Feeling down or being depressed is kind of like being at a mental standstill, where you are unable to make any progress in life—everything slows down, and the brain doesn’t receive as many impressions as before. Moving your body is diametrically opposite to this. Depression is also often recognized in a person if you withdraw, stop socializing with people, and no longer engage in what you used to enjoy doing. Consequently, the brain gets less stimulation and you feel even worse, creating a vicious circle. John Ratey, an American psychiatrist at Harvard University, describes depression as a loss of contact with the sufferer’s human connections, as well as the person’s brain cells. Engaging in physical activity is one way to break this vicious cycle. You get out, you meet people, and you become less solitary; at the same time, your brain cells break out of their isolation.
These sorts of behavioral changes are often more difficult to measure than, say, levels of dopamine and BDNF, for which you can obtain a measurable number. But just because terms such as self-efficacy and behavior modification don’t sound as objective as “increased levels of dopamine” doesn’t mean they are not important.
A more positive personality
The woman I talked about at the beginning of this chapter is just one of many people who have felt much better after starting regular workouts. In her case, as well as the cases of several others, it also seems like their entire personality changed for the better. First, I thought this was just a coincidence. Surely, exercise and training won’t transform your personality? As a matter of fact, research shows that people who exercise regularly don’t just become happier; they also seem to experience small changes in their fundamental personality traits.
Research in Finland, Japan, and South Africa has shown that those who train regularly tend to be less cynical and less neurotic. In addition, they feel a greater rapport with people in their environment. The same exact pattern was observed in Holland when they examined close to twenty thousand pairs of twins. Those who exercised twice a week were more socially open and less neurotic.
The answer to which came first—the chicken or the egg—is of course not obvious. Training could make a person less cynical and less neurotic; it might also just as easily mean that people who are cynical and neurotic don’t exercise as much. What can vouch for training affecting personality is that we’re gradually beginning to understand the role of molecules in certain personality traits.
Serotonin and dopamine aren’t just important in how you feel; the variations in levels of those substances in individual people probably contribute to our differences in personality. Dopamine, for example, has been linked to curiosity and a willingness to try new experiences, while serotonin is linked to compromise, and also to how neurotic a person is.
Boiling personality down to molecules and mental processes is not easy. The biology that determines your personality and how you feel is tremendously complex. By the same token, it is just biology. Even if these two neurotransmitters can’t begin to explain your entire personality, they still play a part in it. The fact that dopamine and serotonin levels are influenced, over the short and long term, by exercise means that it is not unreasonable at all to suppose that training can affect personality.
Training becomes a drug
One of exercise’s effects on how we feel is more extreme than others. It’s a fact that we can feel completely high from moving our bodies, in which case exercise becomes a sort of endogenous drug. I am talking, of course, about what is commonly known as runner’s high, which you might have experienced at some point yourself. You should not chase runner’s high if you’re suffering from depression, but it still deserves a mention in a book such as this. The story of what it is, and what causes it, is nothing short of thrilling.
The hunt for the mystical morphine
It has been known for over two thousand years that opium can blot out pain and cause euphoria. The dried sap from the opium poppy, from which opium is made, was used as medicine and as a popular drug during the Roman Empire. At the start of the nineteenth century, German scientists managed to isolate morphine, the active ingredient in opium, and began using it in healthcare situations, most notably as a painkiller for wounded soldiers. It proved to be amazingly effective. Even when soldiers had lost their arms or legs, small doses in increments weighing tenths of a gram could almost knock out all their pain. It was incredible that such a low dose could have that deep an impact, especially when compared to alcohol, which can also dull pain, but only in doses hundreds of times larger to achieve a similar effect.
At the beginning of the 1970s, it was discovered that there is a type of receptor on the brain cells’ surface that morphine binds to, which explains why the drug is so powerful. This raised the question of why these receptors even existed. Did nature want us to turn into morphine addicts? That doesn’t seem likely; a more plausible reason was that the brain could produce its own morphine-like substance, and that the receptors were meant for this self-made and still-unknown substance.
Scientists all over the world raced to identify the brain’s own morphine, and those efforts quickly produced results. In 1974, it was discovered that pigs’ brains released a mysterious substance; it appeared that the animal’s own brain produced a substance that had a structure similar to morphine’s. That same year, an American psychiatrist made the same discovery when he examined calves’ brains. The mysterious substances found in the pigs and calves, which were closely related, turned out to be a “self-morphine.” This substance, which exists even in humans, received the name endogenous morphine—morphine originating from the body. However, it became known by a shorter name: endorphins.
Endorphins, like morphine, are incredibly effective at suppressing pain. And just like morphine, they can produce feelings of euphoria. But why would the brain reward itself with a dose of morphine? Why does this mechanism exist, and when does the brain reward itself? The question was raised as to whether there was a natural circumstance in which human beings experience pain relief and euphoria simultaneously, without the help of medication or drugs.
