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Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations
Open accessAbstract
Background: Adequate hydration is crucial for athletic performance and health, particularly in adolescent athletes with distinct physiological demands. Comprehensive data on the daily and training-specific hydration status of populations like Chinese youth taekwondo athletes remain limited, hindering evidence-based strategy development. Objective: This study aimed to rigorously evaluate the daily and training session hydration status of taekwondo athletes in the Chinese youth team. Methods: This study evaluated the daily and training session hydration status of 58 Chinese youth taekwondo athletes (30 males, 28 females; age 17.7 ± 2.2 years) over a 7-day period. Assessment included 24-h rehydration behavior, daily fluid intake surveys, and objective hydration indices (urine osmolality, specific gravity, sweat ion concentrations). Results: A significant prevalence of suboptimal hydration, with 48.3% of athletes demonstrating persistent dehydration (defined as urine specific gravity >1.020 and urine osmolality ≥800 mOsm/kg) throughout the entire 7-day period. Median daily fluid intake for male athletes was 27.98 mL/kg BM, and for female athletes was 29.70 mL/kg BM; both values were below the daily fluid replacement volume of urine specific gravity ≤ 1.020 subjects for this athletic population. Training sessions significantly exacerbated dehydration, evidenced by elevated post-session urine specific gravity and osmolality of technical/tactical training session ( P < 0.05 ), alongside substantial median body mass loss rate of 2.51% for technical/tactical, 2.16% for physical fitness, and 1.97% for strength training sessions. Conclusion: This study identifies inadequate daily and training-induced hydration in Chinese youth taekwondo athletes. Based on the median values observed in euhydrated athletes in our cohort, daily fluid intake >30.35 mL/kg BM/day for males and >32.63 mL/kg BM/day for females on training days, alongside a training session intake of 1.87–2.78 mL/kg BM/h, may support maintenance of optimal hydration. However, total intake volume alone does not guarantee euhydration; beverage composition, timing of consumption, and pre-training hydration status are also important factors.
Overview
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TL;DR
In a 7-day field study, Chinese youth taekwondo athletes showed a high prevalence of suboptimal hydration, with 48.3% persistently dehydrated by combined urine specific gravity and osmolality criteria. The authors propose training-day fluid targets derived from euhydrated athletes in the cohort: >30.35 mL/kg BM/day for males and >32.63 mL/kg BM/day for females, plus 1.87–2.78 mL/kg BM/h during sessions.
Key findings
- Of 58 athletes (30 males, 28 females; age 17.7 ± 2.2 years), 48.3% were hypohydrated for the entire 7-day period using urine specific gravity >1.020 and urine osmolality ≥800 mOsm/kg; 85.5% had urine specific gravity >1.020 and 88.2% had urine osmolality ≥800 mOsm/kg across measurements.
- Median daily fluid intake was 27.98 mL/kg BM for males and 29.70 mL/kg BM for females, below the authors’ euhydrated training-day reference values; overall median 7-day intake was 29.0 (22.0–34.0) mL/kg BM, or 1,861 mL.
- Training exacerbated dehydration: post-session urine specific gravity and osmolality increased significantly after technical/tactical training (P<0.05), with median body mass loss rates of 2.51% for technical/tactical, 2.16% for physical fitness, and 1.97% for strength sessions; >2% body mass loss occurred in 81.0%, 62.7%, and 46.9% of athletes, respectively.
- Based on euhydrated athletes in the cohort, suggested intakes were >30.35 mL/kg BM/day for males and >32.63 mL/kg BM/day for females on training days, and 1.87–2.78 mL/kg BM/h during training sessions.
Methods
- Design: 7-day repeated-measures observational field study at the National Winter Sports Training and Research Base in Beijing, June 2023, including 5 training days and 2 rest days; training sessions were monitored on Day 4 and Day 6 (technical/tactical, physical fitness, strength).
- Sample: 66 youth taekwondo athletes were recruited by whole-team sampling; 58 completed the full 7-day daily monitoring protocol (30 males, 28 females; age 17.7 ± 2.2 years; average training experience 4.7 years). Training-session subsets were 58 for technical/tactical, 59 for physical fitness, and 49 for strength training.
