Spinal Direct Current Stimulation and dorsiflexor motor performance

Purpose: To determine the effect of anodal, cathodal, and sham Transcutaneous Spinal Direct Current Stimulation (TSDCS) on motor actions of the dorsiflexor muscles during fatiguing and non-fatiguing contractions. Hypothesis: Cathodal and anodal TSDCS would produce distinct motor-performance modulations compared with sham. Methods: 17 participants (mean age: 26.6 ± 8.6; 9 women and 10 men) received 3 different conditions of TSDCS (anodal, cathodal, and sham) on separate test sessions. TSDCS was delivered at 2.5 mA for 15 minutes (charge density: 0.018 mAh/cm2) with an active electrode on T10 and two reference electrodes on the iliac crests. Rate of force development (RFD) was measured at 50, 100, and 200 ms from the onset of a maximal explosive contraction. Force fluctuations at 5% and 10% of the maximal voluntary contraction (MVC) was quantified using the coefficient of variation (CV) of force. Performance fatigability was quantified as the reduction in force from the beginning to the end of a 60-second MVC. Results: RFD was similar across TSDCS conditions for anodal, cathodal and sham (P > 0.05) (50 ms: 289.1 ± 145.7, 299.7 ± 121.4, 314.2 ± 126, respectively; 100 ms: 411.9 ± 131.1, 424.9 ± 116.2, 452.3 ± 110.3, respectively, 200 ms: 366.2 ± 50.7, 366.9 ± 54, 380.9 ± 44.8, respectively). The percentage reduction in force during the 60-second MVC was similar across anodal, cathodal and sham (47.8 ± 7.9, 48.9 ± 10.5, 43.7 ± 10.5%, respectively, condition effect: P > 0.05). Force fluctuations were higher in women than men (5%MVC: 6.3 ± 1.7% vs 3.7 ± 1.1%; 10%MVC: 3.3 ± 0.9 vs 2.2 ± 0.6%, respectively; sex effect: P < 0.001 for both intensities), but without TSDCS effect. Conclusion: These preliminary data suggest that TSDSC does not alter dorsiflexor motor performance during maximal and submaximal isometric contractions in healthy young individuals. Future studies should investigate different TSDCS applications and populations. Funding Sources: This project was supported through a Research Fellowship granted by the College of Arts and Sciences at the University of Oklahoma. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.