Urine specific gravity as an indicator of dehydration in Olympic combat sport athletes; considerations for research and practice

ABSTRACTUrine specific gravity (USG) is the most commonly reported biochemical marker used in research and applied settings to detect fluid deficits in athletes, including those participating in combat sports. Despite the popularity of its use, there has been a growing debate regarding the diagnostic accuracy and the applicability of USG in characterizing whole-body fluid status and fluctuations. Moreover, recent investigations report universally high prevalence of hypohydration (∼90%) via USG assessment in combat sport athletes, often in spite of stable body-mass. Given the widespread use in both research and practice, and its use in a regulatory sense as a ‘hydration test’ in combat sports as a means to detect dehydration at the time of weigh-in; understanding the limitations and applicability of USG assessment is of paramount importance. Inconsistencies in findings of USG readings, possibly as a consequence of diverse methodological research approaches and/or overlooked confounding factors, preclude a ...