Chronic low back pain and back muscle activity during functional tasks.

There is evidence that patients with low back pain favor their trunk muscles when moving. However, it is unknown whether this maladaptive behavior is generalized across different functional tasks. This study analyzed the back muscle activity of patients with chronic low back pain compared to asymptomatic controls during five functional tasks. The secondary aim of this study was to test whether the electromyographic activity of patients' back muscles was correlated with either the TAMPA scale score or the Örebro Questionnaire. Forty patients with chronic, non-specific low back pain and 40 asymptomatic participants were assessed on the electromyographic activity of the lumbar longissimus, ilio-costal and multifidus while picking up and placing an object on the ground, sitting down and standing up, and climbing stairs. There was statistical evidence of two-way interactions involving group by task (F4,308 = 7.921, p < 0.001, η2 = 0.049) and task by muscle (F18,1386 = 2.912, p < 0.001, η2 = 0.004), but not group by muscle (F7,539 = 1.104, p = 0.359, η2 = 0.004). Patients with chronic low back pain showed an increase in back muscle activity regardless of the type of functional task, except the left side of multifidus muscle during the picking up of a ball on the ground task. There was no correlation between the measure of kinesiophobia or the Örebro questionnaire score and the level of electromyographic activity.