000169944 001__ 169944
000169944 005__ 20260306154908.0
000169944 0247_ $$2doi$$a10.3390/nu18030466
000169944 0248_ $$2sideral$$a148484
000169944 037__ $$aART-2026-148484
000169944 041__ $$aeng
000169944 100__ $$aRojas-Valverde, Daniel
000169944 245__ $$aAgreement and Reliability Between Urine Reagent Strips and Refractometry for Field Assessment of Hydration in Ultra-Trail Runners
000169944 260__ $$c2026
000169944 5060_ $$aAccess copy available to the general public$$fUnrestricted
000169944 5203_ $$aBackground/Objectives: Accurate hydration assessment is critical for optimizing performance and preventing heat-related complications in ultra-endurance athletes. This study evaluated the agreement and reliability between urine reagent strips and refractometry for field-based hydration assessment via urine-specific gravity (USG) in ultra-trail runners. Methods: Thirty-four ultra-trail runners (22 males, 12 females; mean age 43.71 ± 11.50 years) participated during The Coastal Challenge, a 241-km multi-stage ultra-trail competition. Urine samples were collected before and after the first two stages (Stage 1: 41 km, 1071 m elevation; Stage 2: 40 km, 1828 m elevation). USG was measured using semi-quantitative urine reagent strips (Combur10Test M) and a handheld digital refractometer (Palm Abbe™). Agreement was assessed via paired t-tests, Pearson and Spearman correlations, intraclass correlation coefficients, and Bland-Altman plots across four measurement time points. Results: Strong agreement existed between methods with correlation coefficients of 0.92–0.99 (p < 0.01) within the hydration range typical of well-prepared ultra-endurance athletes (USG 1.010–1.020). No significant differences were found between devices at any time point (all p > 0.05). Bland-Altman analyses revealed minimal mean bias (range: −0.002 to +0.001 g/mL) and narrow limits of agreement, with fewer than 5% of values falling outside limits. Both methods detected significant increases in USG from pre- to post-stage (p < 0.01), indicating exercise-induced hypohydration. Conclusions: Semi-quantitative urine reagent strips and handheld refractometers demonstrate strong agreement for hydration assessment in ultra-trail runners under field conditions when not severely hypohydrated, supporting their interchangeable use for practical monitoring.
000169944 536__ $$9info:eu-repo/grantAgreement/ES/DGA/S53-23R$$9info:eu-repo/grantAgreement/ES/MCIU/FPU17-00407
000169944 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttps://creativecommons.org/licenses/by/4.0/deed.es
000169944 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion
000169944 700__ $$aScheer, Volker
000169944 700__ $$aTuesta, Marcelo
000169944 700__ $$0(orcid)0000-0002-4084-8124$$aGómez-Carmona, Carlos D.$$uUniversidad de Zaragoza
000169944 7102_ $$13001$$2187$$aUniversidad de Zaragoza$$bDpto. Expres.Music.Plást.Corp.$$cÁrea Didáctica Expres.Corporal
000169944 773__ $$g18, 3 (2026), 466 [10 pp.]$$pNutrients$$tNutrients$$x2072-6643
000169944 8564_ $$s1004109$$uhttps://zaguan.unizar.es/record/169944/files/texto_completo.pdf$$yVersión publicada
000169944 8564_ $$s2463955$$uhttps://zaguan.unizar.es/record/169944/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada
000169944 909CO $$ooai:zaguan.unizar.es:169944$$particulos$$pdriver
000169944 951__ $$a2026-03-06-14:51:02
000169944 980__ $$aARTICLE