Scientists have linked physical exercise to brain health for many years.
In fact, there’s compelling evidence that physical exercise helps build a brain that not only resists shrinkage, but increases cognitive abilities1 by promoting neurogenesis, i.e. your brain’s ability to adapt and grow new brain cells.
February 26, 2016 
Story at-a-glance
- Physical exercise decreases risk of age-related brain shrinkage, and increases cognitive abilities by promoting neurogenesis — your brain’s ability to adapt and grow new brain cells
- Low physical fitness correlates to smaller brain volume over time
- Any movement that strengthens your leg muscles, such as walking, leg extensions, and squats, helps protect your brain against cognitive decline and memory loss
By Dr. Mercola
Scientists have linked physical exercise to brain health for many years.In fact, there’s compelling evidence that physical exercise helps build a brain that not only resists shrinkage, but increases cognitive abilities1 by promoting neurogenesis, i.e. your brain’s ability to adapt and grow new brain cells.In essence, physical activity produces biochemical changes that strengthen and renew not only your body but also your brain — particularly areas associated with memory and learning.The converse is also true. Researchers have shown a sedentary lifestyle correlates to brain shrinkage, which increases your risk of memory loss and other cognitive problems.As recently reported by Newsweek:2“A new study3 published ... in Neurology links low levels of physical fitness in midlife to lower brain tissue volume two decades later. These findings affirm the role physical fitness plays in protecting the brain as we age.‘Brain volume is one marker of brain aging...and this atrophy is related to cognitive decline and increased risk for dementia,’ says lead author Nicole Spartano ...‘So it is important to determine the factors — especially modifiable factors, such as fitness — that contribute to brain aging.’”
Low Physical Fitness Correlates to Smaller Brain Volume
Exercise helps protect and improve your brain function by improving and increasing blood flow to your brain; increasing production of nerve-protecting compounds; improving development and survival of neurons; and reducing damaging plaques in your brain.Over time, the cumulative effects help slow down the rate at which your brain ages.In this study4,5 data on more than 1,580 participants in the Framingham Heart Study were analyzed. At the outset, all were free of dementia and heart disease. Each person took a treadmill test, which was then duplicated 20 years later. An MRI scan was also done during the follow-up.The participants’ exercise capacity was measured by the time they could run on the treadmill before reaching a target heart rate. In the end, lower levels of physical fitness correlated with smaller brain volume. As noted in the featured article:“For every eight units lower a person scored on the treadmill test, the smaller their brain volume was two decades later. An eight-unit interval represented a reduction in brain volume that was equivalent to one year of aging.The researcher also observed that participants who had an especially high heart rate and blood pressure during the most vigorous exercise had notably smaller brain volumes two decades later.”
Exercise Boosts Brain Growth and Regeneration
As mentioned earlier, your brain is capable of rejuvenating and regenerating itself throughout your life. This information is completely contrary to what was known when I was in medical school in the ‘70s.At that time, it was believed that once neurons die, nothing could be done about it. Hence deterioration and progressive memory decline was considered a more or less inevitable part of aging. Today, we know there’s nothing “inevitable” about age-related cognitive decline at all.In his book “Spark: The Revolutionary New Science of Exercise and the Brain,” psychiatrist Dr. John J. Ratey discusses the evidence showing that exercise actually produces large cognitive gains and helps fight dementia.Research6 has also shown that those who exercise maintain a greater volume of gray matter specifically in the hippocampal region; an area of your brain associated with memory.Exercise also helps preserve gray and white matter in your frontal, temporal, and parietal cortexes, which also helps prevent cognitive deterioration.7,8Perhaps most exciting of all, brain shrinkage can be quelled even if you start exercising later in life.For example, one observational study9 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.
For Optimal Health, Get More Non-Exercise Movement Into Your Day
Eighty percent of Americans fail to meet the recommended amount of exercise, which is 2.5 hours of moderate-intensity activity or 1.25 hours of vigorous-intensity activity each week, along with twice weekly strength-training workouts. These are the “official” U.S. government exercise recommendations.If you fall into this category, take heart, because there’s compelling evidence to suggest that non-exercise movement may actually be even more important than a regular exercise program. Even if you’re a fit athlete who exercises regularly, you may still endanger your health simply by sitting too much.Research has demonstrated that six hours of uninterrupted sitting counteracts the positive health benefits of one hour of exercise, so the foundation for good health is relatively constant or regular movement.Upon this foundation you can then build your fitness to increasingly higherlevels by adding on a few workout sessions each week. For maximum benefits with a minimal time investment, high-intensity interval training (HIIT) is an ideal add-on, two or three times a week.
Standing and Walking — Two Key Components of Non-Exercise Movement
You can look at non-exercise movement as a two-part equation involving:
- Avoiding sitting as much as possible during the day. Just standing up produces beneficial biological effects, including improved blood flow, which is as important for your brain as it is for the rest of your body.
If you’re an office worker, consider investing in a stand-up desk. Ideally, employers would provide a stand-up desk option to improve the health of their employees, which is what I did in my Chicago office. I also use a stand-up desk in my home office (see video above).- Walking more, ideally 7,000 to 10,000 steps or about one hour per day. A fitness tracker can be a great tool to help you reach your goal on a daily basis, and every step counts.
