Symmetrical resistance training induces corticospinal and cortical network plasticity; however, the neural consequences of asymmetrical resistance training (offset loading or OL) remain unclear. In this preliminary study, fourteen healthy adults completed eighteen supervised upper-extremity training sessions over a 6-week intervention period. Participants were allocated to either an offset loading (OL) intervention group (n = 8) or a conventional symmetrical resistance training active control group (AC; n = 6). Electroencephalography (EEG) recordings were acquired during motor task performance at baseline, 3 weeks, and 6 weeks. Directed functional connectivity among predefined cortical regions was quantified, and longitudinal changes were assessed using Friedman tests with false-discovery-rate correction for multiple comparisons. Significant changes in the OL group were observed involving two cortical pathways after correction for multiple testing. Connectivity from the right parietal cortex to the right sensorimotor cortex increased over time (Friedman χ² = 8.00, q = 0.037), with post hoc analyses showing a significant increase between the midpoint and post-training assessments (q = 0.047; effect size r = 0.894). No significant longitudinal changes in cortical connectivity were identified in the AC group. Six weeks of OL training was associated with selective strengthening of directed connectivity within prefrontal-to-sensorimotor and parietal-to-sensorimotor cortical pathways. In contrast, conventional symmetrical resistance training was not associated with detectable changes in connectivity. These findings suggest that asymmetrical loading may induce task-specific reorganization of cortical networks involved in sensorimotor processing and motor control.

Purpose Resistance training induces corticospinal and cortical network plasticity; however, the neural consequences of offset loading (OL) remain unclear. We examined how six weeks of upper-extremity OL affects brain connectivity in healthy adults. Methods Fourteen participants completed 18 supervised sessions of OL or conventional symmetrical training (active control, AC), with EEG recordings taken during motor tasks to track brain communication. Results OL strengthened the connection from the left prefrontal to left sensorimotor cortex (Friedman χ ² = 8.00, p = 0.018; Pre vs. Post Wilcoxon p = 0.016), indicating enhanced cognitive control of movement. There was also increased functional connectivity from the right parietal to right sensorimotor cortex, reflecting improved sensory-motor integration. These changes were not seen in the AC group, nor were any significant interhemispheric changes observed. Conclusion This suggests that OL selectively targets specific cortical networks rather than inducing widespread connectivity changes across the brain. By challenging coordination and motor planning simultaneously, OL appears to promote meaningful, task-specific brain plasticity. These findings highlight a promising approach to enhancing brain function, with potential applications in neurorehabilitation, skill training, and injury prevention.