Voluntary drinking and hydration in non-acclimatized girls exercising in the heat

Abstract

The intent of this study was to assess the influence of drink flavor and composition on voluntary drinking and hydration status in girls exercising intermittently in the heat (35 +/- 1 degrees C, 45-50% relative humidity). Twelve physically active, nonacclimatized girls (9-12 years) performed three 3 h identical sessions, each consisting of four 20 min cycling bouts at 50% (VO(2max)), separated by 25 min of rest. One of the three beverages (chilled to 8-10 degrees C) was assigned to each session: unflavored water (W), grape-flavored water (FW) and grape-flavored water plus 6% carbohydrate and 18 mmol l(-1) NaCl (CNa). Drinking was ad libitum. Body weight (BW), drink intake (DI), heart rate, rectal and skin temperatures, and perceptions of thirst and stomach fullness were monitored periodically. Total DI was 759, 940, 1,045 g in W, FW and CNa, respectively (P < 0.05 for CNa-W and FW-W). BW changes were -0.15, 0.16, and 0.45% in W, FW and CNa, respectively, but only the difference between CNa and W was significant (P < 0.05). Other physiological and perceptual variables were not different between trials. In conclusion, beverage flavoring regardless if its combination with carbohydrate and NaCl, mildly enhanced voluntary drinking in young non-acclimatized girls. In contrast to previous research in young boys, euhydration was maintained in the girls by an adequate intake of unflavored water.

Voluntary drinking and hydration in trained, heat-acclimatized girls exercising in a hot and humid climate

“…We conWrmed this Wnding by showing that a Xavored beverage containing carbohydrate and NaCl increased voluntary drink intake by 32% (compared to unXavored water) in trained, heat-acclimatized boys who experienced much higher sweating rates during prolonged exercise (Rivera-Brown et al 1999). In contrast, a recent study by Wilk et al (2007) showed that beverage Xavoring, but not the addition of NaCl, enhanced voluntary drinking in non-acclimatized girls exercising in the heat and that even thirst-guided drinking of plain water was suYcient to maintain euhydration in these girls.…”

Sport Nutrition and Youth

“…Furthermore, in non-acclimatised girls exercising in the heat, voluntary drinking was enhanced with flavoured compared with unflavoured water regardless of combination with CHO and NaCl, but hydration was promoted to a greater extent with the drink containing CHO and NaCl (Wilk et al 2007). Similarly, there was a tendency towards a lower hypohydration and greater fluid retention with the consumption of a CHO plus NaCl drink in trained, heat-acclimatised girls with high sweating rates, although voluntary dehydration was not prevented completely (Rivera-Brown et al 2008).…”

Body weight changes in child and adolescent athletes during a triathlon competition

“…Consequently, succeeding investigations tended to utilize experimental designs in which the child was fully hydrated at the start of an exercise session and was allowed to drink at least ad libitum during the session; the degree of dehydration reached in these studies seldom exceeded 1% of initial body weight (Meyer et al, 1995;Rivera-Brown et al, 1999;Rivera-Brown et al, 2008;Wilk et al, 2000;Wilk & Bar-Or, 1996;Wilk et al, 2007). It remains unclear, however, to what extent these artificial conditions truly reflect the young athlete's real-life responses, when competing under hot climatic conditions.…”