Body Mass Index does not appear to have a relationship to pain or disability after rehabilitation for people with mild to moderate low back pain.


Chronic lower back pain ( lower back pain lasting for more than 12 weeks) is a serious health concern that affects 70 per cent to 85 per cent of people at some point of their life. In Australia where this study was done chronic low back pain cost $9.17 billion (yes, billion) dollars annually. The cost accounts for treatment related expenses and missed work. Obesity is also a serious health concern and it is common among people who experience low back pain. This study wanted to examine if there was a link between changes in body mass index (BMI) which is weight divided by height squared (kg/m2) {m is squared}. BMI is classified as follows: 18.5 kg/m2= underweight; 18.5 to 24.9 kg/m2= normal weight; 25 to 29.9kg/m2= overweight; 30 kg/m2 or more obese. BMI has been critizied because of its inability to discern between muscle mass and fat differences in the body.

Research on the relationship between BMI and chronic low back pain has not yielded consistent results. Studies have had inconsistent findings but these two issues present commonly enough that there relationship should be explored. Exercise is a common intervention for both health conditions and known to be helpful in controlling low back pain. Recent findings suggest that exercise may moderate the relationship between obesity and chronic low back pain. This study investivgated the relationship between BMI and exercise-related changes in pain and disability in patients with chronic lower back pain.

The study used 128 people from 18 to 55 years old that had low back pain for 12 weeks minimum. BMI was calculated for each person, a pain scale was used where particpants put a line an 100mm bar; from “no pain” to “worst pain imaginable” and a self-reported disability questionarie. In the study there were no correlations seen between initial BMI and initial pain reports or initial disability questionarie. In the group 77 per cent of the patients were classified as overweight or obese, yet there was no baseline relationship between BMI and pain or disability.

The study lasted eight weeks and each patient went through exercises after there baseline assessment. However, the type of exercises differed among patients, meaning that some used an indoor cycle, some did core stability exercises. Exercise sessions were three to five, one hour sessions with at least one being supervised.

In conclusion, the study considers that the criticism of BMI might be valid. Other measures might be more beneficial is studying the link between obesity and chronic low back pain. An example would to be measure the amount of fat tissue, as that has been linked to chronic low back pain. The study did not report on changes the exercise impact on individual markers of pain or disability. BMI changes are not related to pain or disability changes after exercise in this study.