- Data and analysis: daily 24-h fluid intake records, first-morning urine for specific gravity and osmolality, regional sweat patches for sodium/potassium/chloride, pre-/post-training body mass, and heart-rate/energy-expenditure monitoring. Data are reported mainly as median from quantile regression; non-normal data were analyzed with Kruskal–Wallis tests and Bonferroni-adjusted pairwise comparisons, with ANOVA for normal data and interpolation for missing values.
Limitations
- Stated: regional sweat sampling and estimation equations may not fully capture whole-body electrolyte losses; the Baker equations were validated in adults, not youth. Fluid intake was self-reported via 24-h recall, and food/metabolic water and dietary electrolyte intake were not assessed. The study was conducted in summer, with environmental temperatures varying from 27.1 °C to 35.8 °C, confounding comparisons of body mass loss across sessions. Urine output during training was not measured, so body mass loss estimates may be lower-bound. First-morning urine samples may overestimate dehydration prevalence, and no non-athlete control group was included.
- Evident from the text: training-session analyses used overlapping but non-identical subsets (58, 59, and 49 athletes), which may limit direct comparability across session types.
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In the paper
“Corresponding median sweat chloride concentrations were 34.18, 38.33, and 27.79 mmol/L, respectively.”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Results > Measurement of hydration of training lessons
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In the paper
“Consequently, technical and tactical training typically constitutes the largest portion of the training schedule among the taekwondo athletes in our study.”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Discussion
plain- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“Using established clinical thresholds (urine osmolality ≤ 500 mOsm/kg) for optimal hydration (32) and >800 mOsm/kg indicating dehydration (28, 33), our data show that approximately 70% of taekwondo athletes maintained hypohydrated states during the study period.”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Discussion
What the sources say
- Not checked yetcites [32] Perrier, 2015, Twenty-four-hour urine osmolality as a physiological index of adequate water intake, Dis Markers. source
- Not checked yetcites [28] Zhang, 2019, The total fluids intake among young adults from Hebei province in spring, Zhonghua Yu Fang Yi Xue Za Zhi. source
- Not checked yetcites [33] Armstrong, 1998, Urinary indices during dehydration, exercise, and rehydration, Int J Sport Nutr. source
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“surpasses the average consumption of Chinese male college students (1,134 mL) (28)”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Discussion
What the sources say
- Not checked yetcites [28] Zhang, 2019, The total fluids intake among young adults from Hebei province in spring, Zhonghua Yu Fang Yi Xue Za Zhi. source
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“This study also found that the dehydration of athletes was more pronounced after the technical and tactical training, which suggests that coaches and dietitians as well as the athletes themselves need to pay more attention to the hydration status of the technical and tactical training.”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Discussion
plainstates an association- Asserted: passes — The authors put it forward as true.
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Percentages, sums and reported differences re-computed from the paper’s own numbers.
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Rated major: it would touch a result — a value a result rests on, reported and recomputed p-values on opposite sides of the significance level, two passages that conflict with no sign which is right, or a cited work retracted before this paper was published.
In the paper
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Results > Appropriate rehydration regimen for taekwondo athletes
“| Technical and tactical training | Male | 10.15 (7.52) | 2.78 (3.70) | | Technical and tactical training | Female | 10.60 (7.65) | 2.22 (0.00) |”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Materials and methods > Training session monitoring
“The content of the technical and tactical class was mainly kicking with different heights and routes, and the training duration was 177 min. The content of the physical fitness class was the comprehensive ability training such as frog jump and hill climb jump, and the training duration was 128 min. The content of the strength class was the resistance training such as squatting with different angles and body mass, and the grip push, and the training duration was 139 min.”
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Results > Measurement of hydration of training lessons
“| Stature (m) | 1.88 ± 0.66 | 1.80 ± 0.07 | 1.87 ± 0.07 | 1.80 ± 0.06 | 1.86 ± 0.06 | 1.81 ± 0.06 |”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Results > Characteristics of athletes
“| Male | 17.4 ± 1.9 | 1.87 ± 0.06 | 70.90 ± 11.11 | 20.36 ± 2.26 | 1.94 ± 0.17 | 30 (52) |”
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Abstract > Conclusion
“alongside a training session intake of 1.87–2.78 mL/kg BM/h, may support maintenance of optimal hydration.”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Results > Appropriate rehydration regimen for taekwondo athletes
“| Physical fitness training | Female | 6.43 (6.81) | 2.86 (1.70) |”
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Materials and methods > Environmental conditions
“The temperature of the training and residence of the athletes ranged from 26.3 to 35.8 °C and the humidity ranged 21%−49% (Table 1).”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Materials and methods > Environmental conditions
“| D1 | 26.4 | 48% | Dormitory | 26.5 | 49% | Dormitory | 25.8 | 40% | Dormitory |”
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Discussion
“Consequently, the body mass loss values reported in our study should be interpreted as lower-bound estimates, and the corresponding fluid intake recommendations should be considered conservative.”
