The Differential Impact of Cognitive Versus Motor Dual-Tasks on Lower Limb Neuromuscular Control during Gait: A Cognitive-Load Perspective

Sadeghi, Sara; Hajilou, Behrouz; Behrad, Behnam · 2026 · Crossref

DOI: 10.21203/rs.3.rs-8464573/v1

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Summary

This study investigates the differential neuromuscular impacts of cognitive versus motor dual-tasks on lower limb control during gait, addressing a gap in understanding how specific secondary tasks alter muscle activation patterns. While dual-task interference is known to disrupt gait, the distinct neuromuscular signatures of cognitive (e.g., mental arithmetic) versus motor (e.g., object carrying) secondary tasks remain poorly differentiated. Motivated by cognitive-load theories, specifically the Limited Capacity Model and Multiple Resource Theory, the authors hypothesized that cognitive tasks would elicit unique activation patterns reflecting greater demand on central executive resources compared to motor tasks. The experimental design involved twenty-four healthy adults who walked under three conditions: single-task (normal gait), cognitive dual-task (serial subtraction by threes), and motor dual-task (carrying a full glass of water). Surface electromyography recorded activity from eight lower limb muscles. Data were processed using bandpass filtering and normalized to peak activity within each gait cycle. Statistical analysis employed repeated-measures ANOVA to compare muscle activity intensity across conditions. Results revealed that dual-tasking significantly altered muscle activity for all muscles except the rectus femoris. Crucially, the type of secondary task dictated distinct activation patterns. The cognitive dual-task significantly increased activity in distal ankle muscles—specifically the medial gastrocnemius, soleus, and tibialis anterior—compared to both normal walking and the motor dual-task. Conversely, the motor dual-task primarily increased activity in proximal muscles, including the vastus medialis, vastus lateralis, and hamstrings, with hamstring activity being significantly higher during the motor task than the cognitive task. These findings confirm that cognitive and motor tasks compete for different resource pools, leading to divergent compensatory strategies. The study concludes that cognitive load acts as a primary driver of gait interference, inducing a "distal stiffening" strategy at the ankle to compensate for reduced attentional resources available for continuous gait adjustments. In contrast, motor tasks require proximal stabilization to manage external objects and balance. These findings imply that dual-tasking is not a uniform source of gait degradation but rather a probe for specific cognitive-motor integration processes. Clinically, this underscores the importance of task-specific assessment in fall risk evaluation and rehabilitation, suggesting that cognitive dual-tasks may be more sensitive indicators of executive function deficits, while motor dual-tasks better assess dynamic balance and limb coordination.

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• dual task performance