High-intensity exercise, like sprinting or lifting heavy weights, will keep you fit and strong. But it will also provide great benefits for you brain, a new study has found.
It has long been known that exercise has many gains. It increases blood flow, suppresses stress hormones, helps release endorphins, and keeps you fit.
But scientists have found high-intensity exercise can also spark a chain of processes which release a hormone that promotes the growth, survival, and maintenance of nerve cells.
Dr Marcus Moberg, lead author, senior lecturer at the Swedish School of Sport and Health Sciences, Stockholm, said: "We speculate rather that the intensity of exercise is important if brain health is the desired goal. High-intensity exercise a couple of times per week, thus exposing the brain to high levels of lactate, should be recommended for healthy neurological aging.”
When your body is pushed to the limit, it is unable to get enough oxygen to meet the muscles' needs and instead breaks down glucose in a process called anaerobic glycolysis. This triggers the release of lactate, also known as lactic acid.
Researchers discovered that lactate helps increase levels of a brain-related substance called pro-BDNF, which is important for brain health and function. It is found in the liver, brain, skeletal muscle, and fat tissue.

"In the future, these findings can aid in the targeted, individualised prescription of exercise in clinical settings, especially for populations with compromised brain health,” said Dr Moberg.
The researchers said it was not previously known how exercise was boosting levels of BDNF and suspected it may be triggered by lactate.
Researchers studied 18 volunteers, aged 20-40 years old. 12 volunteers fasted overnight and then received an IV infusion of sodium lactate, and then, separately, a saline infusion, seven to 30 days later. A separate group of six volunteers only underwent a saline infusion.
Scientists took blood from each volunteer every ten minutes during both treatments, and six times within two hours after. They also took a leg muscle biopsy before and immediately after each infusion, as well as an hour and two hours later.
They found that pro-BDNF levels in the blood increased 15 minutes after the infusion and remained high for two hours after.
"Also, since lactate is known to exert hormonal-like effects, there is a potential for pharmacological interventions. This would require additional research to pinpoint the exact mechanism by which lactate controls BDNF metabolism in humans,” Dr Moberg said.

According to the World Health Organisation, around 31 per cent of people aren’t regularly doing enough physical activity in their day-to-day lives.
WHO recommends that each week adults should aim for either a minimum of 150 minutes of moderate intensity aerobic exercise, meaning it is hard to hold a conversation, or 75 minutes of vigorous intensity exercise, where you are gasping for air at the end of it.
It also suggests that people should include muscle-strengthening activities, like weight-lifting or high-impact exercise, like sprinting, into their weekly workouts.
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