The new evidence supports the possibility that obesity and physical inactivity play a role in a person's risk of developing chronic pain in those areas, said study co-author Dr Paul Mork, of Norwegian University of Science and Technology said.
Dr Mork and colleagues followed more than 30,000 adults in a large Norwegian health study. They recorded body mass index (BMI) at baseline, as well as exercise habits, and then tracked subjects for 11 years.
The authors divided the participants into four categories based on how often they exercised, and four categories based on BMI.
Overall, 10% developed lower back pain, and 19% developed shoulder or neck pain, according to a paper published online June 11 in the American Journal of Epidemiology.
After taking into account participants' age, BMI, smoking status, and whether subjects' did manual labour at work, the research team found that men who were exercising 2 hours or more per week at the start of the study were 25% less likely to have lower back pain 11 years later, and 20% less likely to have neck or shoulder pain, compared to men who didn't exercise at all.
And women who exercised at least two hours per week were 8% less likely to develop lower back pain than women who were inactive, and 9% less likely to develop neck and shoulder pain.
Weight, not surprisingly, also affected the risk of chronic pain later on. Obese men were almost 21% more likely to develop chronic lower back pain than men of normal weight, and 22% more likely to develop neck or shoulder pain. Obese women were also 21% more likely to develop lower back pain than women of normal weight, and 19% more likely to develop neck and shoulder pain.
Based on the results, Dr Mork believes that even moderate physical exercise - just one hour or more per week - "can, to some extent, compensate for the adverse effect of being overweight and obese on future risk of chronic pain."
"Chronic neck and back pain are important to public health due to their substantial influence on quality of life, disability, and health care resources," Dr Adam Goode from Duke University in Durham, North Carolina said. Dr Goode, a physical therapist, was not involved in the study by Dr Mork's group.
Back in the mid-1990s, a study from the Netherlands estimated that low back pain cost that country nearly 2% of its gross national product. In their new paper Dr Mork and colleagues write that "just a small reduction in the incidence of chronic lower back pain would have a profound economic impact."
Because of the way it was designed, the Norwegian study can't prove that lack of exercise and being overweight actually caused people's chronic pain, or that regular exercise and a more healthy weight prevented it. It could be that the people who did or didn't have chronic pain are different in ways the study did not measure.
However, given the known benefits of exercise and maintaining a healthy weight, Dr Mork believes that "community based measures aimed at reducing the incidence of chronic pain... should aim at promoting regular physical exercise and the maintenance of normal body weight." (Reuters Health/ June 2011)
Diet and Nutrition