This article reviews several clinical hydration assessment techniques for\r\ndetecting changes in hydration status, provides criteria for the most\r\naccurate and reliable methods, and offers application guidance for athletes\r\nand coaches. The most common assessment techniques include total body\r\nwater, plasma osmolality, urine osmolality and body mass. Plasma\r\nosmolality\r\nand total body water measurements are the best ways to assess fluid needs\r\nbut are technically difficult and not very practical. A more practical way\r\nfor athletes to monitor fluid needs is to 1) assess day-to-day body weight,\r\n2) monitor urine frequency and color and 3) pay attention to thirst.\r\nMaintaining a stable body weight, frequent, pale urination and occasional\r\nthirst are all indications of good body fluid balance. While any one of\r\nthese can be a sufficient monitor, attention to all three will provide\r\nbetter assurance for hydration status.