Published in: 2016
Imagine traveling back to 10,000 years B.C. The people you meet would speak a different language and have completely different experiences. But by and large, they would be like you. We humans, including our brains, have not changed much in 12,000 years. But our lifestyle has changed tremendously in just 100 years, even more in 12,000 years. For millions of years, our ancestors had to be on the move to obtain food and survive. The result is that we not only have a body that is built for movement, but also a brain that is. This is a book about exercise and how we have walked out of step with our biology – or rather: we sit out of step with it.
BIOLOGICAL MISMATCH. If you look at the history of mankind as a day, we were hunters and gatherers until 23:40. We became industrialized at 23:59:40 (20 seconds before twelve o’clock) and digitized, connected to the internet, 23:59:59 (one second before twelve o’clock).
NATURE VS NURTURE. Your DNA alone does not determine how your brain will develop. You have about 23,000 genes. And you have 100 billion brain cells that have about 100,000 billion connections between each other. 23,000 genes cannot determine all of these links. The brain is too complex to be completely controlled by a genetic program where it is predetermined how it will develop. The genes set a framework for how brain cells are formed and die, connect to each other and break connections. Exactly how this happens, what qualities you develop and how you function, is affected by what you been through, what environment you live in and what lifestyle you choose.
THE HPA AXIS. The body has a stress system called the HPA axis. When the brain detects something it perceives as a threat, the Hypothalamus (“H” in HPA) sends a signal to a gland in the brain, the Pituitary (“P” in HPA), which responds by releasing a hormone that travels into the bloodstream with your Adrenal glands (“A” in HPA), that responds by releasing the stress hormone cortisol which makes the heart beat faster and harder. The motor of the HPA axis is the amygdala, which is the brain’s alarm system. The amygdala activates the stress system, but can also be triggered by it. When the amygdala signals danger this leads to increased cortisol levels, which makes the amygdala even more active and increases cortisol levels even more. If the amygdala is allowed to unwind uncontrollably, you will eventually panic.
AMYGDALA ACCELERATES, HIPPOCAMPUS BRAKES. To slow down the stress system, the body and brain have several brake pedals built in. One of these is located in the memory center hippocampus, which has an ability to slow down the stress system and act as a counterweight to the stress motor amygdala. There is always a balance where they pull in different directions. When the hippocampus can no longer slow down the amygdala, the stress system begins to live its own life. Another stress brake is the frontal lobe / prefrontal cortex, a seat of “higher thinking”, which has a central role in not overreacting emotionally and acting irrationally. Here, too, a balance is created with the amygdala.
CORTISOL LEVELS MUST DECREASE. It is natural that cortisol levels increase from stress. But it is important that they decrease when the stressful situation is over. The stress hormone cortisol is almost a poison to the brain cells in the hippocampus (which can die from too much cortisol), and if there is too much for a long time (rather months and years rather than hours and days) the hippocampus risks shrinking slightly. This can make the memory worse.
EXERCISE AS MEDICINE. Exercise means stress for the body. Cortisol levels increase while running, cycling or other physical activity. But after the workout, the body does not need the same stress boost. Then cortisol levels drop to lower levels than before. If you continue to exercise regularly, cortisol will gradually increase less and less each time, and decrease more afterwards. It will also increase less and less even when you are stressed for other reasons. In fact, the frontal lobe and the hippocampus are the two parts of the brain that are most strengthened by your movement. But it is important to make exercise a habit – it takes time before the hippocampus and frontal lobe are strengthened.
GABA – ACTIVATED BY EXERCISE. GABA (Gamma-aminobutyric acid) is a substance whose function is to calm the brain and dampen the activity of brain cells (when the activity is calmed, the feelings of stress disappear). GABA activation means fast and effective stress relief – just like when you drink alcohol or take sedatives. GABA is also activated by movement. You get some effect if you walk, but the best thing is to run or cycle.
EXERCISE ATTACKS STREES FROM SEVERAL ANGLES. Stress reduces the brain’s ability to change (plasticity) while exercise increases it. Increased stress slows down the transition from short-term to long-term memories while exercise improves it. The really nice effects on well-being and stress resistance are only noticeable after a couple of months of regular training. Exercise attacks stress and anxiety from several angles. Cortisol levels drop after a workout and will not rise as sharply next time. The “brake pedals” hippocampus and frontal lobe are strengthened and become better at breaking the anxiety motor amygdala. The activity of the brain’s braking system GABA increases and the muscles’ ability to neutralize a stress substance increases. All this is happening at the same time.
EXERCISE – A DOSE AGAINST STRESS AND ANXIETY. Most indications are that cardio training provides more from a stress perspective than strength training. Be active for at least 20 minutes, preferably 30-45 minutes. Make sure to get your heart rate up at least 2-3 times a week. Exercise intensily once a week, for example with interval training (has an extra good effect against anxiety).
EXERCISE – A DOSE FOR BETTER CONCENTRATION. Run instead of walk. If you move more intensely, the brain releases more dopamine and norepinephrine. You should reach 70-75% of your maximum heart rate. For concentration, it is usually better to exercise in the morning so that the effect can last during the day. You should be active for at least 20 minutes, but preferably 30 minutes to get a good effect.
THE EXERCISE – A DOSE TO FEEL BETTER. Run three times a week for 30-45 minutes each time. The intensity should be at least 70 percent of your maximum capacity. Cycling or other cardio training is as good as running. Keep this for at least six weeks.
EXERCISE – A DOSE FOR BETTER MEMORY. For memory, a walk of 30 of minutes is enough – it’s probably better than running for several hours. It is best to vary between cardio and strength training. The effects of cardio training on the hippocampus are what have been studied the most, but there seem to be effects on memory that you only, or mainly, get from strength training. Do not exert yourself too intensely, a walk or a lighter run is enough. You get the greatest effect on memory the day or days after training. Exercise regularly for several months straight.
THE TRAINING – A DOSE THAT INCREASES CREATIVITY. The best thing is to run, but also to walk has an effect. Run for at least 20-30 minutes. The effect on creativity comes afterwards and lasts for about 2 hours. Do not take yourself out completely, then creativity will be worse for several hours after training (but not in the long run). The training improves the ability to brainstorm, above all, but it can differ from person to person.
”The moment my legs begin to move, my thoughts begin to flow” – Henry David Thoreau