Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer players

BackgroundPurple grape juice (PGJ), a natural carbohydrate- and polyphenol-rich supplement, may enhance exercise performance. This study, incorporating individual response analysis, examined the acute effects of PGJ ingestion on endurance, explosive power, and perceived fatigue in elite male soccer...

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Main Authors: Alireza Niknam, Kamran Tahmasebi, Mohammad Hemmatinafar, Walaa Jumah Alkasasbeh, Mark E. T. Willems, Maryam Koushkie Jahromi, Morteza Bagheri Kalayeh, Mohammad Hadi Zare
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-06-01
Series:Frontiers in Nutrition
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Online Access:https://www.frontiersin.org/articles/10.3389/fnut.2025.1559917/full
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author Alireza Niknam
Kamran Tahmasebi
Mohammad Hemmatinafar
Walaa Jumah Alkasasbeh
Walaa Jumah Alkasasbeh
Mark E. T. Willems
Maryam Koushkie Jahromi
Morteza Bagheri Kalayeh
Mohammad Hadi Zare
author_facet Alireza Niknam
Kamran Tahmasebi
Mohammad Hemmatinafar
Walaa Jumah Alkasasbeh
Walaa Jumah Alkasasbeh
Mark E. T. Willems
Maryam Koushkie Jahromi
Morteza Bagheri Kalayeh
Mohammad Hadi Zare
author_sort Alireza Niknam
collection DOAJ
description BackgroundPurple grape juice (PGJ), a natural carbohydrate- and polyphenol-rich supplement, may enhance exercise performance. This study, incorporating individual response analysis, examined the acute effects of PGJ ingestion on endurance, explosive power, and perceived fatigue in elite male soccer players.MethodologyTwenty-two U-20 male soccer players [Age: 19.7 ± 0.3; height: 178 ± 4 cm; body mass: 72 ± 5 kg; body mass index (BMI): 22.6 ± 0.9 kg/m2] participated in an equally allocated, double-blind, crossover design study. Participants were allocated to one of two conditions: (1) purple grape juice (PGJ, n = 11) or (2) placebo (PLA, n = 11). The PGJ or placebo was ingested in four equal portions (10 ml/kg of body mass PGJ or PLA diluted with water) starting 4 h before the test and continuing every hour, with the final ingestion 60 min before the 30-15 Intermittent Fitness Test (IFT). The placebo consisted of a calorie-free, grape-flavored liquid designed to match the taste and appearance of the PGJ. A 7 days washout period was maintained between the two conditions. Perceived fatigue and standing long jump (SLJ) performance were assessed at baseline, immediately and 5 min after the IFT. Maximum oxygen consumption (VO2max), time to exhaustion (TTE), and final velocity in the IFT (VIFT) were recorded during the test. The smallest worthwhile change (SWC) analysis was used to evaluate individual responses.ResultsPurple grape juice improved VIFT (P < 0.001, Cohen’s d = 0.58), TTE (P < 0.001, Cohen’s d = 0.69), and VO2max (P < 0.001, Cohen’s d = 0.56) compared to PLA. No effects were found for SLJ or perceived fatigue (P > 0.05), SWC analysis revealed that 77% of participants showed improvements in VIFT and VO2max, and 54% showed improvements in SLJ 5 min post-IFT.ConclusionPurple grape juice supplementation enhanced endurance performance parameters in most participants, with significant individual variability in response. These findings highlight the potential benefits of PGJ, particularly for athletes more responsive to its effects, emphasizing the need for personalized supplementation strategies.
