In studies in which subjects undergo painful tests such as having a heated instrument applied to an arm, they rapidly become less sensitive to the pain. In just one week of daily 20-minute pain sessions, subjects in a study at the University of Hamburg in Germany increased the threshold temperature at which they started to feel pain from about 110° to nearly 118°. But the increased resistance was not restricted to the arm that was exposed to the heated instrument. Subjects became more tolerant in the other arm and in their legs as well, suggesting that the change was occurring in the brain, not the skin. In another Hamburg study, scientists found that the brains of subjects on a similar weeklong pain program grew more gray matter in the sensory area of the brain responsible for the arm that was being heated, as well as in other areas. (Conversely, patients with chronic pain that develops for unclear reasons and has no definitive end become more sensitive to pain over time, and scientists have documented a decrease in gray matter in those patients' brains.) Perhaps, as Bettis says, some of the change is due to knowledge, which is itself a form of brain reprogramming. That which (your brain learns) does not kill you makes you stronger.
Jeroen Swart, an exercise physiologist at the Sports Science Institute in Cape Town and also South Africa's 2002 cross-country mountain biking champion, has studied how cyclists such as those who climb the Alps in the Tour de France manage pain and fatigue. His work has confirmed that knowledge of what is to come is power—literally measured in watts. In 2009 Swart and colleagues tested competitive cyclists on four successive 40-kilometer time trials and found that the better the athletes learned the course, the better they could withstand a given amount of pain. "In the fourth trial, when they were most familiar with the task," Swart says, "the pain was actually less even though they continued at the same or faster pace."
But in a fifth trial, when information about how far they had gone was purposely withheld from the athletes, they were unable to push through mid-race exhaustion, and their power output declined rapidly through the middle of the race, until they caught sight of the finish and surged. "As the end gets closer," Swart says, "the brain starts to shut down some of the signals such as pain and breathlessness," allowing athletes in all sports to make the excruciating sprint for the finish. Throughout a task, the brain manages the allowable increase in pain and exertion, according to Swart, and "experience of the chosen distance and accurate feedback of how much has been completed is critical to how well the brain can calculate." And whether in sports or a chronic-pain clinic, changing the data that the brain uses for its calculations changes the perception of pain.
In fact, most of the breakthroughs in pain treatment over the last few years involve not new drugs but various forms of brain reprogramming—sometimes using electrical stimulation or other, far more basic technology. Some amputees who feel pain from a phantom limb have had success with "mirror therapy," in which a mirror is placed to make it appear to the amputee that the absent limb is still intact. The idea is to trick the brain, so that it will cease registering the phantom pain. Early results with wounded soldiers have been promising.
There are simpler remedies still. When patients are given control of their own pain—such as women in childbirth who are handed the reins of their own epidural—they often require much less medicine to achieve relief. In studies in which subjects are tested for sensitivity to heat, those people who are led to believe that they have control over the testing machine, even when they do not, show increased activity in the prefrontal cortex and decreased activity in the insular cortex, a part of the brain associated with the emotional dimension of pain.
The large prefrontal cortex is the uniquely human piece of the brain, responsible for functions such as choosing right from wrong, predicting events, interpreting social cues and suppressing sexual urges. The fact that a more active prefrontal cortex coincides with a dampened emotional response to pain is likely not a coincidence. For better and worse, humans have a complex capacity for modulating pain, for dwelling on its unpleasantness or suppressing it altogether. "We think certain parts of the prefrontal cortex can act like a pain governor," says Jeffrey Borckardt, associate professor of psychiatry at the Medical University of South Carolina. "If you're really intently wrapped up in a goal, the prefrontal cortex might turn down the volume on that emotional dimension of the pain experience. We have the ability to override our pain experience. You might be able to press on through the pain."
That night in Whistler, Petra Majdič showed up at the medal ceremony in a wheelchair, with a tube in her chest to relieve the pressure from air built up around her collapsed lung. But she would never have been on the podium if not for doctors who had told her repeatedly during the competition that what she was feeling was just pain, not injury.
When emergency patients cannot identify a cause of their pain, they are often cured simply by the presence of a doctor, or his or her assurance that there is no serious problem. Mogil, the McGill pain researcher, relates his own experience: He once awoke with a strange pain in his inner thigh. His wife, a chiropractor, suggested it might be a hernia, and he went to the hospital. The pain worsened as successive doctors agreed that it could be a hernia. "Then they called the expert," Mogil says. "He took one look and said, 'It's not the right place for a hernia. It's a muscle spasm. You'll be fine by the afternoon.' The pain was gone before I even got back into my car."
Majdič was given a degree of control over her pain, being told by her coaches that she could bow out of the race at her discretion. But she also took control of her pain by focusing on the underdog status of her small and underfunded Slovene team. As with the UFC fighter and the injured factory worker, Majdič's mental state might have made her less susceptible to pain. In multiple studies, women who were told offhandedly that their minority ethnic group was more sensitive to pain suddenly became more tolerant of it. After the experience, Majdič would speak of how important it was that she had been surrounded by her Slovene support team and that when she wanted to quit she reminded herself that she had a chance to show the world that you "don't joke with small nations because we can beat you!"
And, of course, she was in the heat of a big competition, one for which she'd prepared for two decades. Whether she knew it or not, throughout her years of strenuous training as well as on that medal-winning day in Whistler, Majdič had been constantly telling herself that the pain was in her head.