By Dr. Mercola
The fear of losing cognitive ability tends to overshadow the fear of physical disability; 60 percent of American adults say they are “very worried” or “somewhat worried” about memory loss.1
Chances are, you’re among this majority. The good news is that your brain is a dynamic organ, constantly adapting and changing, for better or for worse.
While some activities, such as lack of sleep, can have a detrimental effect on your memory and brain function, a healthy lifestyle will support your brain health over the long haul, and can even encourage your brain to grow new neurons—a process known as neurogenesis or neuroplasticity.
This phenomenon was not known when I was in medical school. Back then, we were taught that the loss of brain cells was an irreversible condition and there was nothing you could do to change it.
It’s Never Too Late for Your Brain to Regenerate Brain Cells
Your brain's hippocampus, i.e. your memory center, is particularly adaptable and capable of growing new cells throughout your entire lifetime, even into your 90s, provided you give it the tools to do so!
For example, one year-long study found that adults who exercised were actually enlarging their brain's memory center by one to two percent per year, where typically that center declines in size with age.
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. Indeed, research has shown that exercise helps protect your brain by:
- Improving and increasing blood flow to your brain
- Increasing production of nerve-protecting compounds
- Improving development and survival of neurons
- Altering the way damaging proteins reside inside your brain, which appears to slow the development of Alzheimer's disease.
In animal studies, significantly fewer damaging plaques and fewer beta-amyloid peptides, associated with Alzheimer's, were found in mice that exercised. Diet, sleep, and exercise are three lifestyle factors that can significantly influence your brain health and memory. Here, we’ll discuss the influence of exercise, as recent research has again confirmed its ability to improve memory.
One way by which exercise benefits your memory is by prompting nerve cells to release proteins known as neurotrophic factors. These growth factors signal brain stem cells and muscle satellite cells to convert into new neurons and new muscle cells respectively.
This in part explains how exercise benefits both your muscles and your brain at the same time. One growth factor in particular, called brain-derived neurotrophic factor (BDNF), triggers numerous other chemicals that promote neural health, and directly benefits cognitive functions, including learning. Fasting also triggers BDNF, and in combination (i.e. exercising while fasting) can go a long way toward keeping your brain, neuromotors, and muscle fibers biologically young.
Lifting Weights Improves Memory, Study Shows
A 2010 study2 on primates revealed that regular exercise helped the monkeys learn new tasks twice as quickly as non-exercising monkeys. This is a benefit the researchers believed would hold true for people as well. More recently, researchers at Georgia Institute of Technology in Atlanta found that a mere 20 minute weight training session could improve long-term memory in the participants. You can see that in the above video.
According to lead researcher Lisa Weinberg: “Our study indicates that people don't have to dedicate large amounts of time to give their brain a boost.” 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, classified as either positive, neutral, or negative. 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 simply sit and let the machine move their leg for them. Two days later, the participants were again shown a series of images, including ones they’d not seen previously. Interestingly, even though it was two days since they performed the leg extensions, those in the active group had markedly improved image recall. As reported by Medical News Today:3
“The researchers found about 50 percent of the original photos were recalled by the passive group, while the active group remembered about 60 percent of the images. All of the participants were better at recalling the positive and negative images than the neutral images, but this was even more true for the active participants. The researchers suggest that this is because people are more likely to remember emotional experiences following short-term stress.
The team believes their results are consistent with previous research in a rodent model that found stress responses result in releases of norepinephrine - a hormone that may improve memory... The Georgia Tech study looked at weight exercises, but... other forms of resistance exercise – such as squats or knee bends – would most likely produce similar results.”
