By Dr. Mercola
Scientists have been linking physical exercise to brain health for many years. In fact, compelling evidence shows that physical exercise helps build a brain that not only resists shrinkage, but increases cognitive abilities.1
For example, we now know that exercise promotes a process known as neurogenesis, i.e. your brain’s ability to adapt and grow new brain cells, regardless of your age.
The featured article in Real Simple magazine2 highlights a number of brain-boosting benefits of exercise, including the following.
Exercise Shields You from Stress and Depression
Exercise is one of the “secret weapons” to overcoming depression, and studies have shown its efficiency typically surpasses that of antidepressant drugs. In fact, research has shown that in most cases these drugswork no better than a placebo – and can also have serious side effects.
One of the ways exercise promotes mental health is by normalizing insulin resistance and boosting natural “feel good” hormones and neurotransmitters associated with mood control, including endorphins, serotonin, dopamine, glutamate, and GABA.
Swedish researchers3 have also teased out the mechanism by which exercise helps reduce stress and related depression. As it turns out, mice with well-trained muscles have higher levels of an enzyme that helps metabolize a stress chemical called kynurenine.
Their finding suggests that exercising your muscles actually helps rid your body of stress chemicals that can lead to depression. According to the authors:4
“Our initial research hypothesis was that trained muscle would produce a substance with beneficial effects on the brain. We actually found the opposite: well-trained muscle produces an enzyme that purges the body of harmful substances. So in this context the muscle’s function is reminiscent of that of the kidney or the liver.”
Recent research has also shown the clear links between inactivity and depression. Women who sat for more than seven hours a day were found to have a 47 percent higher risk of depression than women who sat for four hours or less per day. Those who didn't participate in any physical activity at all had a 99 percent higher risk of developing depression than women who exercised.
To Boost Creativity, Get Moving!
As noted in the featured article, exercise can also boost your creativity, and help you come up with new solutions to problems. For example, researchers at Stanford University found that walking can increase creativity up to 60 percent.5,6 Even a casual stroll around your office can be helpful.
According to the authors:7
“Four experiments demonstrate that walking boosts creative ideation in real time and shortly after... Walking opens up the free flow of ideas, and it is a simple and robust solution to the goals of increasing creativity and increasing physical activity.”
Exercise Boosts Brain Growth and Regeneration
As mentioned earlier, fascinating research shows that your brain is capable of rejuvenating and regenerating itself throughout your life. This information is completely contrary to what I was taught in medical school. At that time, it was believed that once neurons die, there’s nothing you can do about it. Hence deterioration and progressive memory decline was considered a more or less inevitable part of aging. Fortunately, that’s simply not true.
According to John J. Ratey, a psychiatrist who wrote the book Spark: The Revolutionary New Science of Exercise and the Brain, there’s overwhelming evidence that exercise produces large cognitive gains and helps fight dementia. The featured article cites research8 showing that those who exercise have a greater volume of gray matter in the hippocampal region of their brains, which is important for memory. According to the authors:
“After controlling for age, gender, and total brain volume, total minutes of weekly exercise correlated significantly with volume of the right hippocampus. Findings highlight the relationship between regular physical exercise and brain structure during early to middle adulthood.”
Exercise also prevents age-related shrinkage of your brain, preserving both gray and white matter in your frontal, temporal, and parietal cortexes, thereby preventing cognitive deterioration.9,10 The authors stated that:
“These results suggest that cardiovascular fitness is associated with the sparing of brain tissue in aging humans. Furthermore, these results suggest a strong biological basis for the role of aerobic fitness in maintaining and enhancing central nervous system health and cognitive functioning in older adults.”
Similar findings have been found by other scientists. For example, one observational study11 that followed more than 600 seniors, starting at age 70, found that those who engaged in the most physical exercise showed the least amount of brain shrinkage over a follow-up period of three years.
How Does Exercise Affect Brain Power?
One of the mechanisms by which your brain benefits from physical exercise is via a protein called Brain Derived Neurotrophic Factor (BDNF). Exercise initially stimulates the production of a protein called FNDC5, which in turn triggers the production of BDNF. BDNF is a remarkable rejuvenator in several respects. In your brain, BDNF not only preserves existing brain cells,12 it also activates brain stem cells to convert into new neurons, and effectively makes your brain grow larger.
