Author Identifier (ORCID)
Abstract
Transcutaneous spinal stimulation aims to target dorsal spinal roots, which deliver sensory information to the spinal cord. However, the stimulation waveform that most effectively recruits sensory fibers at the lowest intensity has not been identified. The purpose of this study was to compare conventional and high-frequency burst-modulated stimulation waveforms in their ability to recruit sensory fibers, as assessed by H-reflex threshold, recruitment characteristics, and motor fiber activation. In participants with intact neurological function (n ¼ 12), soleus H-reflex recruitment curves were recorded for 10 stimulation waveforms: a conventional waveform (400 μs), serving as the reference condition, high-frequency burst-modulated waveforms (2, 5, and 10 kHz) with the same total phase duration, and a longer conventional waveform (1,000 μs), each delivered as biphasic and monophasic pulses. H-reflex threshold was higher for high-frequency waveforms: 2 kHz (biphasic: þ 63%, monophasic: þ 35%); 5 kHz (biphasic: þ 179%, monophasic: þ 109%); 10 kHz (biphasic: þ 307%, monophasic: þ 249%); and lower for the conventional 1,000 μs waveform (biphasic: ‒39%, monophasic: ‒44%). Similarly, recruitment curve peak slope (mV/mA) was less steep for high-frequency waveforms: 2 kHz (biphasic: ‒43%, monophasic: ‒40%); 5 kHz (biphasic: ‒77%, monophasic: ‒40%); 10 kHz (biphasic: ‒82%, monophasic: ‒48%); and increased (þ 38%) for the monophasic conventional 1,000 μs waveform. At stimulus intensity near the H-reflex threshold, M-wave amplitude was larger for high-frequency waveforms. Overall, high-frequency waveforms were less effective than conventional waveforms of equal phase duration at eliciting H-reflexes and showed more motor activation at near-threshold intensities.
Keywords
biphasic/monophasic pulse, H-reflex, high-frequency kilohertz waveforms, neurostimulation, peripheral nerve stimulation
Document Type
Journal Article
Date of Publication
7-1-2026
E-ISSN
15221601
ISSN
87507587
Volume
141
Issue
1
PubMed ID
42268699
Publication Title
Journal of Applied Physiology
Publisher
American Physiological Society
School
School of Medical and Health Sciences
RAS ID
101787
Funding Information
Funding for this study has been received from SpinalCure Australia and Catwalk NZ. S.C.G. is supported by the National Health and Medical Research Council of Australia (NHMRC 2020/GNT1195699). J.P. is supported by the Fonds de recherche du Québec Health https://doi.org/10.69777/325828 (Canada) and by the University International Postgraduate Award from UNSW (Australia).
Funding received from the National Health and Medical Research Council (NHMRC)
2020/GNT1195699
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
First Page
246
Last Page
260
Recommended Citation
Provencher, J., Finn, H. T., Taylor, J. L., Gandevia, S. C., Butler, J. E., & Héroux, M. E. (2026). Peripheral nerve sensory fibers are recruited with less current and greater selectivity by conventional waveforms compared with high-frequency waveforms. Journal of Applied Physiology, 141(1), 246–260. https://doi.org/10.1152/japplphysiol.00920.2025