When you're stressed, overwhelmed, or exhausted, exercise often is extremely unappealing – but neuroscience tells us that movement is exactly what's needed in these moments. That's because, along with its well-known calorie-burning, heart-strengthening, muscle-building benefits, exercise changes your brain – literally – to boost your mood, energy, and focus. 

"Exercise is the most transformative thing that you can do for your brain today," Wendy Suzuki, PhD, a neuroscientist and author, said in a TED talk that's been viewed 11 million times.

The benefits of exercise radiate far and wide – eating, sleeping, and relationships are all shown to improve with daily movement. If you establish a core habit of exercise, other healthy habits will fall into place more easily. Here's what science tells us about the brain-boosting effects of exercise:

What happens to your brain when you exercise?

You've likely heard about the runner's high – that feel-good boost of serotonin that happens during or after a long workout – but research shows much more going on in your brain when you exercise. 

Your brain grows new cells … 

… Resulting in better memory and executive functioning.

Aerobic exercise promotes the growth of new neurons and synapses, mainly in your hippocampus (your memory center) and prefrontal cortex (your executive function center).

In one recent study, researchers used magnetic resonance imaging (MRI) scans to measure the brain activity of older adults before, during, and after they took part in a yearlong aerobic walking program. These were compared to the brain scans of people in a control group who completed a stretching program.

Researchers found that the exercisers had higher levels of BDNF (brain-derived neurotrophic factor), a growth factor that promotes neuron formation. "Think of BDNF as fertilizer for your brain. It helps existing neurons grow stronger connections and supports the birth of new brain cells," explained psychiatrist Tracey Marks, MD, in a YouTube video titled "How Exercise Rewires Your Brain for Better Mental Wellbeing."

The growth of these neurons was confirmed by the MRI scans, which showed that the exercisers had a 2% increase in the size of the hippocampus over the year, while the control group showed a 1.4% decrease in the hippocampus (a common result of aging). 

The conclusion reached by researchers is arresting: Moderate-intensity exercise can change the size of your brain's memory center into late adulthood. 

Your brain enjoys better blood flow … 

… Resulting in better executive functioning

Exercise also stimulates the growth of new blood vessels in your brain, which pump in more oxygen and nutrients. "Brain cells are extremely energy hungry," Marks said. "The more blood vessels you have feeding your brain, the better equipped it is to handle demands and recover from stress."

One study of young adults found that after completing a three-month moderate-intensity exercise program, the people in the study had better cerebral blood flow and executive function, compared to people in a control group who got health education lessons that didn't involve exercise. Another study found that in older adults, exercise helped counter some of the lack of brain blood flow that happens with age.

"My lab shows that a single workout can improve your ability to shift and focus attention," said Suzuki, who runs the Suzuki Lab. "That focus improvement will last for at least two hours." 

Your brain releases neurotransmitters … 

… Resulting in improvements in mood, increased energy, and decreased anxiety and depression

Studies show that exercise triggers the release of serotonin, dopamine, and norepinephrine – neurotransmitters that affect our emotional functioning. The brain chemicals can improve your mood and energy, reduce anxiety, and offer other benefits. 

  • Norepinephrine triggers your fight-or-flight response. It also increases blood pressure and heart rate, and enhances alertness, arousal, decision-making, and focus. 
  • Serotonin helps regulate and stabilize mood and sleep.
  • Dopamine is the feel-good hormone that lights up our reward center and helps with focus, memory, sleep, mood, and motivation.

How does exercise help solidify other habits?

Better mood, energy, and focus are all inherently good for you – and they also help you stick with new habits, like, for instance, exercise. Working out kicks off a virtuous cycle of positive change; when you exercise, your brain runs better, improving the odds that you'll make the good choice to exercise again. 

In Suzuki's study on increasing workouts to four to seven days a week, she also found that exercising more often increased the motivation to exercise again. This increase in motivation applies to other habits as well, including eating healthy and getting a good night's sleep.

How much exercise do you need?

You don't have to work out for an hour or push yourself until you feel that runner's high. While the CDC recommends doing aerobic exercise three to four times a week for a minimum of 30 minutes, any movement that increases your heart rate can trigger positive brain changes: brisk walking, dancing, pushing a lawnmower, or taking the stairs.

"Every time you move your body, you're releasing a flood of neurochemicals in your brain," Suzuki said in an interview. "The neurochemical flood starts with a 10-minute walk."

 

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