TY - CONF

T1 - The utility of hydration markers to identify mild hypertonic and isotonic hypohydration

AU - Owen, Julian

PY - 2013/2/1

Y1 - 2013/2/1

N2 - The study aim was to assess the utility of common hydrationmarkers to identify mild hypertonic and isotonic hypohydration.Fifteen males completed three randomized 48-hr trials,where energy intake was standardized throughout. On day 1,participants completed a hydration assessment followed byhigh-intensity aerobic exercise. After exercise, they began oneof three trials. On the control trial (CON) participants consumedadequate fluid to maintain euhydration. On the isotonic hypohydrationtrial (IH) participants ingested the same fluid as onCON, but at 0800 hr on day 3 they consumed 0.65 mg/kg ofthe diuretic furosemide. On the hypertonic hypohydration trial(HH), drinking fluids were restricted to 2ml/kg/day for 48 hrafter the exercise on day 1. After 48 hr, the participants completeda second hydration assessment. Dehydration on HH andIH was equal to 1.9% and 2.0% of body mass, respectively. Urinarymarkers showed the best utility to identify mild hypertonichypohydration (Ucol: 2 ± 1, 6 ± 1, 2 ± 1; Usg: 1.008 ± 0.004,1.028 ± 0.005, 1.011 ± 0.004; Uosm: 260 ± 136, 1043 ± 130,404 ± 106, CON, HH, and IH, respectively; HH vs CON effectsizes: d = 5.6, 4.4, 5.6, Ucol, Usg, and Uosm, respectively),while plasma osmolality (Posm), saliva osmolality (Sosm), andsaliva flow rate (Sfr) showed moderate utility (Posm: 286 ± 4,296 ± 6, 286 ± 4; Sosm: 55 ± 13, 65 ± 12, 56 ± 12; Sfr: 380 ±240, 212 ± 173, 431 ± 310, CON, HH, and IH, respectively;HH vs CON effect sizes: d = 1.8, 0.7, 0.8, Posm, Sosm, andSfr, respectively). Isotonic dehydration was poorly identified bymost hydration markers, with the exception of heart rate change(LSΔHR) from lying to standing (LSΔHR: 14 ± 8, 19 ± 10, 26± 12, CON, HH, and IH, respectively; HH vs CON effect size:d = 0.6). Hydration marker utility is dependent on the type ofhypohydration. These results highlight how some commonlyused hydration markers may misdiagnose athletes and patients.

AB - The study aim was to assess the utility of common hydrationmarkers to identify mild hypertonic and isotonic hypohydration.Fifteen males completed three randomized 48-hr trials,where energy intake was standardized throughout. On day 1,participants completed a hydration assessment followed byhigh-intensity aerobic exercise. After exercise, they began oneof three trials. On the control trial (CON) participants consumedadequate fluid to maintain euhydration. On the isotonic hypohydrationtrial (IH) participants ingested the same fluid as onCON, but at 0800 hr on day 3 they consumed 0.65 mg/kg ofthe diuretic furosemide. On the hypertonic hypohydration trial(HH), drinking fluids were restricted to 2ml/kg/day for 48 hrafter the exercise on day 1. After 48 hr, the participants completeda second hydration assessment. Dehydration on HH andIH was equal to 1.9% and 2.0% of body mass, respectively. Urinarymarkers showed the best utility to identify mild hypertonichypohydration (Ucol: 2 ± 1, 6 ± 1, 2 ± 1; Usg: 1.008 ± 0.004,1.028 ± 0.005, 1.011 ± 0.004; Uosm: 260 ± 136, 1043 ± 130,404 ± 106, CON, HH, and IH, respectively; HH vs CON effectsizes: d = 5.6, 4.4, 5.6, Ucol, Usg, and Uosm, respectively),while plasma osmolality (Posm), saliva osmolality (Sosm), andsaliva flow rate (Sfr) showed moderate utility (Posm: 286 ± 4,296 ± 6, 286 ± 4; Sosm: 55 ± 13, 65 ± 12, 56 ± 12; Sfr: 380 ±240, 212 ± 173, 431 ± 310, CON, HH, and IH, respectively;HH vs CON effect sizes: d = 1.8, 0.7, 0.8, Posm, Sosm, andSfr, respectively). Isotonic dehydration was poorly identified bymost hydration markers, with the exception of heart rate change(LSΔHR) from lying to standing (LSΔHR: 14 ± 8, 19 ± 10, 26± 12, CON, HH, and IH, respectively; HH vs CON effect size:d = 0.6). Hydration marker utility is dependent on the type ofhypohydration. These results highlight how some commonlyused hydration markers may misdiagnose athletes and patients.

M3 - Poster

SP - S7

T2 - International Sports and Exercise Nutrition Conference in Newcastle upon Tyne.

Y2 - 13 December 2012 through 15 December 2012

ER -