There are many creative ways to get more walking into each day, from parking your car further away from the front door of your office; taking the stairs instead of the elevator; conducting walking meetings; or walking rather than driving when going out to lunch.
Walking Helps Protect Your Ability to Think and Learn
A recent study that supports these recommendations actually showed that when you work your leg muscles, your cognitive function benefits. According to the authors, simply walking more could help maintain brain function well into old age. This study10,11,12,13 followed 324 female twins, aged 43 to 73, for a decade. Cognitive function such as learning and memory was tested at the outset and at the conclusion of the study.Interestingly, as reported by MedicineNet.com:14“The researchers found that leg strength was a better predictor of brain health than any other lifestyle factorlooked at in the study. Generally, the twin with more leg strength at the start of the study maintained her mental abilities better and had fewer age-related brain changes than the twin with weaker legs ...‘It's compelling to see such differences in cognition [thinking] and brain structure in identical twins, who had different leg power 10 years before,’ [lead author Claire] Steves, Ph.D. added. ‘It suggests that simple lifestyle changes to boost our physical activity may help to keep us both mentally and physically healthy.’"The study on twins is said to be the first showing a specific link between leg power and cognition in normal, healthy people, and this is great news, as your leg muscles are among the largest in your body and can be easily worked, either through seated leg exercises, or by standing and walking.
Weighted Leg Extensions Boost Memory
Another study15 linking leg strength to cognitive gains was published in 2014. Here, working out the leg muscles by doing just 20 minutes of weighted leg extensions enhanced long-term memory by about 10 percent. In this experiment, 46 volunteers were randomly assigned to one of two groups — one active, and one passive. Initially, all of the participants viewed a series of 90 images. Afterward, they were asked to recall as many images as they could.Next, the active group was told to do 50 leg extensions at personal maximum effort using a resistance exercise machine. The passive participants were asked to let the machine move their leg, without exerting any personal effort.Two days later the participants returned to the lab, where they were shown a series of 180 pictures — the 90 original photos, plus 90 new ones. Interestingly, even though it was two days since they performed the leg extensions, those in the active group had markedly improved image recall. The passive control group recalled about 50 percent of the original photos, whereas the active group remembered about 60 percent of the previously shown images.As reported by the Epoch Times:16“Our study indicates that people don’t have to dedicate large amounts of time to give their brain a boost,’ says Lisa Weinberg ... who led the project. Although the study used weight exercises ... resistance activities such as squats or knee bends would likely produce the same results. In other words, exercises that don’t require the person to be in good enough to shape to bike, run, or participate in prolonged aerobic exercises ...”
How Muscle Strength Can Translate Into Brain Health
So what might account for these findings? We know that improved blood flow increases oxygenation to your brain, which of course has potent benefits, but what is it about muscle strength that influences brain function? Interestingly, previous research has demonstrated that exercise prompts the release of various hormones, growth factors, and proteins — a number of which have a direct impact on your brain health:
- Brain-derived neurotrophic factor (BDNF) is a growth factor that influences both muscles and neurons. In your neuromuscular system, BDNF protects neuromotors from degradation. (The neuromotor is the most critical element in your muscle. Without the neuromotor, your muscle is like an engine without ignition. Neuromotor degradation is part of the process that explains age-related muscle atrophy).
In your brain, BDNF triggers chemicals that promote neural health and directly benefit cognitive functions, including learning.- Muscle regulatory factors (MRFs) signal brain stem cells and muscle satellite cells to convert into new neurons and new muscle cells respectively.
- Exercise lowers the activity of bone-morphogenetic protein (BMP). BMP slows the production of new brain cells, so by dampening its activity, brain cells can more easily be renewed.
- Exercise also increases Noggin, a brain protein that acts as a BMP antagonist. The more Noggin present in your brain, the less BMP activity there is, and the more stem cell divisions and neurogenesis (production of new brain cells) takes place.
- Exercise also has a powerful molecular biological action, as it is one of the most potent stimulators of mitochondrial biogenesis through the signaling mechanisms of AMPK and SIRT1.
To Optimize Your Health and Longevity, Stay in Motion
The type of exercise program that will benefit your brain is identical to the one that will benefit the rest of your body, starting with non-exercise movements like standing and walking. Keep in mind that there are many muscle-strengthening exercises you can do without having to switch out of your work clothes. You can easily pull off a few squats right by your desk, or do a few walking lunges when moving from room to room for example.
You can also turn a walk into a high-intensity exercise by intermittently picking up the speed. Once you’ve got the non-exercise portion down, begin implementing a comprehensive exercise routine that includes high-intensity interval exercise(HIIT), strength training, core work, and stretching.
Dementia is on the rise, but there’s a lot you can do to prevent it. Staying active is one component. Eating right and avoiding toxic exposures are two others. For a refresher on the dietary and lifestyle modifications shown to protect against and possibly even treat cognitive decline, please see my previous article on Alzheimer’s prevention. You don’t have to become a statistic, and every step you take — both literally and figuratively — will improve your odds.