One such state is explained by the American long-distance runner James Fixx in his best-selling book The Complete Book of Running. Sometimes when Fixx was running long distances, he experienced a feeling of euphoria and pain relief that he called runner’s high. Turns out he was far from alone in experiencing runner’s high, and reports soon came in from other athletes who participated in different types of aerobic training. Swimmers, cyclists, and rowers had all felt the same sensation but had simply called it by different names. Rowers called it, appropriately enough, rower’s high.
Run yourself high!
Jame Fixx’s book came out during the running craze of the 1970s, and runner’s high soon became a buzzword. It was widely accepted that the newly discovered endorphins were at the crux of this effect. Today, most runners know about runner’s high, though not many have experienced it. The effect is so much stronger than simply feeling a bit more alert—runner’s high is the most extreme impact physical training can have on our mood.
I, myself, have felt it twice, and it’s impossible to explain the feeling other than to say that it’s pure magic! It’s not the same type of calm you feel at the end of a workout. No, it’s more akin to the euphoria of when all pain disappears, all impressions become more intense, and you feel like you could run forever and ever, as fast as the wind. The feeling is so intense that you will most definitely remember it if you ever experience it. If you’re unsure if you’ve felt runner’s high—it’s more than likely that you haven’t.
It seems logical that it’s the endorphins that are behind this feeling, because it is so reminiscent of the effect of morphine. However, the source of runner’s high is still being debated, and some scientists believe that there’s more to this happy state than just endorphins. To shed some light on the issue, a few scientists in Munich, Germany, decided to examine the brains of runners in their local runners’ club. They measured the level of endorphins with a
PET scan before and two hours after a high-speed run. The results were unambiguous: all the runners had lots of endorphins after the run, especially in their prefrontal cortex and limbic systems, the two areas in the brain central to controlling feelings. When the runners rated their levels of euphoria, it was obvious that the more euphoria the runner reported feeling, the more endorphins were present in the brain.
This is where the debate on what causes runner’s high could have ended, but there are a few counterarguments against the notion that endorphins are the lone reason for this feeling. First, endorphin molecules are big, which would make it difficult for them to break the blood-brain barrier. Second, when long-distance runners were given a substance to block morphine, and thus by extension endorphins, runners could still feel runner’s high.
Are highs only caused by endorphins?
Another possibility is that runner’s high is caused by endocannabinoids. Like endorphins, they are a type of painkilling substance produced by the body; however, they are smaller than endorphins and can therefore make their way into the brain more easily. Like in the case of endorphins, there are specific receptors for endocannabinoids on the brain cells that addictive drugs can bind to. (Endocannabinoids use the same receptors in the brain as the active ingredient in hashish and marijuana.)
The suggestion that endocannabinoids might have something to do with runner’s high was bolstered when French scientists genetically modified mice so they lacked endocannabinoid receptors. The rodents’ desire to move subsequently changed. Normally, it’s enough that mice in a cage have access to a wheel to make them run of their own volition. However, the genetically modified mice didn’t care to move at all and only ran half as much as mice typically do. The extent to which a mouse can experience euphoria and runner’s high is difficult to assess, but it has been possible to see that levels of endocannabinoids increase in humans after they have run. Walking is not enough; one must run for at least forty-five to sixty minutes. This fits with what’s required to reach a runner’s high—by definition, it cannot be achieved by walking.
Some scientists believe that aside from endorphins and endocannabinoids, running increases levels of dopamine and serotonin. Others believe that it’s linked to body temperature and that we become euphoric as we heat up. The most plausible explanation is that runner’s high doesn’t rely on one lone factor but several of them, and that endorphins and endocannabinoids both contribute to it. Whatever the biological source may be, it is mostly of interest to scientists. Otherwise, for runners, cyclists, and tennis players—or whatever else we do when we’re physically active—it’s enough to know that runner’s high happens, not why it happens.
Our heritage from the savanna
Becoming euphoric by running is probably a leftover effect from our ancestors’ life on the savanna. No doubt, some had to run long distances while hunting, a method that Australian aborigines and the Kalahari Desert’s bushmen still use. When you stalked prey for several miles to tire it out, it was important not to give up the chase, which is when endorphins came in handy. If you twisted your ankle or your muscles ached, endorphins blotted out the pain, and when the going got tough, that feeling of euphoria made it easier to keep going. This increased the likelihood of a kill, which is probably why we still experience runner’s high, even today.
There is quite a lot of evidence indicating that runner’s high may be a natural way to get us to keep running and catch our food. It has been shown that if we decrease our level of body fat, levels of leptin—a hormone that is released by fat—decreases, which sounds the alarm that energy levels are dropping and need to be topped up. Our body doesn’t want us to be skinny, quite the opposite, in fact. It wants us to carry around a substantial reserve of energy. If this hypothesis is correct—that we need a shot of pleasure to keep up the strength to continue searching for food—then our body is letting us know, via runner’s high: “Your stores of energy are soon depleted—don’t give up, keep moving and find more food!” To help us along, it makes us feel euphoric.
How do you achieve a runner’s high?
We know that you must run for at least forty-five minutes, and the more you run, the bigger the chance of feeling a runner’s high. The brain appears to give itself ever-increasing doses of endorphins the more you train. Consequently, the likelihood of feeling a runner’s high increases over time, so don’t give up! However, there are no guarantees, because not everyone will get to feel it.
