Table I. —List of suggestions for future longitudinal studies based on muscle synergies.

Aspect	Suggestions
Enrolled patients and volunteers	Detailed characterization of the study population. Larger sample size. Patient-specific analyses to minimize inter-subject variability. Careful selection of control groups for accurate comparisons. Uniform definition of stroke type and recovery stage.
Types of interventions	Optimization of robotic devices and protocols for effectiveness. Investigation of different forms of robotic assistance. Exploration of muscle synergies across various rehabilitative contexts.
Protocols for rehabilitation sessions	Incorporation of movement variability in protocols. Comparison between patient’s affected and unaffected limb and healthy subject’s limb. Introduction of complex, 3D and multi-planar movements. Personalized rehabilitation programs based on muscle synergies.
Protocols for synergy extraction	Use of diverse models and algorithms for synergy extraction. Consideration of temporal coefficients in synergy analyses. Standardization of electrode positioning. Training and familiarization of subjects with experimental tasks.
Variation of the number of synergies	Investigation of the impact of interventions on muscle synergy number. Understanding of the relationship between synergy number and motor impairment severity. When possible, avoid fixing the number of synergies a priori. Use multiple R2/VAF thresholds or more accurate methods for determining the number of muscle synergies.
Variation of synergies structure	Examination of how interventions impact muscle synergy structure. Understanding of the relationship between muscle synergy structure and motor function recovery.
Variation of temporal coefficients	Emphasis on changes in temporal coefficients post-intervention. Exploration of the relationship between temporal coefficients and motor function recovery.
Clinical and instrumental findings	Investigation of the relationship between muscle synergies and clinical outcomes. Use of multidomain assessments (e.g., kinematics, EEG). Exploration of muscle synergies as a biomarker for motor impairment and recovery.