{"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":1781882054828,"version":"3.54.5"},"reference-count":30,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T00:00:00Z","timestamp":1770336000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background\/Objectives: Spinal excitability may undergo adaptive modulation in response to training load, sport-specific demands, and fatigue. While high-impact sports are known to influence reflex responsiveness, the extent to which these changes differ from athletes in lower-impact disciplines remains unclear. This study aimed to investigate post-exercise changes in Hmax\/Mmax ratio among trained runners with varied sport backgrounds, and to identify emergent physiological profiles that may reflect differential spinal adaptation to fatigue. Methods: Twenty-two trained athletes underwent unilateral H-reflex testing before and after treadmill running performed to voluntary exhaustion. Amplitudes of the H-reflex and M-wave were recorded, and Hmax\/Mmax ratios were analyzed. Based on a physiologically relevant threshold commonly used to distinguish normal from suppressed reflex amplitudes, participants were post hoc classified into three groups: Group A (pre- and post-test ratios above threshold), Group B (pre above, post below), and Group C (both below). A two-way repeated-measures ANOVA was used to assess between-group effects. Results: Significant differences were found across groups and conditions (p &lt; 0.001). Group A maintained reflex ratios above the threshold, indicating stable excitability. Group B showed the greatest suppression (approximately 66%), transitioning from normal to subthreshold values. Group C remained consistently below-threshold. A significant interaction (p &lt; 0.0001) confirmed that reflex modulation varied by physiological profile. A small but statistically significant reduction in H-reflex latency was also observed; however, this change remained within normal physiological variability. Conclusions: Postexercise H-reflex modulation revealed heterogeneous neuromuscular responses among athletes. These findings may contribute to understanding how sport-specific demands and fatigue shape spinal excitability and may help identify individuals with adaptive or potentially pathological profiles relevant to sports diagnostics.<\/jats:p>","DOI":"10.3390\/jcm15031297","type":"journal-article","created":{"date-parts":[[2026,2,6]],"date-time":"2026-02-06T10:05:47Z","timestamp":1770372347000},"page":"1297","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["The Gray Zone of H-Reflex in Runners: When Should We Suspect Pathology? A Pilot Study"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-8974-3189","authenticated-orcid":false,"given":"L. H. M. P.","family":"De Silva","sequence":"first","affiliation":[{"name":"Department of Physical Education, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego Str. 1, 80-336 Gdansk, Poland"},{"name":"Department of Sports Science, University of Sri Jayewardenepura,  Nugegoda 10250, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2312-4412","authenticated-orcid":false,"given":"Andriy","family":"Maznychenko","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego Str. 1, 80-336 Gdansk, Poland"},{"name":"Department of Movement Physiology, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str. 4, 01024 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6371-472X","authenticated-orcid":false,"given":"Andriy","family":"Gorkovenko","sequence":"additional","affiliation":[{"name":"Department of Movement Physiology, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str. 4, 01024 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9263-805X","authenticated-orcid":false,"given":"Olena","family":"Kolosova","sequence":"additional","affiliation":[{"name":"Department of Movement Physiology, Bogomoletz Institute of Physiology NAS of Ukraine, Bogomoletz Str. 4, 01024 Kyiv, Ukraine"},{"name":"Scientific Research Center, National University of Ukraine on Physical Education and Sport, Fizkultury Str. 1, 03150 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tetiana","family":"Abramovych","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego Str. 1, 80-336 Gdansk, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8759-630X","authenticated-orcid":false,"given":"Oleh V.","family":"Vlasenko","sequence":"additional","affiliation":[{"name":"Department of Biomedical Foundations of Physical Education and Physical Rehabilitation, Vinnytsia Mykhailo Kotsiubynskyi State Pedagogical University, Ostroz\u2019koho Str. 32, 21001 Vinnytsia, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7145-9957","authenticated-orcid":false,"given":"Vasyl","family":"Melenko","sequence":"additional","affiliation":[{"name":"Department of Spinal Surgery, State Institution \u201cInstitute of Traumatology and Orthopedics\u201d, National Academy of Medical Science of Ukraine, Bulvarno-Kudriavska Str. 27, 01054 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1314-8915","authenticated-orcid":false,"given":"Oleksii","family":"Sulyma","sequence":"additional","affiliation":[{"name":"Department of Spinal Surgery, State Institution \u201cInstitute of Traumatology and Orthopedics\u201d, National Academy of Medical Science of Ukraine, Bulvarno-Kudriavska Str. 27, 01054 Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-9528-1954","authenticated-orcid":false,"given":"Tetyana","family":"Poruchynska","sequence":"additional","affiliation":[{"name":"Department of Anatomy, Normal and Pathological Physiology, Lesia Ukrainka Volyn National University, Voli Ave. 13, 43025 Lutsk, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Inna","family":"Sokolowska","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Gdansk University of Physical Education and Sport, Kazimierza Gorskiego Str. 1, 80-336 Gdansk, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,6]]},"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. Athl. Train."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1002\/(SICI)1097-4598(199804)21:4<439::AID-MUS2>3.0.CO;2-A","article-title":"Presynaptic and postsynaptic mechanisms underlying H-reflex changes produced by a selective voluntary contraction","volume":"21","author":"Abbruzzese","year":"1998","journal-title":"Muscle Nerve"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"144","DOI":"10.1002\/mus.10372","article-title":"The H-reflex as a tool in neurophysiology: Its limitations and uses in understanding nervous system function","volume":"28","author":"Misiaszek","year":"2003","journal-title":"Muscle Nerve"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Aslam, S., Habyarimana, J.D.D., and Bin, S.Y. (2025). Neuromuscular adaptations to resistance training in elite versus recreational athletes. Front. Physiol., 16.","DOI":"10.3389\/fphys.2025.1598149"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"424","DOI":"10.1002\/mus.26639","article-title":"Utility of the H-reflex in diagnosing polyneuropathy","volume":"60","author":"Teigland","year":"2019","journal-title":"Muscle Nerve"},{"key":"ref_6","first-page":"427","article-title":"Neurophysiological Assessment of H-Reflex Alterations in Compressive Radiculopathy","volume":"73","year":"2024","journal-title":"Physiol. Res."