It has been shown that your pain threshold increases when you’ve been running for a while—the same as with morphine. By sticking people with a needle or pinching them to test their tolerance to pain, we’ve noticed that it takes more for you to feel pain during running than if the pain threshold was tested at rest. This supports the idea that endorphins not only make us feel euphoria, but also provide pain relief. And there is no doubt that pain relief can be powerful: it has been calculated that the endorphins felt during high-speed running is equal to a ten-milligram shot of morphine, a commonly administered dose for an arm or leg fracture. That’s why we sometimes see runners continually running even when they have stress fractures (caused by long-term overuse and repetitive motions). They don’t feel the pain so long as they run, though it flares up the moment they stop and the effect of the endorphins wears out. While runner’s high is exercise’s most extreme effect on the brain, your well-being will improve even if you don’t feel a dramatic rush of endorphins. Anyone who exercises is rewarded with endorphins and endocannabinoids, even if they don’t reach runner’s high.
THE RIGHT PRESCRIPTION TO FEEL BETTER OVERALL
Do you feel tired and down in the dumps, even if you are not depressed? Then get out and run! Running, or participating in an activity that raises your heart rate, can produce wonders so long as you do it often and for extended periods of time. You should keep the following guidelines in mind:
Run three times a week, about thirty to forty minutes each time. The intensity should be at least 70 percent of your VO2 max. Keeping a normal speed works well, but you should still feel winded and break a sweat.
Biking or any other type of cardiovascular training is a good substitute for running. It’s the intensity and the length of time that count, not what you do or where you do it.
Keep this up for at least three weeks! It’s true that many feel better after exercising just once, but to feel better during the day and not just after a workout, you need to train regularly over several weeks. Don’t expect too many results in the first weeks.
IF YOU SUFFER FROM DEPRESSION
Training is as effective as medication for mild or nonclinical depressive conditions, but you must run (or partake in an equivalent type of exercise) three times a week, and for forty-five minutes each time. It takes about six weeks to notice some changes, so don’t give up!
Medication works best for clinical depression and suicidal thinking. It’s not realistic to expect the sufferer to begin exercising as treatment, since it might take all their strength just to get out of bed. Always speak to your physician, and never quit your medication on your own!
It’s not a question of either-or here. Training is good. Medication is good. The ideal is a combination of both. Regular exercise and physical activity could also help prevent future depressive episodes. You become more resilient to stress, which is the most common cause of depression. Everything is connected!
5. JOG YOUR MEMORY
Take care of all your memories.
For you cannot relive them.
BOB DYLAN
In the mid-1990s, a group of scientists decided to see which part of the brain is most affected by exercise. They already had a theory before the study began: the cerebral cortex and the cerebellum (situated where the spinal cord meets the brain) are both important for coordination of physical movement, so it seemed natural that these areas would be the most affected by physical activity, just as running has more influence on cardiovascular fitness than on muscular strength.
&nbs
p; The starting point was to see which part of the brain creates the most BDNF (the brain’s own miracle medication I described in the chapter The real happy pill) in mice that run in a wheel in their cage. The strange thing was that when the mice brains were examined, it was revealed that it was neither the cortex nor the cerebellum that produced the most BDNF, but the hippocampus—the brain’s memory center. This discovery became one of the most important clues as to why exercise has such a huge effect on memory. Over the past decade, research on animals and humans has proved that our memory is strengthened by physical activity. In fact, nothing seems to be more important for our memory than physical activity.
STOP YOUR BRAIN FROM SHRINKING
The brain shrinks throughout life, and unfortunately this process begins much earlier than most of us would like. The brain is at its largest when we’re about twenty-five years old, after which it gets a little smaller every passing year. Certainly, new brain cells are created throughout our lifetime, but cells die more quickly than new ones are generated. The net effect is that we lose approximately one hundred thousand brain cells per second every twenty-four hours. This goes on constantly. Year-round. Even if there are plenty of cells to glean from—the brain contains about a hundred billion cells—the loss will become noticeable over time. Over one year, the brain’s volume will decrease by between 0.5 and 1 percent.
The memory center, the hippocampus—big as a thumb and shaped like a seahorse—is one of the areas of the brain that shrinks as we age. We have two hippocampi, one in each side of the brain, and they are located deep inside each temporal lobe. Its size decreases by about 1 percent each year. Those slowly but steadily shrinking hippocampi are why our memory gets worse as years go by.
For a long time, we thought that the brain’s development could only be adversely—never positively—impacted by such things as alcohol and drugs, which accelerate the brain’s aging and hasten the shrinking of the hippocampus. To stop this development, or to even turn it around, was considered impossible. It is against this backdrop that we will now see some of the most convincing evidence of the amazing effect exercise and physical training have not only on memory, but on the brain as a whole. American scientists used MRI scans to examine the brains of 120 individuals and to measure their hippocampi at two different times, with one gap year in between. The test subjects were randomly assigned to two groups that performed two different types of activities. One group did endurance training while the other engaged in mellow exercises like stretching that did not raise their heart rates.
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