Effects of glycerol hyperhidration on the running economy of long-distance runners: a randomized crossover clinical trial

BackgroundEndurance athletes experience significant water loss during exercise, which can impair performance and increase the risk of dehydration. Glycerol hyperhydration has been explored as a strategy to enhance pre-exercise hydration, particularly when fluid intake opportunities are limited. This...

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Main Authors: Carlos Abraham Herrera-Amante, Gustavo García-Zepeda, Carlos Eduardo García-Zepeda, Rodrigo Yáñez-Sepúlveda, Vicente Javier Clemente-Suárez, José Francisco López-Gil, César Octavio Ramos-García
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-08-01
Series:Frontiers in Nutrition
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Online Access:https://www.frontiersin.org/articles/10.3389/fnut.2025.1630462/full
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author Carlos Abraham Herrera-Amante
Carlos Abraham Herrera-Amante
Carlos Abraham Herrera-Amante
Gustavo García-Zepeda
Carlos Eduardo García-Zepeda
Rodrigo Yáñez-Sepúlveda
Vicente Javier Clemente-Suárez
Vicente Javier Clemente-Suárez
José Francisco López-Gil
José Francisco López-Gil
César Octavio Ramos-García
César Octavio Ramos-García
César Octavio Ramos-García
author_facet Carlos Abraham Herrera-Amante
Carlos Abraham Herrera-Amante
Carlos Abraham Herrera-Amante
Gustavo García-Zepeda
Carlos Eduardo García-Zepeda
Rodrigo Yáñez-Sepúlveda
Vicente Javier Clemente-Suárez
Vicente Javier Clemente-Suárez
José Francisco López-Gil
José Francisco López-Gil
César Octavio Ramos-García
César Octavio Ramos-García
César Octavio Ramos-García
author_sort Carlos Abraham Herrera-Amante
collection DOAJ
description BackgroundEndurance athletes experience significant water loss during exercise, which can impair performance and increase the risk of dehydration. Glycerol hyperhydration has been explored as a strategy to enhance pre-exercise hydration, particularly when fluid intake opportunities are limited. This study aimed to evaluate the effects of glycerol hyperhydration on running economy (RE) in trained runners.MethodsA randomized crossover clinical trial was conducted with 30 trained runners (15 men, 15 women) across three sessions. In the first session, peak oxygen uptake (VO₂peak) was determined to establish individualized running speeds for the subsequent tests. In the second and third sessions, participants performed submaximal running tests under two conditions: euhydration (control) and glycerol-induced hyperhydration. The glycerol protocol consisted of ingesting 1.2 g/kg body mass of glycerol diluted in 22 mL/kg of water, 120 min before exercise. The assessed variables included caloric cost unit (CCU), oxygen cost unit (OCU), heart rate (HR), body temperature (BT), and rating of perceived exertion (RPE). Effect sizes were calculated using standardized mean differences (Cohen’s d).ResultsGlycerol supplementation significantly improved running economy, reducing CCU (p = 0.025, d = 0.43), OCU (p = 0.011, r = 0.46), HR (p = 0.029, d = 0.42), and RPE (p = 0.003, d = 0.60). Although BT showed a slight decrease (p = 0.053, d = 0.37), it did not reach statistical significance, suggesting a trend toward improved thermoregulation.ConclusionThese findings indicate that glycerol supplementation enhances key metabolic and physiological factors associated with running economy, including CCU, OCU, cardiovascular responses, and perceived exertion in trained runners.Clinical trial registrationhttps://clinicaltrials.gov, identifier: NCT06818253.
