Sensor-based assessment of the acute effects of NMES combined with weighted squats on muscle activation and lower limb joint coordination during the stop-and-cut task.

Background: The stop-and-cut (SAC) is a key movement pattern in many competitive sports and directly influences braking, directional transition, and re-acceleration performance. However, the acute effects of neuromuscular electrical stimulation (NMES) combined with weighted squats on SAC-related performance, muscle activation, and lower limb joint coordination remain unclear. Methods: Thirty-six male basketball athletes were randomly assigned to a loaded squat group (LS), a sham stimulation combined with loaded squat group (SSLS), or a true stimulation combined with loaded squat group (TSLS). A randomized, single-blind, pre-post intervention design was adopted. The key feature of this study was the integration of external performance testing with synchronized motion-sensor assessment during the SAC task, including surface electromyography, infrared 3D motion capture, and force plate data. V-cut test performance was used as the external indicator, while root mean square (RMS), integrated electromyography (iEMG), and lower limb joint coordination variables were extracted during the SAC support phase. A 3-group × 2-time mixed-design ANOVA was used for statistical analysis. Results: Only the TSLS group showed a significant improvement in V-cut test performance, with a significant intervention effect observed (F = 16.27, P< 0.001, η² = 0.606). During the SAC full support phase, significant group × time interactions in RMS were found for GM (F = 14.62, P< 0.001, η² = 0.587), VM (F = 13.48, P< 0.001, η² = 0.565), and BF (F = 12.91, P< 0.001, η² = 0.551). Similar significant interactions in iEMG were also observed for GM (F = 15.26, P< 0.001, η² = 0.601), VM (F = 14.11, P< 0.001, η² = 0.578), and BF (F = 13.37, P< 0.001, η² = 0.562). For lower limb joint coordination, more evident significant effects were observed in the hip-knee and knee-ankle couplings, whereas fewer significant changes were found in the hip-ankle coupling. Conclusion: NMES combined with weighted squats was more effective than weighted squats alone or sham stimulation combined with weighted squats in acutely improving SAC-related performance. This improvement was accompanied by enhanced activation of key lower limb muscles and more evident changes in lower limb joint coordination, suggesting that this combined intervention may be an effective acute strategy for improving SAC-related movement performance and control.