Which is the weaker sex when it comes to pain? It may be hard to say since women and men have different experiences with pain.
New research has found that women report more pain throughout their lifetime. Compared to men, women feel pain in more areas of their body and for longer durations.
"The bottom line seems to be that women are suffering more than men," said Ed Keogh, a psychologist from the Pain Management Unit at the University of Bath.
In one study, Keogh and his collaborators interviewed patients in a pain management program. Although the program reduced chronic pain for all the subjects, in follow up exams the women in the group reported pain levels as high as before the treatment -- whereas the improvements in the male group were longer lasting.
In another set of experiments, volunteers were asked to put their arms in an ice water bath. Men were found to have higher pain thresholds (the point where they began to feel pain), as well as higher pain tolerances (the point where the pain became too much).
With the notion of gender distinctions in pain perception becoming more widely accepted, scientists are now asking why men and women suffer differently, and whether treatments need to be made sex-specific.
Part of pain perception is clearly dependent on the genetic and biochemical differences between men and women.
"There is evidence for hormones, like estrogen and testosterone, affecting a person's pain experience," Keogh told LiveScience in a telephone interview.
Women report varying pain experiences throughout their menstrual cycle, when estrogen levels vary widely. Moreover, pregnant women -- who often have elevated estrogen levels -- can tolerate the intense physical pain of childbirth.
Testosterone may have a similar protective effect for men, Keogh said. But he also thinks that the cultural differences between men and women are important as well.
"Social and psychological factors cannot be ignored," Keogh said. "We have found that women will focus on the emotional response to stress."
In contrast, men typically think only of the sensation itself, which may explain their higher thresholds and tolerances.
"Women who concentrate on the emotional aspects of their pain may actually experience more pain as a result, possibly because the emotions associated with pain are negative," Keogh said.
When Keogh and his colleagues instructed female subjects to focus on their sensations, the researchers found that it had little effect on how the women responded to a pain stimulus. Males, on the other hand, had higher thresholds and tolerances when told to concentrate on their sensory feelings as opposed to their emotional feelings.
More work is necessary to find what lies at the heart of these differences. With greater understanding, doctors may one day improve the effectiveness of treatments by tailoring them to the gender of the patient.