Running is an activity that conjures images of both euphoria and suffering, pleasure and pain, agony and ecstasy. This is possible because when you put on foot in front of the other for a long period of time, elaborate and intense events take place in the brain that actually produce pleasurable feelings. These remarkable chemical changes are largely what enables the body to continue running despite discomfort and pain.
Endorphins
The brain, whether at rest or active, has the ability to make its own pain-killing opiates, called endorphins. Endorphins are as potent at blocking pain as morphine. And, like opiates, endorphins produce euphoria. This is the brain's way of managing the body's pain. It's long been thought, and only recently proved, that your body sends a signal to release endorphins and manage pain under prolonged or extreme physical exertion, such as childbirth or running long distances.
Runner's High
Endorphins are the elusive yet probable cause of "runner's high." This is the feeling of exhilaration some athletes claim to experience after prolonged, and sometimes painful, exercise. One scientist tested runners' reaction to pain before running. Then he had them run one mile and tested them again. Their tolerance spiked by almost 70 percent. Not satisfied, the researcher gave the runners a drug blocking the production of endorphins and had them run another mile. Their tolerance to pain dropped to their levels before their first run.
Evolution
It's easy to see why endorphins are released during childbirth. Having children is an evolutionary function of prolonging the species; the body has adapted to make it as easy as possible, and having your brain squirt out painkillers as you bear down in delivery certainly makes sense. But why running? Recent theorizing holds that more than 1 million years ago, human beings adapted to become natural runners in order to eat. Though not fast, humans could run long. Awash in endorphins, man could, the theory goes, literally run a gazelle to death for dinner.
Other Uses
The way a runner's brain helps a runner keep running can help people who have never run a step. Scientists are investigating whether exercise can be used as a therapy in patients who suffer from chronic pain. The are also tinkering with whether endorphins can help alleviate depression, anxiety disorders and even treat addiction -- although they're probably not going to get anyone to quit if the addiction they have is to running.
