"Some studies say that obese people are more tolerant of pain, while other studies say they are less tolerant," Emery said.
About a third of the study's 62 participants were obese. Researchers determined who was obese based on participants' body mass index (BMI) scores, which relates height to weight. Obese patients in this study had a BMI greater than 30 but less than 35. (Scores higher than 35 are considered morbidly obese.)
The participants underwent two rounds of electrical stimulation ?once before, and once after a 45-minute training session where they learned different ways of coping with pain, including instruction in progressive muscle relaxation therapy.
The electrical stimulation came from an iPod-sized device that delivered a slight electrical shock to a patient's sural nerve, a nerve that extends along the ankle and into the calf. This kind of electrical stimulation causes sensations of tingling and mild pain in the lower leg.
The researchers determined the body's response to sural nerve stimulation by measuring the reflex of the lower leg muscles that surround the sural nerve. When the brain senses pain, it sends a message to the body to contract and move the muscles in order to get away from the source of the pain.
"This kind of evaluation is in some ways a more objective way of measuring the body's response to pain, as opposed to simply asking someone if they feel pain," Emery said.
But the researchers did ask participants how much pain they felt. Participants completed questionnaires about anxiety and pain perception after each round of electrical stimulations. All participants, obese or not, reported that they felt less pain after the relaxation session than they did before.
Yet results of the sural nerve stimulus test showed that the obes
Source:Ohio State University