{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T10:12:11Z","timestamp":1784542331973,"version":"3.55.0"},"reference-count":48,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T00:00:00Z","timestamp":1784246400000},"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>Objectives: To determine whether acute oral hydration alters thoracolumbar fascia stiffness in healthy adults and to characterize concurrent changes in urine-specific gravity and bioimpedance-derived fluid compartments. Methods: In this prospective single-arm repeated-measures study, 50 healthy adults were assessed at baseline (T0), 60 min after ingestion of 2 L of water (T1), and 6 h later (T2). Thoracolumbar fascia stiffness was measured by shear wave elastography at four standardized points (P1\u2013P4). Hydration was assessed using urine specific gravity and bioimpedance-derived intracellular water, extracellular water, and the extracellular-to-intracellular water ratio. Repeated-measures analyses of variance and Holm-adjusted pairwise comparisons were used. Results: Urine specific gravity changed markedly over time (F(2,98) = 290.175, p &lt; 0.001, \u03b7p2 = 0.856), decreasing from 1.016 \u00b1 0.002 at T0 to 1.006 \u00b1 0.002 at T1, with partial return at T2 (1.014 \u00b1 0.002). Mean thoracolumbar fascia stiffness remained unchanged (45.88 \u00b1 2.01, 45.87 \u00b1 2.01, and 45.89 \u00b1 2.02 kPa at T0, T1, and T2, respectively; F(2,98) = 0.671, p = 0.514, \u03b7p2 = 0.013). The two-factor shear wave elastography model showed no effect of point (F(3,147) = 2.147, p = 0.097) and no time-by-point interaction (F(6,294) = 0.195, p = 0.978). Bioimpedance parameters also showed no significant change (all p \u2265 0.381). An exploratory correlation between change in urine specific gravity and change in mean stiffness was observed from T0 to T1 (r = \u22120.346, p = 0.028). Conclusions: In this single-arm repeated-measures study, acute oral water ingestion was followed by a clear urinary hydration response but by no detectable short-term within-participant change in thoracolumbar fascia stiffness or bioimpedance-derived fluid distribution in healthy adults. Because no non-hydration or placebo control condition was included, these findings should be interpreted as evidence of temporal stability under the tested protocol rather than as a definitive controlled estimate of the causal effect of hydration. Clinical Registration: ISRCTN96046168 (31 March 2026).<\/jats:p>","DOI":"10.3390\/jcm15145624","type":"journal-article","created":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T07:54:13Z","timestamp":1784534053000},"page":"5624","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Acute Oral Hydration and Thoracolumbar Fascia Stiffness in Healthy Adults"],"prefix":"10.3390","volume":"15","author":[{"given":"Beata","family":"Borecka","sequence":"first","affiliation":[{"name":"Physiotherapy Center \u201cBaterie Zdrowia\u201d, Zaj\u0105czki Drugie, 42-160 Krzepice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4543-0798","authenticated-orcid":false,"given":"Carla","family":"Gon\u00e7alves","sequence":"additional","affiliation":[{"name":"Escola Superior de Desporto e Lazer, Instituto Polit\u00e9cnico de Viana do Castelo, 4900-347 Viana do Castelo, Portugal"},{"name":"The Sport Physical Activity and Health Research & Innovation Center, 4900-347 Viana do Castelo, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9199-0721","authenticated-orcid":false,"given":"Hsing-Kuo","family":"Wang","sequence":"additional","affiliation":[{"name":"School and Graduate Institute of Physical Therapy, National Taiwan University, Taipei 106319, Taiwan"},{"name":"Center of Physical Therapy, National Taiwan University Hospital, Taipei 100229, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dariusz","family":"Ciborowski","sequence":"additional","affiliation":[{"name":"Body Medica Physiotherapy Center, ul. G\u00f3recka 108, 61-483 Pozna\u0144, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tomasz","family":"Senderek","sequence":"additional","affiliation":[{"name":"Department of Rehabilitation and Physiotherapy, Faculty of Health Sciences, Medical University of Lublin, 20-059 Lublin, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4276-4813","authenticated-orcid":false,"given":"Robert","family":"Trybulski","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, Katowice Business University, 40-659 Katowice, Poland"},{"name":"Provita Medical Centre, 44-240 \u017bory, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"507","DOI":"10.1111\/j.1469-7580.2012.01511.x","article-title":"The Thoracolumbar Fascia: Anatomy, Function and Clinical Considerations","volume":"221","author":"Willard","year":"2012","journal-title":"J. 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