Research13 confirming this includes a study by Kirk Erickson, PhD, in which seniors aged 60 to 80 who walked 30 to 45 minutes, three days per week for one year, increased the volume of their hippocampus by two percent. The hippocampus is a region of your brain important for memory. Erickson told WebMD:14
"Generally in this age range, people are losing one to three percent per year of hippocampal volume. The changes in the size of the hippocampus were correlated with changes in the blood levels of the brain-derived neurotrophic factor (BDNF)."
Erickson also found that higher fitness levels were associated with a larger prefrontal cortex. He called exercise "one of the most promising non-pharmaceutical treatments to improve brain health." Two additional mechanisms by which exercise protects and boosts your brain health include the following:
- Reducing plaque formation: By altering the way damaging proteins reside inside your brain, exercise may help slow the development of Alzheimer's disease. In one animal study,15 significantly fewer damaging plaques and fewer bits of beta-amyloid peptides, associated with Alzheimer's, were found in mice that exercised.
- Decreasing BMP and boosting Noggin: Bone-morphogenetic protein (BMP) slows down the creation of new neurons, thereby reducing neurogenesis. If you have high levels of BMP, your brain grows slower and less nimble. Exercise reduces the impact of BMP, so that your adult stem cells can continue performing their vital functions of keeping your brain agile.
In animal research,16,17 mice with access to running wheels reduced the BMP in their brains by half in just one week. In addition, they also had a notable increase in another brain protein called Noggin, which acts as a BMP antagonist. So, exercise not only reduces the detrimental effects of BMP, it simultaneously boosts the more beneficial Noggin as well. This complex interplay between BMP and Noggin appears to be yet another powerful factor that helps ensure the proliferation and youthfulness of your neurons.
Exercise Prevents Both Brain and Muscle Decay
Showing the interconnectedness between muscle and brain health, BDNF also expresses itself in the neuro-muscular system where it protects neuro-motors from degradation. The neuromotor is the most critical element in your muscle. Without the neuromotor, your muscle is like an engine without ignition. Neuro-motor degradation is part of the process that explains age-related muscle atrophy.
So BDNF is actively involved in both your muscles and your brain, and this cross-connection appears to be a major part of the explanation for why a physical workout can have such a beneficial impact on your brain tissue. It, quite literally, helps prevent, and even reverse, brain decay as much as it prevents and reverses age-related muscle decay. The most important message from studies like these is that mental decline is by no means inevitable, and that exercise is as good for your brain as it is for the rest of your body.
Diet and Fasting Also Plays a Role
Interestingly, fasting and exercise trigger very similar genes and growth factors that recycle and rejuvenate both your brain and muscle tissues. These growth factors include BDNF and muscle regulatory factors (MRFs). These growth factors signal brain stem cells and muscle satellite cells to convert into new neurons and new muscle cells respectively. This also helps explain why exercise while fasting can help keep your brain, neuro-motors, and muscle fibers biologically young.
For more information on how to incorporate intermittent fasting into your exercise routine for maximum benefits, please see my previous article, “High-Intensity Interval Training and Intermittent Fasting - A Winning Combo.” Besides the issue of when you eat, what you eat is of great importance. Sugar suppresses BDNF, which helps explain why a low-sugar diet in combination with regular exercise is so effective for protecting memory and staving off depression. Sugar, and fructose in particular, will also obliterate your body’s production of human growth hormone (HGH) when consumed within two hours after a workout, and HGH production is a major benefit of high intensity interval training (HIIT).
Exercise Can Help Keep You Sharp Well Into Old Age
While it's never too late to start exercising, the earlier you begin and the more consistent you are, the greater your long-term rewards. Having an active lifestyle is really an investment in your future well-being, both physically and mentally. I believe that, overall, high-intensity interval training really helps maximize the health benefits of exercise, while simultaneously being the most efficient and therefore requiring the least amount of time. That said, ideally you’ll want to strive for a varied and well-rounded fitness program that incorporates a wide variety of exercises.
I also strongly recommend avoiding sitting as much as possible, and making it a point to walk more every day. A fitness tracker can be very helpful for this. I suggest aiming for 7,000 to 10,000 steps per day, in addition to your regular fitness regimen, not in lieu of it. The science is really clear on this point: you do not have to lose your mind with advancing age. Your brain has the capacity to regenerate and grow throughout the entire human lifespan, and exercise is perhaps the most potent way to ensure your brain’s continued growth and rejuvenation.