This substrate switch allows the brain to utilize alternative fuels and initiates the production of key neurotrophic factors such as BDNF," says Gibbons.

The team is now keen to add more experiments to the mix, such as three whole days of fasting, to see how this affects BDNF levels in the blood. The combined effects of fasting and intense exercise are another potential avenue to explore.

We now have numerous studies linking together exercise with benefits that can be noticed in the brain, whether it's improving concentration or giving a boost to cognitive function, and it's likely that there are many more discoveries to come.

"It is becoming more and more clear that exercise benefits brain health at all stages of life," says Kate Thomas, exercise physiologist and study author at the University of Otago.

"These data show one avenue by which intense exercise may play a role. Fortunately, exercise is widely accessible, equitable, and affordable."

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