§ Optimizing hydration in Chinese youth taekwondo athletes: evidence-based daily and training session-specific fluid intake recommendations > Materials and methods > Body mass loss analysis
“Bodymassloss(kg); = pre-trainingbodymass-post-trainingbodymass; + fluidintakeduringtraining;”
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Citations
Cites
von Elm, E., Altman, D. G., Egger, M., Pocock, S. J., Gøtzsche, P. C., & Vandenbroucke, J. P. (2007) · The Lancet · doi:10.1016/s0140-6736(07)61602-x · Cited by 21,320
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Wearable potentiometric ion sensors
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Urinary Indices during Dehydration, Exercise, and Rehydration
Armstrong, L. E., Herrera Soto, J. A., Hacker, F. T., Casa, D. J., Kavouras, S. A., & Maresh, C. M. (1998) · International Journal of Sport Nutrition · doi:10.1123/ijsn.8.4.345 · Cited by 306
Human Hydration Indices: Acute and Longitudinal Reference Values
Armstrong, L. E., Pumerantz, A. C., Fiala, K. A., Roti, M. W., Kavouras, S. A., Casa, D. J., & Maresh, C. M. (2010) · International Journal of Sport Nutrition and Exercise Metabolism · doi:10.1123/ijsnem.20.2.145 · Cited by 261
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Bhave, G., & Neilson, E. G. (2011) · Journal of the American Society of Nephrology · doi:10.1681/asn.2011080865 · Cited by 215
Research works printed but not linked: 5
- Li, 2020, Fluids intake, volume of urine and hydration status among male college athletic in one university of Beijing in spring, Zhong Guo Xue Xiao Wei Sheng, 10.16835/j.cnki.1000-9817.2020.03.005 · DOI
- Du Bois, 1989, A formula to estimate the approximate surface area if height and weight be known, Nutrition
- Society, 2014, Chinese Dietary Reference Intakes 2013, 452
- Holmes, 2016, The effect of exercise intensity on sweat rate and sweat sodium and potassium losses in trained endurance athletes, Ann Sports Med Res., 3, 1063
- Wolinsky, 2011, Nutritional Assessment of Athletes (Second Edition)
Cited by
Lagua-Saquinga, E. L., Poveda-Morales, T. C., & Estrada-Velasco, L. J. (2026) · CIENCIAMATRIA · doi:10.35381/cm.v12i4.3042
Metadata
- Authors
- Song, G., Chen, Y., Li, J., Pan, X., Sui, H., Chen, J., Lin, Y., & Yan, Y.
- Affiliations
- Beijing Sport University (CN)
- Xi'an University of Architecture and Technology (CN)
- Department of Sport Biochemistry, School of Sport Science, Beijing Sport University
- General Administration of Sport of China (CN)
- Corresponding author
- Yan, Yi
- Venue
- Frontiers in Nutrition
- Publisher
- Frontiers Media SA
- Published
- 2026-10-13
- Volume
- 13
- Pages
- 1923019-1923019
- ISSN
- 2296-861X (ISSN-L)
- PMC
- PMC13710252
- OpenAlex
- W7221594161
- Semantic Scholar
- 7f0e8087f7d2b1cbbc3955c70fd8c338199cf3a6
- Cited by
- 1
- References
- 54
- Citations by year
- 2026: 1
- FWCI
- 3.12
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- Frontiers in Nutrition (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
- Funders
- Fundamental Research Funds for the Central Universities (2024YJSY001)
- Topics
- Health Sciences › Medicine › Physiology (medical) › Thermoregulation and physiological responses
- Health Sciences › Medicine › Orthopedics and Sports Medicine › Sports Performance and Training
- Social Sciences › Safety Research › Martial Arts: Techniques, Psychology, and Education
- Keywords
- hydration, fluid intake, taekwondo, youth athletes, urine osmolality, sweat electrolytes, weight loss, hydration status, Chinese athletes
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