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ORIGINAL RESEARCH article

Front. Bioeng. Biotechnol.

Sec. Biomechanics

Volume 13 - 2025 | doi: 10.3389/fbioe.2025.1585127

This article is part of the Research TopicEnhancing Sports Injury Management through Medical-Engineering InnovationsView all 15 articles

Assessment of Synergy-Assisted EMG-Driven NMSK Model for Upper Limb Muscle Activation Prediction in Cross-Country Sit-Skiing Double Poling

Provisionally accepted
Xue  ChenXue Chen1Zhongxue  YuanZhongxue Yuan2Xianzhi  GaoXianzhi Gao1Yanxin  ZhangYanxin Zhang2Chenglin  LiuChenglin Liu3*Bo  HuoBo Huo3*
  • 1Beijing Institute of Technology, Beijing, Beijing Municipality, China
  • 2The University of Auckland, Auckland, Auckland, New Zealand
  • 3Capital Institute of Physical Education and Sports, Beijing, China

The final, formatted version of the article will be published soon.

Cross-country sit-skiers are often individuals with spinal cord injuries, cerebral palsy, or lower limb disabilities, relying heavily on upper limb strength to generate propulsion during skiing. However, frequent shoulder joint movements significantly increase the incidence of shoulder joint disorders. Therefore, quantifying muscle forces during movement is crucial for understanding upper limb force generation patterns. Currently, electromyography (EMG)-driven neuromusculoskeletal (NMSK) models are the predominant method for calculating muscle forces and joint moments. However, this approach heavily depends on the quality and quantity of EMG data. Surface electrodes are typically used to collect activity data from superficial muscles, but during dynamic movements, factors such as skin stretching, sweating, or friction may cause electrode detachment or poor contact, leading to EMG signal acquisition failures or data loss. In this study, we propose a synergy-assisted EMGdriven NMSK model to predict the activation patterns of missing muscles for cross-country sit-skiing double poling. This method is based on individualized EMG-driven NMSK models constructed for each participant, incorporating data from 10 muscles. By utilizing the activation data of 9 known muscles, the model predicts the activation of one missing muscle through synergy analysis. For synergy method selection, we systematically compared four approaches: Non-negative Matrix Factorization (NMF), Principal Component Analysis (PCA), Independent Component Analysis (ICA), and Factor Analysis (FA). The results demonstrated NMF's superior performance at 5 synergies, accurately predicting any missing muscle activation among 10 muscles ( r = 0.79 ± 0.25 vs. 0.14 ± 0.60-0.45 ± 0.63 for alternatives, p < 0.05), with lower errors (RMSE: 0.21 ± 0.11, p < 0.05 vs. ICA/FA, p < 0.1 vs. PCA; MAE: 0.17 ± 0.09, all p < 0.05). This finding validates the effectiveness of the proposed method in predicting upper limb muscle activation during coupled shoulder and elbow joint movements.

Keywords: EMG-Driven model, Muscle Synergy, cross-country sit-skiing, Muscle activation, Upper limb

Received: 28 Feb 2025; Accepted: 31 Jul 2025.

Copyright: © 2025 Chen, Yuan, Gao, Zhang, Liu and Huo. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Chenglin Liu, Capital Institute of Physical Education and Sports, Beijing, China
Bo Huo, Capital Institute of Physical Education and Sports, Beijing, China

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