engleski

Reliability of Urinary Dehydration Markers in Elite Youth Boxers

Purpose: 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. Methods: 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-OSM), urine specific gravity (U-SG), total protein content (T-PC), 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-WB) and heavyweight (H-WB) boxers. Results: Data presented on U-OSM demonstrated a uniform increment by 11.2% +/- 12.8% (L-WB) and 19.9% +/- 22.7% (H-WB) (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(-1) . d(-1)). The intraclass correlation coefficients (ICCs) ranged from .52 to .55 for U-SG and .38 to .52 for U-OSM, further indicating inconsistency of the urinary dehydration markers. Poor correlations were found between U-SG and TPC metabolites (r = .27, P = .211). Conclusions: Urinary dehydration markers (both U-SG and U-OSM) 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.

combat sports ; urine ; validity

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