Increased body fat, not lean mass, a factor in level of back pain and disability

One of the first cross-sectional studies investigating the role of body composition in back pain and disability shows a direct connection between increased body fat in relation to the intensity of lower back pain and disability. A greater amount of lean tissue mass was also ruled out as a potential factor.

Researchers studied 135 participants from 25 years to 62 years of age who ranged from a normal body weight to obese. The body mass index (BMI) of each subject was calculated: height and weight were measured using a stadiometer to the nearest 0.1 cm and with a pair of electronic scales to the nearest 0.1 kg, respectively. Bulky clothes and shoes were removed for the measurements.

Donna M. Urquhart, PhD, and her colleagues assessed the level of strenuous physical activity of the participants by using the Chronic Pain Grade questionnaire, asking such questions as, “In the past 6 months, on average, how intense was your pain rated on a 0-10 scale?” The questionnaire also collects data on whether pain levels in subjects prevents them from doing daily activities such as going to work or school and taking part in social functions.

Body composition was measured using dual radiograph absorptiometry with a weight limit of 130 kg, the study stated. Participants were then measured by the fat mass in their upper and lower limbs, trunk and abdomen as well as their total body mass. Researchers created a multivariate model which adjusted results for age, sex, height, and physical activity.

The results showed that, over the last 6 months, mean total body fat mass was significantly higher in subjects who reported high pain intensity than in those who reported no pain. Specifically, total body and lower limb fat mass were the only related factors contributing to higher pain intensity when just both fat and lean tissue mass were included in the model.

“For each 5 kg increase in body fat mass, the odds of high-intensity back pain increased by 19%,” a press release stated. “Thus the increase in back pain intensity among people with higher BMIs was wholly related to their higher body fat content—not just the fact that they were heavier.”

Men and women, when analyzed separately, produced similar results.

Reference:

Urquhart DM, Berry P, Wluka AE, et al. 2011 Young Investigator Award winner: Increased fat mass is associated with high levels of low back pain intensity and disability. Spine. 2011. Jul 15;36(16):1320-5.

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