Exercise Builds New Brain Cells and Boosts Brain Performance
The hippocampus belongs to the more ancient part of your brain known as the limbic system, and plays an important role in the consolidation of information from your short-term memory to your long-term memory, as well as spatial navigation. Previous animal research4 has found that not only does exercise activate hippocampal neurons, it actually promotes their growth. In one study,5 exercising mice grew an average of 6,000 new brain cells in every cubic millimeter of tissue sampled. The growth occurred in the hippocampus, the memory center of the brain, and the mice showed significant improvements in the ability to recall memories without any confusion. A number of other studies have investigated the impact of exercise on brain performance and IQ. Some of the research highlights6 include:
- Among elementary school students, 40 minutes of daily exercise increased IQ by an average of nearly four points
- Among 6th graders, the fittest students scored 30 percent higher than average students, and the less fit students scored 20 percent lower
- Among older students, those who play vigorous sports have a 20 percent improvement in Math, Science, English, and Social Studies
- Students who exercised before class improved test scores 17 percent, and those who worked out for 40 minutes improved an entire letter grade
- Employees who exercise regularly are 15 percent more efficient than those who do not, which means a fit employee only needs to work 42.5 hours in a week to do the same work as an average employee does in 50
Exercising After Studying Boosts Retention
In a Danish study,7 published in 2012, men were asked to learn a tracking skill on a computer, which required them to use a joystick to trace a red line as it squiggled across the screen. Some of the men exercised before learning the new task, some did no physical exercise at all, and some exercised just after learning the new skill. At follow-up testing an hour later, the men’s performance remained about the same, but as the experiment went on, those who exercised gained a clear advantage. Those who fared the best belonged to the group who exercised just after learning the task.
At testing sessions one day, and then one week, later, they traced the line more accurately and with greater agility. The group that exercised prior to learning the new skill also performed better than those who didn't exercise (though not as well as the group that exercised after). It appears, then, that if you want to help strengthen your memory, the new information you're receiving can be more successfully imprinted into your brain for later recall if you work out immediately following your study session.
How to Get the Most Out of Your Strength Training Routine
The type of exercise program that will benefit your brain is identical to the one that will benefit the rest of your body. Ideally, you’d want to strive for a comprehensive routine that includes high-intensity interval exercise (HIIT), strength training, core work, and regular intermittent movement to avoid the hazards associated with prolonged sitting. If you’ve been sitting for an hour, you’ve sat too long. Stretching is also important, especially if you’re doing sprints.
High intensity exercises form the core of my Peak Fitness program and can be done using a number of different machines, such as a recumbent bike or an elliptical, or you can do sprints. HIIT maximizes your secretion of human growth hormone (HGH), optimizes your metabolism, and helps regulate your insulin and blood sugar. And nothing beats it in terms of efficiency. You can complete an entire Peak Fitness workout in 20 minutes or less. For detailed instructions and a demonstration, please see my previous article, "High Intensity Interval Training 101."
You can also turn your strength training routine into a high intensity exercise by slowing it down. This technique offers the same benefits as other high intensity exercises, and may actually be even more beneficial in some ways. It’s a particularly well-suited form of high intensity exercise for older individuals. Super-slow weight training is safer than conventional weight lifting as it actively prevents you from accidentally harming your joints or suffering repetitive use injury.
In the video below, I discuss and demonstrate the proper execution of a number of different super-slow weight training exercises. They can all be done using either free weights or machines. The benefit of using a quality machine is that it will allow you to focus your mind on the effort, as opposed on the movement. The typical super-slow resistance workout can be completed in about 15 minutes. Just one or two of these workouts are needed each week, as you need to make sure you’re sufficiently recovered.
Download Interview Transcript
Your Brain Craves Regular Activity
If you work out religiously for three months, then suddenly stop for an extended period, your muscle tone isn’t the only thing that will suffer. Your brain will too. Two studies presented at the 2012 annual meeting of the Society for Neuroscience revealed just how quickly the brain benefits of exercise fade if your exercise program stops.8
In the first study, active rats that had a week of inactivity were pitted against completely inactive rats while performing memory tests. The previously active rats completed the tests much faster and had at least twice as many new neurons in the hippocampus region of their brains. But remember, this was after just one week of inactivity. At three weeks of inactivity, their new neurons began to decrease, as did their performance on the memory test. After six weeks of inactivity, the neurons declined even more, as did their memory test scores, leading the study authors to suggest the "exercise-induced benefits may be transient."
In the second study, rats that were active for 10 weeks, followed by three weeks of inactivity, had brains that were nearly identical to those of rats that had been completely inactive. The bottom line is that your brain needs regular, ongoing physical activity, not just a brief stint here and there. The same can be said for your body, as mounting research now shows that bouts of exercise, even when done regularly, cannot counteract the ill effects of many hours’ worth of sitting. So another key for overall health is to avoid sitting as much as possible. At minimum, strive to move about or stand up for 5-10 minutes for every hour of sitting.