An Exploratory Study on the Effect of Pain Interference and Attentional Interference on Neuromuscular Responses During Rapid Arm Flexion Movements

Objectives: This study examined the effect of pain interference and attentional interference on the anticipatory postural adjustments of trunk muscles in patients with nonspecific chronic low back pain. Methods: Fifty-nine patients performed rapid flexion movements of the right arm under 6 conditions, namely a control condition and conditions with different attention demands. The latency between the activations of the shoulder and different trunk muscles, as measured with surface electromyography, was used as the outcome. Using repeated measures analysis of variance, attention conditions and group comparisons were tested between those who scored high and low on pain intensity, fear of movement, or pain catastrophizing. Results: There were significant (although minimal) interactive effects but significant and potentially clinically relevant group and attention main effects. The group with the lowest scores showed delayed activity (14 to 29 ms) relative to those with higher scores. One attention-demanding condition delayed (20 to 35 ms) the latencies of some trunk muscles relative to the control condition, namely the one that was the most attention-demanding according to the reaction time results. Discussion: These findings suggest that patients with chronic low back pain, who are characterized by higher scores on some pain-related variables (visual analog scale, Tampa Scale of Kinesiophobia, Pain Catastrophizing Scale), react favorably to protect the spine from further pain and injuries but would be at greater risk of injury when performing a complex physical task requiring more attention demand.