Biomaterial Database

Drinking to thirst versus drinking ad libitum during road cycling. 2014

Lawrence E Armstrong, and Evan C Johnson, and Laura J Kunces, and Matthew S Ganio, and Daniel A Judelson, and Brian R Kupchak, and Jakob L Vingren, and Colleen X Munoz, and Robert A Huggins, and Jay R Hydren, and Nicole E Moyen, and Keith H Williamson

University of Connecticut, Storrs.

BACKGROUND The sensation of thirst is different from the complex behavior of drinking ad libitum. Rehydration recommendations to athletes differ, depending on the source, yet no previous researchers have systematically compared drinking to thirst (D(TT)) versus ad libitum drinking behavior (D(AL)). OBJECTIVE To compare 2 groups of trained cyclists (D(TT) and D(AL)) who had similar physical characteristics and training programs (P > .05). The D(TT) group (n = 12, age = 47 ± 7 years) drank only when thirsty, whereas the D(AL) group (n = 12, age = 44 ± 7 years) consumed fluid ad libitum (ie, whenever and in whatever volume desired). METHODS Cohort study. METHODS Road cycling (164 km) in the heat (36.1 °C ± 6.5 °C). METHODS Ultraendurance cyclists (4 women, 20 men). METHODS We recorded measurements 1 day before the event, on event day before the start, at 3 roadside aid stations, at the finish line, and 1 day after the event. METHODS Body mass, urinary hydration indices, and food and fluids consumed. RESULTS No between-groups differences were seen on event day for total exercise time (DTT = 6.69 ± 0.89 hours, DAL = 6.66 ± 0.77 hours), urinary indices (specific gravity, color), body mass change (D(TT) = -2.22% ± 1.73%, DAL = -2.29% ± 1.62%), fluid intake (D(TT) = 5.63 ± 2.59 L/6.7 h, D(AL) = 6.04 ± 2.37 L/6.7 h), dietary energy intake, macronutrient intake, ratings of thirst (D(TT) start = 2 ± 1, D(TT) finish = 6 ± 1, DAL start = 2 ± 1, D(AL) finish = 6 ± 1), pain, perceived exertion, or thermal sensation. Total fluid intake on recovery day +1 was the primary significant difference (D(AL) = 5.13 ± 1.87 L/24 h, D(TT) = 3.13 ± 1.53 L/24 h, t18 = 2.59, P = .02). CONCLUSIONS Observations on event day indicated that drinking to thirst and drinking ad libitum resulted in similar physiologic and perceptual outcomes. This suggests that specific instructions to "drink to thirst" were unnecessary. Indeed, if athletes drink ad libitum, they can focus on training and competition rather than being distracted by ongoing evaluation of thirst sensations.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D003681	Dehydration	The condition that results from excessive loss of water from a living organism.	Water Stress,Stress, Water
D004326	Drinking	The consumption of liquids.	Water Consumption,Water Intake,Drinkings
D005260	Female		Females
D005440	Fluid Therapy	Therapy whose basic objective is to restore the volume and composition of the body fluids to normal with respect to WATER-ELECTROLYTE BALANCE. Fluids may be administered intravenously, orally, by intermittent gavage, or by HYPODERMOCLYSIS.	Oral Rehydration Therapy,Rehydration,Rehydration, Oral,Oral Rehydration,Rehydration Therapy, Oral,Therapy, Fluid,Therapy, Oral Rehydration,Fluid Therapies,Oral Rehydration Therapies,Oral Rehydrations,Rehydration Therapies, Oral,Rehydrations,Rehydrations, Oral,Therapies, Fluid,Therapies, Oral Rehydration
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D001642	Bicycling	The use of a bicycle for transportation or recreation. It does not include the use of a bicycle in studying the body's response to physical exertion (BICYCLE ERGOMETRY TEST see EXERCISE TEST).
D013894	Thirst	A drive stemming from a physiological need for WATER.	Thirsts