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Effects of spinal cord transcutaneous stimulation priming on single-leg balance control
Simone Zaccaron, Mattia D’Alleva, Lara Mari, Jacopo Stafuzza, Stefano Lazzer, Enrico Rejc
Simone Zaccaron, Mattia D’Alleva, Lara Mari, Jacopo Stafuzza, Stefano Lazzer, Enrico Rejc, Department of Medicine, University of Udine, Udine 33100, Friuli Venezia Giulia, Italy
Simone Zaccaron, Mattia D’Alleva, Lara Mari, Jacopo Stafuzza, Stefano Lazzer, Enrico Rejc, School of Sport Sciences, University of Udine, Udine 33100, Friuli Venezia Giulia, Italy
Simone Zaccaron, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona 37124, Veneto, Italy
Mattia D’Alleva, Department of Theoretical and Applied Sciences, eCampus University, Como 22060, Lombardy, Italy
Author contributions: Zaccaron S, D’Alleva M, Mari L, Stafuzza J, and Lazzer S contributed to data collection; Zaccaron S and Rejc E designed the study, performed data analysis, prepared figures, interpreted the results of experiments and drafted the manuscript; Rejc E conceived the research. All authors edited and read the manuscript, and agreed to its published version.
Institutional review board statement: The experimental protocol was conducted in accordance with the Declaration of Helsinki and was approved by the Institutional Review Boards of the University of Udine (Approval No. 197/2023).
Clinical trial registration statement: The study was not formally registered in a clinical trial database. This pilot human study was designed to investigate mechanisms of balance control, and not health-related outcomes.
Informed consent statement: Before the start of the study, subjects were carefully informed about its purpose and risks, and written informed consent was obtained from all of them.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
CONSORT 2010 statement: The authors have read the CONSORT 2010 Statement, and the manuscript was prepared and revised according to the CONSORT 2010 Statement.
Data sharing statement: The datasets generated and analyzed during the current study are available from the corresponding author through material transfer agreement upon reasonable request.
Corresponding author: Enrico Rejc, PhD, Associate Professor, Department of Medicine, University of Udine, Piazzale Kolbe 4, Udine 33100, Friuli Venezia Giulia, Italy.
enrico.rejc@uniud.it
Received: December 3, 2025
Revised: January 11, 2026
Accepted: February 25, 2026
Published online: June 20, 2026
Processing time: 146 Days and 2.4 Hours
BACKGROUND
Balance control relies on proprioceptive, visual and vestibular inputs, contributing to functional performance and injury prevention. Neuromodulation strategies targeting the spinal circuitry controlling lower limbs are emerging as potential approaches to enhance lower limb neuromuscular performance. For example, non-invasive lumbosacral spinal cord transcutaneous stimulation (scTS) applied to prime the nervous system can improve lower limb performance during repeated, high-level efforts. However, it is unclear whether such neural priming approach can influence low-level motor outcomes and balance control.
AIM
To assess the effects of scTS priming on single-leg stance balance control with and without visual input.
METHODS
Twelve young active males (age: 22.7 ± 2.1 years) participated in this randomized crossover, sham-controlled study. Single-leg stance balance control with eyes open and eyes closed was assessed before and after the priming protocol with scTS or sham stimulation for approximately 25 minutes over a total of two different experimental sessions. Anterior-posterior, medio-lateral and a composite of the two directions were assessed on the force platform as well as electromyography of tibialis anterior (TA) and medial gastrocnemius muscles.
RESULTS
Priming protocols with scTS or sham application did not influence single-leg stance performance, as reflected by trial duration, kinetic and electromyography outcomes (priming effect: P-values ranging from 0.343 to 0.759). A significant effect of vision emerged, with shorter trial duration (P = 0.018), larger anterior-posterior (P = 0.004), medio-lateral (P < 0.001) and total displacement (P < 0.001), as well as longer co-contraction between TA and medial gastrocnemius (P < 0.001) with eyes closed compared to eyes open. Also, a time × priming × eyes interaction was found for the TA muscle activation (P = 0.046), indicating increased TA activation at the end vs beginning of eyes open trials following scTS priming.
CONCLUSION
The scTS priming did not affect single-leg stance balance performance under both eyes closed and open conditions. Also, as expected, impaired balance control was found with eyes closed.
Core Tip: Previous studies showed that non-invasive, spinal cord transcutaneous stimulation (scTS) priming can improve lower limb neuromuscular performance during high-intensity, fatiguing efforts but not during a low-level, torque steadiness task. Here, balance control with eyes open and eyes closed was assessed before and after the application of scTS or sham stimulation. scTS did not affect single-leg stance balance control in young active males. Also, as expected, balance control was impaired with visual deprivation (i.e., eyes closed). These findings, together with previous observations, contribute to define the potential framework and applications of scTS priming.
