• Effect of Fluid Administration on Fluid Consumption and Hydration Status

      Finn, Megan E. (2011-09-20)
      The use of an external fluid administrator (EFA) to deliver fluids is a recent phenomenon in athletics. However, this has yet to be compared to the traditional method of self administration(SA). PURPOSE: To examine the influence fluid administration methods have on fluid consumption, hydration status, and perceptual variables. METHODS: Nineteen recreationally active individuals [14 males, 5 females (30±10y; 176±8cm; 72.5Kg) participated in two days of exercise with varying the method of fluid administration (self-administration SA; external fluid administration EFA) between days. EFA refers to when someone else squirts water into the participant’s mouth, whereas SA, the participant squirts water into their own mouth. The water bottle (WB) was kept equal distance from the mouth for both conditions. Participants weight (t-shirt and/or shorts only) and urine samples were collected prior to exercise. Participants then completed a 10-min warm-up. Participants had a 2-min fluid break before the exercise protocol (EP), which included a series of five 15-minute stations. Exercises provided aerobic and anaerobic demands, including hill jogging, push-ups, jumping jacks, ladder drills, and intermittent rest. After completing each station, participants received a 5-min fluid breaks where they drank ad libitum. Fluid variables and perceptual variables were collected during every fluid break. Following the final fluid break,participants provided a post-exercise weight and urine sample. The order of conditions and exercise stations were randomly assigned. Fluid variables assessed were volume consumed perfluid break (VC/FB), number of squirts per fluid break (#Sq/FB), squirt volume per fluid break (SqV/FB), total squirts (TSq), total volume consumed (TVC), and average volume per squirt (AV/Sq). Hydration status was assessed via urine specific gravity (USG), body mass loss (BML),sweat loss (SwL), and sweat rate (SwRt). Perceptual measures assessed include thirst and fullness. Repeated-measures ANOVA was used to analyze condition by time for VC/FB,#Sq/FB, SqV/FB, USG, thirst and fullness. A paired t-test was used for post-hoc analysis.Independent samples t-tests were used to analyze TSq, TVC, AV/Sq, BML, SwL, and SwRt.P<0.05 a priori RESULTS: No significant interaction was indicated for VC/FB or SqV/FB (p>0.05). A significant interaction was noted for #Sq/FB (p<0.05). TSq between conditions did not indicate significance, however TVC and AV/Sq were significantly different (p<0.05). With no significant interaction for USG, participants arrived (SA=1.016±.009; EFA=1.019±.008) and remained (SA=1.019±.008; EFA=1.020±.007) hydrated throughout the EP. BML, SwL, SwRt, thirst and fullness also indicated no significant differences between conditions (p>0.05). CONCLUSION: SA promoted more TVC likely due to greater VSq. Both conditions remained euhydrated, but EFA consumed less fluids. Euhydration may have been maintained because of regularly spaced fluid breaks and when regular fluid breaks are unavailable, EFA may result in more BML and hypohydration.
    • The Effect of Instrument Type on the Measure of Hydration Status

      Niemann, Andrew (2012-10-18)
      Context: Although some instruments have been validated for clinical measure of hydration status, new and currently invalid instruments are available for purchase and clinical use. Athletic trainers commonly use these instruments to assess hydration status for weight checks and body mass loss charts due to their ease of use. However, the validity of these popular instruments has not yet been established. Objective: To determine the validity of urine specific gravity (USG) for the assessment of hydration status via the following instruments: handheld clinical refractometer, pen style digital refractometer, and midget urinometer as compared to the gold standard urine osmometer (OSMO). Design: Descriptive diagnostic validity study. Setting: Biochemical research laboratory. Patients or Other Participants: Healthy active men and women (n=108; mean age=22±4yrs; self reported height=174±20cm and mass=75±17kg) were recruited among faculty and students on a university campus. Interventions: The independent variable was instrument type with four levels: osmometer, handheld clinical refractometer, pen style digital refractometer, and midget urinometer. After recruitment, participants completed an informed consent and a short health history questionnaire to rule out any exclusionary criteria such as kidney disease or chronic urinary tract infection. Participants were then given a clean standard urine cup and asked to provide as much sample as possible, providing more than one cup when possible. Main Outcome Measures: Hydration status was measured by USG and OSM. USG was evaluated by a handheld clinical refractometer, pen style digital refractometer, and midget urinometer. The gold standard OSM was calculated by a freezing point depression osmometer. Z scores were calculated for each instrument and Pearson product-moment correlation coefficients were evaluated to examine the relationship between each instrument of USG and OSM. Results: Strong significant correlations were identified for the digital refractometer (r=0.814, p< 0.001) and handheld clinical refractometer (r=0.943, p< 0.001) with OSM. A weak statistically insignificant correlation was established between the midget urinometer (r=0.133, p< 0.142) and OSM. Average hydration status indicated variability among some of the instruments: digital refractometer USG=1.0194±0.0075, clinical refractometer USG=1.020±0.007, urinometer USG=1.028±0.091, osmometer OSM=743±271) Conclusions: Handheld clinical refractometry can be used confidently for assessing hydration status as it shows a strong significant correlation with the gold standard osmometer, which is consistent with previous literature. Additionally, the use of the pen style digital refractometer showed a strong, significant correlation with the gold standard osmometer and provides clinicians with another option for the clinical assessment of USG and hydration status. The findings of this also study suggest that the use of a midget urinometer should be performed with extreme caution, as it showed a weak correlation with the gold standard osmometer, indicating it might not provide accurate results when used to determine hydration status.