HYD: During Continuous Endurance Exercise (2007)
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Assessment
What fluid and electrolytes are needed during continuous endurance physical activity/exercise of 1-4 hours in duration in adults (19 years or older) to maintain hydration?
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Conclusion
Beverages provided in a volume that equals 100% of fluid lost during moderate- to vigorous exercise (65-85% VO2 max), and contain CHO (5.5-15% CHO)* and Na+ (55-164 mEq Na)* compared to non-carbohydrate-electrolyte solution (CES) beverages are more effective at maintaining hydration status (including thermoregulatory function) in hydrated young (20 – 35 years) men during 1-4 hours of moderate to vigorous, competitive or recreational activity in moderately hot and humid conditions. The amounts of CHO and Na+, as well as the volume of the beverage consumed are important factors for maintenance of hydration during higher-intensity activities, especially in the heat.
Care must be taken in choosing a beverage to be consumed during exercise, so as to avoid gastrointestinal distress and/or subjective feelings of discomfort, nausea, and bloating. Care must also be taken when applying these conclusions beyond the limited populations studied.
Limited research is available to evaluate the effectiveness of K+ in beverages consumed during exercise, relevant to hydration maintenance. Research is needed to determine fluid and electrolyte needs in:
- women
- pregnant and/or lactating women
- athletes older than 35 years
- individuals exercising for prolonged periods of time in cold and/or dry climates.
The comparison between CES and non-CES beverages effect on performance was not evaluated in this question.
* See Conversion Table for information on converting mmol to mEq and mg and % CHO to grams.
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Grade: II
- Grade I means there is Good/Strong evidence supporting the statement;
- Grade II is Fair;
- Grade III is Limited/Weak;
- Grade IV is Expert Opinion Only;
- Grade V is Not Assignable.
- High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
- Moderate (B) means we are moderately confident in the effect estimate;
- Low (C) means our confidence in the effect estimate is limited;
- Very Low (D) means we have very little confidence in the effect estimate.
- Ungraded means a grade is not assignable.
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Evidence Summary: Fluid and Electrolyte Needs During Continuous Endurance Physical Activity/Exercise
- Detail
- Quality Rating Summary
For a summary of the Quality Rating results, click here.
- Worksheets
- Bachle L, Eckerson J, Albertson L, Ebersole K, Good win J, Petzel J. The effect of fluid replacement on endurance performance, J Strength and Conditioning Research 2001; 15 (2): 217-224.
- Cheuvront, AN and Haymes, EM. Ad libitum fluid intake and thermoregulatory responses of female distance runners in three environments. Journal of Sports Sciences. 2001;19:845-854.
- Cheuvront SN, Haymes EM, Sawka MN. Comparison of sweat loss estimates for women during prolonged high-intensity running. Med Science Sports Exerc 2002;34:1344-1350.
- Davis JM, Burgess WA, Slentz CA, Bartoli WP, Pate RR. Effects of ingesting 6% and 12% glucose/electrolyte beverages during prolonged intermittent cycling in the heat. Eur J Appl Physiol 1988; 57: 563-69.
- Davis JM, Burgess WA, Slentz CA, Bartoli WP. Fluid availability of sports drinks differing in carbohydrate type and concentration, AJCN 1990; 54: 1054-7.
- Davis JM, Lamb DR, Pate RR, Slentz CA, Burgess WA, Bartoli WP. Carbohydrate-electrolyte drinks: effects on endurance cycling in the heat, AJCN 1988; 48: 1023-30.
- de Carvalho MV, Marins JCB, Silami-Garcia E. The influence of water versus CES hydration on blood components during a 16 km military march, Military Medicine 2007; 172 (1): 79-82.
- Galloway SDR, Maughan RJ. The effects of substrate and fluid provision on thermoregulatory and metabolic responses to prolonged exercise in a hot environment. J Sports Sciences 2000; 18: 339-51.
- Greenleaf, JE., Looft-Wilson, R., Wisherd, JL., Jackson, CGR., Fung, PP., Ertl, AC., Barnes, PR., Jensen, CD., and Whitman, JH. Hypovolemia in men from fluid ingestion at rest and during exercise. Aviation, Space and Environmental Medicine. 1998; 69(4):374-386.
- Hill RJ, Bluck LJC, Davies PSW. The hydration ability of three commercially-available sports drinks and water, J Sci and Medicine in Sport 2007, doi:10.1016/j.jams.2006.12.117.
- Maughan RJ, Bethell LR, Leiper JB. Effects of ingested fluids on exercise capacity and on cardiovascular and metabolic responses to prolonged exercise in man. Experimental Physiology 1996; 81: 847-59.
- McConell, GK., Stephens, TJ., and Canny, BJ. Fluid Ingestion does not influence intense 1-h exercise performance in a mild environment. Med Sci Sports Exer. 1999;31(3):386-392.
- Millard-Stafford ML, Sparling PB, Rosskopf LB, DiCicarlo LJ. Carbohydrate-electrolyte replacement improves distance running performance in the heat, Med Sci Sports Exer 1992; 24(8): 934-40.
- Millard-Stafford ML, Sparling PB, Rosskopf LB, Snow TK. Should carbohydrate concentration of a sports drink be less than 8% during exercise in the heat? Int J Sports Nutr Exerc Metab. 2005; 15 (2): 117-130.
- Mitchell JB & Voss KW. The influence of volume on gastric emptying and fluid balance during prolonged exercise. Medicine & Science in Sports & Exercise 1991; 23(3): 314-9.
- Murray R, Bartoli W, Stofan J, Horn M, Eddy D. A comparison of the gastric emptying characteristics of selected sports drinks, Int J Sport Nutr 1999; 9: 263-74.
- Robinson TA, Hawley JA, Palmer GS, Wilson GR, Gray DA, Noakes TD, Dennis SC. Water ingestion does not improve 1-h cycling performance in moderate ambient temperatures, Eur J Appl Physiol 1995; 71: 153-60.
- Sanders B, Noakes TD, Dennis SC. Water and electrolyte shifts with partial fluid replacement during exercise. Eur J Appl Physiol 1999;80:318-323.
- Twerenbold R, Knechtle B, Kakebeeke TH, Eser P, Muller G, von Arx P, Knecht H. Effects of different sodium concentrations in replacement fluids during prolonged exercise in women. Br J Sports Med 2003;37:300-303.
- White JA, Pomfret D, Rennie S, Gissane C, Womg J, Ford M. Fluid replacement needs of well-trained male and female athletes during indoor and outdoor steady-state running, J Sci and Medicine in Sport 1998; 1 (3): 131-42.
- Detail
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Search Plan and Results: HYD: Fluid/Electrolyte Needs: During Physical Activity/Exercise 2007
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Conclusion