Effective unilateral/bilateral robot-assisted training for upper limb motor function rehabilitation: a cross-sectional study

Guang Feng; Guohong Chai; Jiaji Zhang; Tao Song; Changcheng Shi; Jialin Xu; Guokun Zuo

doi:10.3389/fnhum.2025.1571624

Effective unilateral/bilateral robot-assisted training for upper limb motor function rehabilitation: a cross-sectional study

Front Hum Neurosci. 2025 Jun 18:19:1571624. doi: 10.3389/fnhum.2025.1571624. eCollection 2025.

Authors

Guang Feng^#^{1

2}, Guohong Chai^#^{1

3}, Jiaji Zhang^{1

3}, Tao Song^{1

3}, Changcheng Shi^{1

3}, Jialin Xu^{1

3}, Guokun Zuo^{1

3}

Affiliations

¹ Laboratory of Advanced Theranostic Materials and Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, China.
² Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, China.
³ Ningbo Cixi Institute of Biomedical Engineering, Ningbo, China.

^# Contributed equally.

Abstract

Objective: The therapeutic effect of robot-assisted training is still indecisive due to the lack of patient-tailored protocols and dose-matched training strategies when compared to traditional treatment. The objective of this study was to investigate the optimal robot-assisted training strategies for the upper limb functional recovery in hemiparetic stroke patients.

Approach: A bilateral upper limb rehabilitation robot was employed to execute unilateral and bilateral training. Eighteen able-bodied subjects were recruited to test the effective of robot-assisted training strategies before transferring them to stroke patients. We compared unilateral passive training (UPT), bilateral passive training (BPT), and unilateral active training (UAT) with various feedback types (visual, force, and visual-force, none). These trainings were performed on three kinds of virtually-guided (straight-line, circular, S-shaped) tasks. Tracking error (TE), interactive force (IF) and target muscle activation level were quantified to characterize the motion capability and active participation of subjects.

Main results: Results revealed that BPT-visual (0.63 ± 0.26) significantly increased muscle activation level when compared to those of BPT-none (0.45 ± 0.27) and UPT-visual (0.24 ± 0.05) (p < 0.01). UAT with single-modality feedback (visual/force) enabled higher TE (22.5 ± 3.40 mm) and active participation (0.78 ± 0.12) when compared with UAT with multi-modality (visual-force) feedback (TE: 6.6 ± 0.8 mm; activation level: 0.53 ± 0.13) (p < 0.01). The relatively complex circular and S-shaped tasks significantly enhanced the benefits of various training strategies.

Significance: The current outcomes provide valuable guidelines for designing individualized robot-assisted training protocols, potentially promoting the clinical rehabilitation effect.

Keywords: motor function recovery; multiple-modality feedback; rehabilitation robot; training strategy; unilateral/bilateral training.