Development of an Integral Index of Loaded Walking Based on Biomechanical and Electromyographic Parameters

Introduction. Walking with additional load, such as a backpack, weights, or specialized equipment, has a significant effect on the musculoskeletal system. Carrying extra weight increases the load on the lower limb joints, enhances muscular activity, and modifies the spatiotemporal characteristics of gait, which is accompanied by increased energy expenditure. Notably, these effects depend not only on the mass but also on the distribution of the load. Contemporary studies are increasingly employing the integration of biomechanical, kinetic, and electromyographic data to quantitatively assess the body’s adaptation mechanisms to external loading. The development of integrated metrics for loaded walking is relevant for objective characterization of the biomechanical cost of different loading conditions, being promising for application in sports science, ergonomics, military training, and clinical practice.

Aim. To develop an integral index that quantitatively reflects changes in human gait under two external loads: 3 kg attached to the lower legs and 12 kg evenly distributed in a backpack. A functional analysis of loaded human gait, represented by a set of biomechanical and electromyographic parameters, was carried out.

Materials and methods. Seven healthy volunteers were subjected to examination using the methods of 3D optical motion capture and simultaneous surface electromyography from seven muscle groups. The primary trajectories were processed in QTM, exported to TXT/TSV, and further organized by Python scripts. The aggregated values (maximum, minimum, ROM) were automatically transferred to Excel. Inter-parameter dependencies were examined using Spearman’s correlation coefficient. The statistical significance of individual changes was assessed using the Friedman test followed by cluster analysis.

Results. An integral index (I_total) using global min–max normalization and equal weighting of the selected metrics was developed.

Conclusion. Distal loading increases double-support time and decreases step frequency, whereas proximal loading alters muscle activation patterns and pelvic positioning, partially normalizing spatiotemporal gait parameters. The proposed integral index combines changes in biomechanical and EMG parameters, enabling a quantitative assessment of the biomechanical cost associated with the applied load.

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