Dehydration not only reduces athletic performance, but also places athletes at risk of health problems and even death. For athletes, monitoring hydration has significant value in maximising performance during training and competition. It also offers medical personnel the opportunity to reduce health risks in situations where athletes engage in intentional weight loss. Simple non-invasive techniques, [...]

The physical properties and chemical composition of urine are highly variable and are determined in large measure by the quantity and the type of food consumed. The specific gravity is the ratio of the density to that of water, and it is dependent on the number and weight of solute particles and on the temperature [...]

BACKGROUND: Knowledge of the biological variability of the hydration factor (HF), ie, the ratio between total body water and fat-free mass, is important when calculating total body fat by means of the commonly used two-component model, which is based on estimates of body weight and total body water. The effect of pregnancy on the biological [...]

Acknowledging that total body water (TBW) turnover is complex, and that no measurement is valid for all situations, this review evaluates 13 hydration assessment techniques. Although validated laboratory methods exist for TBW and extracellular volume, no evidence incontrovertibly demonstrates that any concentration measurement, including plasma osmolality (P(osm)), accurately represents TBW gain and loss during daily [...]

This study aims to characterize the relationship between increased protein intake and hydration indexes. Five men participated in a 12-week, randomized, crossover, controlled diet intervention study. Subjects consumed eucaloric diets containing 3.6 (high protein), 1.8 (moderate protein), and 0.8 (low protein) g/kg/day of protein for 4 weeks each. Energy intakes were based on requirements established [...]

Water in the human body is essential for metabolism, temperature regulation, and numerous other physiological processes that are consistent with good health. Accurate, precise, and reliable methods to assess body fluid compartments are needed. This review describes the hydration assessment techniques of isotope dilution, neutron activation analysis, bioelectrical impedance, body mass change, thirst, tracer appearance, [...]

Bioelectrical impedance analysis (BIA) has been suggested as a simple, rapid method to assess changes in hydration status. BIA measures the electrical impedance to a low amperage current that is affected by both water and electrolyte content of the body. While BIA can reliably estimate total body water and body density in euhydrated individuals under [...]

OBJECTIVE: This study tested the hypothesis that bioelectrical impedance vectors, group and individual, are valid indicators of total body water (TBW) and hydration status in women experiencing fluid gain and loss during and after pregnancy. METHODS: We measured TBW, assessed with D(2)O dilution, and resistance (R) and reactance (Xc), determined with 800 microA at 50 [...]

To reduce the adverse consequences of exertion-related and acute intentional dehydration research has focused on monitoring hydration status. This investigation: 1) compared sensitivity of urine specific gravity (Usg), urine osmolality (U(osm)) and a criterion measurement of hydration, plasma osmolality (P(osm)), at progressive stages of acute hypertonic dehydration and 2) using a medical decision model, determined [...]

PURPOSE: To determine whether: a) plasma osmolarity (Posm) is sensitive to small incremental changes in hydration status, b) urine specific gravity (Usg) can accurately identify a state of euhydration, c) Usg is a sensitive indicator of a change in hydration status, and d) Usg correlates with Posm. METHODS: Euhydrated (Posm = 288 +/- 4 mOsm.L-1) [...]