The relevance of dual tasking for improving trunk muscle endurance after back surgery

Abstract Objective To determine the effect of dual tasking on trunk muscle endurance in patients after lumbar discectomy. Design Cross-sectional study. Setting Rehabilitation hospital setting. Participants Fourteen people undergoing primary lumbar discectomy. Interventions Using a randomized design on two separate days, muscle endurance was evaluated during prone bridging and Biering-Sorensen tests. Each test was randomly performed under two cognitive conditions: 1) single task without cognitive condition and 2) self-regulated dual task (i.e., mathematical task). Outcomes measures The primary outcomes were time to failure and pain assessed by the Visual Analog Scale (VAS) from 0 to 100 mm. The secondary outcomes were kinesiophobia assessed by the Tampa Scale and disability assessed by the Oswestry Disability Index. Associations were tested using a repeated measures ANOVA with relevant interaction test. Results A significant interaction between condition x endurance tests x kinesiophobia (p = 0.005) was found. The post hoc comparison showed positive effects between cognitive conditions in both endurance tests (mean difference: prone bridging test 15.7 s [95% CI: 7.5 s to 24 s], p = 0.001 and Biering-Sorensen test 7.9 s [95% CI: 1.9 s to 14 s], p = 0.014). The linear regression analysis between TSK-11SV and the difference of time to failure between cognitive conditions showed a positive correlation only during the Biering-Sorensen test (r = 0.80, p = 0.001). Conclusion A self-regulated dual task increases trunk muscle endurance in patients after lumbar discectomy. The results suggest that the difference observed in time to failure between the single task and dual task is associated with fear avoidance, especially during back extension. This strategy seems especially relevant for patients with high levels of fear avoidance and may be used to improve trunk muscle endurance.