Effect of dual-task-induced uncertainty on gait biomechanics in patients with multiple sclerosis with 2-6.5 EDSS grade

•Dual-task-induced uncertainty causes a reduction in the mean stride length and displacement and horizontal velocity of the CM in MS patients.•Balance is severely influenced by uncertainty, as compared to situations without uncertainty in patients with SM.•Uncertainty caused by dual-tasking should be incorporated intentionally and in a controlled way into physical exercise programs for MS patients. This would help persons with MS to increase their balance in daily activities and avoid fall incidents.

The goal of this study was to assess the effect that uncertainty induced by dual task conditions has on reaction-response time parameters and gait patterns of patients with multiple sclerosis (MS) with a 2-6.5 EDSS grade. The study involved eleven patients - nine women and two men - diagnosed with multiple sclerosis (age, 48 ± 10 years; height, 1.65 ± 0.1 m; weight, 72 ± 22 kg) with capacity to walk five meters without any aid or assistance. We employed an intra-group repeated measures design. Each participant was asked to walk with and without task-related uncertainty. Reaction-response and gait cycle times, as well as center of mass (CM) dynamics were measured using three force plates synchronized with a video camera through an electronic device that also controlled the system of uncertainty. The results obtained reveal that uncertainty induced by dual tasking is related to a reduction in the mean stride length and mean displacement and horizontal velocity of the CM in patients with MS. The values obtained for CM parameters indicate that uncertainty affects balance, as compared to no-uncertainty situations. These results confirm the necessity of including controlled dual-task-induced uncertainty in physical training programs for MS patients.