Fluid and carbohydrate ingestion independently improve performance during 1 h of intense exercise

Below, P. R.; Mora-Rodríguez, Ricardo; González‐Alonso, José; Coyle, Edward F.

doi:10.1249/00005768-199502000-00009

Cited by 295 publications

(244 citation statements)

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“…5,6,13 Although the finding is still debated by some, 17 dehydration of more than 2% of body weight has been shown to result in reduced aerobic performance capacity for many people. 5,[18][19][20] The scientific community has devoted much attention to the type, quantity, and timing of fluid athletes should consume. As the popularity of distance running increases, a growing population may face the negative performance or health consequences of inadequate hydration strategies.…”

Section: Resultsmentioning

confidence: 99%

Half-Marathon and Full-Marathon Runners' Hydration Practices and Perceptions

OʼNeal

Wingo

Richardson

et al. 2011

Journal of Athletic Training

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Context:The behaviors and beliefs of recreational runners with regard to hydration maintenance are not well elucidated.Objective: To examine which beverages runners choose to drink and why, negative performance and health experiences related to dehydration, and methods used to assess hydration status.Design: Cross-sectional study. Setting: Marathon registration site. Patients or Other Participants: Men (n = 146) and women (n = 130) (age = 38.3 ± 11.3 years) registered for the 2010 Little Rock Half-Marathon or Full Marathon. Intervention(s):A 23-item questionnaire was administered to runners when they picked up their race timing chips.Main Outcome Measure(s): Runners were separated into tertiles (Low, Mod, High) based on z scores derived from training volume, expected performance, and running experience. We used a 100-mm visual analog scale with anchors of 0 (never) and 100 (always). Total sample responses and comparisons between tertile groups for questionnaire items are presented. Results:The High group (58±31) reported greater consumption of sport beverages in exercise environments than the Low (42 ± 35 mm) and Mod (39 ± 32 mm) groups (P < .05) and perceived sport beverages to be superior to water in meeting hydration needs (P < .05) and improving performance during runs greater than 1 hour (P < .05). Seventy percent of runners experienced 1 or more incidents in which they believed dehydration resulted in a major performance decrement, and 45% perceived dehydration to have resulted in adverse health effects. Twenty percent of runners reported monitoring their hydration status. Urine color was the method most often reported (7%), whereas only 2% reported measuring changes in body weight.Conclusions: Greater attention should be paid to informing runners of valid techniques to monitor hydration status and developing an appropriate individualized hydration strategy.Key Words: dehydration, sport beverages, hydration monitoring Key Points• Most runners had experienced performance decrements that they attributed to dehydration. Almost half the runners had sustained heat-related illness symptoms that they related to dehydration.• Despite these adverse events, few participants monitored their hydration levels or used specific hydration plans.• Better dissemination of accurate scientific information about appropriate hydration practices may increase runners' safety.

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Section: Resultsmentioning

confidence: 99%

Half-Marathon and Full-Marathon Runners' Hydration Practices and Perceptions

OʼNeal

Wingo

Richardson

et al. 2011

Journal of Athletic Training

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“…Exercise performance over approximately 60 min in a hot environment has been observed to be impaired by both Below et al (1995) and Walsh et al (1994) with dehydration amounting to 2% and 1.8%, respectively. Therefore, dehydration by 2% of body weight during exercise in a hot environment (31-328C) clearly impairs endurance performance, but when exercise is performed in a temperate environment (20-218C), dehydration by 2% appears to have a lesser and insignificant effect on endurance performance.…”

Section: Effects Of Dehydration On Endurance Performancementioning

confidence: 99%

Fluid and fuel intake during exercise

Coyle¹

2004

Journal of Sports Sciences

330

205

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The amounts of water, carbohydrate and salt that athletes are advised to ingest during exercise are based upon their effectiveness in attenuating both fatigue as well as illness due to hyperthermia, dehydration or hyperhydration. When possible, fluid should be ingested at rates that most closely match sweating rate. When that is not possible or practical or sufficiently ergogenic, some athletes might tolerate body water losses amounting to 2% of body weight without significant risk to physical well-being or performance when the environment is cold (e.g. 5-108C) or temperate (e.g. 21-228C). However, when exercising in a hot environment ( 4308C), dehydration by 2% of body weight impairs absolute power production and predisposes individuals to heat injury. Fluid should not be ingested at rates in excess of sweating rate and thus body water and weight should not increase during exercise. Fatigue can be reduced by adding carbohydrate to the fluids consumed so that 30-60 g of rapidly absorbed carbohydrate are ingested throughout each hour of an athletic event. Furthermore, sodium should be included in fluids consumed during exercise lasting longer than 2 h or by individuals during any event that stimulates heavy sodium loss (more than 3-4 g of sodium). Athletes do not benefit by ingesting glycerol, amino acids or alleged precursors of neurotransmitter. Ingestion of other substances during exercise, with the possible exception of caffeine, is discouraged. Athletes will benefit the most by tailoring their individual needs for water, carbohydrate and salt to the specific challenges of their sport, especially considering the environment's impact on sweating and heat stress.Keywords: carbohydrate, dehydration, fatigue, gastrointestinal function, hyperthermia, sodium. IntroductionWhen athletes exercise during training or while competing, it is clear that they sometimes benefit by ingesting various mixtures of water, carbohydrate and electrolytes (Convertino et al., 1996;Casa, 2000). The benefits can be expressed through improved performance and/or reduced physiological stress, on an athlete's cardiovascular, central nervous and muscular systems. Although ample scientific evidence exists to support the general theory for encouraging athletes to consume water, carbohydrate and electrolytes during exercise, the practical recommendations for optimally applying these general theories is not simple. This is due to the quite varied nature of the physical stresses encountered during training and competition for a wide range of sports, as well as the unique rules of each sport regarding the allowance for fluid and fuel intake during competition. Furthermore, variations in the physical intensity, duration and environment, as well as individual characteristics of a given athlete, might alter their optimal rate of water, carbohydrate and salt intake as well as the rate of gastrointestinal absorption and feelings of fullness. This task of developing consensus for general recommendations becomes less daunting when approached systematical...

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“…The question of whether CHO ingestion slowed the rate of muscle glycogenolysis during exercise was raised again by Coyle andco-workers in 1986 (Coyle et al, 1986). Utilising essentially the same protocol as in their earlier study (Coyle et al, 1983), they studied the decreases in muscle glycogen concentration during cycling, with and without CHO feedings.…”

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confidence: 99%