Abstract
This study examined the effects of beverage composition on the voluntary drinking pattern, body fluid balance and body temperature responses of heat-acclimatized trained girls exercising intermittently in outdoor conditions (WBGT = 30.9 ± 0.2°C). Twelve trained, heat-acclimatized girls (age = 10.6 ± 0.2 years) performed three 3-h sessions, each consisting of four 20-min cycling bouts at 60% VO2max, alternating with 25-min rest. One of three beverages was assigned: unflavored water (W), flavored water (FW) or flavored water plus 6% carbohydrate and 18 mmol/l NaCl (CNa). Drinking was ad libitum. Total intake was similar among conditions (W = 953.3 ± 107.8 ; FW = 1026.5 ± 138.1; CNa = 906.4 ± 107.5 g). A mild hypohydration occurred during the three conditions (W = −1.12%; FW = −0.95%; CNa = −0.74% BW, P > 0.05). Sweat loss, higher than previously reported for sedentary girls, was not different among conditions (W = 1,051.5 ± 90.8; FW = 979.9 ± 72.8; CNa = 1,052.7 ± 52.6 g). The average amount of urine produced (W = 269.8 ± 85.9; FW = 320.8 ± 87.2; CNa = 85.6 ± 9.3 g) was 73 and 68% higher during FW and W, respectively, compared to CNa (CNa vs. FW, P < 0.05). The increase in rectal temperature, heart rate and all perceptual variables did not differ among conditions. In conclusion, flavoring of the water and addition of 6% carbohydrate plus 18 mmol/l NaCl do not prevent mild hypohydration in trained, heat-acclimatized girls with high sweating rates. However, there is a tendency towards a greater fluid retention with the CNa beverage.
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Acknowledgments
The authors thank Maribel Torres, Aurea Reíllo, David Bahamundi, Reynaldo Soler, Francisco José Otero, Sandra Rodríguez, Carmen Beabraut, Dr. Enrique Amy, Dr. William Micheo and Dr. Luis Aragón for their help during testing and Dr. Brian Timmons for his critical review of the manuscript. They especially thank the girls who participated in this study and their coaches and parents for their support. This study was supported in part by the Gatorade Sports Science Institute.
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An erratum to this article can be found at http://dx.doi.org/10.1007/s00421-008-0752-4
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Rivera-Brown, A.M., Ramírez-Marrero, F.A., Wilk, B. et al. Voluntary drinking and hydration in trained, heat-acclimatized girls exercising in a hot and humid climate. Eur J Appl Physiol 103, 109–116 (2008). https://doi.org/10.1007/s00421-008-0682-1
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DOI: https://doi.org/10.1007/s00421-008-0682-1