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spelling doaj-art-c76ebf6ecce54eecb29805357fcc23102025-08-20T02:31:20ZengFrontiers Media S.A.Frontiers in Nutrition2296-861X2025-06-011210.3389/fnut.2025.15599171559917Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer playersAlireza Niknam0Kamran Tahmasebi1Mohammad Hemmatinafar2Walaa Jumah Alkasasbeh3Walaa Jumah Alkasasbeh4Mark E. T. Willems5Maryam Koushkie Jahromi6Morteza Bagheri Kalayeh7Mohammad Hadi Zare8Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz, IranDepartment of Exercise Physiology, Faculty of Sport Sciences, University of Isfahan, Isfahan, IranDepartment of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz, IranDepartment of Administration and Curriculum, Program of Sports Management and Training, Faculty of Arts and Educational Sciences, Middle East University, Amman, JordanDepartment of Physical Education, Faculty of Sport Science, The University of Jordan, Amman, JordanInstitute of Applied Sciences, University of Chichester, Chichester, United KingdomDepartment of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz, IranDepartment of Exercise Physiology, Faculty of Sport Sciences and Health, University of Tehran, Tehran, IranDepartment of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz, IranBackgroundPurple grape juice (PGJ), a natural carbohydrate- and polyphenol-rich supplement, may enhance exercise performance. This study, incorporating individual response analysis, examined the acute effects of PGJ ingestion on endurance, explosive power, and perceived fatigue in elite male soccer players.MethodologyTwenty-two U-20 male soccer players [Age: 19.7 ± 0.3; height: 178 ± 4 cm; body mass: 72 ± 5 kg; body mass index (BMI): 22.6 ± 0.9 kg/m2] participated in an equally allocated, double-blind, crossover design study. Participants were allocated to one of two conditions: (1) purple grape juice (PGJ, n = 11) or (2) placebo (PLA, n = 11). The PGJ or placebo was ingested in four equal portions (10 ml/kg of body mass PGJ or PLA diluted with water) starting 4 h before the test and continuing every hour, with the final ingestion 60 min before the 30-15 Intermittent Fitness Test (IFT). The placebo consisted of a calorie-free, grape-flavored liquid designed to match the taste and appearance of the PGJ. A 7 days washout period was maintained between the two conditions. Perceived fatigue and standing long jump (SLJ) performance were assessed at baseline, immediately and 5 min after the IFT. Maximum oxygen consumption (VO2max), time to exhaustion (TTE), and final velocity in the IFT (VIFT) were recorded during the test. The smallest worthwhile change (SWC) analysis was used to evaluate individual responses.ResultsPurple grape juice improved VIFT (P < 0.001, Cohen’s d = 0.58), TTE (P < 0.001, Cohen’s d = 0.69), and VO2max (P < 0.001, Cohen’s d = 0.56) compared to PLA. No effects were found for SLJ or perceived fatigue (P > 0.05), SWC analysis revealed that 77% of participants showed improvements in VIFT and VO2max, and 54% showed improvements in SLJ 5 min post-IFT.ConclusionPurple grape juice supplementation enhanced endurance performance parameters in most participants, with significant individual variability in response. These findings highlight the potential benefits of PGJ, particularly for athletes more responsive to its effects, emphasizing the need for personalized supplementation strategies.https://www.frontiersin.org/articles/10.3389/fnut.2025.1559917/fullcarbohydrateendurance performancegrape juicejump performancesoccer players
spellingShingle Alireza Niknam
Kamran Tahmasebi
Mohammad Hemmatinafar
Walaa Jumah Alkasasbeh
Walaa Jumah Alkasasbeh
Mark E. T. Willems
Maryam Koushkie Jahromi
Morteza Bagheri Kalayeh
Mohammad Hadi Zare
Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer players
Frontiers in Nutrition
carbohydrate
endurance performance
grape juice
jump performance
soccer players
title Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer players
title_full Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer players
title_fullStr Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer players
title_full_unstemmed Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer players
title_short Individual responses to purple grape juice consumption on endurance, explosive power, and fatigue in young male elite soccer players
title_sort individual responses to purple grape juice consumption on endurance explosive power and fatigue in young male elite soccer players
topic carbohydrate
endurance performance
grape juice
jump performance
soccer players
url https://www.frontiersin.org/articles/10.3389/fnut.2025.1559917/full
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