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"19","DOI":"10.51371\/issn.1840-2976.2021.15.S1.3","article-title":"Running-induced changes in H-reflex amplitudes in non-trained men","volume":"15","author":"Maznychenko","year":"2021","journal-title":"Acta Kinesiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2309","DOI":"10.1152\/japplphysiol.01185.2001","article-title":"Neural adaptation to resistance training: Changes in evoked V-wave and H-reflex responses","volume":"92","author":"Aagaard","year":"2002","journal-title":"J. Appl. Physiol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e2023065129","DOI":"10.1542\/peds.2023-065129","article-title":"Overuse injuries, overtraining, and burnout in young athletes","volume":"153","author":"Brenner","year":"2024","journal-title":"Pediatrics"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2325967114528862","DOI":"10.1177\/2325967114528862","article-title":"High prevalence of disc degeneration and spondylolysis in the lumbar spine of professional beach volleyball players","volume":"2","author":"Florianz","year":"2014","journal-title":"Orthop. J. Sports Med."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1186\/s40798-019-0199-7","article-title":"Lumbar spine injuries in sports: Review of the literature and current treatment recommendations","volume":"5","author":"Ball","year":"2019","journal-title":"Sports Med. Open"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1016\/j.autneu.2014.10.018","article-title":"Autonomic responses to exercise: Group III\/IV muscle afferents and fatigue","volume":"188","author":"Amann","year":"2015","journal-title":"Auton. Neurosci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/0003-9993(94)90327-1","article-title":"Normal limits of side-to-side H-reflex amplitude variability","volume":"75","author":"Jankus","year":"1994","journal-title":"Arch. Phys. Med. Rehabil."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"216","DOI":"10.1249\/MSS.0000000000003038","article-title":"Effects of 12 wk of omega-3 fatty acid supplementation in long-distance runners","volume":"55","author":"Tomczyk","year":"2022","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_15","first-page":"165","article-title":"M-wave stability in H-reflex testing: Analysis of three rejection criteria","volume":"35","author":"Allison","year":"1995","journal-title":"Electromyogr. Clin. Neurophysiol."},{"key":"ref_16","first-page":"204","article-title":"Reliability of the FCR H-reflex","volume":"22","author":"Christie","year":"2005","journal-title":"J. Clin. Neurophysiol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1152\/japplphysiol.00802.2011","article-title":"Changes in H reflex and V wave following short-term endurance and strength training","volume":"112","author":"Falla","year":"2012","journal-title":"J. Appl. Physiol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"68","DOI":"10.3200\/JMBR.39.1.68-78","article-title":"Training-specific adaptations of H- and stretch reflexes in human soleus muscle","volume":"39","author":"Gruber","year":"2007","journal-title":"J. Mot. Behav."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1249\/01.mss.0001155908.41534.32","article-title":"Chronic Adaptations To Resistance Training Of Soleus H-reflex: 540","volume":"57","author":"Ashcraft","year":"2025","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Schumann, M., and R\u00f8nnestad, B. (2019). Neural Adaptations to Endurance Training. Concurrent Aerobic and Strength Training, Springer.","DOI":"10.1007\/978-3-319-75547-2"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1725","DOI":"10.1152\/physrev.2001.81.4.1725","article-title":"Spinal and supraspinal factors in human muscle fatigue","volume":"81","author":"Gandevia","year":"2001","journal-title":"Physiol. Rev."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1242\/jeb.123158","article-title":"Neural control of lengthening contractions","volume":"219","author":"Duchateau","year":"2016","journal-title":"J. Exp. Biol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"287","DOI":"10.1113\/jphysiol.1991.sp018596","article-title":"Dynamic control of muscle stiffness and H reflex modulation during hopping and jumping in man","volume":"437","author":"Simonsen","year":"1991","journal-title":"J. Physiol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1113\/jphysiol.2007.136200","article-title":"The continuing case for the Renshaw cell","volume":"584","author":"Alvarez","year":"2007","journal-title":"J. Physiol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"867","DOI":"10.1002\/mus.1084","article-title":"Effects of temperature on neuromuscular electrophysiology","volume":"24","author":"Rutkove","year":"2001","journal-title":"Muscle Nerve"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1016\/S0733-8619(01)00004-4","article-title":"H reflexes and F waves Fundamentals, normal and abnormal patterns","volume":"20","author":"Fisher","year":"2002","journal-title":"Neurol. Clin."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1139\/h04-020","article-title":"Membrane excitability, weakness, and fatigue","volume":"29","author":"Green","year":"2004","journal-title":"Can. J. Appl. Physiol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2157","DOI":"10.1113\/JP286454","article-title":"The complex nature of skeletal muscle fatigue: Understanding the interaction of metabolic stress and membrane excitability","volume":"602","author":"Winther","year":"2024","journal-title":"J. Physiol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"5203","DOI":"10.1113\/JP282564","article-title":"Critical considerations of the contribution of the corticomotoneuronal pathway to central fatigue","volume":"600","author":"Amann","year":"2022","journal-title":"J. Physiol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"997","DOI":"10.1002\/j.2040-4603.2012.tb00427.x","article-title":"Skeletal muscle fatigue","volume":"2","author":"Fitts","year":"2012","journal-title":"Compr. 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