When Wendy Suzuki began her teaching career in New York, she lived almost exclusively for her experiences. Six years of running after tenure, meals taken on the go, no sport, little social life. She feels tired, fuzzy, unable to really concentrate, but blames it on work.
Then she went to a gym, started dancing, lifted a little weight, and also improved her diet. Eighteen months later, she has lost 25 pounds and notices something else above all: her ideas come together more quickly, the writing of her research projects becomes fluid. Her brain changed without her realizing it.
Hippocampus, memory: how exercise grows new neurons
At the heart of this story is the hippocampus, a key region of memory. When this area was removed from patient Henry Molaison to treat his epilepsy, he was never again able to create new memories of facts or events. This structure has a rare feature: it can produce new neurons in adulthood, especially when the body moves and oxygen-rich blood flows to the brain and the prefrontal cortex.
This “neurochemical bath” which improves mood and concentration
Wendy Suzuki sums up what happens during exercise with a striking formula: “Every time you move your body, including when you run, you are giving your brain what I like to call a wonderful bath of neurochemistry,” Wendy Suzuki told Big Think. This bath contains dopamine, serotonin, norepinephrine, endorphins, a cocktail that promotes good mood, energy and motivation.
After exercise, other molecules come into play: growth factors. They behave like a watering can that continuously nourishes the hippocampus and helps it produce “shiny” new cells. With repetition, this stimulation makes the hippocampus larger and the prefrontal cortex more effective for concentrating, changing tasks or making a decision.
How much physical activity to stimulate the brain and slow decline?
For those who don’t like sports, the good news is that the minimum dose is modest. Studies cited by Wendy Suzuki show that just 10 minutes of walking is enough to improve mood and reduce anxiety. In his laboratory, less active people who did cardio 2 to 3 times for 45 minutes per week for three months saw their mood, memory and attention improve significantly.
In the long term, the issue goes beyond simple daily well-being. A Swedish study following women for 45 years showed that those who were the most fit delayed the onset of dementia by about nine years compared to those who were the least active. This result remains correlative, but it is consistent with a strong idea of brain plasticity: even after years of sedentary lifestyle, each session can help build a more robust brain for aging.