Effect of dual-tasking on dynamic postural control in individuals with and without nonspecific low back pain.

This study’s goal was to compare the effect of dual tasking on postural and cognitive performance between participants with and without nonspecific chronic low back pain. In this 3-factor mixed-design study, dynamic postural stability was assessed in 15 patients with chronic nonspecific low back pain and 15 age-, sex-, and size-matched asymptomatic participants. Bilateral stance on a Biodex Balance System was investigated at 3 levels of postural task difficulty (different platform stabilities levels with eyes open and closed) and 2 levels of cognitive task difficulty (with or without auditory Stroop test). We measured anterior-posterior, medial-lateral, and overall indices for postural performance. Average reaction time and error ratio of a modified auditory Stroop test were calculated as measures of the cognitive task performance. Mixed-design 3-way analyses of variance revealed significant interactions. Post hoc 2-way analyses of variance showed significant group by cognitive task difficulty for anterior-posterior (P < .001), medial-lateral (P = .003), and overall stability indices (P < .001) on a stiffness level of 5 with eyes closed. At this level, significant differences between single- and dual-task conditions for anterior-posterior (P < .001), medial-lateral (P = .02), and overall stability indices (P < .001) were found only in the chronic low back pain group. Also, at the most difficult postural conditions, participants with chronic low back pain increased their error ratio (P = .002), whereas matched asymptomatic individuals’ reaction time increased (P < .01) of the auditory Stroop test.

The study found that postural task performance is attenuated by cognitive loading at a moderate level of postural task difficulty. Due to this, to observe the effect of attentional demands of postural control, task difficulty ought to be considered.