Zubac Damir, Cular Drazen, Marusic Uros
Int J Sports Physiol Perform. 2018 Mar 1;13(3):374-381. doi: 10.1123/ijspp.2016-0621. Epub 2018 Mar 6.
To determine the reliability and diagnostic accuracy of noninvasive urinary dehydration markers in field-based settings on a day-to-day basis in elite adolescent amateur boxers.
Sixty-nine urine samples were collected daily from 23 athletes (17.3 ± 1.9 y) during their weight-stable phase and analyzed by field and laboratory measures of hydration status. Urine osmolality (U), urine specific gravity (U), total protein content (T), and body-mass stability were evaluated to determine fluid balance and hydration status. Overall macronutrient and water intake were determined using dietary records. According to their anthropometric characteristics, athletes were assigned into 2 groups: lightweight (L) and heavyweight (H) boxers.
Data presented on U demonstrated a uniform increment by 11.2% ± 12.8% (L) and 19.9% ± 22.7% (H) (P < .001) over the course of the study, even during the weight-stable phase (body mass, ICC = .99) and ad libitum fluid intake (42 ± 4 mL · kg · d). The intraclass correlation coefficients (ICCs) ranged from .52 to .55 for U and .38 to .52 for U, further indicating inconsistency of the urinary dehydration markers. Poor correlations were found between U and T metabolites (r = .27, P = .211).
Urinary dehydration markers (both U and U) exhibit high variability and seem to be unreliable diagnostic tools to track actual body-weight loss in real-life settings. The ad libitum fluid intake was apparently inadequate to match acute fluid loss during and after intense preparation. The applicability of a single-time-point hydration-status assessment concept may preclude accurate assessment of actual body-weight deficits in youth boxers.
确定在日常实地环境中，非侵入性尿液脱水标志物在精英青少年业余拳击手中的可靠性和诊断准确性。
在23名运动员（17.3±1.9岁）体重稳定期，每天收集69份尿液样本，并通过实地和实验室方法分析其水合状态。评估尿渗透压（U）、尿比重（U）、总蛋白含量（T）和体重稳定性，以确定液体平衡和水合状态。通过饮食记录确定总体宏量营养素和水分摄入量。根据人体测量特征，将运动员分为两组：轻量级（L）和重量级（H）拳击手。
研究过程中，U的数据显示，即使在体重稳定期（体重，组内相关系数ICC=.99）和随意饮水（42±4mL·kg·d）情况下，U仍均匀增加了11.2%±12.8%（L）和19.9%±22.7%（H）（P<.001）。U的组内相关系数（ICC）范围为0.52至0.55，U的ICC范围为0.38至0.52，进一步表明尿液脱水标志物的不一致性。U与T代谢物之间的相关性较差（r=0.27，P=0.211）。
尿液脱水标志物（U和U）表现出高度变异性，似乎是现实生活中追踪实际体重减轻的不可靠诊断工具。随意饮水显然不足以匹配高强度训练期间和之后的急性液体流失。单次水合状态评估概念的适用性可能会妨碍对青少年拳击手实际体重不足的准确评估。
