The purpose of this study was to assess the influence of rehydration with a caffeinated beverage during non exercise periods on hydration status throughout consecutive practices in the heat. Ten (7 women, 3 men) partially heat-acclimated athletes (age 24 ± ly, body fat 19.2 ± 2%, weight 68.4 ± 4.0 kg, height 170 ± 3 cm) completed 3 successive days of 2-a-day practices (2 h/ practice, 4 h/d) in mild heat (WBGT = 23 °C). The 2 trials (double-blind, random, cross-over design) included; 1) caffeine (CAF) rehydrated with Coca-Cola® and 2) caffeine-free (CF) rehydrated with Caffeine-Free Coca-Cola®. Urine and psychological measures were determined before and after each 2-h practice. A significant difference was found for urine color for the post-AM time point, F = 5.526, P = 0.031. No differences were found among other variables (P > 0.05). In summary, there is little evidence to suggest that the use of beverages containing caffeine during non exercise might hinder hydration status.
Kelly A. Fiala, Douglas J. Casa, and Melissa W. Roti
Kelly A. Fiala and Donna M. Ritenour
Jason D. Vescovi, Teena M. Murray, Kelly A. Fiala, and Jaci L. VanHeest
The primary purpose of this study was to determine whether tests performed at the National Hockey League (NHL) Combine could distinguish draft status (ie, the round selected). A secondary aim was to provide performance ranges and percentiles for each of the dependent variables.
A retrospective, cross-sectional study design was used with performance data and draft order from 2001, 2002, and 2003 Combine participants. Draft round was divided into 5 classifications (rounds 1, 2, 3, 4, and 5 through 9), and performances on 12 physical tests served as dependent variables. Three multiple analyses of covariance (MANCOVAs) were used to determine the significance of performance scores at the NHL Combine on draft selection. Age (years), body mass (kg), height (cm), and percentage body fat were treated as covariates.
Overall, MANCOVA results indicated no significant effect of performance on draft selection for 2001, 2002, or 2003. Subsequent univariate tests revealed that no single dependent variable was able to distinguish between draft rounds for any of the 3 years sampled.
Using draft status as an indicator of ice hockey performance, it appears that off-ice tests cannot accurately predict ice hockey playing ability in an elite group of athletes. This might stem from homogeneity of the Combine participants, a lack of validity of the tests, or other factors (eg, on-ice hockey skills, psychological variables, etc) that play a role in draft selection.
Lawrence E. Armstrong, Amy C. Pumerantz, Kelly A. Fiala, Melissa W. Roti, Stavros A. Kavouras, Douglas J. Casa, and Carl M. Maresh
It is difficult to describe hydration status and hydration extremes because fluid intakes and excretion patterns of free-living individuals are poorly documented and regulation of human water balance is complex and dynamic. This investigation provided reference values for euhydration (i.e., body mass, daily fluid intake, serum osmolality; M ± SD); it also compared urinary indices in initial morning samples and 24-hr collections. Five observations of 59 healthy, active men (age 22 ± 3 yr, body mass 75.1 ± 7.9 kg) occurred during a 12-d period. Participants maintained detailed records of daily food and fluid intake and exercise. Results indicated that the mean total fluid intake in beverages, pure water, and solid foods was >2.1 L/24 hr (range 1.382–3.261, 95% confidence interval 0.970–3.778 L/24 hr); mean urine volume was >1.3 L/24 hr (0.875–2.250 and 0.675–3.000 L/24 hr); mean urine specific gravity was >1.018 (1.011–1.027 and 1.009–1.030); and mean urine color was ≥4 (4–6 and 2–7). However, these men rarely (0–2% of measurements) achieved a urine specific gravity below 1.010 or color of 1. The first morning urine sample was more concentrated than the 24-h urine collection, likely because fluids were not consumed overnight. Furthermore, urine specific gravity and osmolality were strongly correlated (r2 = .81–.91, p < .001) in both morning and 24-hr collections. These findings provide euhydration reference values and hydration extremes for 7 commonly used indices in free-living, healthy, active men who were not exercising in a hot environment or training strenuously.