{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T15:14:14Z","timestamp":1781882054813,"version":"3.54.5"},"reference-count":33,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T00:00:00Z","timestamp":1768780800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005739","name":"Universidad Nacional Aut\u00f3noma de M\u00e9xico","doi-asserted-by":"publisher","award":["TA101324"],"award-info":[{"award-number":["TA101324"]}],"id":[{"id":"10.13039\/501100005739","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medical Sciences"],"abstract":"<jats:p>Background: Rate-dependent depression of the Hoffmann reflex (RDD-HR) is a neurophysiological marker of spinal inhibition altered in several neurological conditions, yet no consensus exists on optimal stimulation frequency, number of stimuli, or the feasibility of upper limb recordings. This study aimed to define practical, standardized parameters for reliable RDD-HR assessment in upper and lower limbs of healthy adults, as a first step toward clinical application. Methods: In this observational study, bilateral Hoffmann reflexes were recorded from the flexor carpi radialis and soleus muscles in 21 healthy adults. Stimulation was delivered using three 10-pulse trains at seven frequencies (0.1\u20135 Hz). RDD-HR was quantified as the median H-reflex area, expressed as a percentage of the first response (lower values indicate greater depression). Optimal frequencies and minimal stimuli were identified by sigmoid fitting and confidence analyses, with train and stimulus effects tested by two-way ANOVA. Results: RDD-HR displayed a sigmoidal frequency\u2013response across all limbs. Maximal depression occurred at 1\u20135 Hz, with no significant differences between these frequencies, supporting 1 Hz as optimal. Depression was greater in lower limbs (~30%) than upper limbs (~47%). Reliable estimates were obtained using a single train of seven stimuli, with no benefit from averaging across trains. Upper limb recordings required lower stimulation intensities. Conclusions: RDD-HR can be reliably assessed using a simplified protocol based on a single seven-pulse train at two key frequencies. This standardized approach provides a methodological foundation for future clinical validation of RDD-HR as a biomarker of spinal inhibitory dysfunction.<\/jats:p>","DOI":"10.3390\/medsci14010050","type":"journal-article","created":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T11:35:27Z","timestamp":1768822527000},"page":"50","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Optimizing Hoffmann Reflex Rate-Dependent Depression: A Feasible Protocol for Assessing Spinal Inhibition in Upper and Lower Limbs"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-0439-8499","authenticated-orcid":false,"given":"Andrea S.","family":"Ce\u00f1al Cisneros","sequence":"first","affiliation":[{"name":"Departamento de Fisiologia, Facultad de Medicina, Universidad Nacional Aut\u00f3noma de M\u00e9xico, Mexico City 04360, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3048-3640","authenticated-orcid":false,"given":"Rodolfo","family":"Delgado-Lezama","sequence":"additional","affiliation":[{"name":"Departamento de Fisiolog\u00eda, Biof\u00edsica y Neurociencias, Cinvestav, Mexico City 07300, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9404-3914","authenticated-orcid":false,"given":"Carlos A.","family":"Cuellar","sequence":"additional","affiliation":[{"name":"School of Sport Sciences, Universidad An\u00e1huac M\u00e9xico, Huixquilucan 52786, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9982-7571","authenticated-orcid":false,"given":"Oscar","family":"Arias-Carri\u00f3n","sequence":"additional","affiliation":[{"name":"Divisi\u00f3n de Neurociencias Cl\u00ednica, Instituto Nacional de Rehabilitaci\u00f3n Luis Guillermo Ibarra Ibarra, Mexico City 14389, Mexico"},{"name":"Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Mexico City 14380, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0765-060X","authenticated-orcid":false,"given":"Isabel","family":"Ruelas Galindo","sequence":"additional","affiliation":[{"name":"Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnolog\u00eda, UNAM, Cuernavaca 62210, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mario","family":"V\u00e1zquez Garc\u00eda","sequence":"additional","affiliation":[{"name":"Departamento de Fisiologia, Facultad de Medicina, Universidad Nacional Aut\u00f3noma de M\u00e9xico, Mexico City 04360, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paulina","family":"Cervantes Sosa","sequence":"additional","affiliation":[{"name":"Departamento de Fisiologia, Facultad de Medicina, Universidad Nacional Aut\u00f3noma de M\u00e9xico, Mexico City 04360, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0934-0699","authenticated-orcid":false,"given":"Luis A.","family":"Mart\u00ednez Zald\u00edvar","sequence":"additional","affiliation":[{"name":"Departamento de Fisiologia, Facultad de Medicina, Universidad Nacional Aut\u00f3noma de M\u00e9xico, Mexico City 04360, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1667-2253","authenticated-orcid":false,"given":"Emmanuel","family":"Ortega-Robles","sequence":"additional","affiliation":[{"name":"Divisi\u00f3n de Neurociencias Cl\u00ednica, Instituto Nacional de Rehabilitaci\u00f3n Luis Guillermo Ibarra Ibarra, Mexico City 14389, Mexico"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,19]]},"reference":[{"key":"ref_1","first-page":"268","article-title":"The hoffmann reflex: Methodologic considerations and applications for use in sports medicine and athletic training research","volume":"39","author":"Palmieri","year":"2004","journal-title":"J. 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