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spelling doaj-art-3751e654907a4cfebf757cb286a67f0d2025-08-20T03:41:57ZengFrontiers Media S.A.Frontiers in Nutrition2296-861X2025-08-011210.3389/fnut.2025.16304621630462Effects of glycerol hyperhidration on the running economy of long-distance runners: a randomized crossover clinical trialCarlos Abraham Herrera-Amante0Carlos Abraham Herrera-Amante1Carlos Abraham Herrera-Amante2Gustavo García-Zepeda3Carlos Eduardo García-Zepeda4Rodrigo Yáñez-Sepúlveda5Vicente Javier Clemente-Suárez6Vicente Javier Clemente-Suárez7José Francisco López-Gil8José Francisco López-Gil9César Octavio Ramos-García10César Octavio Ramos-García11César Octavio Ramos-García12Nutritional Assessment and Nutritional Care Laboratory (LECEN), Division of Health Sciences, Tonalá University Center, University of Guadalajara, Tonalá, MexicoResearch Division, Ibero-American Institute of Sports Sciences and Human Movement (IICDEM), Guadalajara, MexicoIbero-American Network of Researchers in Applied Anthropometry (RIBA2), Almería, SpainIbero-American Network of Researchers in Applied Anthropometry (RIBA2), Almería, SpainIbero-American Network of Researchers in Applied Anthropometry (RIBA2), Almería, SpainFaculty of Education and Social Sciences, Universidad Andres Bello (UNAB), Viña del Mar, ChileFaculty of Sports Sciences, Universidad Europea de Madrid (UE), Madrid, SpainGrupo de Investigación en Cultura, Educación y Sociedad, Universidad de la Costa, Barranquilla, ColombiaSchool of Medicine, Universidad Espíritu Santo, Samborondón, EcuadorVicerrectoría de Investigación y Postgrado, Universidad de Los Lagos, Osorno, ChileNutritional Assessment and Nutritional Care Laboratory (LECEN), Division of Health Sciences, Tonalá University Center, University of Guadalajara, Tonalá, MexicoResearch Division, Ibero-American Institute of Sports Sciences and Human Movement (IICDEM), Guadalajara, MexicoIbero-American Network of Researchers in Applied Anthropometry (RIBA2), Almería, SpainBackgroundEndurance athletes experience significant water loss during exercise, which can impair performance and increase the risk of dehydration. Glycerol hyperhydration has been explored as a strategy to enhance pre-exercise hydration, particularly when fluid intake opportunities are limited. This study aimed to evaluate the effects of glycerol hyperhydration on running economy (RE) in trained runners.MethodsA randomized crossover clinical trial was conducted with 30 trained runners (15 men, 15 women) across three sessions. In the first session, peak oxygen uptake (VO₂peak) was determined to establish individualized running speeds for the subsequent tests. In the second and third sessions, participants performed submaximal running tests under two conditions: euhydration (control) and glycerol-induced hyperhydration. The glycerol protocol consisted of ingesting 1.2 g/kg body mass of glycerol diluted in 22 mL/kg of water, 120 min before exercise. The assessed variables included caloric cost unit (CCU), oxygen cost unit (OCU), heart rate (HR), body temperature (BT), and rating of perceived exertion (RPE). Effect sizes were calculated using standardized mean differences (Cohen’s d).ResultsGlycerol supplementation significantly improved running economy, reducing CCU (p = 0.025, d = 0.43), OCU (p = 0.011, r = 0.46), HR (p = 0.029, d = 0.42), and RPE (p = 0.003, d = 0.60). Although BT showed a slight decrease (p = 0.053, d = 0.37), it did not reach statistical significance, suggesting a trend toward improved thermoregulation.ConclusionThese findings indicate that glycerol supplementation enhances key metabolic and physiological factors associated with running economy, including CCU, OCU, cardiovascular responses, and perceived exertion in trained runners.Clinical trial registrationhttps://clinicaltrials.gov, identifier: NCT06818253.https://www.frontiersin.org/articles/10.3389/fnut.2025.1630462/fullglycerolathletic performancesports nutritional sciencesthermoregulationrunningperformance-enhancing substances
spellingShingle Carlos Abraham Herrera-Amante
Carlos Abraham Herrera-Amante
Carlos Abraham Herrera-Amante
Gustavo García-Zepeda
Carlos Eduardo García-Zepeda
Rodrigo Yáñez-Sepúlveda
Vicente Javier Clemente-Suárez
Vicente Javier Clemente-Suárez
José Francisco López-Gil
José Francisco López-Gil
César Octavio Ramos-García
César Octavio Ramos-García
César Octavio Ramos-García
Effects of glycerol hyperhidration on the running economy of long-distance runners: a randomized crossover clinical trial
Frontiers in Nutrition
glycerol
athletic performance
sports nutritional sciences
thermoregulation
running
performance-enhancing substances
title Effects of glycerol hyperhidration on the running economy of long-distance runners: a randomized crossover clinical trial
title_full Effects of glycerol hyperhidration on the running economy of long-distance runners: a randomized crossover clinical trial
title_fullStr Effects of glycerol hyperhidration on the running economy of long-distance runners: a randomized crossover clinical trial
title_full_unstemmed Effects of glycerol hyperhidration on the running economy of long-distance runners: a randomized crossover clinical trial
title_short Effects of glycerol hyperhidration on the running economy of long-distance runners: a randomized crossover clinical trial
title_sort effects of glycerol hyperhidration on the running economy of long distance runners a randomized crossover clinical trial
topic glycerol
athletic performance
sports nutritional sciences
thermoregulation
running
performance-enhancing substances
url https://www.frontiersin.org/articles/10.3389/fnut.2025.1630462/full
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