One of the greatest threats posed to combat sports participants are the injuries associated with profound dehydration from rapid extreme weight cuts. To this end regulators have been struggling with reforms to minimize these practices.
California, to take one example, added checks for dehydration using urine specific gravity as part of a 10 point plan looking to reform rapid extreme weight cut practices. A recent study has concluded that such a test, unfortunately, may not be reliable in tracking dehydration.
The study, recently published in the International Journal of Sports Physiology and Performance, concluded that objective markers in urine were “unreliable” in tracking actual body-weight loss in real-life scenario.
The full abstract of the study, titled Reliability of Urinary Dehydration Markers Among Elite Youth Boxers” reads as follows:
The aim of the present study was to determine the reliability and diagnostic accuracy of non-invasive urinary dehydration markers, in field-based settings on a day-to-day basis in elite adolescent amateur boxers.
Sixty-nine urine samples were collected on a day-to-day basis, from twenty-three athletes (17.3±1.9 y), during their weigh-stable phase and analyzed by field and laboratory measures of hydration status. Urine osmolality (UOSM), urine specific gravity (USG), total protein content (TPC) and body-mass (BM) stability were evaluated to determine fluid balance and hydration status. The overall macronutrient and water intake were determined using dietary records. According to their anthropometric characteristics, athletes were assigned into two groups: light-weight (LWB) and heavy-weight (HWB) boxers.
Data presented on UOSM demonstrated a uniform increment by 11.2±12.8% (LWB) and 19.9±22.7% (HWB) (p<0.001), over the course of the study, even during the weight-stable phase (BM, ICC=0.99) and ad libitum fluid intake (42±4 mL•kg-1•day-1). The intra-class correlation coefficients (ICC-s) ranged from 0.52-0.55 for USG to 0.38-0.52 for UOSM, further indicating inconsistency of the urinary dehydration markers. Poor correlations were found between USG and TPC metabolites (r=0.27, p=0.211).
Urinary dehydration markers (both USG and UOSM) exhibit high variability and seem to be unreliable diagnostic tools to track for actual body-weight loss in real-life scenario. The ad libitum fluid intake was apparently inadequate to match acute fluid-loss during and following intense preparation. The applicability of a single time-point hydration status assessment concept may preclude accurate assessment of actual body-weight deficit(s) in youth boxers.