You've known it for years. Exercise -- we've all been told over and over -- improves mood, reduces stress, makes us more productive, etc. But have you ever wondered about why these things are true? Endocrinology can help us understand these positive effects and the science behind serotonin, adrenaline, dopamine, and testosterone -- the four emotionally beneficial chemicals that are produced when we exercise.
What most of us don’t realize is just how much power hormones have over us and our sense of well-being. For example, men who are chronically angry may be producing too much testosterone. Social butterflies have been found to have excess oxytocin, a hormone that promotes bonding-like feelings with other people. Drug and food addicts have been shown to be very low in the feel-good hormone dopamine and must rely on food or abusive substances to feel normal.
Luckily for us triathletes, exercise promotes optimal hormone levels in all areas. It's why several studies are all in conclusion that exercise benefits us emotionally and psychologically. It’s the hormones -- the feel-good chemicals, the confidence-boosting chemicals, and the performance-enhancing chemicals -- that provide these benefits. Let's see the star players:
Serotonin is the feel-good hormone that causes us to relax. The brain produces it when we consume carbohydrates, stay out in the sun, and exercise; we also get a huge kick of serotonin in the morning, as a combat to all the melatonin that is still flooding our bodies.
This morning kick is due to the fact that serotonin and melatonin both work together to control our sleep cycles. Serotonin works with adrenaline to wake us up, and melatonin puts us to sleep. It make sense for someone who is depressed to report feeling tired or sluggish all the time -- their serotonin levels are too low, so the melatonin sleep-inducing hormone takes over and causes them to feel tired. Exercise has long been one of the treatment options for depression, and this is why: serotonin, along with adrenaline and dopamine (we’ll get to those in a second) all combat depression, and are all produced during exercise.
The feel-good effect of serotonin is why exercise is considered a way to combat stress. Serotonin is sometimes referred to as the “off-switch” of anger, and thus people who exercise regularly report feeling calmer and report less ups and downs emotionally. This is good stuff, these hormones.
One drawback is that serotonin has a nasty effect on concentration. Relaxing and feeling good is not always what we need during our jobs. There is such a thing as too much serotonin -- with all the unwinding we'd be doing, we'd never get anything done. That’s where the next two hormones come in.
Stress is very beneficial to us, up to a point. It causes a change in our bodies’ homeostasis, and when our bodies then react to that change, they adapt. It’s why strength training increases strength, endurance training increases endurance, and memory exercises increase memory retention. It’s only when we get into a situation—such as trying to perform in a job environment we hate, while being chronically sleep-deprived--where there is too much stress, that things go south.
So what does this have to do with adrenaline and cortisol? In the short-run, these hormones can be looked at as natural performance-enhancing drugs. They increase muscle-tension, blood pressure, blood glucose, and the rate at which the neurons in your brain fire. This causes us to think fast and act fast, very beneficial when we are under attack. However, these hormones also shut down “unnecessary processes” such as digestion and the immune system; this is why chronic stress is extremely unhealthy.
But, as I said before, a certain amount of stress is beneficial. Since the stress hormones cause our neurons to fire more rapidly, we become extremely focused and responsive to our environment. This causes an increase in motivation and productivity, two very good things when it comes to performance. It’s why exercise (which produces both adrenaline and cortisol) has long been touted as a way to improve focus.
Ahh, dopamine, the addict's favorite hormone. Stimulants, such as cocaine and amphetamines cause a massive release of dopamine when taken, creating a sense of euphoria. Other drugs, such as heroine, imitate dopamine, causing the same rush. Sugary, sweet foods -- especially chocolate -- also cause a dopamine rush which can lead to addiction.
People with low dopamine levels are more susceptible to addiction than people with normal levels. This hormone is released during an experience of pleasure, so low levels of dopamine make it more difficult to feel good. Luckily, though, exercise not only also triggers a release of dopamine, it also increases your sensitivity to it as well. This means that overtime, it will take less and less amounts of dopamine to cause that euphoric feeling, enabling you to not only kick that sugar habit, but also take pleasure in the smaller things.
Also, dopamine is released during times of pain. That numbing feeling you get after a while when you have to do something grueling is dopamine; this is where a runner's high comes from. It also works with serotonin to contribute to the anger-blunting effects of exercise.
Finally, dopamine works with adrenaline to allow someone to be focused. One of the symptoms of Attention Deficit Hyperactivity Disorder is low levels of dopamine. It's all in the hormones.
Testosterone has time and time again been linked with confident and even dominant behavior in social situations for both men and women. It’s an anabolic hormone that the body releases in response to stresses that cause a breakdown of muscle and bone -- in other words, exercise. And since intense and extremely stressful exercise such as sprinting or lifting weights triggers quite a bit of tissue breakdown, and thus quite a large release of testosterone, these guys who live in the gym have higher-than-normal levels of testosterone flowing throughout their bodies.
Exercise, especially very intense exercise, such as sprinting or weight lifting -- both critical to a triathlete's training -- promotes testosterone production. Testosterone has been shown to increase confidence, thus making social interaction less stressful, leaving you well on your way to benefiting emotionally. Men with low levels of testosterone have also reported low levels of motivation, which is why the more dominant and assertive men with more testosterone in their systems tend to be more successful. Oh, by the way, this works in women too.
So the next time that you are stuck wondering why exactly exercise makes you feel so darn good, you can reflect back on this. It’s simply hormones.